Creates a binding between source_property on source and target_property
on target.
Whenever the source_property is changed the target_property is
updated using the same value. For instance:
g_object_bind_property (action, "active", widget, "sensitive", 0);
Will result in the "sensitive" property of the widget #GObject instance to be updated with the same value of the "active" property of the action #GObject instance.
If flags contains %G_BINDING_BIDIRECTIONAL then the binding will be mutual:
if target_property on target changes then the source_property on source
will be updated as well.
The binding will automatically be removed when either the source or the
target instances are finalized. To remove the binding without affecting the
source and the target you can just call g_object_unref() on the returned
#GBinding instance.
Removing the binding by calling g_object_unref() on it must only be done if
the binding, source and target are only used from a single thread and it
is clear that both source and target outlive the binding. Especially it
is not safe to rely on this if the binding, source or target can be
finalized from different threads. Keep another reference to the binding and
use g_binding_unbind() instead to be on the safe side.
A #GObject can have multiple bindings.
the property on source to bind
the target #GObject
the property on target to bind
flags to pass to #GBinding
Creates a binding between source_property on source and target_property
on target, allowing you to set the transformation functions to be used by
the binding.
This function is the language bindings friendly version of g_object_bind_property_full(), using #GClosures instead of function pointers.
the property on source to bind
the target #GObject
the property on target to bind
flags to pass to #GBinding
a #GClosure wrapping the transformation function from the source to the target, or %NULL to use the default
a #GClosure wrapping the transformation function from the target to the source, or %NULL to use the default
Checks on the readiness of datagram_based to perform operations. The
operations specified in condition are checked for and masked against the
currently-satisfied conditions on datagram_based. The result is returned.
%G_IO_IN will be set in the return value if data is available to read with
g_datagram_based_receive_messages(), or if the connection is closed remotely
(EOS); and if the datagram_based has not been closed locally using some
implementation-specific method (such as g_socket_close() or
g_socket_shutdown() with shutdown_read set, if it’s a #GSocket).
If the connection is shut down or closed (by calling g_socket_close() or
g_socket_shutdown() with shutdown_read set, if it’s a #GSocket, for
example), all calls to this function will return %G_IO_ERROR_CLOSED.
%G_IO_OUT will be set if it is expected that at least one byte can be sent using g_datagram_based_send_messages() without blocking. It will not be set if the datagram_based has been closed locally.
%G_IO_HUP will be set if the connection has been closed locally.
%G_IO_ERR will be set if there was an asynchronous error in transmitting data previously enqueued using g_datagram_based_send_messages().
Note that on Windows, it is possible for an operation to return %G_IO_ERROR_WOULD_BLOCK even immediately after g_datagram_based_condition_check() has claimed that the #GDatagramBased is ready for writing. Rather than calling g_datagram_based_condition_check() and then writing to the #GDatagramBased if it succeeds, it is generally better to simply try writing right away, and try again later if the initial attempt returns %G_IO_ERROR_WOULD_BLOCK.
It is meaningless to specify %G_IO_ERR or %G_IO_HUP in condition; these
conditions will always be set in the output if they are true. Apart from
these flags, the output is guaranteed to be masked by condition.
This call never blocks.
a #GIOCondition mask to check
Waits for up to timeout microseconds for condition to become true on
datagram_based. If the condition is met, %TRUE is returned.
If cancellable is cancelled before the condition is met, or if timeout is
reached before the condition is met, then %FALSE is returned and error is
set appropriately (%G_IO_ERROR_CANCELLED or %G_IO_ERROR_TIMED_OUT).
a #GIOCondition mask to wait for
the maximum time (in microseconds) to wait, 0 to not block, or -1 to block indefinitely
a #GCancellable
Creates a #GSource that can be attached to a #GMainContext to monitor for
the availability of the specified condition on the #GDatagramBased. The
#GSource keeps a reference to the datagram_based.
The callback on the source is of the #GDatagramBasedSourceFunc type.
It is meaningless to specify %G_IO_ERR or %G_IO_HUP in condition; these
conditions will always be reported in the callback if they are true.
