1 | =head1 NAME
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2 |
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3 | perlembed - how to embed perl in your C program
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4 |
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5 | =head1 DESCRIPTION
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6 |
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7 | =head2 PREAMBLE
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8 |
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9 | Do you want to:
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10 |
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11 | =over 5
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12 |
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13 | =item B<Use C from Perl?>
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14 |
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15 | Read L<perlxstut>, L<perlxs>, L<h2xs>, L<perlguts>, and L<perlapi>.
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16 |
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17 | =item B<Use a Unix program from Perl?>
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18 |
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19 | Read about back-quotes and about C<system> and C<exec> in L<perlfunc>.
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20 |
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21 | =item B<Use Perl from Perl?>
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22 |
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23 | Read about L<perlfunc/do> and L<perlfunc/eval> and L<perlfunc/require>
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24 | and L<perlfunc/use>.
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25 |
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26 | =item B<Use C from C?>
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27 |
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28 | Rethink your design.
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29 |
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30 | =item B<Use Perl from C?>
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31 |
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32 | Read on...
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33 |
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34 | =back
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35 |
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36 | =head2 ROADMAP
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37 |
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38 | =over 5
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39 |
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40 | =item *
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41 |
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42 | Compiling your C program
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43 |
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44 | =item *
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45 |
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46 | Adding a Perl interpreter to your C program
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47 |
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48 | =item *
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49 |
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50 | Calling a Perl subroutine from your C program
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51 |
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52 | =item *
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53 |
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54 | Evaluating a Perl statement from your C program
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55 |
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56 | =item *
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57 |
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58 | Performing Perl pattern matches and substitutions from your C program
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59 |
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60 | =item *
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61 |
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62 | Fiddling with the Perl stack from your C program
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63 |
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64 | =item *
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65 |
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66 | Maintaining a persistent interpreter
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67 |
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68 | =item *
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69 |
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70 | Maintaining multiple interpreter instances
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71 |
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72 | =item *
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73 |
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74 | Using Perl modules, which themselves use C libraries, from your C program
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75 |
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76 | =item *
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77 |
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78 | Embedding Perl under Win32
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79 |
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80 | =back
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81 |
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82 | =head2 Compiling your C program
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83 |
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84 | If you have trouble compiling the scripts in this documentation,
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85 | you're not alone. The cardinal rule: COMPILE THE PROGRAMS IN EXACTLY
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86 | THE SAME WAY THAT YOUR PERL WAS COMPILED. (Sorry for yelling.)
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87 |
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88 | Also, every C program that uses Perl must link in the I<perl library>.
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89 | What's that, you ask? Perl is itself written in C; the perl library
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90 | is the collection of compiled C programs that were used to create your
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91 | perl executable (I</usr/bin/perl> or equivalent). (Corollary: you
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92 | can't use Perl from your C program unless Perl has been compiled on
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93 | your machine, or installed properly--that's why you shouldn't blithely
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94 | copy Perl executables from machine to machine without also copying the
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95 | I<lib> directory.)
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96 |
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97 | When you use Perl from C, your C program will--usually--allocate,
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98 | "run", and deallocate a I<PerlInterpreter> object, which is defined by
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99 | the perl library.
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100 |
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101 | If your copy of Perl is recent enough to contain this documentation
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102 | (version 5.002 or later), then the perl library (and I<EXTERN.h> and
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103 | I<perl.h>, which you'll also need) will reside in a directory
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104 | that looks like this:
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105 |
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106 | /usr/local/lib/perl5/your_architecture_here/CORE
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107 |
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108 | or perhaps just
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109 |
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110 | /usr/local/lib/perl5/CORE
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111 |
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112 | or maybe something like
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113 |
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114 | /usr/opt/perl5/CORE
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115 |
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116 | Execute this statement for a hint about where to find CORE:
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117 |
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118 | perl -MConfig -e 'print $Config{archlib}'
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119 |
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120 | Here's how you'd compile the example in the next section,
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121 | L<Adding a Perl interpreter to your C program>, on my Linux box:
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122 |
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123 | % gcc -O2 -Dbool=char -DHAS_BOOL -I/usr/local/include
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124 | -I/usr/local/lib/perl5/i586-linux/5.003/CORE
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125 | -L/usr/local/lib/perl5/i586-linux/5.003/CORE
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126 | -o interp interp.c -lperl -lm
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127 |
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128 | (That's all one line.) On my DEC Alpha running old 5.003_05, the
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129 | incantation is a bit different:
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130 |
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131 | % cc -O2 -Olimit 2900 -DSTANDARD_C -I/usr/local/include
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132 | -I/usr/local/lib/perl5/alpha-dec_osf/5.00305/CORE
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133 | -L/usr/local/lib/perl5/alpha-dec_osf/5.00305/CORE -L/usr/local/lib
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134 | -D__LANGUAGE_C__ -D_NO_PROTO -o interp interp.c -lperl -lm
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135 |
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136 | How can you figure out what to add? Assuming your Perl is post-5.001,
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137 | execute a C<perl -V> command and pay special attention to the "cc" and
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138 | "ccflags" information.
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139 |
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140 | You'll have to choose the appropriate compiler (I<cc>, I<gcc>, et al.) for
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141 | your machine: C<perl -MConfig -e 'print $Config{cc}'> will tell you what
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142 | to use.
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143 |
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144 | You'll also have to choose the appropriate library directory
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145 | (I</usr/local/lib/...>) for your machine. If your compiler complains
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146 | that certain functions are undefined, or that it can't locate
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147 | I<-lperl>, then you need to change the path following the C<-L>. If it
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148 | complains that it can't find I<EXTERN.h> and I<perl.h>, you need to
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149 | change the path following the C<-I>.
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150 |
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151 | You may have to add extra libraries as well. Which ones?
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152 | Perhaps those printed by
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153 |
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154 | perl -MConfig -e 'print $Config{libs}'
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155 |
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156 | Provided your perl binary was properly configured and installed the
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157 | B<ExtUtils::Embed> module will determine all of this information for
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158 | you:
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159 |
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160 | % cc -o interp interp.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
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161 |
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162 | If the B<ExtUtils::Embed> module isn't part of your Perl distribution,
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163 | you can retrieve it from
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164 | http://www.perl.com/perl/CPAN/modules/by-module/ExtUtils/
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165 | (If this documentation came from your Perl distribution, then you're
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166 | running 5.004 or better and you already have it.)
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167 |
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168 | The B<ExtUtils::Embed> kit on CPAN also contains all source code for
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169 | the examples in this document, tests, additional examples and other
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170 | information you may find useful.
