View Source: perlembed(1) - Waikato Linux Users Group

Edit PageHistory Diff Info LikePages
PERLEMBED
!!!PERLEMBED
NAME
DESCRIPTION
Embedding Perl under Win32
MORAL
AUTHOR
COPYRIGHT
----
!!NAME


perlembed - how to embed perl in your C program
!!DESCRIPTION


__PREAMBLE__


Do you want to:


__Use C from Perl?__


Read perlxstut, perlxs, h2xs, perlguts, and
perlapi.


__Use a Unix program from Perl?__


Read about back-quotes and about system and
exec in perlfunc.


__Use Perl from Perl?__


Read about ``do'' in perlfunc and ``eval'' in perlfunc and
``require'' in perlfunc and ``use'' in
perlfunc.


__Use C from C?__


Rethink your design.


__Use Perl from C?__


Read on...


__ROADMAP__


Compiling your C program


Adding a Perl interpreter to your C program


Calling a Perl subroutine from your C program


Evaluating a Perl statement from your C program


Performing Perl pattern matches and substitutions from your
C program


Fiddling with the Perl stack from your C
program


Maintaining a persistent interpreter


Maintaining multiple interpreter instances


Using Perl modules, which themselves use C libraries, from
your C program


Embedding Perl under Win32


__Compiling your C program__


If you have trouble compiling the scripts in this
documentation, you're not alone. The cardinal rule:
COMPILE THE PROGRAMS IN EXACTLY THE SAME WAY THAT
YOUR PERL WAS COMPILED . (Sorry for
yelling.)


Also, every C program that uses Perl must link in the
''perl library''. What's that, you ask? Perl is itself
written in C; the perl library is the collection of compiled
C programs that were used to create your perl executable
(''/usr/bin/perl'' or equivalent). (Corollary: you can't
use Perl from your C program unless Perl has been compiled
on your machine, or installed properly--that's why you
shouldn't blithely copy Perl executables from machine to
machine without also copying the ''lib''
directory.)


When you use Perl from C, your C program
will--usually--allocate, ``run'', and deallocate a
''!PerlInterpreter'' object, which is defined by the perl
library.


If your copy of Perl is recent enough to contain this
documentation (version 5.002 or later), then the perl
library (and ''EXTERN .h'' and
''perl.h'', which you'll also need) will reside in a
directory that looks like this:


    /usr/local/lib/perl5/your_architecture_here/CORE
or perhaps just


    /usr/local/lib/perl5/CORE
or maybe something like


    /usr/opt/perl5/CORE
Execute this statement for a hint about where to find CORE:


    perl -MConfig -e 'print $Config{archlib}'
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
-I/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 old 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
-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 perl -V command and pay special attention to the ``cc'' and ``ccflags'' information.


You'll have to choose the appropriate compiler (''cc'',
''gcc'', et al.) for your machine: perl -MConfig -e
'print $Config{cc}' will tell you what to
use.


You'll also have to choose the appropriate library directory
(''/usr/local/lib/...'') for your machine. If your
compiler complains that certain functions are undefined, or
that it can't locate ''-lperl'', then you need to change
the path following the -L. If it complains that it
can't find ''EXTERN .h'' and
''perl.h'', you need to change the path following the
-I.


You may have to add extra libraries as well. Which ones?
Perhaps those printed by


   perl -MConfig -e 'print $Config{libs}'
Provided your perl binary was properly configured and installed the __!ExtUtils::Embed__ module will determine all of this information for you:


   % cc -o interp interp.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
If the __!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/. (If this documentation came from your Perl distribution, then you're running 5.004 or better and you already have it.)


The __!ExtUtils::Embed__ kit on CPAN also
contains all source code for the examples in this document,
tests, additional examples and other information you may
find useful.


__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 ''miniperlmain.c'', included in the source
distribution. Here's a bastardized, nonportable version of
''miniperlmain.c'' containing the essentials of
embedding:


    #include
    static !PerlInterpreter *my_perl;  /***    The Perl interpreter    ***/
    int main(int argc, char **argv, char **env)
{
my_perl = perl_alloc();
perl_construct(my_perl);
perl_parse(my_perl, NULL, argc, argv, (char **)NULL);
perl_run(my_perl);
perl_destruct(my_perl);
perl_free(my_perl);
}
Notice that we don't use the env pointer. Normally handed to perl_parse as its final argument, env here is replaced by NULL, which means that the current environment will be used.


Now compile this program (I'll call it ''interp.c'') into
an executable:


    % cc -o interp interp.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
After a successful compilation, you'll be able to use ''interp'' just like perl itself:


    % interp
print
or


    % interp -e 'printf(
You can also read and execute Perl statements from a file while in the midst of your C program, by placing the filename in ''argv[[1]'' before calling ''perl_run''.