If non-%NULL, cancellable can be used to cancel the source, which will
cause the source to trigger, reporting the current condition (which is
likely 0 unless cancellation happened at the same time as a condition
change). You can check for this in the callback using
g_cancellable_is_cancelled().
a #GIOCondition mask to monitor
a #GCancellable
This function is intended for #GObject implementations to re-enforce a [floating][floating-ref] object reference. Doing this is seldom required: all #GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink().
Increases the freeze count on object. If the freeze count is
non-zero, the emission of "notify" signals on object is
stopped. The signals are queued until the freeze count is decreased
to zero. Duplicate notifications are squashed so that at most one
#GObject::notify signal is emitted for each property modified while the
object is frozen.
This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.
Gets a named field from the objects table of associations (see g_object_set_data()).
name of the key for that association
Gets a property of an object.
The value can be:
In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling g_value_unset().
Note that g_object_get_property() is really intended for language bindings, g_object_get() is much more convenient for C programming.
the name of the property to get
return location for the property value
This function gets back user data pointers stored via g_object_set_qdata().
A #GQuark, naming the user data pointer
Gets n_properties properties for an object.
Obtained properties will be set to values. All properties must be valid.
Warnings will be emitted and undefined behaviour may result if invalid
properties are passed in.
the names of each property to get
the values of each property to get
Checks whether object has a [floating][floating-ref] reference.
Emits a "notify" signal for the property property_name on object.
When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.
Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.
the name of a property installed on the class of object.
Emits a "notify" signal for the property specified by pspec on object.
This function omits the property name lookup, hence it is faster than g_object_notify().
One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with g_object_class_install_property() inside a static array, e.g.:
enum
{
PROP_0,
PROP_FOO,
PROP_LAST
};
static GParamSpec *properties[PROP_LAST];
static void
my_object_class_init (MyObjectClass *klass)
{
properties[PROP_FOO] = g_param_spec_int ("foo", "Foo", "The foo",
0, 100,
50,
G_PARAM_READWRITE);
g_object_class_install_property (gobject_class,
PROP_FOO,
properties[PROP_FOO]);
}
and then notify a change on the "foo" property with:
g_object_notify_by_pspec (self, properties[PROP_FOO]);
the #GParamSpec of a property installed on the class of object.
Receive one or more data messages from datagram_based in one go.
messages must point to an array of #GInputMessage structs and
num_messages must be the length of this array. Each #GInputMessage
contains a pointer to an array of #GInputVector structs describing the
buffers that the data received in each message will be written to.
flags modify how all messages are received. The commonly available
arguments for this are available in the #GSocketMsgFlags enum, but the
values there are the same as the system values, and the flags
are passed in as-is, so you can pass in system-specific flags too. These
flags affect the overall receive operation. Flags affecting individual
messages are returned in #GInputMessage.flags.
The other members of #GInputMessage are treated as described in its documentation.
If timeout is negative the call will block until num_messages have been
received, the connection is closed remotely (EOS), cancellable is cancelled,
or an error occurs.
If timeout is 0 the call will return up to num_messages without blocking,
or %G_IO_ERROR_WOULD_BLOCK if no messages are queued in the operating system
to be received.
If timeout is positive the call will block on the same conditions as if
timeout were negative. If the timeout is reached
before any messages are received, %G_IO_ERROR_TIMED_OUT is returned,
otherwise it will return the number of messages received before timing out.
(Note: This is effectively the behaviour of MSG_WAITFORONE with
recvmmsg().)
To be notified when messages are available, wait for the %G_IO_IN condition. Note though that you may still receive %G_IO_ERROR_WOULD_BLOCK from g_datagram_based_receive_messages() even if you were previously notified of a %G_IO_IN condition.
If the remote peer closes the connection, any messages queued in the underlying receive buffer will be returned, and subsequent calls to g_datagram_based_receive_messages() will return 0 (with no error set).
If the connection is shut down or closed (by calling g_socket_close() or
g_socket_shutdown() with shutdown_read set, if it’s a #GSocket, for
example), all calls to this function will return %G_IO_ERROR_CLOSED.
On error -1 is returned and error is set accordingly. An error will only
be returned if zero messages could be received; otherwise the number of
messages successfully received before the error will be returned. If
cancellable is cancelled, %G_IO_ERROR_CANCELLED is returned as with any
other error.
an array of #GInputMessage structs
an int containing #GSocketMsgFlags flags for the overall operation
the maximum time (in microseconds) to wait, 0 to not block, or -1 to block indefinitely
a %GCancellable
Increase the reference count of object, and possibly remove the
[floating][floating-ref] reference, if object has a floating reference.
