=item B<Use C from Perl?>
-Read L<perlcall> and L<perlxs>.
+Read L<perlxs>, L<perlxstut> and L<h2xs>.
-=item B<Use a UNIX program from Perl?>
+=item B<Use a Unix program from Perl?>
Read about back-quotes and about C<system> and C<exec> in L<perlfunc>.
=item B<Use Perl from Perl?>
-Read about L<perlfunc/do> and L<perlfunc/eval> and L<perlfunc/require>
-and L<perlfunc/use>.
+Read about do(), eval(), require(), and use() in L<perlfunc>.
=item B<Use C from C?>
=head2 ROADMAP
-L<Compiling your C program>
+Compiling your C program
-There's one example in each of the eight sections:
+There's one example in each of the nine sections:
-L<Adding a Perl interpreter to your C program>
+=over 4
-L<Calling a Perl subroutine from your C program>
+=item *
-L<Evaluating a Perl statement from your C program>
+Adding a Perl interpreter to your C program
-L<Performing Perl pattern matches and substitutions from your C program>
+=item *
-L<Fiddling with the Perl stack from your C program>
+Calling a Perl subroutine from your C program
-L<Maintaining a persistent interpreter>
+=item *
-L<Maintaining multiple interpreter instances>
+Evaluating a Perl statement from your C program
-L<Using Perl modules, which themselves use C libraries, from your C program>
+=item *
-This documentation is Unix specific; if you have information about how
-to embed Perl on other platforms, please send e-mail to <F<orwant@tpj.com>>.
+Performing Perl pattern matches and substitutions from your C program
+
+=item *
+
+Fiddling with the Perl stack from your C program
+
+=item *
+
+Maintaining a persistent interpreter
+
+=item *
+
+Maintaining multiple interpreter instances
+
+=item *
+
+Using Perl modules, which themselves use C libraries, from your C program
+
+=item *
+
+Embedding Perl under Win32
+
+=back
=head2 Compiling your C program
perl -MConfig -e 'print $Config{archlib}'
-Here's how you'd compile the example in the next section,
-L<Adding a Perl interpreter to your C program>, on my Linux box:
+Here's how you'd compile the example in the next section,
+Adding a Perl interpreter to your C program, on my Linux box:
- % gcc -O2 -Dbool=char -DHAS_BOOL -I/usr/local/include
+ % gcc -O2 -Dbool=char -DHAS_BOOL -I/usr/local/include
-I/usr/local/lib/perl5/i586-linux/5.003/CORE
- -L/usr/local/lib/perl5/i586-linux/5.003/CORE
+ -L/usr/local/lib/perl5/i586-linux/5.003/CORE
-o interp interp.c -lperl -lm
-(That's all one line.) On my DEC Alpha running 5.00305, the incantation
+(That's all one line.) On my DEC Alpha running 5.003_05, the incantation
is a bit different:
- % cc -O2 -Olimit 2900 -DSTANDARD_C -I/usr/local/include
- -I/usr/local/lib/perl5/alpha-dec_osf/5.00305/CORE
- -L/usr/local/lib/perl5/alpha-dec_osf/5.00305/CORE -L/usr/local/lib
+ % cc -O2 -Olimit 2900 -DSTANDARD_C -I/usr/local/include
+ -I/usr/local/lib/perl5/alpha-dec_osf/5.00305/CORE
+ -L/usr/local/lib/perl5/alpha-dec_osf/5.00305/CORE -L/usr/local/lib
-D__LANGUAGE_C__ -D_NO_PROTO -o interp interp.c -lperl -lm
How can you figure out what to add? Assuming your Perl is post-5.001,
execute a C<perl -V> command and pay special attention to the "cc" and
-"ccflags" information.
+"ccflags" information.
-You'll have to choose the appropriate compiler (I<cc>, I<gcc>, et al.) for
+You'll have to choose the appropriate compiler (I<cc>, I<gcc>, et al.) for
your machine: C<perl -MConfig -e 'print $Config{cc}'> will tell you what
-to use.
+to use.
You'll also have to choose the appropriate library directory
(I</usr/local/lib/...>) for your machine. If your compiler complains
perl -MConfig -e 'print $Config{libs}'
-Provided your perl binary was properly configured and installed the
+Provided your perl binary was properly configured and installed the
B<ExtUtils::Embed> module will determine all of this information for
you:
running 5.004 or better and you already have it.)
