=item B<Use C from Perl?>
-Read L<perlxstut>, L<perlxs>, L<h2xs>, and L<perlguts>.
+Read L<perlxstut>, L<perlxs>, L<h2xs>, L<perlguts>, and L<perlapi>.
=item B<Use a Unix program from Perl?>
=head2 ROADMAP
+=over 5
+
L<Compiling your C program>
L<Adding a Perl interpreter to your C program>
If the B<ExtUtils::Embed> module isn't part of your Perl distribution,
you can retrieve it from
-http://www.perl.com/perl/CPAN/modules/by-module/ExtUtils::Embed. (If
+http://www.perl.com/perl/CPAN/modules/by-module/ExtUtils/. (If
this documentation came from your Perl distribution, then you're
running 5.004 or better and you already have it.)
=head2 Calling a Perl subroutine from your C program
-To call individual Perl subroutines, you can use any of the B<perl_call_*>
+To call individual Perl subroutines, you can use any of the B<call_*>
functions documented in L<perlcall>.
-In this example we'll use C<perl_call_argv>.
+In this example we'll use C<call_argv>.
That's shown below, in a program I'll call I<showtime.c>.
/*** skipping perl_run() ***/
- perl_call_argv("showtime", G_DISCARD | G_NOARGS, args);
+ call_argv("showtime", G_DISCARD | G_NOARGS, args);
perl_destruct(my_perl);
perl_free(my_perl);
If you want to pass arguments to the Perl subroutine, you can add
strings to the C<NULL>-terminated C<args> list passed to
-I<perl_call_argv>. For other data types, or to examine return values,
+I<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>.
=head2 Evaluating a Perl statement from your C program
Perl provides two API functions to evaluate pieces of Perl code.
-These are L<perlguts/perl_eval_sv> and L<perlguts/perl_eval_pv>.
+These are L<perlapi/eval_sv> and L<perlapi/eval_pv>.
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
L<perlfunc/use>, L<perlfunc/require>, and L<perlfunc/do> to
include external Perl files.
-I<perl_eval_pv> lets us evaluate individual Perl strings, and then
+I<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;
-
+
main (int argc, char **argv, char **env)
{
+ STRLEN n_a;
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; $a **= 2", TRUE);
- printf("a = %d\n", SvIV(perl_get_sv("a", FALSE)));
-
+ eval_pv("$a = 3; $a **= 2", TRUE);
+ printf("a = %d\n", SvIV(get_sv("a", FALSE)));
+
/** Treat $a as a float **/
- perl_eval_pv("$a = 3.14; $a **= 2", TRUE);
- printf("a = %f\n", SvNV(perl_get_sv("a", FALSE)));
-
+ eval_pv("$a = 3.14; $a **= 2", TRUE);
+ printf("a = %f\n", SvNV(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), PL_na));
-
+ eval_pv("$a = 'rekcaH lreP rehtonA tsuJ'; $a = reverse($a);", TRUE);
+ printf("a = %s\n", SvPV(get_sv("a", FALSE), n_a));
+
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>.
+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>.
If you compile and run I<string.c>, you'll see the results of using
I<SvIV()> to create an C<int>, I<SvNV()> to create a C<float>, and
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 I<perl_eval_pv()> instead. Example:
+from I<eval_pv()> instead. Example:
...
- SV *val = perl_eval_pv("reverse 'rekcaH lreP rehtonA tsuJ'", TRUE);
- printf("%s\n", SvPV(val,PL_na));
+ STRLEN n_a;
+ SV *val = eval_pv("reverse 'rekcaH lreP rehtonA tsuJ'", TRUE);
+ printf("%s\n", SvPV(val,n_a));
...
This way, we avoid namespace pollution by not creating global
=head2 Performing Perl pattern matches and substitutions from your C program
-The I<perl_eval_sv()> function lets us evaluate strings of Perl code, so we can
+The I<eval_sv()> function lets us evaluate strings 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()>.
#include <EXTERN.h>
#include <perl.h>
-
- /** my_perl_eval_sv(code, error_check)
- ** kinda like perl_eval_sv(),
+
+ /** my_eval_sv(code, error_check)
+ ** kinda like eval_sv(),
** but we pop the return value off the stack
**/
- SV* my_perl_eval_sv(SV *sv, I32 croak_on_error)
+ SV* my_eval_sv(SV *sv, I32 croak_on_error)
{
dSP;
SV* retval;
-
+ STRLEN n_a;
+
PUSHMARK(SP);
- perl_eval_sv(sv, G_SCALAR);
-
+ eval_sv(sv, G_SCALAR);
+
SPAGAIN;
retval = POPs;
PUTBACK;
-
+
if (croak_on_error && SvTRUE(ERRSV))
- croak(SvPVx(ERRSV, PL_na));
-
+ croak(SvPVx(ERRSV, n_a));
+
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;
-
+ STRLEN n_a;
+
sv_setpvf(command, "my $string = '%s'; $string =~ %s",
- SvPV(string,PL_na), pattern);
-
- retval = my_perl_eval_sv(command, TRUE);
+ SvPV(string,n_a), pattern);
+
+ retval = my_eval_sv(command, TRUE);
SvREFCNT_dec(command);
-
+
return SvIV(retval);
}
-
+
/** substitute(string, pattern)