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171 |
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172 | =head2 Adding a Perl interpreter to your C program
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173 |
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174 | In a sense, perl (the C program) is a good example of embedding Perl
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175 | (the language), so I'll demonstrate embedding with I<miniperlmain.c>,
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176 | included in the source distribution. Here's a bastardized, nonportable
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177 | version of I<miniperlmain.c> containing the essentials of embedding:
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178 |
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179 | #include <EXTERN.h> /* from the Perl distribution */
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180 | #include <perl.h> /* from the Perl distribution */
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181 |
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182 | static PerlInterpreter *my_perl; /*** The Perl interpreter ***/
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183 |
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184 | int main(int argc, char **argv, char **env)
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185 | {
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186 | PERL_SYS_INIT3(&argc,&argv,&env);
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187 | my_perl = perl_alloc();
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188 | perl_construct(my_perl);
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189 | PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
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190 | perl_parse(my_perl, NULL, argc, argv, (char **)NULL);
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191 | perl_run(my_perl);
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192 | perl_destruct(my_perl);
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193 | perl_free(my_perl);
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194 | PERL_SYS_TERM();
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195 | }
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196 |
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197 | Notice that we don't use the C<env> pointer. Normally handed to
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198 | C<perl_parse> as its final argument, C<env> here is replaced by
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199 | C<NULL>, which means that the current environment will be used. The macros
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200 | PERL_SYS_INIT3() and PERL_SYS_TERM() provide system-specific tune up
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201 | of the C runtime environment necessary to run Perl interpreters; since
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202 | PERL_SYS_INIT3() may change C<env>, it may be more appropriate to provide
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203 | C<env> as an argument to perl_parse().
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204 |
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205 | Now compile this program (I'll call it I<interp.c>) into an executable:
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206 |
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207 | % cc -o interp interp.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
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208 |
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209 | After a successful compilation, you'll be able to use I<interp> just
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210 | like perl itself:
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211 |
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212 | % interp
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213 | print "Pretty Good Perl \n";
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214 | print "10890 - 9801 is ", 10890 - 9801;
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215 | <CTRL-D>
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216 | Pretty Good Perl
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217 | 10890 - 9801 is 1089
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218 |
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219 | or
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220 |
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221 | % interp -e 'printf("%x", 3735928559)'
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222 | deadbeef
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223 |
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224 | You can also read and execute Perl statements from a file while in the
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225 | midst of your C program, by placing the filename in I<argv[1]> before
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226 | calling I<perl_run>.
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227 |
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228 | =head2 Calling a Perl subroutine from your C program
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229 |
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230 | To call individual Perl subroutines, you can use any of the B<call_*>
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231 | functions documented in L<perlcall>.
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232 | In this example we'll use C<call_argv>.
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233 |
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234 | That's shown below, in a program I'll call I<showtime.c>.
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235 |
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236 | #include <EXTERN.h>
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237 | #include <perl.h>
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238 |
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239 | static PerlInterpreter *my_perl;
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240 |
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241 | int main(int argc, char **argv, char **env)
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242 | {
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243 | char *args[] = { NULL };
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244 | PERL_SYS_INIT3(&argc,&argv,&env);
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245 | my_perl = perl_alloc();
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246 | perl_construct(my_perl);
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247 |
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248 | perl_parse(my_perl, NULL, argc, argv, NULL);
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249 | PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
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250 |
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251 | /*** skipping perl_run() ***/
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252 |
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253 | call_argv("showtime", G_DISCARD | G_NOARGS, args);
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254 |
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255 | perl_destruct(my_perl);
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256 | perl_free(my_perl);
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257 | PERL_SYS_TERM();
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258 | }
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259 |
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260 | where I<showtime> is a Perl subroutine that takes no arguments (that's the
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261 | I<G_NOARGS>) and for which I'll ignore the return value (that's the
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262 | I<G_DISCARD>). Those flags, and others, are discussed in L<perlcall>.
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263 |
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264 | I'll define the I<showtime> subroutine in a file called I<showtime.pl>:
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265 |
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266 | print "I shan't be printed.";
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267 |
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268 | sub showtime {
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269 | print time;
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270 | }
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271 |
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272 | Simple enough. Now compile and run:
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273 |
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274 | % cc -o showtime showtime.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
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275 |
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276 | % showtime showtime.pl
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277 | 818284590
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278 |
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279 | yielding the number of seconds that elapsed between January 1, 1970
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280 | (the beginning of the Unix epoch), and the moment I began writing this
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281 | sentence.
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282 |
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283 | In this particular case we don't have to call I<perl_run>, as we set
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284 | the PL_exit_flag PERL_EXIT_DESTRUCT_END which executes END blocks in
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285 | perl_destruct.
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286 |
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287 | If you want to pass arguments to the Perl subroutine, you can add
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288 | strings to the C<NULL>-terminated C<args> list passed to
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289 | I<call_argv>. For other data types, or to examine return values,
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290 | you'll need to manipulate the Perl stack. That's demonstrated in
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291 | L<Fiddling with the Perl stack from your C program>.
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292 |
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293 | =head2 Evaluating a Perl statement from your C program
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294 |
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295 | Perl provides two API functions to evaluate pieces of Perl code.
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296 | These are L<perlapi/eval_sv> and L<perlapi/eval_pv>.
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297 |
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298 | Arguably, these are the only routines you'll ever need to execute
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299 | snippets of Perl code from within your C program. Your code can be as
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300 | long as you wish; it can contain multiple statements; it can employ
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301 | L<perlfunc/use>, L<perlfunc/require>, and L<perlfunc/do> to
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302 | include external Perl files.
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303 |
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304 | I<eval_pv> lets us evaluate individual Perl strings, and then
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305 | extract variables for coercion into C types. The following program,
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306 | I<string.c>, executes three Perl strings, extracting an C<int> from
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307 | the first, a C<float> from the second, and a C<char *> from the third.
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308 |
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309 | #include <EXTERN.h>
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310 | #include <perl.h>
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311 |
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312 | static PerlInterpreter *my_perl;
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313 |
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314 | main (int argc, char **argv, char **env)
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315 | {
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316 | STRLEN n_a;
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317 | char *embedding[] = { "", "-e", "0" };
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318 |
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319 | PERL_SYS_INIT3(&argc,&argv,&env);
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320 | my_perl = perl_alloc();
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321 | perl_construct( my_perl );
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322 |
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323 | perl_parse(my_perl, NULL, 3, embedding, NULL);
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324 | PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
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325 | perl_run(my_perl);
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326 |
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327 | /** Treat $a as an integer **/
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328 | eval_pv("$a = 3; $a **= 2", TRUE);
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329 | printf("a = %d\n", SvIV(get_sv("a", FALSE)));
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330 |
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331 | /** Treat $a as a float **/
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332 | eval_pv("$a = 3.14; $a **= 2", TRUE);
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333 | printf("a = %f\n", SvNV(get_sv("a", FALSE)));
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334 |
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335 | /** Treat $a as a string **/
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336 | eval_pv("$a = 'rekcaH lreP rehtonA tsuJ'; $a = reverse($a);", TRUE);
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337 | printf("a = %s\n", SvPV(get_sv("a", FALSE), n_a));
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338 |
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339 | perl_destruct(my_perl);
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340 | perl_free(my_perl);
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341 | PERL_SYS_TERM();
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342 | }
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343 |
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344 | All of those strange functions with I<sv> in their names help convert Perl scalars to C types. They're described in L<perlguts> and L<perlapi>.