The B<ExtUtils::Embed> kit on CPAN also contains all source code for
-the examples in this document, tests, additional examples and other
+the examples in this document, tests, additional examples and other
information you may find useful.
=head2 Adding a Perl interpreter to your C program
In a sense, perl (the C program) is a good example of embedding Perl
(the language), so I'll demonstrate embedding with I<miniperlmain.c>,
-from the source distribution. Here's a bastardized, non-portable
+from the source distribution. Here's a bastardized, nonportable
version of I<miniperlmain.c> containing the essentials of embedding:
#include <EXTERN.h> /* from the Perl distribution */
=head2 Calling a Perl subroutine from your C program
To call individual Perl subroutines, you can use any of the B<perl_call_*>
-functions documented in the L<perlcall> man page.
-In this example we'll use I<perl_call_argv>.
+functions documented in L<perlcall>.
+In this example we'll use perl_call_argv().
That's shown below, in a program I'll call I<showtime.c>.
strings to the C<NULL>-terminated C<args> list passed to
I<perl_call_argv>. For other data types, or to examine return values,
you'll need to manipulate the Perl stack. That's demonstrated in the
-last section of this document: L<Fiddling with the Perl stack from
-your C program>.
+last section of this document: Fiddling with the Perl stack from
+your C program.
=head2 Evaluating a Perl statement from your C program
-One way to evaluate pieces of Perl code is to use
-L<perlguts/perl_eval_sv()>. We've wrapped this inside our own
-I<perl_eval()> function, which converts a command string to an SV,
-passing this and the L<perlcall/G_DISCARD> flag to
-L<perlguts/perl_eval_sv()>.
+Perl provides two API functions to evaluate pieces of Perl code.
+These are perl_eval_sv() and perl_eval_pv().
-Arguably, this is the only routine you'll ever need to execute
-snippets of Perl code from within your C program. Your string can be
+Arguably, these are the only routines you'll ever need to execute
+snippets of Perl code from within your C program. Your code can be
as long as you wish; it can contain multiple statements; it can employ
-L<perlfunc/use>, L<perlfunc/require> and L<perlfunc/do> to include
-external Perl files.
+use(), require(), and do() to include external Perl files.
-Our I<perl_eval()> lets us evaluate individual Perl strings, and then
+perl_eval_pv() lets us evaluate individual Perl strings, and then
extract variables for coercion into C types. The following program,
I<string.c>, executes three Perl strings, extracting an C<int> from
the first, a C<float> from the second, and a C<char *> from the third.
#include <EXTERN.h>
#include <perl.h>
-
+
static PerlInterpreter *my_perl;
-
- I32 perl_eval(char *string)
- {
- return perl_eval_sv(newSVpv(string,0), G_DISCARD);
- }
-
+
main (int argc, char **argv, char **env)
{
- char *embedding[] = { "", "-e", "0" };
- STRLEN length;
-
- my_perl = perl_alloc();
- perl_construct( my_perl );
-
- perl_parse(my_perl, NULL, 3, embedding, NULL);
- perl_run(my_perl);
- /** Treat $a as an integer **/
- perl_eval("$a = 3; $a **= 2");
- printf("a = %d\n", SvIV(perl_get_sv("a", FALSE)));
-
- /** Treat $a as a float **/
- perl_eval("$a = 3.14; $a **= 2");
- printf("a = %f\n", SvNV(perl_get_sv("a", FALSE)));
-
- /** Treat $a as a string **/
- perl_eval("$a = 'rekcaH lreP rehtonA tsuJ'; $a = reverse($a); ");
- printf("a = %s\n", SvPV(perl_get_sv("a", FALSE), length));
-
- perl_destruct(my_perl);
- perl_free(my_perl);
+ char *embedding[] = { "", "-e", "0" };
+
+ my_perl = perl_alloc();
+ perl_construct( my_perl );
+
+ perl_parse(my_perl, NULL, 3, embedding, NULL);
+ perl_run(my_perl);
+
+ /** Treat $a as an integer **/
+ perl_eval_pv("$a = 3; $a **= 2", TRUE);
+ printf("a = %d\n", SvIV(perl_get_sv("a", FALSE)));
+
+ /** Treat $a as a float **/
+ perl_eval_pv("$a = 3.14; $a **= 2", TRUE);
+ printf("a = %f\n", SvNV(perl_get_sv("a", FALSE)));
+
+ /** Treat $a as a string **/
+ perl_eval_pv("$a = 'rekcaH lreP rehtonA tsuJ'; $a = reverse($a);", TRUE);
+ printf("a = %s\n", SvPV(perl_get_sv("a", FALSE), na));
+
+ perl_destruct(my_perl);
+ perl_free(my_perl);
}
All of those strange functions with I<sv> in their names help convert Perl scalars to C types. They're described in L<perlguts>.
