FFI::C::Def(3pm)

Usage

In your C code:

 #include <stdint.h>
 #include <stdio.h>
 
 typedef struct {
   uint8_t red;
   uint8_t green;
   uint8_t blue;
 } color_t;
 
 void
 print_color(color_t *c)
 {
   printf("[%02x %02x %02x]\n",
     c->red,
     c->green,
     c->blue
   );
 }

In your Perl code:

 use FFI::Platypus 1.00;
 use FFI::C::StructDef;
 
 my $ffi = FFI::Platypus->new( api => 1 );
 # See FFI::Platypus::Bundle for how bundle works.
 $ffi->bundle;
 
 my $def = FFI::C::StructDef->new(
   $ffi,
   name  => 'color_t',
   class => 'Color',
   members => [
     red   => 'uint8',
     green => 'uint8',
     blue  => 'uint8',
   ],
 );
 
 my $red = Color->new({ red => 255 });
 
 my $green = Color->new({ green => 255 });
 
 $ffi->attach( print_color => ['color_t'] );
 
 print_color($red);   # [ff 00 00]
 print_color($green); # [00 ff 00]
 
 # that red is a tad bright!
 $red->red( 200 );
 
 print_color($red);   # [c8 00 00]

Version

version 0.15

Overview

This class is the base class for all def classes in the FFI::C collection. The def classes are for defining C "struct", "union" and array types that can be used from Perl and passed to C via FFI::Platypus.

You don't create an instance of this class directly, rather one of the subclasses: FFI::C::StructDef, FFI::C::UnionDef, FFI::C::ArrayDef.

Constructor

new

 my $def = FFI::C::StructDef->new(%opts);
 my $def = FFI::C::StructDef->new($ffi, %opts);
 my $def = FFI::C::UnionDef->new(%opts);
 my $def = FFI::C::UnionDef->new($ffi, %opts);
 my $def = FFI::C::ArrayDef->new(%opts);
 my $def = FFI::C::ArrayDef->new($ffi, %opts);

The constructor for this class shouldn't be invoked directly. If you try and exception will be thrown.

For subclasses, the first argument should be the FFI::Platypus instance that you want to use with the def. If you do not provide it, then one will be created internally for you. All def classes accept these standard options:

name: The FFI::Platypus alias for this def. This name can be used in function signatures when creating or attaching functions in FFI::Platypus.

class: The Perl class for this def. The Perl class can be used to create an instance of this def instead of invoking the "create" method below.

members: This is an array reference, which specifies the member fields for the def. How exactly it works depends on the subclass, so see the documentation for the specific def class that you are using.

nullable: If true, then the type can be "undef" when passed into C. "undef" will be translated to "NULL".

Methods

ffi

 my $ffi = $def->ffi;

Returns the FFI::Platypus instance used by this def.

name

 my $name = $def->name;

Return the FFI::Platypus alias for this def. This name can be used in function signatures when creating or attaching functions in FFI::Platypus.

class

 my $class = $def->class;

Returns the Perl class for this def, if one was specified. The Perl class can be used to create an instance of this def instead of invoking the "create" method below.

size

 my $size = $def->size;

Returns the size of the def in bytes.

align

 my $align = $def->align;

Returns the alignment in bytes of the def.

nullable

 my $bool = $def->nullable;

Returns true if "undef" is allowed to be passed in to C functions. "undef" will be translated to "NULL".

create

 my $instance = $def->create;
 my $instance = $def->class->new;  # if class was specified

Creates an instance of the def.

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

Unchanged in 2 releases since Debian 12 (Bookworm).

12–13