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345 |
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346 | If you compile and run I<string.c>, you'll see the results of using
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347 | I<SvIV()> to create an C<int>, I<SvNV()> to create a C<float>, and
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348 | I<SvPV()> to create a string:
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349 |
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350 | a = 9
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351 | a = 9.859600
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352 | a = Just Another Perl Hacker
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353 |
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354 | In the example above, we've created a global variable to temporarily
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355 | store the computed value of our eval'd expression. It is also
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356 | possible and in most cases a better strategy to fetch the return value
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357 | from I<eval_pv()> instead. Example:
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358 |
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359 | ...
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360 | STRLEN n_a;
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361 | SV *val = eval_pv("reverse 'rekcaH lreP rehtonA tsuJ'", TRUE);
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362 | printf("%s\n", SvPV(val,n_a));
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363 | ...
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364 |
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365 | This way, we avoid namespace pollution by not creating global
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366 | variables and we've simplified our code as well.
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367 |
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368 | =head2 Performing Perl pattern matches and substitutions from your C program
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369 |
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370 | The I<eval_sv()> function lets us evaluate strings of Perl code, so we can
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371 | define some functions that use it to "specialize" in matches and
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372 | substitutions: I<match()>, I<substitute()>, and I<matches()>.
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373 |
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374 | I32 match(SV *string, char *pattern);
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375 |
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376 | Given a string and a pattern (e.g., C<m/clasp/> or C</\b\w*\b/>, which
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377 | in your C program might appear as "/\\b\\w*\\b/"), match()
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378 | returns 1 if the string matches the pattern and 0 otherwise.
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379 |
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380 | int substitute(SV **string, char *pattern);
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381 |
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382 | Given a pointer to an C<SV> and an C<=~> operation (e.g.,
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383 | C<s/bob/robert/g> or C<tr[A-Z][a-z]>), substitute() modifies the string
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384 | within the C<SV> as according to the operation, returning the number of substitutions
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385 | made.
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386 |
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387 | int matches(SV *string, char *pattern, AV **matches);
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388 |
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389 | Given an C<SV>, a pattern, and a pointer to an empty C<AV>,
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390 | matches() evaluates C<$string =~ $pattern> in a list context, and
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391 | fills in I<matches> with the array elements, returning the number of matches found.
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392 |
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393 | Here's a sample program, I<match.c>, that uses all three (long lines have
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394 | been wrapped here):
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395 |
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396 | #include <EXTERN.h>
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397 | #include <perl.h>
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398 |
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399 | static PerlInterpreter *my_perl;
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400 |
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401 | /** my_eval_sv(code, error_check)
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402 | ** kinda like eval_sv(),
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403 | ** but we pop the return value off the stack
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404 | **/
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405 | SV* my_eval_sv(SV *sv, I32 croak_on_error)
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406 | {
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407 | dSP;
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408 | SV* retval;
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409 | STRLEN n_a;
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410 |
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411 | PUSHMARK(SP);
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412 | eval_sv(sv, G_SCALAR);
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413 |
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414 | SPAGAIN;
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415 | retval = POPs;
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416 | PUTBACK;
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417 |
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418 | if (croak_on_error && SvTRUE(ERRSV))
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419 | croak(SvPVx(ERRSV, n_a));
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420 |
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421 | return retval;
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422 | }
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423 |
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424 | /** match(string, pattern)
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425 | **
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426 | ** Used for matches in a scalar context.
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427 | **
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428 | ** Returns 1 if the match was successful; 0 otherwise.
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429 | **/
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430 |
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431 | I32 match(SV *string, char *pattern)
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432 | {
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433 | SV *command = NEWSV(1099, 0), *retval;
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434 | STRLEN n_a;
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435 |
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436 | sv_setpvf(command, "my $string = '%s'; $string =~ %s",
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437 | SvPV(string,n_a), pattern);
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438 |
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439 | retval = my_eval_sv(command, TRUE);
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440 | SvREFCNT_dec(command);
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441 |
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442 | return SvIV(retval);
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443 | }
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444 |
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445 | /** substitute(string, pattern)
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446 | **
|
---|
447 | ** Used for =~ operations that modify their left-hand side (s/// and tr///)
|
---|
448 | **
|
---|
449 | ** Returns the number of successful matches, and
|
---|
450 | ** modifies the input string if there were any.
|
---|
451 | **/
|
---|
452 |
|
---|
453 | I32 substitute(SV **string, char *pattern)
|
---|
454 | {
|
---|
455 | SV *command = NEWSV(1099, 0), *retval;
|
---|
456 | STRLEN n_a;
|
---|
457 |
|
---|
458 | sv_setpvf(command, "$string = '%s'; ($string =~ %s)",
|
---|
459 | SvPV(*string,n_a), pattern);
|
---|
460 |
|
---|
461 | retval = my_eval_sv(command, TRUE);
|
---|
462 | SvREFCNT_dec(command);
|
---|
463 |
|
---|
464 | *string = get_sv("string", FALSE);
|
---|
465 | return SvIV(retval);
|
---|
466 | }
|
---|
467 |
|
---|
468 | /** matches(string, pattern, matches)
|
---|
469 | **
|
---|
470 | ** Used for matches in a list context.