In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one.
Since GLib 2.56, the type of object will be propagated to the return type
under the same conditions as for g_object_ref().
Releases all references to other objects. This can be used to break reference cycles.
This function should only be called from object system implementations.
Send one or more data messages from datagram_based in one go.
messages must point to an array of #GOutputMessage structs and
num_messages must be the length of this array. Each #GOutputMessage
contains an address to send the data to, and a pointer to an array of
#GOutputVector structs to describe the buffers that the data to be sent
for each message will be gathered from.
flags modify how the message is sent. The commonly available arguments
for this are available in the #GSocketMsgFlags enum, but the
values there are the same as the system values, and the flags
are passed in as-is, so you can pass in system-specific flags too.
The other members of #GOutputMessage are treated as described in its documentation.
If timeout is negative the call will block until num_messages have been
sent, cancellable is cancelled, or an error occurs.
If timeout is 0 the call will send up to num_messages without blocking,
or will return %G_IO_ERROR_WOULD_BLOCK if there is no space to send messages.
If timeout is positive the call will block on the same conditions as if
timeout were negative. If the timeout is reached before any messages are
sent, %G_IO_ERROR_TIMED_OUT is returned, otherwise it will return the number
of messages sent before timing out.
To be notified when messages can be sent, wait for the %G_IO_OUT condition. Note though that you may still receive %G_IO_ERROR_WOULD_BLOCK from g_datagram_based_send_messages() even if you were previously notified of a %G_IO_OUT condition. (On Windows in particular, this is very common due to the way the underlying APIs work.)
If the connection is shut down or closed (by calling g_socket_close() or
g_socket_shutdown() with shutdown_write set, if it’s a #GSocket, for
example), all calls to this function will return %G_IO_ERROR_CLOSED.
On error -1 is returned and error is set accordingly. An error will only
be returned if zero messages could be sent; otherwise the number of messages
successfully sent before the error will be returned. If cancellable is
cancelled, %G_IO_ERROR_CANCELLED is returned as with any other error.
an array of #GOutputMessage structs
an int containing #GSocketMsgFlags flags
the maximum time (in microseconds) to wait, 0 to not block, or -1 to block indefinitely
a %GCancellable
Each object carries around a table of associations from strings to pointers. This function lets you set an association.
If the object already had an association with that name, the old association will be destroyed.
Internally, the key is converted to a #GQuark using g_quark_from_string().
This means a copy of key is kept permanently (even after object has been
finalized) — so it is recommended to only use a small, bounded set of values
for key in your program, to avoid the #GQuark storage growing unbounded.
name of the key
data to associate with that key
Sets a property on an object.
the name of the property to set
the value
Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
name of the key
This function gets back user data pointers stored via
g_object_set_qdata() and removes the data from object
without invoking its destroy() function (if any was
set).
Usually, calling this function is only required to update
user data pointers with a destroy notifier, for example:
void
object_add_to_user_list (GObject *object,
const gchar *new_string)
{
// the quark, naming the object data
GQuark quark_string_list = g_quark_from_static_string ("my-string-list");
// retrieve the old string list
GList *list = g_object_steal_qdata (object, quark_string_list);
// prepend new string
list = g_list_prepend (list, g_strdup (new_string));
// this changed 'list', so we need to set it again
g_object_set_qdata_full (object, quark_string_list, list, free_string_list);
}
static void
free_string_list (gpointer data)
{
GList *node, *list = data;
for (node = list; node; node = node->next)
g_free (node->data);
g_list_free (list);
}
Using g_object_get_qdata() in the above example, instead of g_object_steal_qdata() would have left the destroy function set, and thus the partial string list would have been freed upon g_object_set_qdata_full().
A #GQuark, naming the user data pointer
Reverts the effect of a previous call to
g_object_freeze_notify(). The freeze count is decreased on object
and when it reaches zero, queued "notify" signals are emitted.
Duplicate notifications for each property are squashed so that at most one #GObject::notify signal is emitted for each property, in the reverse order in which they have been queued.
It is an error to call this function when the freeze count is zero.
Decreases the reference count of object. When its reference count
drops to 0, the object is finalized (i.e. its memory is freed).
