Struct gio::AsyncResult

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pub struct AsyncResult { /* private fields */ }
Expand 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 GAsyncReadyCallback. To begin an asynchronous operation, provide a GAsyncReadyCallback to the asynchronous function. This callback will be triggered when the operation has completed, and must be run in a later iteration of the [thread-default main context][g-main-context-push-thread-default] from where the operation was initiated. It will be passed a AsyncResult instance 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, passing the object the function was called for, the AsyncResult instance, and (optionally) an error to grab any error conditions that may have occurred.

The “_finish()” function for an operation takes the generic result (of type AsyncResult) and returns the specific result that the operation in question yields (e.g. a FileEnumerator for a “enumerate children” operation). If the result or error status of the operation is not needed, there is no need to call the “_finish()” function; GIO will take care of cleaning up the result and error information after the GAsyncReadyCallback returns. You can pass None for the GAsyncReadyCallback if you don’t need to take any action at all after the operation completes. Applications may also take a reference to the AsyncResult and call “_finish()” later; however, the “_finish()” function may be called at most once.

Example of a typical asynchronous operation flow:

⚠️ The following code is in C ⚠️

void _theoretical_frobnitz_async (Theoretical         *t,
                                  GCancellable        *c,
                                  GAsyncReadyCallback  cb,
                                  gpointer             u);

gboolean _theoretical_frobnitz_finish (Theoretical   *t,
                                       GAsyncResult  *res,
                                       GError       **e);

static void
frobnitz_result_func (GObject      *source_object,
         GAsyncResult *res,
         gpointer      user_data)
{
  gboolean success = FALSE;

  success = _theoretical_frobnitz_finish (source_object, res, NULL);

  if (success)
    g_printf ("Hurray!\n");
  else
    g_printf ("Uh oh!\n");

  ...

}

int main (int argc, void *argv[])
{
   ...

   _theoretical_frobnitz_async (theoretical_data,
                                NULL,
                                frobnitz_result_func,
                                NULL);

   ...
}

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 result is a IOErrorEnum::Cancelled error.

I/O Priority # {io-priority}

Many I/O-related asynchronous operations have a priority parameter, which is used in certain cases to determine the order in which operations are executed. They are not used to determine system-wide I/O scheduling. Priorities are integers, with lower numbers indicating higher priority. It is recommended to choose priorities between G_PRIORITY_LOW and G_PRIORITY_HIGH, with G_PRIORITY_DEFAULT as a default.

Implements

AsyncResultExt

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impl AsyncResult

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pub const NONE: Option<&'static AsyncResult> = None

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impl Clone for AsyncResult

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fn clone(&self) -> Self

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for AsyncResult

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl Display for AsyncResult

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl HasParamSpec for AsyncResult

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type ParamSpec = ParamSpecObject

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type SetValue = AsyncResult

Preferred value to be used as setter for the associated ParamSpec.
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type BuilderFn = fn(_: &str) -> ParamSpecObjectBuilder<'_, AsyncResult>

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fn param_spec_builder() -> Self::BuilderFn

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impl Hash for AsyncResult

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fn hash<H>(&self, state: &mut H)
where H: Hasher,

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl Ord for AsyncResult

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fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other. Read more
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fn max(self, other: Self) -> Self
where Self: Sized,

Compares and returns the maximum of two values. Read more
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fn min(self, other: Self) -> Self
where Self: Sized,

Compares and returns the minimum of two values. Read more
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fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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impl<OT: ObjectType> PartialEq<OT> for AsyncResult

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fn eq(&self, other: &OT) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<OT: ObjectType> PartialOrd<OT> for AsyncResult

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fn partial_cmp(&self, other: &OT) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
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fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
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fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
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fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
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fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl StaticType for AsyncResult

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fn static_type() -> Type

Returns the type identifier of Self.
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impl Eq for AsyncResult

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impl<V: ValueType> IsA<AsyncResult> for LocalTask<V>

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impl<V: ValueType + Send> IsA<AsyncResult> for Task<V>