|
---|
471 | **
|
---|
472 | ** Returns the number of matches,
|
---|
473 | ** and fills in **matches with the matching substrings
|
---|
474 | **/
|
---|
475 |
|
---|
476 | I32 matches(SV *string, char *pattern, AV **match_list)
|
---|
477 | {
|
---|
478 | SV *command = NEWSV(1099, 0);
|
---|
479 | I32 num_matches;
|
---|
480 | STRLEN n_a;
|
---|
481 |
|
---|
482 | sv_setpvf(command, "my $string = '%s'; @array = ($string =~ %s)",
|
---|
483 | SvPV(string,n_a), pattern);
|
---|
484 |
|
---|
485 | my_eval_sv(command, TRUE);
|
---|
486 | SvREFCNT_dec(command);
|
---|
487 |
|
---|
488 | *match_list = get_av("array", FALSE);
|
---|
489 | num_matches = av_len(*match_list) + 1; /** assume $[ is 0 **/
|
---|
490 |
|
---|
491 | return num_matches;
|
---|
492 | }
|
---|
493 |
|
---|
494 | main (int argc, char **argv, char **env)
|
---|
495 | {
|
---|
496 | char *embedding[] = { "", "-e", "0" };
|
---|
497 | AV *match_list;
|
---|
498 | I32 num_matches, i;
|
---|
499 | SV *text;
|
---|
500 | STRLEN n_a;
|
---|
501 |
|
---|
502 | PERL_SYS_INIT3(&argc,&argv,&env);
|
---|
503 | my_perl = perl_alloc();
|
---|
504 | perl_construct(my_perl);
|
---|
505 | perl_parse(my_perl, NULL, 3, embedding, NULL);
|
---|
506 | PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
|
---|
507 |
|
---|
508 | text = NEWSV(1099,0);
|
---|
509 | sv_setpv(text, "When he is at a convenience store and the "
|
---|
510 | "bill comes to some amount like 76 cents, Maynard is "
|
---|
511 | "aware that there is something he *should* do, something "
|
---|
512 | "that will enable him to get back a quarter, but he has "
|
---|
513 | "no idea *what*. He fumbles through his red squeezey "
|
---|
514 | "changepurse and gives the boy three extra pennies with "
|
---|
515 | "his dollar, hoping that he might luck into the correct "
|
---|
516 | "amount. The boy gives him back two of his own pennies "
|
---|
517 | "and then the big shiny quarter that is his prize. "
|
---|
518 | "-RICHH");
|
---|
519 |
|
---|
520 | if (match(text, "m/quarter/")) /** Does text contain 'quarter'? **/
|
---|
521 | printf("match: Text contains the word 'quarter'.\n\n");
|
---|
522 | else
|
---|
523 | printf("match: Text doesn't contain the word 'quarter'.\n\n");
|
---|
524 |
|
---|
525 | if (match(text, "m/eighth/")) /** Does text contain 'eighth'? **/
|
---|
526 | printf("match: Text contains the word 'eighth'.\n\n");
|
---|
527 | else
|
---|
528 | printf("match: Text doesn't contain the word 'eighth'.\n\n");
|
---|
529 |
|
---|
530 | /** Match all occurrences of /wi../ **/
|
---|
531 | num_matches = matches(text, "m/(wi..)/g", &match_list);
|
---|
532 | printf("matches: m/(wi..)/g found %d matches...\n", num_matches);
|
---|
533 |
|
---|
534 | for (i = 0; i < num_matches; i++)
|
---|
535 | printf("match: %s\n", SvPV(*av_fetch(match_list, i, FALSE),n_a));
|
---|
536 | printf("\n");
|
---|
537 |
|
---|
538 | /** Remove all vowels from text **/
|
---|
539 | num_matches = substitute(&text, "s/[aeiou]//gi");
|
---|
540 | if (num_matches) {
|
---|
541 | printf("substitute: s/[aeiou]//gi...%d substitutions made.\n",
|
---|
542 | num_matches);
|
---|
543 | printf("Now text is: %s\n\n", SvPV(text,n_a));
|
---|
544 | }
|
---|
545 |
|
---|
546 | /** Attempt a substitution **/
|
---|
547 | if (!substitute(&text, "s/Perl/C/")) {
|
---|
548 | printf("substitute: s/Perl/C...No substitution made.\n\n");
|
---|
549 | }
|
---|
550 |
|
---|
551 | SvREFCNT_dec(text);
|
---|
552 | PL_perl_destruct_level = 1;
|
---|
553 | perl_destruct(my_perl);
|
---|
554 | perl_free(my_perl);
|
---|
555 | PERL_SYS_TERM();
|
---|
556 | }
|
---|
557 |
|
---|
558 | which produces the output (again, long lines have been wrapped here)
|
---|
559 |
|
---|
560 | match: Text contains the word 'quarter'.
|
---|
561 |
|
---|
562 | match: Text doesn't contain the word 'eighth'.
|
---|
563 |
|
---|
564 | matches: m/(wi..)/g found 2 matches...
|
---|
565 | match: will
|
---|
566 | match: with
|
---|
567 |
|
---|
568 | substitute: s/[aeiou]//gi...139 substitutions made.
|
---|
569 | Now text is: Whn h s t cnvnnc str nd th bll cms t sm mnt lk 76 cnts,
|
---|
570 | Mynrd s wr tht thr s smthng h *shld* d, smthng tht wll nbl hm t gt bck
|
---|
571 | qrtr, bt h hs n d *wht*. H fmbls thrgh hs rd sqzy chngprs nd gvs th by
|
---|
572 | thr xtr pnns wth hs dllr, hpng tht h mght lck nt th crrct mnt. Th by gvs
|
---|
573 | hm bck tw f hs wn pnns nd thn th bg shny qrtr tht s hs prz. -RCHH
|
---|
574 |
|
---|
575 | substitute: s/Perl/C...No substitution made.
|
---|
576 |
|
---|
577 | =head2 Fiddling with the Perl stack from your C program
|
---|
578 |
|
---|
579 | When trying to explain stacks, most computer science textbooks mumble
|
---|
580 | something about spring-loaded columns of cafeteria plates: the last
|
---|
581 | thing you pushed on the stack is the first thing you pop off. That'll
|
---|
582 | do for our purposes: your C program will push some arguments onto "the Perl
|
---|
583 | stack", shut its eyes while some magic happens, and then pop the
|
---|
584 | results--the return value of your Perl subroutine--off the stack.
|
---|
585 |
|
---|
586 | First you'll need to know how to convert between C types and Perl
|
---|
587 | types, with newSViv() and sv_setnv() and newAV() and all their
|
---|
588 | friends. They're described in L<perlguts> and L<perlapi>.
|
---|
589 |
|
---|
590 | Then you'll need to know how to manipulate the Perl stack. That's
|
---|
591 | described in L<perlcall>.
|
---|
592 |
|
---|
593 | Once you've understood those, embedding Perl in C is easy.
|
---|
594 |
|
---|
595 | Because C has no builtin function for integer exponentiation, let's
|
---|
596 | make Perl's ** operator available to it (this is less useful than it
|
---|
597 | sounds, because Perl implements ** with C's I<pow()> function). First
|
---|
598 | I'll create a stub exponentiation function in I<power.pl>:
|
---|
599 |
|
---|
600 | sub expo {
|
---|
601 | my ($a, $b) = @_;
|
---|
602 | return $a ** $b;
|
---|
603 | }
|
---|
604 |
|
---|
605 | Now I'll create a C program, I<power.c>, with a function
|
---|
606 | I<PerlPower()> that contains all the perlguts necessary to push the
|
---|
607 | two arguments into I<expo()> and to pop the return value out. Take a
|
---|
608 | deep breath...