__Calling a Perl subroutine from your C
program__


To call individual Perl subroutines, you can use any of the
__call_*__ functions documented in perlcall. In this
example we'll use call_argv.


That's shown below, in a program I'll call
''showtime.c''.


    #include
    static !PerlInterpreter *my_perl;
    int main(int argc, char **argv, char **env)
{
char *args[[] = { NULL };
my_perl = perl_alloc();
perl_construct(my_perl);
        perl_parse(my_perl, NULL, argc, argv, NULL);
        /*** skipping perl_run() ***/
        call_argv(
        perl_destruct(my_perl);
perl_free(my_perl);
}
where ''showtime'' is a Perl subroutine that takes no arguments (that's the ''G_NOARGS'') and for which I'll ignore the return value (that's the ''G_DISCARD''). Those flags, and others, are discussed in perlcall.


I'll define the ''showtime'' subroutine in a file called
''showtime.pl'':


    print
    sub showtime {
print time;
}
Simple enough. Now compile and run:


    % cc -o showtime showtime.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
    % showtime showtime.pl
818284590
yielding the number of seconds that elapsed between January 1, 1970 (the beginning of the Unix epoch), and the moment I began writing this sentence.


In this particular case we don't have to call
''perl_run'', but in general it's considered good
practice to ensure proper initialization of library code,
including execution of all object DESTROY methods
and package END {} blocks.


If you want to pass arguments to the Perl subroutine, you
can add strings to the NULL-terminated
args list passed to ''call_argv''. For other
data types, or to examine return values, you'll need to
manipulate the Perl stack. That's demonstrated in ``Fiddling
with the Perl stack from your C program''.


__Evaluating a Perl statement from your C
program__


Perl provides two API functions to evaluate
pieces of Perl code. These are ``eval_sv'' in perlapi and
``eval_pv'' in perlapi.


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 ``use'' in perlfunc,
``require'' in perlfunc, and ``do'' in perlfunc to include
external Perl files.


''eval_pv'' lets us evaluate individual Perl strings, and
then extract variables for coercion into C types. The
following program, ''string.c'', executes three Perl
strings, extracting an int from the first, a
float from the second, and a char * from
the third.


   #include
   static !PerlInterpreter *my_perl;
   main (int argc, char **argv, char **env)
{
STRLEN n_a;
char *embedding[[] = {
       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 **/
eval_pv(
       /** Treat $a as a float **/
eval_pv(
       /** Treat $a as a string **/
eval_pv(
       perl_destruct(my_perl);
perl_free(my_perl);
}
All of those strange functions with ''sv'' in their names help convert Perl scalars to C types. They're described in perlguts and perlapi.


If you compile and run ''string.c'', you'll see the
results of using ''SvIV()'' to create an int,
''SvNV()'' to create a float, and ''SvPV()''
to create a string:


   a = 9
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 ''eval_pv()'' instead. Example:


   ...
STRLEN n_a;
SV *val = eval_pv(
This way, we avoid namespace pollution by not creating global variables and we've simplified our code as well.


__Performing Perl pattern matches and substitutions from
your C program__


The ''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: ''match()'',
''substitute()'', and ''matches()''.


   I32 match(SV *string, char *pattern);
Given a string and a pattern (e.g., m/clasp/ or /bw*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(SV **string, char *pattern);
Given a pointer to an SV and an =~ operation (e.g., s/bob/robert/g or tr[[A-Z][[a-z]), ''substitute()'' modifies the string within the AV at according to the operation, returning the number of substitutions made.


   int matches(SV *string, char *pattern, AV **matches);
Given an SV, a pattern, and a pointer to an empty AV, ''matches()'' evaluates $string =~ $pattern in a list context, and fills in ''matches'' with the array elements, returning the number of matches found.