**
** Used for =~ operations that modify their left-hand side (s/// and tr///)
** Returns the number of successful matches, and
** modifies the input string if there were any.
**/
-
+
I32 substitute(SV **string, char *pattern)
{
SV *command = NEWSV(1099, 0), *retval;
-
+ STRLEN n_a;
+
sv_setpvf(command, "$string = '%s'; ($string =~ %s)",
- SvPV(*string,PL_na), pattern);
-
- retval = my_perl_eval_sv(command, TRUE);
+ SvPV(*string,n_a), pattern);
+
+ retval = my_eval_sv(command, TRUE);
SvREFCNT_dec(command);
-
- *string = perl_get_sv("string", FALSE);
+
+ *string = 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 n_a;
+
sv_setpvf(command, "my $string = '%s'; @array = ($string =~ %s)",
- SvPV(string,PL_na), pattern);
-
- my_perl_eval_sv(command, TRUE);
+ SvPV(string,n_a), pattern);
+
+ my_eval_sv(command, TRUE);
SvREFCNT_dec(command);
-
- *match_list = perl_get_av("array", FALSE);
+
+ *match_list = get_av("array", FALSE);
num_matches = av_len(*match_list) + 1; /** assume $[ is 0 **/
-
+
return num_matches;
}
-
+
main (int argc, char **argv, char **env)
{
PerlInterpreter *my_perl = perl_alloc();
AV *match_list;
I32 num_matches, i;
SV *text = NEWSV(1099,0);
-
+ STRLEN n_a;
+
perl_construct(my_perl);
perl_parse(my_perl, NULL, 3, embedding, NULL);
-
+
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");
else
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");
else
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", SvPV(*av_fetch(match_list, i, FALSE),PL_na));
+ printf("match: %s\n", SvPV(*av_fetch(match_list, i, FALSE),n_a));
printf("\n");
-
+
/** 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", SvPV(text,PL_na));
+ printf("Now text is: %s\n\n", SvPV(text,n_a));
}
-
+
/** Attempt a substitution **/
if (!substitute(&text, "s/Perl/C/")) {
printf("substitute: s/Perl/C...No substitution made.\n\n");
}
-
+
SvREFCNT_dec(text);
PL_perl_destruct_level = 1;
perl_destruct(my_perl);
First you'll need to know how to convert between C types and Perl
types, with newSViv() and sv_setnv() and newAV() and all their
-friends. They're described in L<perlguts>.
+friends. They're described in L<perlguts> and L<perlapi>.
Then you'll need to know how to manipulate the Perl stack. That's
described in L<perlcall>.
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 */
- perl_call_pv("expo", G_SCALAR); /* call the function */
+ call_pv("expo", G_SCALAR); /* call the function */
SPAGAIN; /* refresh stack pointer */
/* pop the return value from stack */
printf ("%d to the %dth power is %d.\n", a, b, POPi);
the code into that package using L<perlfunc/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 L<perlapi/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.
#persistent.pl
use strict;
- use vars '%Cache';
+ our %Cache;
use Symbol qw(delete_package);
sub valid_package_name {
char *args[] = { "", DO_CLEAN, NULL };
char filename [1024];
int exitstatus = 0;
+ STRLEN n_a;
if((perl = perl_alloc()) == NULL) {
fprintf(stderr, "no memory!");
/* call the subroutine, passing it the filename as an argument */
args[0] = filename;
- perl_call_argv("Embed::Persistent::eval_file",
+ call_argv("Embed::Persistent::eval_file",
G_DISCARD | G_EVAL, args);
/* check $@ */
if(SvTRUE(ERRSV))
- fprintf(stderr, "eval error: %s\n", SvPV(ERRSV,PL_na));
+ fprintf(stderr, "eval error: %s\n", SvPV(ERRSV,n_a));
}
}
# define EXTERN_C extern
#endif
- static void xs_init _((void));
+ static void xs_init (void);
- EXTERN_C void boot_DynaLoader _((CV* cv));
- EXTERN_C void boot_Socket _((CV* cv));
+ EXTERN_C void boot_DynaLoader (CV* cv);
+ EXTERN_C void boot_Socket (CV* cv);
EXTERN_C void
% cc -c interp.c `perl -MExtUtils::Embed -e ccopts`
% cc -o interp perlxsi.o interp.o `perl -MExtUtils::Embed -e ldopts`
-Consult L<perlxs> and L<perlguts> for more details.
+Consult L<perlxs>, L<perlguts>, and L<perlapi> for more details.
=head1 Embedding Perl under Win32
examples in this documentation, as significant changes were made to
the internal Perl API. However, it is possible to embed ActiveState's
Perl runtime. For details, see the Perl for Win32 FAQ at
-http://www.perl.com/perl/faq/win32/Perl_for_Win32_FAQ.html.
+http://www.perl.com/CPAN/doc/FAQs/win32/perlwin32faq.html.
With the "official" Perl version 5.004 or higher, all the examples
within this documentation will compile and run untouched, although
projects / p5sagit/p5-mst-13.2.git / blobdiff