|
---|
609 |
|
---|
610 | #include <EXTERN.h>
|
---|
611 | #include <perl.h>
|
---|
612 |
|
---|
613 | static PerlInterpreter *my_perl;
|
---|
614 |
|
---|
615 | static void
|
---|
616 | PerlPower(int a, int b)
|
---|
617 | {
|
---|
618 | dSP; /* initialize stack pointer */
|
---|
619 | ENTER; /* everything created after here */
|
---|
620 | SAVETMPS; /* ...is a temporary variable. */
|
---|
621 | PUSHMARK(SP); /* remember the stack pointer */
|
---|
622 | XPUSHs(sv_2mortal(newSViv(a))); /* push the base onto the stack */
|
---|
623 | XPUSHs(sv_2mortal(newSViv(b))); /* push the exponent onto stack */
|
---|
624 | PUTBACK; /* make local stack pointer global */
|
---|
625 | call_pv("expo", G_SCALAR); /* call the function */
|
---|
626 | SPAGAIN; /* refresh stack pointer */
|
---|
627 | /* pop the return value from stack */
|
---|
628 | printf ("%d to the %dth power is %d.\n", a, b, POPi);
|
---|
629 | PUTBACK;
|
---|
630 | FREETMPS; /* free that return value */
|
---|
631 | LEAVE; /* ...and the XPUSHed "mortal" args.*/
|
---|
632 | }
|
---|
633 |
|
---|
634 | int main (int argc, char **argv, char **env)
|
---|
635 | {
|
---|
636 | char *my_argv[] = { "", "power.pl" };
|
---|
637 |
|
---|
638 | PERL_SYS_INIT3(&argc,&argv,&env);
|
---|
639 | my_perl = perl_alloc();
|
---|
640 | perl_construct( my_perl );
|
---|
641 |
|
---|
642 | perl_parse(my_perl, NULL, 2, my_argv, (char **)NULL);
|
---|
643 | PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
|
---|
644 | perl_run(my_perl);
|
---|
645 |
|
---|
646 | PerlPower(3, 4); /*** Compute 3 ** 4 ***/
|
---|
647 |
|
---|
648 | perl_destruct(my_perl);
|
---|
649 | perl_free(my_perl);
|
---|
650 | PERL_SYS_TERM();
|
---|
651 | }
|
---|
652 |
|
---|
653 |
|
---|
654 |
|
---|
655 | Compile and run:
|
---|
656 |
|
---|
657 | % cc -o power power.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
|
---|
658 |
|
---|
659 | % power
|
---|
660 | 3 to the 4th power is 81.
|
---|
661 |
|
---|
662 | =head2 Maintaining a persistent interpreter
|
---|
663 |
|
---|
664 | When developing interactive and/or potentially long-running
|
---|
665 | applications, it's a good idea to maintain a persistent interpreter
|
---|
666 | rather than allocating and constructing a new interpreter multiple
|
---|
667 | times. The major reason is speed: since Perl will only be loaded into
|
---|
668 | memory once.
|
---|
669 |
|
---|
670 | However, you have to be more cautious with namespace and variable
|
---|
671 | scoping when using a persistent interpreter. In previous examples
|
---|
672 | we've been using global variables in the default package C<main>. We
|
---|
673 | knew exactly what code would be run, and assumed we could avoid
|
---|
674 | variable collisions and outrageous symbol table growth.
|
---|
675 |
|
---|
676 | Let's say your application is a server that will occasionally run Perl
|
---|
677 | code from some arbitrary file. Your server has no way of knowing what
|
---|
678 | code it's going to run. Very dangerous.
|
---|
679 |
|
---|
680 | If the file is pulled in by C<perl_parse()>, compiled into a newly
|
---|
681 | constructed interpreter, and subsequently cleaned out with
|
---|
682 | C<perl_destruct()> afterwards, you're shielded from most namespace
|
---|
683 | troubles.
|
---|
684 |
|
---|
685 | One way to avoid namespace collisions in this scenario is to translate
|
---|
686 | the filename into a guaranteed-unique package name, and then compile
|
---|
687 | the code into that package using L<perlfunc/eval>. In the example
|
---|
688 | below, each file will only be compiled once. Or, the application
|
---|
689 | might choose to clean out the symbol table associated with the file
|
---|
690 | after it's no longer needed. Using L<perlapi/call_argv>, We'll
|
---|
691 | call the subroutine C<Embed::Persistent::eval_file> which lives in the
|
---|
692 | file C<persistent.pl> and pass the filename and boolean cleanup/cache
|
---|
693 | flag as arguments.
|
---|
694 |
|
---|
695 | Note that the process will continue to grow for each file that it
|
---|
696 | uses. In addition, there might be C<AUTOLOAD>ed subroutines and other
|
---|
697 | conditions that cause Perl's symbol table to grow. You might want to
|
---|
698 | add some logic that keeps track of the process size, or restarts
|
---|
699 | itself after a certain number of requests, to ensure that memory
|
---|
700 | consumption is minimized. You'll also want to scope your variables
|
---|
701 | with L<perlfunc/my> whenever possible.
|
---|
702 |
|
---|
703 |
|
---|
704 | package Embed::Persistent;
|
---|
705 | #persistent.pl
|
---|
706 |
|
---|
707 | use strict;
|
---|
708 | our %Cache;
|
---|
709 | use Symbol qw(delete_package);
|
---|
710 |
|
---|
711 | sub valid_package_name {
|
---|
712 | my($string) = @_;
|
---|
713 | $string =~ s/([^A-Za-z0-9\/])/sprintf("_%2x",unpack("C",$1))/eg;
|
---|
714 | # second pass only for words starting with a digit
|
---|
715 | $string =~ s|/(\d)|sprintf("/_%2x",unpack("C",$1))|eg;
|
---|
716 |
|
---|
717 | # Dress it up as a real package name
|
---|
718 | $string =~ s|/|::|g;
|
---|
719 | return "Embed" . $string;
|
---|
720 | }
|
---|
721 |
|
---|
722 | sub eval_file {
|
---|
723 | my($filename, $delete) = @_;
|
---|
724 | my $package = valid_package_name($filename);
|
---|
725 | my $mtime = -M $filename;
|
---|
726 | if(defined $Cache{$package}{mtime}
|
---|
727 | &&
|
---|
728 | $Cache{$package}{mtime} <= $mtime)
|
---|
729 | {
|
---|
730 | # we have compiled this subroutine already,
|
---|
731 | # it has not been updated on disk, nothing left to do
|
---|
732 | print STDERR "already compiled $package->handler\n";
|
---|
733 | }
|
---|
734 | else {
|
---|
735 | local *FH;
|
---|
736 | open FH, $filename or die "open '$filename' $!";
|
---|
737 | local($/) = undef;
|
---|
738 | my $sub = <FH>;
|
---|
739 | close FH;
|
---|
740 |
|
---|
741 | #wrap the code into a subroutine inside our unique package
|
---|
742 | my $eval = qq{package $package; sub handler { $sub; }};
|
---|
743 | {
|
---|
744 | # hide our variables within this block
|
---|
745 | my($filename,$mtime,$package,$sub);
|
---|
746 | eval $eval;
|
---|
747 | }
|
---|
748 | die $@ if $@;
|
---|