Here's a sample program, ''match.c'', that uses all three
(long lines have been wrapped here):


 #include
 /** my_eval_sv(code, error_check)
** kinda like eval_sv(),
** but we pop the return value off the stack
**/
SV* my_eval_sv(SV *sv, I32 croak_on_error)
{
dSP;
SV* retval;
STRLEN n_a;
     PUSHMARK(SP);
eval_sv(sv, G_SCALAR);
     SPAGAIN;
retval = POPs;
PUTBACK;
     if (croak_on_error
     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,
     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,
     retval = my_eval_sv(command, TRUE);
SvREFCNT_dec(command);
     *string = get_sv(
 /** matches(string, pattern, matches)
**
** Used for matches in a list 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_eval_sv(command, TRUE);
SvREFCNT_dec(command);
     *match_list = get_av(
     return num_matches;
}
 main (int argc, char **argv, char **env)
{
!PerlInterpreter *my_perl = perl_alloc();
char *embedding[[] = {
     perl_construct(my_perl);
perl_parse(my_perl, NULL, 3, embedding, NULL);
     sv_setpv(text,
     if (match(text,
     if (match(text,
     /** Match all occurrences of /wi../ **/
num_matches = matches(text,
     for (i = 0; i
     /** Remove all vowels from text **/
num_matches = substitute(
     /** Attempt a substitution **/
if (!substitute(
     SvREFCNT_dec(text);
PL_perl_destruct_level = 1;
perl_destruct(my_perl);
perl_free(my_perl);
}
which produces the output (again, long lines have been wrapped here)


   match: Text contains the word 'quarter'.
   match: Text doesn't contain the word 'eighth'.
   matches: m/(wi..)/g found 2 matches...
match: will
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,
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
hm bck tw f hs wn pnns nd thn th bg shny qrtr tht s hs prz. -RCHH
   substitute: s/Perl/C...No substitution made.


__Fiddling with the Perl stack from your C
program__


When trying to explain stacks, most computer science
textbooks mumble something about spring-loaded columns of
cafeteria plates: the last thing you pushed on the stack is
the first thing you pop off. That'll do for our purposes:
your C program will push some arguments onto ``the Perl
stack'', shut its eyes while some magic happens, and then
pop the results--the return value of your Perl
subroutine--off the stack.


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
perlguts and perlapi.


Then you'll need to know how to manipulate the Perl stack.
That's described in perlcall.


Once you've understood those, embedding Perl in C is
easy.


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 ''pow()'' function). First I'll
create a stub exponentiation function in
''power.pl'':


    sub expo {
my ($a, $b) = @_;
return $a ** $b;
}
Now I'll create a C program, ''power.c'', with a function ''!PerlPower()'' that contains all the perlguts necessary to push the two arguments into ''expo()'' and to pop the return value out. Take a deep breath...


    #include
    static !PerlInterpreter *my_perl;
    static void
!PerlPower(int a, int b)
{
dSP;                            /* initialize stack pointer      */
ENTER;                          /* everything created after here */
SAVETMPS;                       /* ...is a temporary variable.   */
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 */
call_pv(
    int main (int argc, char **argv, char **env)
{
char *my_argv[[] = {
      my_perl = perl_alloc();
perl_construct( my_perl );
      perl_parse(my_perl, NULL, 2, my_argv, (char **)NULL);
perl_run(my_perl);
      !PerlPower(3, 4);                      /*** Compute 3 ** 4 ***/
      perl_destruct(my_perl);
perl_free(my_perl);
}
Compile and run:


    % cc -o power power.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
    % power
3 to the 4th power is 81.


__Maintaining a persistent interpreter__


When developing interactive and/or potentially long-running
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.


However, you have to be more cautious with namespace and
variable scoping when using a persistent interpreter. In
previous examples we've been using global variables in the
default package main. We knew exactly what code
would be run, and assumed we could avoid variable collisions
and outrageous symbol table growth.


Let's say your application is a server that will
occasionally run Perl code from some arbitrary file. Your
server has no way of knowing what code it's going to run.
Very dangerous.


If the file is pulled in by perl_parse(), compiled
into a newly constructed interpreter, and subsequently
cleaned out with perl_destruct() afterwards, you're
shielded from most namespace troubles.


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
``eval'' in perlfunc. 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 ``call_argv'' in perlapi, We'll
call the subroutine Embed::Persistent::eval_file
which lives in the file persistent.pl and pass the
filename and boolean cleanup/cache flag as
arguments.


Note that the process will continue to grow for each file
that it uses. In addition, there might be
AUTOLOADed subroutines and other conditions that
cause Perl's symbol table to grow. You might want to 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 ``my'' in perlfunc whenever
possible.