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<O> AsyncResultExt for O
where O: IsA<AsyncResult>,

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fn source_object(&self) -> Option<Object>

Gets the source object from a AsyncResult. Read more
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fn legacy_propagate_error(&self) -> Result<(), Error>

If self is a GSimpleAsyncResult, this is equivalent to g_simple_async_result_propagate_error(). Otherwise it returns false. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> Cast for T
where T: ObjectType,

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fn upcast<T>(self) -> T
where T: ObjectType, Self: IsA<T>,

Upcasts an object to a superclass or interface T. Read more
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fn upcast_ref<T>(&self) -> &T
where T: ObjectType, Self: IsA<T>,

Upcasts an object to a reference of its superclass or interface T. Read more
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fn downcast<T>(self) -> Result<T, Self>
where T: ObjectType, Self: MayDowncastTo<T>,

Tries to downcast to a subclass or interface implementor T. Read more
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fn downcast_ref<T>(&self) -> Option<&T>
where T: ObjectType, Self: MayDowncastTo<T>,

Tries to downcast to a reference of its subclass or interface implementor T. Read more
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fn dynamic_cast<T>(self) -> Result<T, Self>
where T: ObjectType,

Tries to cast to an object of type T. This handles upcasting, downcasting and casting between interface and interface implementors. All checks are performed at runtime, while upcast will do many checks at compile-time already. downcast will perform the same checks at runtime as dynamic_cast, but will also ensure some amount of compile-time safety. Read more
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fn dynamic_cast_ref<T>(&self) -> Option<&T>
where T: ObjectType,

Tries to cast to reference to an object of type T. This handles upcasting, downcasting and casting between interface and interface implementors. All checks are performed at runtime, while downcast and upcast will do many checks at compile-time already. Read more
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unsafe fn unsafe_cast<T>(self) -> T
where T: ObjectType,

Casts to T unconditionally. Read more
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unsafe fn unsafe_cast_ref<T>(&self) -> &T
where T: ObjectType,

Casts to &T unconditionally. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GList> for T

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GPtrArray> for T

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GSList> for T

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GList> for T

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GPtrArray> for T

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GSList> for T

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GList> for T

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GPtrArray> for T

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GSList> for T

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GList> for T

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GPtrArray> for T

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GSList> for T

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoClosureReturnValue for T
where T: Into<Value>,

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impl<T> ObjectExt for T
where T: ObjectType,

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fn is<U>(&self) -> bool
where U: StaticType,

Returns true if the object is an instance of (can be cast to) T.
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fn type_(&self) -> Type

Returns the type of the object.
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fn object_class(&self) -> &Class<Object>

Returns the ObjectClass of the object. Read more
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fn class(&self) -> &Class<T>
where T: IsClass,

Returns the class of the object.
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fn class_of<U>(&self) -> Option<&Class<U>>
where U: IsClass,

Returns the class of the object in the given type T. Read more
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fn interface<U>(&self) -> Option<InterfaceRef<'_, U>>
where U: IsInterface,

Returns the interface T of the object. Read more
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fn set_property(&self, property_name: &str, value: impl Into<Value>)

Sets the property property_name of the object to value value. Read more
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fn set_property_from_value(&self, property_name: &str, value: &Value)

Sets the property property_name of the object to value value. Read more
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fn set_properties(&self, property_values: &[(&str, &dyn ToValue)])

Sets multiple properties of the object at once. Read more
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fn set_properties_from_value(&self, property_values: &[(&str, Value)])

Sets multiple properties of the object at once. Read more
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fn property<V>(&self, property_name: &str) -> V
where V: for<'b> FromValue<'b> + 'static,

Gets the property property_name of the object and cast it to the type V. Read more
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fn property_value(&self, property_name: &str) -> Value

Gets the property property_name of the object. Read more
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fn has_property(&self, property_name: &str, type_: Option<Type>) -> bool

Check if the object has a property property_name of the given type_. Read more
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fn property_type(&self, property_name: &str) -> Option<Type>

Get the type of the property property_name of this object. Read more
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fn find_property(&self, property_name: &str) -> Option<ParamSpec>