749 |
|
---|
750 | #cache it unless we're cleaning out each time
|
---|
751 | $Cache{$package}{mtime} = $mtime unless $delete;
|
---|
752 | }
|
---|
753 |
|
---|
754 | eval {$package->handler;};
|
---|
755 | die $@ if $@;
|
---|
756 |
|
---|
757 | delete_package($package) if $delete;
|
---|
758 |
|
---|
759 | #take a look if you want
|
---|
760 | #print Devel::Symdump->rnew($package)->as_string, $/;
|
---|
761 | }
|
---|
762 |
|
---|
763 | 1;
|
---|
764 |
|
---|
765 | __END__
|
---|
766 |
|
---|
767 | /* persistent.c */
|
---|
768 | #include <EXTERN.h>
|
---|
769 | #include <perl.h>
|
---|
770 |
|
---|
771 | /* 1 = clean out filename's symbol table after each request, 0 = don't */
|
---|
772 | #ifndef DO_CLEAN
|
---|
773 | #define DO_CLEAN 0
|
---|
774 | #endif
|
---|
775 |
|
---|
776 | #define BUFFER_SIZE 1024
|
---|
777 |
|
---|
778 | static PerlInterpreter *my_perl = NULL;
|
---|
779 |
|
---|
780 | int
|
---|
781 | main(int argc, char **argv, char **env)
|
---|
782 | {
|
---|
783 | char *embedding[] = { "", "persistent.pl" };
|
---|
784 | char *args[] = { "", DO_CLEAN, NULL };
|
---|
785 | char filename[BUFFER_SIZE];
|
---|
786 | int exitstatus = 0;
|
---|
787 | STRLEN n_a;
|
---|
788 |
|
---|
789 | PERL_SYS_INIT3(&argc,&argv,&env);
|
---|
790 | if((my_perl = perl_alloc()) == NULL) {
|
---|
791 | fprintf(stderr, "no memory!");
|
---|
792 | exit(1);
|
---|
793 | }
|
---|
794 | perl_construct(my_perl);
|
---|
795 |
|
---|
796 | exitstatus = perl_parse(my_perl, NULL, 2, embedding, NULL);
|
---|
797 | PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
|
---|
798 | if(!exitstatus) {
|
---|
799 | exitstatus = perl_run(my_perl);
|
---|
800 |
|
---|
801 | while(printf("Enter file name: ") &&
|
---|
802 | fgets(filename, BUFFER_SIZE, stdin)) {
|
---|
803 |
|
---|
804 | filename[strlen(filename)-1] = '\0'; /* strip \n */
|
---|
805 | /* call the subroutine, passing it the filename as an argument */
|
---|
806 | args[0] = filename;
|
---|
807 | call_argv("Embed::Persistent::eval_file",
|
---|
808 | G_DISCARD | G_EVAL, args);
|
---|
809 |
|
---|
810 | /* check $@ */
|
---|
811 | if(SvTRUE(ERRSV))
|
---|
812 | fprintf(stderr, "eval error: %s\n", SvPV(ERRSV,n_a));
|
---|
813 | }
|
---|
814 | }
|
---|
815 |
|
---|
816 | PL_perl_destruct_level = 0;
|
---|
817 | perl_destruct(my_perl);
|
---|
818 | perl_free(my_perl);
|
---|
819 | PERL_SYS_TERM();
|
---|
820 | exit(exitstatus);
|
---|
821 | }
|
---|
822 |
|
---|
823 | Now compile:
|
---|
824 |
|
---|
825 | % cc -o persistent persistent.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
|
---|
826 |
|
---|
827 | Here's an example script file:
|
---|
828 |
|
---|
829 | #test.pl
|
---|
830 | my $string = "hello";
|
---|
831 | foo($string);
|
---|
832 |
|
---|
833 | sub foo {
|
---|
834 | print "foo says: @_\n";
|
---|
835 | }
|
---|
836 |
|
---|
837 | Now run:
|
---|
838 |
|
---|
839 | % persistent
|
---|
840 | Enter file name: test.pl
|
---|
841 | foo says: hello
|
---|
842 | Enter file name: test.pl
|
---|
843 | already compiled Embed::test_2epl->handler
|
---|
844 | foo says: hello
|
---|
845 | Enter file name: ^C
|
---|
846 |
|
---|
847 | =head2 Execution of END blocks
|
---|
848 |
|
---|
849 | Traditionally END blocks have been executed at the end of the perl_run.
|
---|
850 | This causes problems for applications that never call perl_run. Since
|
---|
851 | perl 5.7.2 you can specify C<PL_exit_flags |= PERL_EXIT_DESTRUCT_END>
|
---|
852 | to get the new behaviour. This also enables the running of END blocks if
|
---|
853 | the perl_parse fails and C<perl_destruct> will return the exit value.
|
---|
854 |
|
---|
855 | =head2 Maintaining multiple interpreter instances
|
---|
856 |
|
---|
857 | Some rare applications will need to create more than one interpreter
|
---|
858 | during a session. Such an application might sporadically decide to
|
---|
859 | release any resources associated with the interpreter.
|
---|
860 |
|
---|
861 | The program must take care to ensure that this takes place I<before>
|
---|
862 | the next interpreter is constructed. By default, when perl is not
|
---|
863 | built with any special options, the global variable
|
---|
864 | C<PL_perl_destruct_level> is set to C<0>, since extra cleaning isn't
|
---|
865 | usually needed when a program only ever creates a single interpreter
|
---|
866 | in its entire lifetime.
|
---|
867 |
|
---|
868 | Setting C<PL_perl_destruct_level> to C<1> makes everything squeaky clean:
|
---|
869 |
|
---|
870 | while(1) {
|
---|
871 | ...
|
---|
872 | /* reset global variables here with PL_perl_destruct_level = 1 */
|
---|
873 | PL_perl_destruct_level = 1;
|
---|
874 | perl_construct(my_perl);
|
---|
875 | ...
|
---|
876 | /* clean and reset _everything_ during perl_destruct */
|
---|
877 | PL_perl_destruct_level = 1;
|
---|
878 | perl_destruct(my_perl);
|
---|
879 | perl_free(my_perl);
|
---|
880 | ...
|
---|
881 | /* let's go do it again! */
|
---|
882 | }
|
---|
883 |
|
---|
884 | When I<perl_destruct()> is called, the interpreter's syntax parse tree
|
---|
885 | and symbol tables are cleaned up, and global variables are reset. The
|
---|
886 | second assignment to C<PL_perl_destruct_level> is needed because
|
---|
887 | perl_construct resets it to C<0>.
|
---|
888 |
|
---|
889 | Now suppose we have more than one interpreter instance running at the
|
---|
890 | same time. This is feasible, but only if you used the Configure option
|
---|
891 | C<-Dusemultiplicity> or the options C<-Dusethreads -Duseithreads> when
|
---|
892 | building perl. By default, enabling one of these Configure options
|
---|
893 | sets the per-interpreter global variable C<PL_perl_destruct_level> to
|
---|
894 | C<1>, so that thorough cleaning is automatic and interpreter variables
|
---|
895 | are initialized correctly. Even if you don't intend to run two or
|
---|
896 | more interpreters at the same time, but to run them sequentially, like
|
---|
897 | in the above example, it is recommended to build perl with the
|
---|
898 | C<-Dusemultiplicity> option otherwise some interpreter variables may
|
---|
899 | not be initialized correctly between consecutive runs and your
|
---|
900 | application may crash.
