FFI::Platypus::Constant(3pm)

Usage

"ffi/foo.c":

 #include <ffi_platypus_bundle.h>
 
 void
 ffi_pl_bundle_constant(const char *package, ffi_platypus_constant_t *c)
 {
   c->set_str("FOO", "BAR");       /* sets $package::FOO to "BAR" */
   c->set_str("ABC::DEF", "GHI");  /* sets ABC::DEF to GHI        */
 }

"lib/Foo.pm":

 package Foo;
 
 use strict;
 use warnings;
 use FFI::Platypus 2.00;
 use Exporter qw( import );
 
 my $ffi = FFI::Platypus->new( api => 2 );
 # sets constants Foo::FOO and ABC::DEF from C
 $ffi->bundle;
 
 1;

Version

version 2.10

Overview

The Platypus bundle interface (see FFI::Platypus::Bundle) has an entry point "ffi_pl_bundle_constant" that lets you define constants in Perl space from C.

 void ffi_pl_bundle_constant(const char *package, ffi_platypus_constant_t *c);

The first argument "package" is the name of the Perl package. The second argument "c" is a struct with function pointers that lets you define constants of different types. The first argument for each function is the name of the constant and the second is the value. If "::" is included in the constant name then it will be defined in that package space. If it isn't then the constant will be defined in whichever package called "bundle".

set_str: c->set_str(name, value);

Sets a string constant.

set_sint: c->set_sint(name, value);

Sets a 64-bit signed integer constant.

set_uint: c->set_uint(name, value);

Sets a 64-bit unsigned integer constant.

set_double: c->set_double(name, value);

Sets a double precision floating point constant.

Example

Suppose you have a header file "myheader.h":

 #ifndef MYHEADER_H
 #define MYHEADER_H
 
 #define MYVERSION_STRING "1.2.3"
 #define MYVERSION_MAJOR 1
 #define MYVERSION_MINOR 2
 #define MYVERSION_PATCH 3
 
 enum {
   MYBAD = -1,
   MYOK  = 1
 };
 
 #define MYPI 3.14
 
 #endif

You can define these constants from C:

 #include <ffi_platypus_bundle.h>
 #include "myheader.h"
 
 void ffi_pl_bundle_constant(const char *package, ffi_platypus_constant_t *c)
 {
   c->set_str("MYVERSION_STRING", MYVERSION_STRING);
   c->set_uint("MYVERSION_MAJOR", MYVERSION_MAJOR);
   c->set_uint("MYVERSION_MINOR", MYVERSION_MINOR);
   c->set_uint("MYVERSION_PATCH", MYVERSION_PATCH);
   c->set_sint("MYBAD", MYBAD);
   c->set_sint("MYOK", MYOK);
   c->set_double("MYPI", MYPI);
 }

Your Perl code doesn't have to do anything when calling bundle:

 package Const;
 
 use strict;
 use warnings;
 use FFI::Platypus 2.00;
 
 {
   my $ffi = FFI::Platypus->new( api => 2 );
   $ffi->bundle;
 }
 
 1;

Copyright and license

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

Releases

3 releases since Debian 11 (Bullseye); the text changed 2 times.

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