Get the ParamSpec of the property property_name of this object.
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fn list_properties(&self) -> PtrSlice<ParamSpec>

Return all ParamSpec of the properties of this object.
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fn freeze_notify(&self) -> PropertyNotificationFreezeGuard

Freeze all property notifications until the return guard object is dropped. Read more
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unsafe fn set_qdata<QD>(&self, key: Quark, value: QD)
where QD: 'static,

Set arbitrary data on this object with the given key. Read more
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unsafe fn qdata<QD>(&self, key: Quark) -> Option<NonNull<QD>>
where QD: 'static,

Return previously set arbitrary data of this object with the given key. Read more
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unsafe fn steal_qdata<QD>(&self, key: Quark) -> Option<QD>
where QD: 'static,

Retrieve previously set arbitrary data of this object with the given key. Read more
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unsafe fn set_data<QD>(&self, key: &str, value: QD)
where QD: 'static,

Set arbitrary data on this object with the given key. Read more
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unsafe fn data<QD>(&self, key: &str) -> Option<NonNull<QD>>
where QD: 'static,

Return previously set arbitrary data of this object with the given key. Read more
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unsafe fn steal_data<QD>(&self, key: &str) -> Option<QD>
where QD: 'static,

Retrieve previously set arbitrary data of this object with the given key. Read more
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fn block_signal(&self, handler_id: &SignalHandlerId)

Block a given signal handler. Read more
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fn unblock_signal(&self, handler_id: &SignalHandlerId)

Unblock a given signal handler.
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fn stop_signal_emission(&self, signal_id: SignalId, detail: Option<Quark>)

Stop emission of the currently emitted signal.
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fn stop_signal_emission_by_name(&self, signal_name: &str)

Stop emission of the currently emitted signal by the (possibly detailed) signal name.
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fn connect<F>( &self, signal_name: &str, after: bool, callback: F ) -> SignalHandlerId
where F: Fn(&[Value]) -> Option<Value> + Send + Sync + 'static,

Connect to the signal signal_name on this object. Read more
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fn connect_id<F>( &self, signal_id: SignalId, details: Option<Quark>, after: bool, callback: F ) -> SignalHandlerId
where F: Fn(&[Value]) -> Option<Value> + Send + Sync + 'static,

Connect to the signal signal_id on this object. Read more
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fn connect_local<F>( &self, signal_name: &str, after: bool, callback: F ) -> SignalHandlerId
where F: Fn(&[Value]) -> Option<Value> + 'static,

Connect to the signal signal_name on this object. Read more
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fn connect_local_id<F>( &self, signal_id: SignalId, details: Option<Quark>, after: bool, callback: F ) -> SignalHandlerId
where F: Fn(&[Value]) -> Option<Value> + 'static,

Connect to the signal signal_id on this object. Read more
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unsafe fn connect_unsafe<F>( &self, signal_name: &str, after: bool, callback: F ) -> SignalHandlerId
where F: Fn(&[Value]) -> Option<Value>,

Connect to the signal signal_name on this object. Read more
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unsafe fn connect_unsafe_id<F>( &self, signal_id: SignalId, details: Option<Quark>, after: bool, callback: F ) -> SignalHandlerId
where F: Fn(&[Value]) -> Option<Value>,

Connect to the signal signal_id on this object. Read more
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fn connect_closure( &self, signal_name: &str, after: bool, closure: RustClosure ) -> SignalHandlerId

Connect a closure to the signal signal_name on this object. Read more
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fn connect_closure_id( &self, signal_id: SignalId, details: Option<Quark>, after: bool, closure: RustClosure ) -> SignalHandlerId

Connect a closure to the signal signal_id on this object. Read more
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fn watch_closure(&self, closure: &impl AsRef<Closure>)

Limits the lifetime of closure to the lifetime of the object. When the object’s reference count drops to zero, the closure will be invalidated. An invalidated closure will ignore any calls to invoke_with_values, or invoke when using Rust closures.
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fn emit<R>(&self, signal_id: SignalId, args: &[&dyn ToValue]) -> R