|
---|
901 |
|
---|
902 | Using C<-Dusethreads -Duseithreads> rather than C<-Dusemultiplicity>
|
---|
903 | is more appropriate if you intend to run multiple interpreters
|
---|
904 | concurrently in different threads, because it enables support for
|
---|
905 | linking in the thread libraries of your system with the interpreter.
|
---|
906 |
|
---|
907 | Let's give it a try:
|
---|
908 |
|
---|
909 |
|
---|
910 | #include <EXTERN.h>
|
---|
911 | #include <perl.h>
|
---|
912 |
|
---|
913 | /* we're going to embed two interpreters */
|
---|
914 | /* we're going to embed two interpreters */
|
---|
915 |
|
---|
916 | #define SAY_HELLO "-e", "print qq(Hi, I'm $^X\n)"
|
---|
917 |
|
---|
918 | int main(int argc, char **argv, char **env)
|
---|
919 | {
|
---|
920 | PerlInterpreter *one_perl, *two_perl;
|
---|
921 | char *one_args[] = { "one_perl", SAY_HELLO };
|
---|
922 | char *two_args[] = { "two_perl", SAY_HELLO };
|
---|
923 |
|
---|
924 | PERL_SYS_INIT3(&argc,&argv,&env);
|
---|
925 | one_perl = perl_alloc();
|
---|
926 | two_perl = perl_alloc();
|
---|
927 |
|
---|
928 | PERL_SET_CONTEXT(one_perl);
|
---|
929 | perl_construct(one_perl);
|
---|
930 | PERL_SET_CONTEXT(two_perl);
|
---|
931 | perl_construct(two_perl);
|
---|
932 |
|
---|
933 | PERL_SET_CONTEXT(one_perl);
|
---|
934 | perl_parse(one_perl, NULL, 3, one_args, (char **)NULL);
|
---|
935 | PERL_SET_CONTEXT(two_perl);
|
---|
936 | perl_parse(two_perl, NULL, 3, two_args, (char **)NULL);
|
---|
937 |
|
---|
938 | PERL_SET_CONTEXT(one_perl);
|
---|
939 | perl_run(one_perl);
|
---|
940 | PERL_SET_CONTEXT(two_perl);
|
---|
941 | perl_run(two_perl);
|
---|
942 |
|
---|
943 | PERL_SET_CONTEXT(one_perl);
|
---|
944 | perl_destruct(one_perl);
|
---|
945 | PERL_SET_CONTEXT(two_perl);
|
---|
946 | perl_destruct(two_perl);
|
---|
947 |
|
---|
948 | PERL_SET_CONTEXT(one_perl);
|
---|
949 | perl_free(one_perl);
|
---|
950 | PERL_SET_CONTEXT(two_perl);
|
---|
951 | perl_free(two_perl);
|
---|
952 | PERL_SYS_TERM();
|
---|
953 | }
|
---|
954 |
|
---|
955 | Note the calls to PERL_SET_CONTEXT(). These are necessary to initialize
|
---|
956 | the global state that tracks which interpreter is the "current" one on
|
---|
957 | the particular process or thread that may be running it. It should
|
---|
958 | always be used if you have more than one interpreter and are making
|
---|
959 | perl API calls on both interpreters in an interleaved fashion.
|
---|
960 |
|
---|
961 | PERL_SET_CONTEXT(interp) should also be called whenever C<interp> is
|
---|
962 | used by a thread that did not create it (using either perl_alloc(), or
|
---|
963 | the more esoteric perl_clone()).
|
---|
964 |
|
---|
965 | Compile as usual:
|
---|
966 |
|
---|
967 | % cc -o multiplicity multiplicity.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
|
---|
968 |
|
---|
969 | Run it, Run it:
|
---|
970 |
|
---|
971 | % multiplicity
|
---|
972 | Hi, I'm one_perl
|
---|
973 | Hi, I'm two_perl
|
---|
974 |
|
---|
975 | =head2 Using Perl modules, which themselves use C libraries, from your C program
|
---|
976 |
|
---|
977 | If you've played with the examples above and tried to embed a script
|
---|
978 | that I<use()>s a Perl module (such as I<Socket>) which itself uses a C or C++ library,
|
---|
979 | this probably happened:
|
---|
980 |
|
---|
981 |
|
---|
982 | Can't load module Socket, dynamic loading not available in this perl.
|
---|
983 | (You may need to build a new perl executable which either supports
|
---|
984 | dynamic loading or has the Socket module statically linked into it.)
|
---|
985 |
|
---|
986 |
|
---|
987 | What's wrong?
|
---|
988 |
|
---|
989 | Your interpreter doesn't know how to communicate with these extensions
|
---|
990 | on its own. A little glue will help. Up until now you've been
|
---|
991 | calling I<perl_parse()>, handing it NULL for the second argument:
|
---|
992 |
|
---|
993 | perl_parse(my_perl, NULL, argc, my_argv, NULL);
|
---|
994 |
|
---|
995 | That's where the glue code can be inserted to create the initial contact between
|
---|
996 | Perl and linked C/C++ routines. Let's take a look some pieces of I<perlmain.c>
|
---|
997 | to see how Perl does this:
|
---|
998 |
|
---|
999 | static void xs_init (pTHX);
|
---|
1000 |
|
---|
1001 | EXTERN_C void boot_DynaLoader (pTHX_ CV* cv);
|
---|
1002 | EXTERN_C void boot_Socket (pTHX_ CV* cv);
|
---|
1003 |
|
---|
1004 |
|
---|
1005 | EXTERN_C void
|
---|
1006 | xs_init(pTHX)
|
---|
1007 | {
|
---|
1008 | char *file = __FILE__;
|
---|
1009 | /* DynaLoader is a special case */
|
---|
1010 | newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
|
---|
1011 | newXS("Socket::bootstrap", boot_Socket, file);
|
---|
1012 | }
|
---|
1013 |
|
---|
1014 | Simply put: for each extension linked with your Perl executable
|
---|
1015 | (determined during its initial configuration on your
|
---|
1016 | computer or when adding a new extension),
|
---|
1017 | a Perl subroutine is created to incorporate the extension's
|
---|
1018 | routines. Normally, that subroutine is named
|
---|
1019 | I<Module::bootstrap()> and is invoked when you say I<use Module>. In
|
---|
1020 | turn, this hooks into an XSUB, I<boot_Module>, which creates a Perl
|
---|
1021 | counterpart for each of the extension's XSUBs. Don't worry about this
|
---|
1022 | part; leave that to the I<xsubpp> and extension authors. If your
|
---|
1023 | extension is dynamically loaded, DynaLoader creates I<Module::bootstrap()>
|
---|
1024 | for you on the fly. In fact, if you have a working DynaLoader then there
|
---|
1025 | is rarely any need to link in any other extensions statically.