a = 9.859600
a = Just Another Perl Hacker
+In the example above, we've created a global variable to temporarily
+store the computed value of our eval'd expression. It is also
+possible and in most cases a better strategy to fetch the return value
+from perl_eval_pv() instead. Example:
+
+ ...
+ SV *val = perl_eval_pv("reverse 'rekcaH lreP rehtonA tsuJ'", TRUE);
+ printf("%s\n", SvPV(val,na));
+ ...
+
+This way, we avoid namespace pollution by not creating global
+variables and we've simplified our code as well.
=head2 Performing Perl pattern matches and substitutions from your C program
-Our I<perl_eval()> lets us evaluate strings of Perl code, so we can
+The I<perl_eval_sv()> function lets us evaluate chunks of Perl code, so we can
define some functions that use it to "specialize" in matches and
substitutions: I<match()>, I<substitute()>, and I<matches()>.
- char match(char *string, char *pattern);
+ char match(SV *string, char *pattern);
Given a string and a pattern (e.g., C<m/clasp/> or C</\b\w*\b/>, which
in your C program might appear as "/\\b\\w*\\b/"), match()
returns 1 if the string matches the pattern and 0 otherwise.
- int substitute(char *string[], char *pattern);
+ int substitute(SV **string, char *pattern);
-Given a pointer to a string and an C<=~> operation (e.g.,
+Given a pointer to an C<SV> and an C<=~> operation (e.g.,
C<s/bob/robert/g> or C<tr[A-Z][a-z]>), substitute() modifies the string
-according to the operation, returning the number of substitutions
+within the C<AV> at according to the operation, returning the number of substitutions
made.
- int matches(char *string, char *pattern, char **matches[]);
+ int matches(SV *string, char *pattern, AV **matches);
-Given a string, a pattern, and a pointer to an empty array of strings,
+Given an C<SV>, a pattern, and a pointer to an empty C<AV>,
matches() evaluates C<$string =~ $pattern> in an array context, and
-fills in I<matches> with the array elements (allocating memory as it
-does so), returning the number of matches found.
+fills in I<matches> with the array elements, returning the number of matches found.
Here's a sample program, I<match.c>, that uses all three (long lines have
been wrapped here):
- #include <EXTERN.h>
- #include <perl.h>
-
- static PerlInterpreter *my_perl;
- I32 perl_eval(char *string)
- {
- return perl_eval_sv(newSVpv(string,0), G_DISCARD);
- }
- /** match(string, pattern)
- **
- ** Used for matches in a scalar context.
- **
- ** Returns 1 if the match was successful; 0 otherwise.
- **/
- char match(char *string, char *pattern)
- {
- char *command;
- command = malloc(sizeof(char) * strlen(string) + strlen(pattern) + 37);
- sprintf(command, "$string = '%s'; $return = $string =~ %s",
- string, pattern);
- perl_eval(command);
- free(command);
- return SvIV(perl_get_sv("return", FALSE));
- }
- /** substitute(string, pattern)
- **
- ** Used for =~ operations that modify their left-hand side (s/// and tr///)
- **
- ** Returns the number of successful matches, and
- ** modifies the input string if there were any.
- **/
- int substitute(char *string[], char *pattern)
- {
- char *command;
- STRLEN length;
- command = malloc(sizeof(char) * strlen(*string) + strlen(pattern) + 35);
- sprintf(command, "$string = '%s'; $ret = ($string =~ %s)",
- *string, pattern);
- perl_eval(command);
- free(command);
- *string = SvPV(perl_get_sv("string", FALSE), length);
- return SvIV(perl_get_sv("ret", FALSE));
- }
- /** matches(string, pattern, matches)
- **
- ** Used for matches in an array context.
- **
- ** Returns the number of matches,
- ** and fills in **matches with the matching substrings (allocates memory!)