 package Embed::Persistent;
#persistent.pl
 use strict;
our %Cache;
use Symbol qw(delete_package);
 sub valid_package_name {
my($string) = @_;
$string =~ s/([[^A-Za-z0-9/])/sprintf(
     # Dress it up as a real package name
$string =~ s/::g;
return
 sub eval_file {
my($filename, $delete) = @_;
my $package = valid_package_name($filename);
my $mtime = -M $filename;
if(defined $Cache{$package}{mtime}
        #wrap the code into a subroutine inside our unique package
my $eval = qq{package $package; sub handler { $sub; }};
{
# hide our variables within this block
my($filename,$mtime,$package,$sub);
eval $eval;
}
die $@ if $@;
        #cache it unless we're cleaning out each time
$Cache{$package}{mtime} = $mtime unless $delete;
}
     eval {$package-
     delete_package($package) if $delete;
     #take a look if you want
#print Devel::Symdump-
 1;
 __END__
 /* persistent.c */
#include
 /* 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 *embedding[[] = {
     if((perl = perl_alloc()) == NULL) {
fprintf(stderr,
     exitstatus = perl_parse(perl, NULL, 2, embedding, NULL);
     if(!exitstatus) {
exitstatus = perl_run(perl);
        while(printf(
            /* call the subroutine, passing it the filename as an argument */
args[[0] = filename;
call_argv(
            /* check $@ */
if(SvTRUE(ERRSV))
fprintf(stderr,
     PL_perl_destruct_level = 0;
perl_destruct(perl);
perl_free(perl);
exit(exitstatus);
}
Now compile:


 % cc -o persistent persistent.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
Here's a example script file:


 #test.pl
my $string =
 sub foo {
print
Now run:


 % persistent
Enter file name: test.pl
foo says: hello
Enter file name: test.pl
already compiled Embed::test_2epl-


__Maintaining multiple interpreter
instances__


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.


The program must take care to ensure that this takes place
''before'' the next interpreter is constructed. By
default, when perl is not built with any special options,
the global variable PL_perl_destruct_level is set
to 0, since extra cleaning isn't usually needed
when a program only ever creates a single interpreter in its
entire lifetime.


Setting PL_perl_destruct_level to 1 makes
everything squeaky clean:


 PL_perl_destruct_level = 1;
 while(1) {
...
/* reset global variables here with PL_perl_destruct_level = 1 */
perl_construct(my_perl);
...
/* clean and reset _everything_ during perl_destruct */
perl_destruct(my_perl);
perl_free(my_perl);
...
/* let's go do it again! */
}
When ''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 Configure option -Dusemultiplicity or the
options -Dusethreads -Duseithreads when building
Perl. By default, enabling one of these Configure options
sets the per-interpreter global variable
PL_perl_destruct_level to 1, so that
thorough cleaning is automatic.


Using -Dusethreads -Duseithreads rather than
-Dusemultiplicity is more appropriate if you intend
to run multiple interpreters concurrently in different
threads, because it enables support for linking in the
thread libraries of your system with the
interpreter.


Let's give it a try:


 #include
 /* we're going to embed two interpreters */
/* we're going to embed two interpreters */
 #define SAY_HELLO
 int main(int argc, char **argv, char **env)
{
!PerlInterpreter
*one_perl = perl_alloc(),
*two_perl = perl_alloc();
char *one_args[[] = {
     PERL_SET_CONTEXT(one_perl);
perl_construct(one_perl);
PERL_SET_CONTEXT(two_perl);
perl_construct(two_perl);
     PERL_SET_CONTEXT(one_perl);
perl_parse(one_perl, NULL, 3, one_args, (char **)NULL);
PERL_SET_CONTEXT(two_perl);
perl_parse(two_perl, NULL, 3, two_args, (char **)NULL);
     PERL_SET_CONTEXT(one_perl);
perl_run(one_perl);
PERL_SET_CONTEXT(two_perl);
perl_run(two_perl);
     PERL_SET_CONTEXT(one_perl);
perl_destruct(one_perl);
PERL_SET_CONTEXT(two_perl);
perl_destruct(two_perl);
     PERL_SET_CONTEXT(one_perl);
perl_free(one_perl);
PERL_SET_CONTEXT(two_perl);
perl_free(two_perl);
}
Note the calls to ''PERL_SET_CONTEXT ()''. These are necessary to initialize the global state that tracks which interpreter is the ``current'' one on the particular process or thread that may be running it. It should always be used if you have more than one interpreter and are making perl API calls on both interpreters in an interleaved fashion.


PERL_SET_CONTEXT (interp) should also be
called whenever interp is used by a thread that did
not create it (using either ''perl_alloc()'', or the more
esoteric ''perl_clone()'').


Compile as usual:


 % cc -o multiplicity multiplicity.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
Run it, Run it:


 % multiplicity
Hi, I'm one_perl
Hi, I'm two_perl


__Using Perl modules, which themselves use C libraries,
from your C program__


If you've played with the examples above and tried to embed
a script that ''use()''s a Perl module (such as
''Socket'') which itself uses a C or C ++
library, this probably happened:


 Can't load module Socket, dynamic loading not available in this perl.
(You may need to build a new perl executable which either supports
dynamic loading or has the Socket module statically linked into it.)
What's wrong?


