XS::Object::Magic - Opaque, extensible XS pointer backed objects using sv_magic
sv_magic
version 0.05
package MyObject; use XS::Object::Magic; sub new { my $class = shift; # create any object representation you like my $self = bless {}, $class; $self->build_struct; return $self; } # or using Moose package MyObject; use Moose; sub BUILD { shift->build_struct; } # then in XS MODULE = MyObject PACKAGE = MyObject void build_struct (SV *self) PREINIT: my_struct_t *thingy; CODE: thingy = create_whatever(); /* note that we dereference self first. This * can be done using an XS typemap of course */ xs_object_magic_attach_struct(aTHX_ SvRV(self), thingy); void foo (SV *self) PREINIT: my_struct_t *thingy; INIT: thingy = xs_object_magic_get_struct_rv(aTHX_ self); CODE: my_struct_foo(thingy); /* delegate to C api */ /* using typemap */ void foo (my_struct_t *thingy) CODE: my_struct_foo(thingy); /* or better yet */ PREFIX = my_struct_ void my_struct_foo (thingy) my_struct_t *thingy; /* don't forget a destructor */ void DESTROY (my_struct_t *thingy) CODE: Safefree(thingy); /* note that xs_object_magic_get_struct() will * still return a pointe which is now invalid */
This way of associating structs with Perl space objects is designed to supersede Perl's builtin T_PTROBJ with something that is designed to be:
T_PTROBJ
The association of the pointer using sv_magicext can be done on any data type, so you can associate C structs with any representation type.
sv_magicext
This means that you can add pointers to any object (hand coded, Moose or otherwise), while still having instance data in regular hashes.
The C pointer is neither visible nor modifiable from Perl space.
This prevents accidental corruption which could lead to segfaults using T_PTROBJ (e.g. $$ptr_obj = 0).
$$ptr_obj = 0
When called on the object reference it will check that the sv is a reference, dereference it and return the associated pointer using xs_object_magic_get_struct.
sv
xs_object_magic_get_struct
Basically the same as xs_object_magic_get_struct(aTHX_ SvRV(sv) but croaks if no magic was found.
xs_object_magic_get_struct(aTHX_ SvRV(sv)
Note that storing a NULL pointer will not cause an error.
NULL
Fetches the pointer associated with sv.
Returns NULL if no pointer is found. There is no way to distinguish this from having a NULL pointer.
Fetches the appropriate MAGIC entry for the struct pointer storage from sv.
MAGIC
This lets you manipulate mg-mg_ptr> if you need to.
mg-
Associates ptr with sv by adding a magic entry to sv.
ptr
Convenience function that creates a hash object blessed to stash and associates it with ptr.
stash
Can be used to easily create a constructor:
SV * new(char *class) CODE: RETVAL = xs_object_magic_create( (void *)test_new(), gv_stashpv(class, 0) ); OUTPUT: RETVAL
Returns 1 if the SV has XS::Object::Magic magic, 0 otherwise.
Returns 1 if the SV references an SV that has XS::Object::Magic magic, 0 otherwise.
This lets you write a quick predicate method, like:
void my_struct_has_struct (self) SV *self; PPCODE: EXTEND(SP, 1); if(xs_object_magic_has_struct_rv(aTHX_ self)) PUSHs(&PL_sv_yes); else PUSHs(&PL_sv_no);
Then you can check for the existence of your struct from the Perl side:
if( $object->has_struct ) { ... }
Removes the XS::Object::Magic magic with attached pointer ptr from the given SV. Returns the number of elements removed if something is removed, 0 otherwise.
Supplying NULL as ptr will result in all XS::Object::Magic magic being removed.
Likes xs_object_magic_detach_struct, but takes a reference to the magic-containing SV instead of the SV itself. The reference to the SV is typically $self.
xs_object_magic_detach_struct
$self
Returns 0 if the SV is not a reference, otherwise returns whatever xs_object_magic_detach_struct returns.
ptr is passwd to xs_object_magic_detach_struct unmodified.
The included typemap provides a T_PTROBJ_MG entry which only supports the INPUT conversion.
T_PTROBJ_MG
INPUT
This typemap entry lets you declare methods that are invoked directly on the associated pointer. In your own typemap add an entry:
TYPEMAP my_pointer_t * T_PTROBJ_MG
and then you can use my_pointer_t as the argument type of the invocant:
my_pointer_t
I32 method (self) my_pointer_t *self; CODE: ...
Note that there is no OUTPUT conversion. In order to return your object you need to use ST(0) or some other means of getting the invocant.
OUTPUT
ST(0)
Bugs may be submitted through the RT bug tracker (or bug-XS-Object-Magic@rt.cpan.org).
יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>
Florian Ragwitz <rafl@debian.org>
Jonathan Rockway <jon@jrock.us>
Karen Etheridge <ether@cpan.org>
Emmanuel Rodriguez <emmanuel.rodriguez@gmail.com>
Jeremiah C. Foster <jeremiah@jeremiahfoster.com>
This software is copyright (c) 2009 by יובל קוג'מן (Yuval Kogman).
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
To install XS::Object::Magic, copy and paste the appropriate command in to your terminal.
cpanm
cpanm XS::Object::Magic
CPAN shell
perl -MCPAN -e shell install XS::Object::Magic
For more information on module installation, please visit the detailed CPAN module installation guide.