- **/
- int matches(char *string, char *pattern, char **match_list[])
- {
- char *command;
- SV *current_match;
- AV *array;
+ #include <EXTERN.h>
+ #include <perl.h>
+
+ /** my_perl_eval_sv(code, error_check)
+ ** kinda like perl_eval_sv(),
+ ** but we pop the return value off the stack
+ **/
+ SV* my_perl_eval_sv(SV *sv, I32 croak_on_error)
+ {
+ dSP;
+ SV* retval;
+
+ PUSHMARK(SP);
+ perl_eval_sv(sv, G_SCALAR);
+
+ SPAGAIN;
+ retval = POPs;
+ PUTBACK;
+
+ if (croak_on_error && SvTRUE(GvSV(errgv)))
+ croak(SvPVx(GvSV(errgv), na));
+
+ return retval;
+ }
+
+ /** match(string, pattern)
+ **
+ ** Used for matches in a scalar context.
+ **
+ ** Returns 1 if the match was successful; 0 otherwise.
+ **/
+
+ I32 match(SV *string, char *pattern)
+ {
+ SV *command = NEWSV(1099, 0), *retval;
+
+ sv_setpvf(command, "my $string = '%s'; $string =~ %s",
+ SvPV(string,na), pattern);
+
+ retval = my_perl_eval_sv(command, TRUE);
+ SvREFCNT_dec(command);
+
+ return SvIV(retval);
+ }
+
+ /** substitute(string, pattern)
+ **
+ ** Used for =~ operations that modify their left-hand side (s/// and tr///)
+ **
+ ** Returns the number of successful matches, and
+ ** modifies the input string if there were any.
+ **/
+
+ I32 substitute(SV **string, char *pattern)
+ {
+ SV *command = NEWSV(1099, 0), *retval;
+
+ sv_setpvf(command, "$string = '%s'; ($string =~ %s)",
+ SvPV(*string,na), pattern);
+
+ retval = my_perl_eval_sv(command, TRUE);
+ SvREFCNT_dec(command);
+
+ *string = perl_get_sv("string", FALSE);
+ return SvIV(retval);
+ }
+
+ /** matches(string, pattern, matches)
+ **
+ ** Used for matches in an array context.
+ **
+ ** Returns the number of matches,
+ ** and fills in **matches with the matching substrings
+ **/
+
+ I32 matches(SV *string, char *pattern, AV **match_list)
+ {
+ SV *command = NEWSV(1099, 0);
I32 num_matches;
- STRLEN length;
- int i;
- command = malloc(sizeof(char) * strlen(string) + strlen(pattern) + 38);
- sprintf(command, "$string = '%s'; @array = ($string =~ %s)",
- string, pattern);
- perl_eval(command);
- free(command);
- array = perl_get_av("array", FALSE);
- num_matches = av_len(array) + 1; /** assume $[ is 0 **/
- *match_list = (char **) malloc(sizeof(char *) * num_matches);
- for (i = 0; i <= num_matches; i++) {
- current_match = av_shift(array);
- (*match_list)[i] = SvPV(current_match, length);
- }
+
+ sv_setpvf(command, "my $string = '%s'; @array = ($string =~ %s)",
+ SvPV(string,na), pattern);
+
+ my_perl_eval_sv(command, TRUE);
+ SvREFCNT_dec(command);
+
+ *match_list = perl_get_av("array", FALSE);
+ num_matches = av_len(*match_list) + 1; /** assume $[ is 0 **/
+
return num_matches;
- }
- main (int argc, char **argv, char **env)
- {
+ }
+
+ main (int argc, char **argv, char **env)
+ {
+ PerlInterpreter *my_perl = perl_alloc();
char *embedding[] = { "", "-e", "0" };
- char *text, **match_list;
- int num_matches, i;
- int j;
- my_perl = perl_alloc();
- perl_construct( my_perl );
+ AV *match_list;
+ I32 num_matches, i;
+ SV *text = NEWSV(1099,0);
+
+ perl_construct(my_perl);
perl_parse(my_perl, NULL, 3, embedding, NULL);
- perl_run(my_perl);
-
- text = (char *) malloc(sizeof(char) * 486); /** A long string follows! **/
- sprintf(text, "%s", "When he is at a convenience store and the bill \
- comes to some amount like 76 cents, Maynard is aware that there is \
- something he *should* do, something that will enable him to get back \
- a quarter, but he has no idea *what*. He fumbles through his red \
- squeezey changepurse and gives the boy three extra pennies with his \
- dollar, hoping that he might luck into the correct amount. The boy \
- gives him back two of his own pennies and then the big shiny quarter \
- that is his prize. -RICHH");
+