If the pointer to the #GObject may be reused in future (for example, if it is an instance variable of another object), it is recommended to clear the pointer to %NULL rather than retain a dangling pointer to a potentially invalid #GObject instance. Use g_clear_object() for this.
This function essentially limits the life time of the closure to
the life time of the object. That is, when the object is finalized,
the closure is invalidated by calling g_closure_invalidate() on
it, in order to prevent invocations of the closure with a finalized
(nonexisting) object. Also, g_object_ref() and g_object_unref() are
added as marshal guards to the closure, to ensure that an extra
reference count is held on object during invocation of the
closure. Usually, this function will be called on closures that
use this object as closure data.
#GClosure to watch
Find the #GParamSpec with the given name for an
interface. Generally, the interface vtable passed in as g_iface
will be the default vtable from g_type_default_interface_ref(), or,
if you know the interface has already been loaded,
g_type_default_interface_peek().
any interface vtable for the interface, or the default vtable for the interface
name of a property to look up.
Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created #GParamSpec, but normally g_object_class_override_property() will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property.
This function is meant to be called from the interface's default
vtable initialization function (the class_init member of
#GTypeInfo.) It must not be called after after class_init has
been called for any object types implementing this interface.
If pspec is a floating reference, it will be consumed.
any interface vtable for the interface, or the default vtable for the interface.
the #GParamSpec for the new property
Lists the properties of an interface.Generally, the interface
vtable passed in as g_iface will be the default vtable from
g_type_default_interface_ref(), or, if you know the interface has
already been loaded, g_type_default_interface_peek().
any interface vtable for the interface, or the default vtable for the interface
Creates a new instance of a #GObject subtype and sets its properties.
Construction parameters (see %G_PARAM_CONSTRUCT, %G_PARAM_CONSTRUCT_ONLY) which are not explicitly specified are set to their default values.
the type id of the #GObject subtype to instantiate
an array of #GParameter
A #GDatagramBased is a networking interface for representing datagram-based communications. It is a more or less direct mapping of the core parts of the BSD socket API in a portable GObject interface. It is implemented by #GSocket, which wraps the UNIX socket API on UNIX and winsock2 on Windows.
#GDatagramBased is entirely platform independent, and is intended to be used alongside higher-level networking APIs such as #GIOStream.
It uses vectored scatter/gather I/O by default, allowing for many messages to be sent or received in a single call. Where possible, implementations of the interface should take advantage of vectored I/O to minimise processing or system calls. For example, #GSocket uses recvmmsg() and sendmmsg() where possible. Callers should take advantage of scatter/gather I/O (the use of multiple buffers per message) to avoid unnecessary copying of data to assemble or disassemble a message.
Each #GDatagramBased operation has a timeout parameter which may be negative for blocking behaviour, zero for non-blocking behaviour, or positive for timeout behaviour. A blocking operation blocks until finished or there is an error. A non-blocking operation will return immediately with a %G_IO_ERROR_WOULD_BLOCK error if it cannot make progress. A timeout operation will block until the operation is complete or the timeout expires; if the timeout expires it will return what progress it made, or %G_IO_ERROR_TIMED_OUT if no progress was made. To know when a call would successfully run you can call g_datagram_based_condition_check() or g_datagram_based_condition_wait(). You can also use g_datagram_based_create_source() and attach it to a #GMainContext to get callbacks when I/O is possible.
When running a non-blocking operation applications should always be able to handle getting a %G_IO_ERROR_WOULD_BLOCK error even when some other function said that I/O was possible. This can easily happen in case of a race condition in the application, but it can also happen for other reasons. For instance, on Windows a socket is always seen as writable until a write returns %G_IO_ERROR_WOULD_BLOCK.
As with #GSocket, #GDatagramBaseds can be either connection oriented (for example, SCTP) or connectionless (for example, UDP). #GDatagramBaseds must be datagram-based, not stream-based. The interface does not cover connection establishment — use methods on the underlying type to establish a connection before sending and receiving data through the #GDatagramBased API. For connectionless socket types the target/source address is specified or received in each I/O operation.
Like most other APIs in GLib, #GDatagramBased is not inherently thread safe. To use a #GDatagramBased concurrently from multiple threads, you must implement your own locking.