|
---|
1026 |
|
---|
1027 |
|
---|
1028 | Once you have this code, slap it into the second argument of I<perl_parse()>:
|
---|
1029 |
|
---|
1030 |
|
---|
1031 | perl_parse(my_perl, xs_init, argc, my_argv, NULL);
|
---|
1032 |
|
---|
1033 |
|
---|
1034 | Then compile:
|
---|
1035 |
|
---|
1036 | % cc -o interp interp.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
|
---|
1037 |
|
---|
1038 | % interp
|
---|
1039 | use Socket;
|
---|
1040 | use SomeDynamicallyLoadedModule;
|
---|
1041 |
|
---|
1042 | print "Now I can use extensions!\n"'
|
---|
1043 |
|
---|
1044 | B<ExtUtils::Embed> can also automate writing the I<xs_init> glue code.
|
---|
1045 |
|
---|
1046 | % perl -MExtUtils::Embed -e xsinit -- -o perlxsi.c
|
---|
1047 | % cc -c perlxsi.c `perl -MExtUtils::Embed -e ccopts`
|
---|
1048 | % cc -c interp.c `perl -MExtUtils::Embed -e ccopts`
|
---|
1049 | % cc -o interp perlxsi.o interp.o `perl -MExtUtils::Embed -e ldopts`
|
---|
1050 |
|
---|
1051 | Consult L<perlxs>, L<perlguts>, and L<perlapi> for more details.
|
---|
1052 |
|
---|
1053 | =head1 Embedding Perl under Win32
|
---|
1054 |
|
---|
1055 | In general, all of the source code shown here should work unmodified under
|
---|
1056 | Windows.
|
---|
1057 |
|
---|
1058 | However, there are some caveats about the command-line examples shown.
|
---|
1059 | For starters, backticks won't work under the Win32 native command shell.
|
---|
1060 | The ExtUtils::Embed kit on CPAN ships with a script called
|
---|
1061 | B<genmake>, which generates a simple makefile to build a program from
|
---|
1062 | a single C source file. It can be used like this:
|
---|
1063 |
|
---|
1064 | C:\ExtUtils-Embed\eg> perl genmake interp.c
|
---|
1065 | C:\ExtUtils-Embed\eg> nmake
|
---|
1066 | C:\ExtUtils-Embed\eg> interp -e "print qq{I'm embedded in Win32!\n}"
|
---|
1067 |
|
---|
1068 | You may wish to use a more robust environment such as the Microsoft
|
---|
1069 | Developer Studio. In this case, run this to generate perlxsi.c:
|
---|
1070 |
|
---|
1071 | perl -MExtUtils::Embed -e xsinit
|
---|
1072 |
|
---|
1073 | Create a new project and Insert -> Files into Project: perlxsi.c,
|
---|
1074 | perl.lib, and your own source files, e.g. interp.c. Typically you'll
|
---|
1075 | find perl.lib in B<C:\perl\lib\CORE>, if not, you should see the
|
---|
1076 | B<CORE> directory relative to C<perl -V:archlib>. The studio will
|
---|
1077 | also need this path so it knows where to find Perl include files.
|
---|
1078 | This path can be added via the Tools -> Options -> Directories menu.
|
---|
1079 | Finally, select Build -> Build interp.exe and you're ready to go.
|
---|
1080 |
|
---|
1081 | =head1 Hiding Perl_
|
---|
1082 |
|
---|
1083 | If you completely hide the short forms forms of the Perl public API,
|
---|
1084 | add -DPERL_NO_SHORT_NAMES to the compilation flags. This means that
|
---|
1085 | for example instead of writing
|
---|
1086 |
|
---|
1087 | warn("%d bottles of beer on the wall", bottlecount);
|
---|
1088 |
|
---|
1089 | you will have to write the explicit full form
|
---|
1090 |
|
---|
1091 | Perl_warn(aTHX_ "%d bottles of beer on the wall", bottlecount);
|
---|
1092 |
|
---|
1093 | (See L<perlguts/Background and PERL_IMPLICIT_CONTEXT for the explanation
|
---|
1094 | of the C<aTHX_>.> ) Hiding the short forms is very useful for avoiding
|
---|
1095 | all sorts of nasty (C preprocessor or otherwise) conflicts with other
|
---|
1096 | software packages (Perl defines about 2400 APIs with these short names,
|
---|
1097 | take or leave few hundred, so there certainly is room for conflict.)
|
---|
1098 |
|
---|
1099 | =head1 MORAL
|
---|
1100 |
|
---|
1101 | You can sometimes I<write faster code> in C, but
|
---|
1102 | you can always I<write code faster> in Perl. Because you can use
|
---|
1103 | each from the other, combine them as you wish.
|
---|
1104 |
|
---|
1105 |
|
---|
1106 | =head1 AUTHOR
|
---|
1107 |
|
---|
1108 | Jon Orwant <F<[email protected]>> and Doug MacEachern
|
---|
1109 | <F<[email protected]>>, with small contributions from Tim Bunce, Tom
|
---|
1110 | Christiansen, Guy Decoux, Hallvard Furuseth, Dov Grobgeld, and Ilya
|
---|
1111 | Zakharevich.
|
---|
1112 |
|
---|
1113 | Doug MacEachern has an article on embedding in Volume 1, Issue 4 of
|
---|
1114 | The Perl Journal ( http://www.tpj.com/ ). Doug is also the developer of the
|
---|
1115 | most widely-used Perl embedding: the mod_perl system
|
---|
1116 | (perl.apache.org), which embeds Perl in the Apache web server.
|
---|
1117 | Oracle, Binary Evolution, ActiveState, and Ben Sugars's nsapi_perl
|
---|
1118 | have used this model for Oracle, Netscape and Internet Information
|
---|
1119 | Server Perl plugins.
|
---|
1120 |
|
---|
1121 | =head1 COPYRIGHT
|
---|
1122 |
|
---|
1123 | Copyright (C) 1995, 1996, 1997, 1998 Doug MacEachern and Jon Orwant. All
|
---|
1124 | Rights Reserved.
|
---|
1125 |
|
---|
1126 | Permission is granted to make and distribute verbatim copies of this
|
---|
1127 | documentation provided the copyright notice and this permission notice are
|
---|
1128 | preserved on all copies.
|
---|
1129 |
|
---|
1130 | Permission is granted to copy and distribute modified versions of this
|
---|
1131 | documentation under the conditions for verbatim copying, provided also
|
---|
1132 | that they are marked clearly as modified versions, that the authors'
|
---|
1133 | names and title are unchanged (though subtitles and additional
|
---|
1134 | authors' names may be added), and that the entire resulting derived
|
---|
1135 | work is distributed under the terms of a permission notice identical
|
---|
1136 | to this one.
|
---|
1137 |
|
---|
1138 | Permission is granted to copy and distribute translations of this
|
---|
1139 | documentation into another language, under the above conditions for
|
---|
1140 | modified versions.
|
---|