Emit signal by signal id. Read more
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fn emit_with_values(&self, signal_id: SignalId, args: &[Value]) -> Option<Value>

Same as Self::emit but takes Value for the arguments.
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fn emit_by_name<R>(&self, signal_name: &str, args: &[&dyn ToValue]) -> R

Emit signal by its name. Read more
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fn emit_by_name_with_values( &self, signal_name: &str, args: &[Value] ) -> Option<Value>

Emit signal by its name. Read more
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fn emit_by_name_with_details<R>( &self, signal_name: &str, details: Quark, args: &[&dyn ToValue] ) -> R

Emit signal by its name with details. Read more
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fn emit_by_name_with_details_and_values( &self, signal_name: &str, details: Quark, args: &[Value] ) -> Option<Value>

Emit signal by its name with details. Read more
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fn emit_with_details<R>( &self, signal_id: SignalId, details: Quark, args: &[&dyn ToValue] ) -> R

Emit signal by signal id with details. Read more
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fn emit_with_details_and_values( &self, signal_id: SignalId, details: Quark, args: &[Value] ) -> Option<Value>

Emit signal by signal id with details. Read more
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fn disconnect(&self, handler_id: SignalHandlerId)

Disconnect a previously connected signal handler.
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fn connect_notify<F>(&self, name: Option<&str>, f: F) -> SignalHandlerId
where F: Fn(&T, &ParamSpec) + Send + Sync + 'static,

Connect to the notify signal of the object. Read more
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fn connect_notify_local<F>(&self, name: Option<&str>, f: F) -> SignalHandlerId
where F: Fn(&T, &ParamSpec) + 'static,

Connect to the notify signal of the object. Read more
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unsafe fn connect_notify_unsafe<F>( &self, name: Option<&str>, f: F ) -> SignalHandlerId
where F: Fn(&T, &ParamSpec),

Connect to the notify signal of the object. Read more
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fn notify(&self, property_name: &str)

Notify that the given property has changed its value. Read more
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fn notify_by_pspec(&self, pspec: &ParamSpec)

Notify that the given property has changed its value. Read more
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fn downgrade(&self) -> WeakRef<T>

Downgrade this object to a weak reference.
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fn add_weak_ref_notify<F>(&self, f: F) -> WeakRefNotify<T>
where F: FnOnce() + Send + 'static,

Add a callback to be notified when the Object is disposed.
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fn add_weak_ref_notify_local<F>(&self, f: F) -> WeakRefNotify<T>
where F: FnOnce() + 'static,

Add a callback to be notified when the Object is disposed. Read more
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fn bind_property<'f, 't, O, 'a>( &'a self, source_property: &'a str, target: &'a O, target_property: &'a str ) -> BindingBuilder<'a, 'f, 't>
where O: ObjectType,

Bind property source_property on this object to the target_property on the target object. Read more
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fn ref_count(&self) -> u32

Returns the strong reference count of this object.
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unsafe fn run_dispose(&self)

Runs the dispose mechanism of the object. Read more
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impl<T> Property for T
where T: HasParamSpec,

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type Value = T

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impl<T> PropertyGet for T
where T: HasParamSpec,

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type Value = T

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fn get<R, F>(&self, f: F) -> R
where F: Fn(&<T as PropertyGet>::Value) -> R,

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impl<T> StaticTypeExt for T
where T: StaticType,

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fn ensure_type()

Ensures that the type has been registered with the type system.
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T> ToString for T
where T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T> TransparentType for T

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T> TryFromClosureReturnValue for T
where T: for<'a> FromValue<'a> + StaticType + 'static,

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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<'a, T, C, E> FromValueOptional<'a> for T
where T: FromValue<'a, Checker = C>, C: ValueTypeChecker<Error = ValueTypeMismatchOrNoneError<E>>, E: Error + Send + 'static,

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impl<Super, Sub> MayDowncastTo<Sub> for Super
where Super: IsA<Super>, Sub: IsA<Super>,