glibmm: Gio::Initable Class Reference

glibmm 2.74.0

Public Member Functions | Static Public Member Functions | Protected Member Functions | Related Functions | List of all members
Gio::Initable Class Reference

Failable object initialization interface. More...

`#include <giomm/initable.h>`

Inheritance diagram for Gio::Initable:
[legend]

## Public Member Functions
| Initable (Initable && src) noexcept
Initable & | operator= (Initable && src) noexcept
| ~Initable () noexcept override
GInitable * | gobj ()
| Provides access to the underlying C GObject. More...
const GInitable * | gobj () const
| Provides access to the underlying C GObject. More...
Public Member Functions inherited from Glib::Interface
| Interface ()
| A Default constructor. More...
| Interface (Interface && src) noexcept
Interface & | operator= (Interface && src) noexcept
| Interface (const Glib::Interface_Class & interface_class)
| Called by constructors of derived classes. More...
| Interface (GObject * castitem)
| Called by constructors of derived classes. More...
| ~Interface () noexcept override
| Interface (const Interface &)=delete
Interface & | operator= (const Interface &)=delete
GObject * | gobj ()
const GObject * | gobj () const
Public Member Functions inherited from Glib::ObjectBase
| ObjectBase (const ObjectBase &)=delete
ObjectBase & | operator= (const ObjectBase &)=delete
void | set_property_value (const Glib::ustring & property_name, const Glib::ValueBase & value)
| You probably want to use a specific property_*() accessor method instead. More...
void | get_property_value (const Glib::ustring & property_name, Glib::ValueBase & value) const
| You probably want to use a specific property_*() accessor method instead. More...
template<class PropertyType >
void | set_property (const Glib::ustring & property_name, const PropertyType & value)
| You probably want to use a specific property_*() accessor method instead. More...
template<class PropertyType >
void | get_property (const Glib::ustring & property_name, PropertyType & value) const
| You probably want to use a specific property_*() accessor method instead. More...
template<class PropertyType >
PropertyType | get_property (const Glib::ustring & property_name) const
| You probably want to use a specific property_*() accessor method instead. More...
sigc::connection | connect_property_changed (const Glib::ustring & property_name, const sigc::slot< void()> & slot)
| You can use the signal_changed() signal of the property proxy instead. More...
sigc::connection | connect_property_changed (const Glib::ustring & property_name, sigc::slot< void()> && slot)
| You can use the signal_changed() signal of the property proxy instead. More...
void | freeze_notify ()
| Increases the freeze count on object. More...
void | thaw_notify ()
| Reverts the effect of a previous call to freeze_notify(). More...
virtual void | reference () const
| Increment the reference count for this object. More...
virtual void | unreference () const
| Decrement the reference count for this object. More...
GObject * | gobj ()
| Provides access to the underlying C GObject. More...
const GObject * | gobj () const
| Provides access to the underlying C GObject. More...
GObject * | gobj_copy () const
| Give a ref-ed copy to someone. Use for direct struct access. More...

## Static Public Member Functions
static void | add_interface (GType gtype_implementer)
static GType | get_type ()
| Get the GType for this class, for use with the underlying GObject type system. More...

## Protected Member Functions
| Initable ()
| You should derive from this class to use it. More...
void | init (const Glib::RefPtr< Cancellable > & cancellable)
| Initializes the object implementing the interface. More...
void | init ()
| A init() convenience overload. More...
virtual bool | init_vfunc (const Glib::RefPtr< Cancellable > & cancellable, GError ** error)
Protected Member Functions inherited from Glib::ObjectBase
| ObjectBase ()
| This default constructor is called implicitly from the constructor of user-derived classes, even if, for instance, Gtk::Button calls a different ObjectBase constructor. More...
| ObjectBase (const char * custom_type_name)
| A derived constructor always overrides this choice. More...
| ObjectBase (const std::type_info & custom_type_info)
| This constructor is a special feature to allow creation of derived types on the fly, without having to use g_object_new() manually. More...
| ObjectBase (ObjectBase && src) noexcept
ObjectBase & | operator= (ObjectBase && src) noexcept
virtual | ~ObjectBase () noexcept=0
void | initialize (GObject * castitem)
void | initialize_move (GObject * castitem, Glib::ObjectBase * previous_wrapper)

## Related Functions
(Note that these are not member functions.)
Glib::RefPtr< Gio::Initable > | wrap (GInitable * object, bool take_copy=false)
| A Glib::wrap() method for this object. More...

