Gio::AsyncResult Class Reference

Provides a base class for implementing asynchronous function results. More...

#include <giomm/asyncresult.h>

Inheritance diagram for Gio::AsyncResult:

Public Member Functions
	AsyncResult (AsyncResult &&src) noexcept
AsyncResult &	operator= (AsyncResult &&src) noexcept
	~AsyncResult () noexcept override
GAsyncResult *	gobj ()
	Provides access to the underlying C GObject.
const GAsyncResult *	gobj () const
	Provides access to the underlying C GObject.
Glib::RefPtr< Glib::ObjectBase >	get_source_object_base ()
Glib::RefPtr< const Glib::ObjectBase >	get_source_object_base () const
bool	is_tagged (gpointer source_tag) const
	Checks if res has the given source_tag (generally a function pointer indicating the function res was created by).
Public Member Functions inherited from Glib::Interface
	Interface ()
	A Default constructor.
	Interface (Interface &&src) noexcept
Interface &	operator= (Interface &&src) noexcept
	Interface (const Glib::Interface_Class &interface_class)
	Called by constructors of derived classes.
	Interface (GObject *castitem)
	Called by constructors of derived classes.
	~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.
void	get_property_value (const Glib::ustring & property_name, Glib::ValueBase & value) const
	You probably want to use a specific property_*() accessor method instead.
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.
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.
template<class PropertyType >
PropertyType	get_property (const Glib::ustring & property_name) const
	You probably want to use a specific property_*() accessor method instead.
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.
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.
void	freeze_notify ()
	Increases the freeze count on object.
void	thaw_notify ()
	Reverts the effect of a previous call to freeze_notify().
virtual void	reference () const
	Increment the reference count for this object.
virtual void	unreference () const
	Decrement the reference count for this object.
GObject *	gobj ()
	Provides access to the underlying C GObject.
const GObject *	gobj () const
	Provides access to the underlying C GObject.
GObject *	gobj_copy () const
	Give a ref-ed copy to someone. Use for direct struct access.

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.

Protected Member Functions
	AsyncResult ()
	You should derive from this class to use it.
virtual Glib::RefPtr< Glib::ObjectBase >	get_source_object_vfunc ()
virtual bool	is_tagged_vfunc (gpointer source_tag)
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.
	ObjectBase (const char *custom_type_name)
	A derived constructor always overrides this choice.
	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.
	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 Symbols
(Note that these are not member symbols.)
using	SlotAsyncReady = sigc::slot< void(Glib::RefPtr< AsyncResult > &)>
	A function that will be called when an asynchronous operation within GIO has been completed.
Glib::RefPtr< Gio::AsyncResult >	wrap (GAsyncResult *object, bool take_copy=false)
	A Glib::wrap() method for this object.

Detailed Description

Provides a base class for implementing asynchronous function results.

Asynchronous operations are broken up into two separate operations which are chained together by a SlotAsyncReady. To begin an asynchronous operation, provide a SlotAsyncReady to the asynchronous function. This callback will be triggered when the operation has completed, and will be passed an AsyncResult instance (an instance of a class that implements the AsyncResult interface) filled with the details of the operation's success or failure, the object the asynchronous function was started for and any error codes returned. The asynchronous callback function is then expected to call the corresponding "_finish()" function of the object the async function was called for, with the AsyncResult instance.

The purpose of the "_finish()" function is to take the generic result of type AsyncResult and return the specific result that the operation in question yields (e.g. a FileEnumerator for an "enumerate children" operation). If the result or error status of the operation is not needed, there is no need to call the "_finish()" function and GIO will take care of cleaning up the result and error information after the SlotAsyncReady returns. You may also store the AsyncResult and call "_finish()" later. However, the "_finish()" function may be called at most once.

Example of a typical asynchronous operation flow:

class Theoretical : public Glib::Object
{
public:
  Glib::RefPtr<Theoretical> create();
 
  void frobnitz_async(const Gio::SlotAsyncReady& slot);
  Glib::ustring frobnitz_finish(const Glib::RefPtr<Gio::AsyncResult>& result);
// ...
};
 
// ...
 
namespace
{
Glib::RefPtr<Theoretical> theoretical;
 
void on_frobnitz_ready(Glib::RefPtr<Gio::AsyncResult>& result)
{
  try
  {
    Glib::ustring s = theoretical->frobnitz_finish(result);
    std::cout << s << std::endl;
  }
  catch (const Glib::Error& err)
  {
    std::cerr << err.what() << std::endl;
  }
  // ...
}
} // anonymous namespace
 
int main(int argc, void* argv[])
{
  // ...
  theoretical = Theoretical::create();
  theoretical->frobnitz_async(sigc::ptr_fun(&on_frobnitz_ready));
  // ...
}

The async function could also take an optional Gio::Cancellable object, allowing the calling function to cancel the asynchronous operation.

The callback for an asynchronous operation is called only once, and is always called, even in the case of a cancelled operation. On cancellation the "_finish()" function will throw a Gio::Error exception with a Gio::Error::CANCELLED error code.

Since glibmm 2.16:

Constructor & Destructor Documentation

AsyncResult() [1/2]

Gio::AsyncResult::AsyncResult ( )

protected

You should derive from this class to use it.

AsyncResult() [2/2]

Gio::AsyncResult::AsyncResult ( AsyncResult &&  src )

noexcept

~AsyncResult()

Gio::AsyncResult::~AsyncResult ( )

overridenoexcept

Member Function Documentation

add_interface()

static void Gio::AsyncResult::add_interface ( GType  gtype_implementer )

static

get_source_object_base() [1/2]

Glib::RefPtr< Glib::ObjectBase > Gio::AsyncResult::get_source_object_base

(

)

get_source_object_base() [2/2]

Glib::RefPtr< const Glib::ObjectBase > Gio::AsyncResult::get_source_object_base

(

)

const

get_source_object_vfunc()

virtual Glib::RefPtr< Glib::ObjectBase > Gio::AsyncResult::get_source_object_vfunc ( )

protectedvirtual

get_type()

static GType Gio::AsyncResult::get_type ( )

static

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

gobj() [1/2]

GAsyncResult * Gio::AsyncResult::gobj ( )

inline

Provides access to the underlying C GObject.

gobj() [2/2]

const GAsyncResult * Gio::AsyncResult::gobj ( ) const

inline

Provides access to the underlying C GObject.

is_tagged()

bool Gio::AsyncResult::is_tagged

(

gpointer

source_tag

)

const

Checks if res has the given source_tag (generally a function pointer indicating the function res was created by).

Since glibmm 2.34:

Parameters

source_tag

An application-defined tag.

Returns

true if res has the indicated source_tag, false if not.

is_tagged_vfunc()

virtual bool Gio::AsyncResult::is_tagged_vfunc ( gpointer  source_tag )

protectedvirtual

operator=()

AsyncResult & Gio::AsyncResult::operator= ( AsyncResult &&  src )

noexcept

Friends And Related Symbol Documentation

SlotAsyncReady

using SlotAsyncReady = sigc::slot<void(Glib::RefPtr<AsyncResult>&)>

related

A function that will be called when an asynchronous operation within GIO has been completed.

Parameters

result

The asynchronous function's results.

For instance,

void on_async_ready(Glib::RefPtr<Gio::AsyncResult>& result);

Since glibmm 2.16:

wrap()

Glib::RefPtr< Gio::AsyncResult > wrap ( GAsyncResult *  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.