+ sv_setpv(text, "When he is at a convenience store and the bill comes to some amount like 76 cents, Maynard is aware that there is something he *should* do, something that will enable him to get back a quarter, but he has no idea *what*. He fumbles through his red squeezey changepurse and gives the boy three extra pennies with his dollar, hoping that he might luck into the correct amount. The boy gives him back two of his own pennies and then the big shiny quarter that is his prize. -RICHH");
+
if (match(text, "m/quarter/")) /** Does text contain 'quarter'? **/
- printf("match: Text contains the word 'quarter'.\n\n");
+ printf("match: Text contains the word 'quarter'.\n\n");
else
- printf("match: Text doesn't contain the word 'quarter'.\n\n");
+ printf("match: Text doesn't contain the word 'quarter'.\n\n");
+
if (match(text, "m/eighth/")) /** Does text contain 'eighth'? **/
- printf("match: Text contains the word 'eighth'.\n\n");
+ printf("match: Text contains the word 'eighth'.\n\n");
else
- printf("match: Text doesn't contain the word 'eighth'.\n\n");
+ printf("match: Text doesn't contain the word 'eighth'.\n\n");
+
/** Match all occurrences of /wi../ **/
num_matches = matches(text, "m/(wi..)/g", &match_list);
printf("matches: m/(wi..)/g found %d matches...\n", num_matches);
+
for (i = 0; i < num_matches; i++)
- printf("match: %s\n", match_list[i]);
+ printf("match: %s\n", SvPV(*av_fetch(match_list, i, FALSE),na));
printf("\n");
- for (i = 0; i < num_matches; i++) {
- free(match_list[i]);
- }
- free(match_list);
+
/** Remove all vowels from text **/
num_matches = substitute(&text, "s/[aeiou]//gi");
if (num_matches) {
- printf("substitute: s/[aeiou]//gi...%d substitutions made.\n",
- num_matches);
- printf("Now text is: %s\n\n", text);
+ printf("substitute: s/[aeiou]//gi...%d substitutions made.\n",
+ num_matches);
+ printf("Now text is: %s\n\n", SvPV(text,na));
}
+
/** Attempt a substitution **/
if (!substitute(&text, "s/Perl/C/")) {
- printf("substitute: s/Perl/C...No substitution made.\n\n");
+ printf("substitute: s/Perl/C...No substitution made.\n\n");
}
- free(text);
+
+ SvREFCNT_dec(text);
+ perl_destruct_level = 1;
perl_destruct(my_perl);
perl_free(my_perl);
- }
+ }
which produces the output (again, long lines have been wrapped here)
match: with
substitute: s/[aeiou]//gi...139 substitutions made.
- Now text is: Whn h s t cnvnnc str nd th bll cms t sm mnt lk 76 cnts,
+ Now text is: Whn h s t cnvnnc str nd th bll cms t sm mnt lk 76 cnts,
Mynrd s wr tht thr s smthng h *shld* d, smthng tht wll nbl hm t gt bck
qrtr, bt h hs n d *wht*. H fmbls thrgh hs rd sqzy chngprs nd gvs th by
thr xtr pnns wth hs dllr, hpng tht h mght lck nt th crrct mnt. Th by gvs
Once you've understood those, embedding Perl in C is easy.
-Because C has no built-in function for integer exponentiation, let's
+Because C has no builtin function for integer exponentiation, let's
make Perl's ** operator available to it (this is less useful than it
sounds, because Perl implements ** with C's I<pow()> function). First
I'll create a stub exponentiation function in I<power.pl>:
dSP; /* initialize stack pointer */
ENTER; /* everything created after here */
SAVETMPS; /* ...is a temporary variable. */
- PUSHMARK(sp); /* remember the stack pointer */
+ PUSHMARK(SP); /* remember the stack pointer */
XPUSHs(sv_2mortal(newSViv(a))); /* push the base onto the stack */
XPUSHs(sv_2mortal(newSViv(b))); /* push the exponent onto stack */
PUTBACK; /* make local stack pointer global */
int main (int argc, char **argv, char **env)
{
- char *my_argv[2];
+ char *my_argv[] = { "", "power.pl" };
my_perl = perl_alloc();
perl_construct( my_perl );
- my_argv[1] = (char *) malloc(10);
- sprintf(my_argv[1], "power.pl");
-
- perl_parse(my_perl, NULL, argc, my_argv, NULL);
+ perl_parse(my_perl, NULL, 2, my_argv, (char **)NULL);
perl_run(my_perl);
PerlPower(3, 4); /*** Compute 3 ** 4 ***/
applications, it's a good idea to maintain a persistent interpreter
rather than allocating and constructing a new interpreter multiple
times. The major reason is speed: since Perl will only be loaded into
-memory once.
