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Manual Reference Pages  -  GLIB::OBJECT::INTROSPECTION (3)

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Glib::Object::Introspection - Dynamically create Perl language bindings



  use Glib::Object::Introspection;
    basename => Gtk,
    version => 3.0,
    package => Gtk3);
  # now GtkWindow, to mention just one example, is available as
  # Gtk3::Window, and you can call gtk_window_new as Gtk3::Window->new


Glib::Object::Introspection uses the gobject-introspection and libffi projects to dynamically create Perl bindings for a wide variety of libraries. Examples include gtk+, webkit, libsoup and many more.



To allow Glib::Object::Introspection to create bindings for a library, the library must have installed a typelib file, for example $prefix/lib/girepository-1.0/Gtk-3.0.typelib. In your code you then simply call Glib::Object::Introspection->setup to set everything up. This method takes a couple of key-value pairs as arguments. These three are mandatory:
basename => $basename The basename of the library that should be wrapped. If your typelib is called Gtk-3.0.typelib, then the basename is ’Gtk’.
version => $version The particular version of the library that should be wrapped, in string form. For Gtk-3.0.typelib, it is ’3.0’.
package => $package The name of the Perl package where every class and method of the library should be rooted. If a library with basename ’Gtk’ contains an object ’GtkWindow’, and you pick as the package ’Gtk3’, then that object will be available as ’Gtk3::Window’.
The rest are optional:
search_path => $search_path A path that should be used when looking for typelibs. If you use typelibs from system directories, or if your environment contains a properly set GI_TYPELIB_PATH variable, then this should not be necessary.
name_corrections => { auto_name => new_name, ... } A hash ref that is used to rename functions and methods. Use this if you don’t like the automatically generated mapping for a function or method. For example, if g_file_hash is automatically represented as Glib::IO::file_hash but you want Glib::IO::File::hash then pass

  name_corrections => {
    Glib::IO::file_hash => Glib::IO::File::hash

class_static_methods => [ function1, ... ] An array ref of function names that you want to be treated as class-static methods. That is, if you want be able to call Gtk3::Window::list_toplevels as Gtk3::Window->list_toplevels, then pass

  class_static_methods => [

The function names refer to those after name corrections.

flatten_array_ref_return_for => [ function1, ... ] An array ref of function names that return an array ref that you want to be flattened so that they return plain lists. For example

  flatten_array_ref_return_for => [

The function names refer to those after name corrections. Functions occuring in flatten_array_ref_return_for may also occur in class_static_methods.

handle_sentinel_boolean_for => [ function1, ... ] An array ref of function names that return multiple values, the first of which is to be interpreted as indicating whether the rest of the returned values are valid. This frequently occurs with functions that have out arguments; the boolean then indicates whether the out arguments have been written. With handle_sentinel_boolean_for, the first return value is taken to be the sentinel boolean. If it is true, the rest of the original return values will be returned, and otherwise an empty list will be returned.

  handle_sentinel_boolean_for => [

The function names refer to those after name corrections. Functions occuring in handle_sentinel_boolean_for may also occur in class_static_methods.

use_generic_signal_marshaller_for => [ [package1, signal1, [arg_converter1]], ... ] Use an introspection-based generic signal marshaller for the signal signal1 of type package1. If given, use the code reference arg_converter1 to convert the arguments that are passed to the signal handler. In contrast to Glib’s normal signal marshaller, the generic signal marshaller supports, among other things, pointer arrays and out arguments.
reblessers => { package => \&reblesser, ... } Tells G:O:I to invoke reblesser whenever a Perl object is created for an object of type package. Currently, this only applies to boxed unions. The reblesser gets passed the pre-created Perl object and needs to return the modified Perl object. For example:

  sub Gtk3::Gdk::Event::_rebless {
    my ($event) = @_;
    return bless $event, lookup_real_package_for ($event);


To invoke specific functions manually, you can use the low-level Glib::Object::Introspection->invoke.

    $basename, $namespace, $function, @args)

o $basename is the basename of a library, like ’Gtk’.
o $namespace refers to a namespace inside that library, like ’Window’. Use undef here if you want to call a library-global function.
o $function is the name of the function you want to invoke. It can also refer to the name of a constant.
o @args are the arguments that should be passed to the function. For a method, this should include the invocant. For a constructor, this should include the package name.
Glib::Object::Introspection->invoke returns whatever the function being invoked returns.


To override the behavior of a specific function or method, create an appropriately named sub in the correct package and have it call Glib::Object::Introspection->invoke. Say you want to override Gtk3::Window::list_toplevels, then do this:

  sub Gtk3::Window::list_toplevels {
    # something...
    my $ref = Glib::Object::Introspection->invoke (
                Gtk, Window, list_toplevels,
    # something...
    return wantarray ? @$ref : $ref->[$#$ref];

The sub’s name and package must be those after name corrections.

    Converting a Perl variable to a GValue

If you need to marshal into a GValue, then Glib::Object::Introspection cannot do this automatically because the type information is missing. If you do have this information in your module, however, you can use Glib::Object::Introspection::GValueWrapper to do the conversion. In the wrapper for a function that expects a GValue, do this:

  my $type = ...; # somehow get the package name that
                  # corresponds to the correct GType
  my $real_value =
    Glib::Object::Introspection::GValueWrapper->new ($type, $value);
  # now use Glib::Object::Introspection->invoke and
  # substitute $real_value where youd use $value

    Handling extendable enumerations

If you need to handle extendable enumerations for which more than the pre-defined values might be valid, then use Glib::Object::Introspection->convert_enum_to_sv and Glib::Object::Introspection->convert_sv_to_enum. They will raise an exception on unknown values; catching it then allows you to implement fallback behavior.

  Glib::Object::Introspection->convert_enum_to_sv (package, enum_value)
  Glib::Object::Introspection->convert_sv_to_enum (package, sv)


gobject-introspection: <>
libffi: <>


Emmanuele Bassi <ebassi at linux intel com>
muppet <scott asofyet org>
Torsten Schoenfeld <kaffeetisch at gmx de>


This library is free software; you can redistribute it and/or modify it under the terms of the Lesser General Public License (LGPL). For more information, see
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perl v5.20.3 GLIB::OBJECT::INTROSPECTION (3) 2015-02-26

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