Your interpreter doesn't know how to communicate with these
extensions on its own. A little glue will help. Up until now
you've been calling ''perl_parse()'', handing it
NULL for the second argument:


 perl_parse(my_perl, NULL, argc, my_argv, NULL);
That's where the glue code can be inserted to create the initial contact between Perl and linked C/C ++ routines. Let's take a look some pieces of ''perlmain.c'' to see how Perl does this:


 static void xs_init (pTHX);
 EXTERN_C void boot_!DynaLoader (pTHX_ CV* cv);
EXTERN_C void boot_Socket (pTHX_ CV* cv);
 EXTERN_C void
xs_init(pTHX)
{
char *file = __FILE__;
/* !DynaLoader is a special case */
newXS(
Simply put: for each extension linked with your Perl executable (determined during its initial configuration on your computer or when adding a new extension), a Perl subroutine is created to incorporate the extension's routines. Normally, that subroutine is named ''Module::bootstrap()'' and is invoked when you say ''use Module''. In turn, this hooks into an XSUB , ''boot_Module'', which creates a Perl counterpart for each of the extension's XSUBs. Don't worry about this part; leave that to the ''xsubpp'' and extension authors. If your extension is dynamically loaded, !DynaLoader creates ''Module::bootstrap()'' for you on the fly. In fact, if you have a working !DynaLoader then there is rarely any need to link in any other extensions statically.


Once you have this code, slap it into the second argument of
''perl_parse()'':


 perl_parse(my_perl, xs_init, argc, my_argv, NULL);
Then compile:


 % cc -o interp interp.c `perl -MExtUtils::Embed -e ccopts -e ldopts`
 % interp
use Socket;
use !SomeDynamicallyLoadedModule;
   print
__!ExtUtils::Embed__ can also automate writing the ''xs_init'' glue code.


 % perl -MExtUtils::Embed -e xsinit -- -o perlxsi.c
% cc -c perlxsi.c `perl -MExtUtils::Embed -e ccopts`
% cc -c interp.c  `perl -MExtUtils::Embed -e ccopts`
% cc -o interp perlxsi.o interp.o `perl -MExtUtils::Embed -e ldopts`
Consult perlxs, perlguts, and perlapi for more details.
!!Embedding Perl under Win32


In general, all of the source code shown here should work
unmodified under Windows.


However, there are some caveats about the command-line
examples shown. For starters, backticks won't work under the
Win32 native command shell. The !ExtUtils::Embed kit on
CPAN ships with a script called
__genmake__, which generates a simple makefile to build a
program from a single C source file. It can be used like
this:


 C:!ExtUtils-Embedeg
You may wish to use a more robust environment such as the Microsoft Developer Studio. In this case, run this to generate perlxsi.c:


 perl -MExtUtils::Embed -e xsinit
Create a new project and Insert -C:perllibCORE__, if not, you should see the __CORE__ directory relative to 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 -
!!MORAL


You can sometimes ''write faster code'' in C, but you can
always ''write code faster'' in Perl. Because you can use
each from the other, combine them as you wish.
!!AUTHOR


Jon Orwant orwant@tpj.com''
''dougm@osf.org''
''


Doug !MacEachern has an article on embedding in Volume 1,
Issue 4 of The Perl Journal (http://tpj.com). Doug is also
the developer of the most widely-used Perl embedding: the
mod_perl system (perl.apache.org), which embeds Perl in the
Apache web server. Oracle, Binary Evolution, !ActiveState,
and Ben Sugars's nsapi_perl have used this model for Oracle,
Netscape and Internet Information Server Perl
plugins.


July 22, 1998
!!COPYRIGHT


Copyright (C) 1995, 1996, 1997, 1998 Doug !MacEachern and Jon
Orwant. All Rights Reserved.


Permission is granted to make and distribute verbatim copies
of this documentation provided the copyright notice and this
permission notice are preserved on all copies.


Permission is granted to copy and distribute modified
versions of this documentation under the conditions for
verbatim copying, provided also that they are marked clearly
as modified versions, that the authors' names and title are
unchanged (though subtitles and additional authors' names
may be added), and that the entire resulting derived work is
distributed under the terms of a permission notice identical
to this one.


Permission is granted to copy and distribute translations of
this documentation into another language, under the above
conditions for modified versions.
----
2 pages link to perlembed(1):
This page is a man page (or other imported legacy content). We are unable to automatically determine the license status of this page.
Last edited on Monday, June 3, 2002 6:50:44 pm by "perry"
Edit PageHistory Diff Info LikePages