## Detailed Description

Failable object initialization interface.

Initable is implemented by objects that can fail during initialization. If an object implements this interface the init() function must be called as the first thing after construction. If init() is not called, or if it returns an error, all further operations on the object should fail, generally with a G_IO_ERROR_NOT_INITIALIZED error.

Users of objects implementing this are not intended to use the interface method directly, instead it will be used automatically in various ways. For C applications you generally just call g_initable_new() directly, or indirectly via a foo_thing_new() wrapper. This will call g_initable_init() under the cover, returning nullptr and setting a GError on failure.

For bindings in languages where the native constructor supports exceptions the binding could check for objects implemention GInitable during normal construction and automatically initialize them, throwing an exception on failure.

Since glibmm 2.24:

## Constructor & Destructor Documentation

## ◆ Initable() [1/2]

Gio::Initable::Initable | ( |  | ) |
| protected

You should derive from this class to use it.

## ◆ Initable() [2/2]

Gio::Initable::Initable | ( | Initable && | src | ) |
| noexcept

## ◆ ~Initable()

Gio::Initable::~Initable | ( |  | ) |
| overridenoexcept

## Member Function Documentation

## ◆ add_interface()

static void Gio::Initable::add_interface | ( | GType | gtype_implementer | ) |
| static

## ◆ get_type()

static GType Gio::Initable::get_type | ( |  | ) |
| static

Get the GType for this class, for use with the underlying GObject type system.

## ◆ gobj() [1/2]

GInitable * Gio::Initable::gobj | ( |  | ) |
| inline

Provides access to the underlying C GObject.

## ◆ gobj() [2/2]

const GInitable * Gio::Initable::gobj | ( |  | ) | const
| inline

Provides access to the underlying C GObject.

## ◆ init() [1/2]

void Gio::Initable::init | ( |  | ) |
| protected

A init() convenience overload.

## ◆ init() [2/2]

void Gio::Initable::init | ( | const Glib::RefPtr< Cancellable > & | cancellable | ) |
| protected

Initializes the object implementing the interface.

This method is intended for language bindings. If writing in C, g_initable_new() should typically be used instead.

The object must be initialized before any real use after initial construction, either with this function or g_async_initable_init_async().

Implementations may also support cancellation. If cancellable is not `nullptr`, then initialization can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error Gio::Error::CANCELLED will be returned. If cancellable is not `nullptr` and the object doesn't support cancellable initialization the error Gio::Error::NOT_SUPPORTED will be returned.

If the object is not initialized, or initialization returns with an error, then all operations on the object except Glib::object_ref() and Glib::object_unref() are considered to be invalid, and have undefined behaviour. See the [introduction][ginitable] for more details.

Callers should not assume that a class which implements Initable can be initialized multiple times, unless the class explicitly documents itself as supporting this. Generally, a class’ implementation of init() can assume (and assert) that it will only be called once. Previously, this documentation recommended all Initable implementations should be idempotent; that recommendation was relaxed in GLib 2.54.

If a class explicitly supports being initialized multiple times, it is recommended that the method is idempotent: multiple calls with the same arguments should return the same results. Only the first call initializes the object; further calls return the result of the first call.

One reason why a class might need to support idempotent initialization is if it is designed to be used via the singleton pattern, with a ObjectClass.constructor that sometimes returns an existing instance. In this pattern, a caller would expect to be able to call g_initable_init() on the result of Glib::object_new(), regardless of whether it is in fact a new instance.

Since glibmm 2.22:

Parameters

  cancellable | Optional Cancellable object, `nullptr` to ignore.

Exceptions

  Glib::Error |

## ◆ init_vfunc()

virtual bool Gio::Initable::init_vfunc | ( | const Glib::RefPtr< Cancellable > & | cancellable,
|  | GError ** | error
| ) |  |
| protectedvirtual

## ◆ operator=()

Initable & Gio::Initable::operator= | ( | Initable && | src | ) |
| noexcept

## Friends And Related Function Documentation

## ◆ wrap()

Glib::RefPtr< Gio::Initable > wrap | ( | GInitable * | object,
|  | bool | take_copy = `false`
| ) |  |
| related

A Glib::wrap() method for this object.

Parameters

  object | The C instance.
  take_copy | False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns
  A C++ instance that wraps this C instance.