+memory once.
However, you have to be more cautious with namespace and variable
scoping when using a persistent interpreter. In previous examples
One way to avoid namespace collisions in this scenario is to translate
the filename into a guaranteed-unique package name, and then compile
-the code into that package using L<perlfunc/eval>. In the example
+the code into that package using eval(). In the example
below, each file will only be compiled once. Or, the application
might choose to clean out the symbol table associated with the file
-after it's no longer needed. Using L<perlcall/perl_call_argv>, We'll
+after it's no longer needed. Using perl_call_argv(), We'll
call the subroutine C<Embed::Persistent::eval_file> which lives in the
file C<persistent.pl> and pass the filename and boolean cleanup/cache
flag as arguments.
add some logic that keeps track of the process size, or restarts
itself after a certain number of requests, to ensure that memory
consumption is minimized. You'll also want to scope your variables
-with L<perlfunc/my> whenever possible.
+with my() whenever possible.
+
-
package Embed::Persistent;
#persistent.pl
-
+
use strict;
use vars '%Cache';
-
+ use Symbol qw(delete_package);
+
sub valid_package_name {
my($string) = @_;
$string =~ s/([^A-Za-z0-9\/])/sprintf("_%2x",unpack("C",$1))/eg;
# second pass only for words starting with a digit
$string =~ s|/(\d)|sprintf("/_%2x",unpack("C",$1))|eg;
-
+
# Dress it up as a real package name
$string =~ s|/|::|g;
return "Embed" . $string;
}
-
- #borrowed from Safe.pm
- sub delete_package {
- my $pkg = shift;
- my ($stem, $leaf);
-
- no strict 'refs';
- $pkg = "main::$pkg\::"; # expand to full symbol table name
- ($stem, $leaf) = $pkg =~ m/(.*::)(\w+::)$/;
-
- my $stem_symtab = *{$stem}{HASH};
-
- delete $stem_symtab->{$leaf};
- }
-
+
sub eval_file {
my($filename, $delete) = @_;
my $package = valid_package_name($filename);
my $mtime = -M $filename;
if(defined $Cache{$package}{mtime}
&&
- $Cache{$package}{mtime} <= $mtime)
+ $Cache{$package}{mtime} <= $mtime)
{
- # we have compiled this subroutine already,
+ # we have compiled this subroutine already,
# it has not been updated on disk, nothing left to do
print STDERR "already compiled $package->handler\n";
}
local($/) = undef;
my $sub = <FH>;
close FH;
-
+
#wrap the code into a subroutine inside our unique package
my $eval = qq{package $package; sub handler { $sub; }};
{
eval $eval;
}
die $@ if $@;
-
+
#cache it unless we're cleaning out each time
$Cache{$package}{mtime} = $mtime unless $delete;
}
-
+
eval {$package->handler;};
die $@ if $@;
-
+
delete_package($package) if $delete;
-
+
#take a look if you want
#print Devel::Symdump->rnew($package)->as_string, $/;
}
-
+
1;
-
+
__END__
/* persistent.c */
- #include <EXTERN.h>
- #include <perl.h>
-
+ #include <EXTERN.h>
+ #include <perl.h>
+
/* 1 = clean out filename's symbol table after each request, 0 = don't */
#ifndef DO_CLEAN
#define DO_CLEAN 0
#endif
-
+
static PerlInterpreter *perl = NULL;
-
+
int
main(int argc, char **argv, char **env)
{
char *args[] = { "", DO_CLEAN, NULL };
char filename [1024];
int exitstatus = 0;
-
+
if((perl = perl_alloc()) == NULL) {
fprintf(stderr, "no memory!");
exit(1);
}
- perl_construct(perl);
-
+ perl_construct(perl);
+
exitstatus = perl_parse(perl, NULL, 2, embedding, NULL);
-
- if(!exitstatus) {
+
+ if(!exitstatus) {
exitstatus = perl_run(perl);
-
+
while(printf("Enter file name: ") && gets(filename)) {
-
+
/* call the subroutine, passing it the filename as an argument */
args[0] = filename;
- perl_call_argv("Embed::Persistent::eval_file",
+ perl_call_argv("Embed::Persistent::eval_file",
G_DISCARD | G_EVAL, args);
-
+
/* check $@ */
- if(SvTRUE(GvSV(errgv)))
+ if(SvTRUE(GvSV(errgv)))
fprintf(stderr, "eval error: %s\n", SvPV(GvSV(errgv),na));
}
}
-
+
perl_destruct_level = 0;
- perl_destruct(perl);
- perl_free(perl);
+ perl_destruct(perl);
+ perl_free(perl);
exit(exitstatus);
}
-
Now compile:
- % cc -o persistent persistent.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
+ % cc -o persistent persistent.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
Here's a example script file:
Some rare applications will need to create more than one interpreter
during a session. Such an application might sporadically decide to
-release any resources associated with the interpreter.
+release any resources associated with the interpreter.
The program must take care to ensure that this takes place I<before>
the next interpreter is constructed. By default, the global variable
Setting C<perl_destruct_level> to C<1> makes everything squeaky clean:
- perl_destruct_level = 1;
+ perl_destruct_level = 1;
while(1) {
...
/* reset global variables here with perl_destruct_level = 1 */
- perl_construct(my_perl);
+ perl_construct(my_perl);
...
/* clean and reset _everything_ during perl_destruct */
- perl_destruct(my_perl);
- perl_free(my_perl);
+ perl_destruct(my_perl);
+ perl_free(my_perl);
...
/* let's go do it again! */
}
-When I<perl_destruct()> is called, the interpreter's syntax parse tree
-and symbol tables are cleaned up, and global variables are reset.
+When I<perl_destruct()> is called, the interpreter's syntax parse tree
+and symbol tables are cleaned up, and global variables are reset.
Now suppose we have more than one interpreter instance running at the
same time. This is feasible, but only if you used the
int main(int argc, char **argv, char **env)
{
- PerlInterpreter
+ PerlInterpreter
*one_perl = perl_alloc(),
- *two_perl = perl_alloc();
+ *two_perl = perl_alloc();
char *one_args[] = { "one_perl", SAY_HELLO };
char *two_args[] = { "two_perl", SAY_HELLO };
Consult L<perlxs> and L<perlguts> for more details.
+=head1 Embedding Perl under Win32
+
+At the time of this writing, there are two versions of Perl which run
+under Win32. Interfacing to Activeware's Perl library is quite
+different from the examples in this documentation, as significant
+changes were made to the internal Perl API. However, it is possible
+to embed Activeware's Perl runtime, see the Perl for Win32 FAQ:
+http://www.perl.com/perl/faq/win32/Perl_for_Win32_FAQ.html
+
+With the "official" Perl version 5.004 or higher, all the examples
+within this documentation will compile and run untouched, although,
+the build process is slightly different between Unix and Win32.
+
+For starters, backticks don't work under the Win32 native command shell!
+The ExtUtils::Embed kit on CPAN ships with a script called
+B<genmake>, which generates a simple makefile to build a program from
+a single C source file. It can be used like so:
+
+ C:\ExtUtils-Embed\eg> perl genmake interp.c
+ C:\ExtUtils-Embed\eg> nmake
+ C:\ExtUtils-Embed\eg> interp -e "print qq{I'm embedded in Win32!\n}"
+
+You may wish to use a more robust environment such as the MS Developer
+stdio. In this case, to generate perlxsi.c run:
+
+ perl -MExtUtils::Embed -e xsinit
+
+Create a new project, Insert -> Files into Project: perlxsi.c, perl.lib,
+and your own source files, e.g. interp.c. Typically you'll find
+perl.lib in B<C:\perl\lib\CORE>, if not, you should see the B<CORE>
+directory relative to C<perl -V:archlib>.
+The studio will also need this path so it knows where to find Perl
+include files. This path can be added via the Tools -> Options ->
+Directories menu. Finnally, select Build -> Build interp.exe and
+you're ready to go!
=head1 MORAL
Check out Doug's article on embedding in Volume 1, Issue 4 of The Perl
Journal. Info about TPJ is available from http://tpj.com.
-February 1, 1997
+July 17, 1997
Some of this material is excerpted from Jon Orwant's book: I<Perl 5
Interactive>, Waite Group Press, 1996 (ISBN 1-57169-064-6) and appears
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