148 lines
6.1 KiB
XML
148 lines
6.1 KiB
XML
<?xml version="1.0" encoding="UTF-8" ?>
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<class name="Signal" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
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<brief_description>
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A built-in type representing a signal of an [Object].
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</brief_description>
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<description>
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[Signal] is a built-in [Variant] type that represents a signal of an [Object] instance. Like all [Variant] types, it can be stored in variables and passed to functions. Signals allow all connected [Callable]s (and by extension their respective objects) to listen and react to events, without directly referencing one another. This keeps the code flexible and easier to manage.
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In GDScript, signals can be declared with the [code]signal[/code] keyword. In C#, you may use the [code][Signal][/code] attribute on a delegate.
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[codeblocks]
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[gdscript]
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signal attacked
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# Additional arguments may be declared.
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# These arguments must be passed when the signal is emitted.
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signal item_dropped(item_name, amount)
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[/gdscript]
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[csharp]
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[Signal]
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delegate void AttackedEventHandler();
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// Additional arguments may be declared.
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// These arguments must be passed when the signal is emitted.
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[Signal]
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delegate void ItemDroppedEventHandler(string itemName, int amount);
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[/csharp]
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[/codeblocks]
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</description>
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<tutorials>
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<link title="Using Signals">$DOCS_URL/getting_started/step_by_step/signals.html</link>
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<link title="GDScript Basics">$DOCS_URL/tutorials/scripting/gdscript/gdscript_basics.html#signals</link>
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</tutorials>
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<constructors>
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<constructor name="Signal">
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<return type="Signal" />
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<description>
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Constructs an empty [Signal] with no object nor signal name bound.
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</description>
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</constructor>
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<constructor name="Signal">
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<return type="Signal" />
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<param index="0" name="from" type="Signal" />
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<description>
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Constructs a [Signal] as a copy of the given [Signal].
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</description>
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</constructor>
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<constructor name="Signal">
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<return type="Signal" />
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<param index="0" name="object" type="Object" />
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<param index="1" name="signal" type="StringName" />
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<description>
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Creates a new [Signal] named [param signal] in the specified [param object].
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</description>
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</constructor>
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</constructors>
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<methods>
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<method name="connect">
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<return type="int" />
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<param index="0" name="callable" type="Callable" />
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<param index="1" name="flags" type="int" default="0" />
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<description>
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Connects this signal to the specified [param callable]. Optional [param flags] can be also added to configure the connection's behavior (see [enum Object.ConnectFlags] constants). You can provide additional arguments to the connected [param callable] by using [method Callable.bind].
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A signal can only be connected once to the same [Callable]. If the signal is already connected, returns [constant ERR_INVALID_PARAMETER] and pushes an error message, unless the signal is connected with [constant Object.CONNECT_REFERENCE_COUNTED]. To prevent this, use [method is_connected] first to check for existing connections.
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[codeblock]
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for button in $Buttons.get_children():
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button.pressed.connect(_on_pressed.bind(button))
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func _on_pressed(button):
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print(button.name, " was pressed")
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[/codeblock]
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</description>
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</method>
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<method name="disconnect">
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<return type="void" />
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<param index="0" name="callable" type="Callable" />
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<description>
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Disconnects this signal from the specified [Callable]. If the connection does not exist, generates an error. Use [method is_connected] to make sure that the connection exists.
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</description>
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</method>
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<method name="emit" qualifiers="vararg const">
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<return type="void" />
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<description>
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Emits this signal. All [Callable]s connected to this signal will be triggered. This method supports a variable number of arguments, so parameters can be passed as a comma separated list.
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</description>
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</method>
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<method name="get_connections" qualifiers="const">
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<return type="Array" />
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<description>
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Returns an [Array] of connections for this signal. Each connection is represented as a [Dictionary] that contains three entries:
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- [code]signal[/code] is a reference to this signal;
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- [code]callable[/code] is a reference to the connected [Callable];
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- [code]flags[/code] is a combination of [enum Object.ConnectFlags].
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</description>
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</method>
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<method name="get_name" qualifiers="const">
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<return type="StringName" />
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<description>
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Returns the name of this signal.
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</description>
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</method>
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<method name="get_object" qualifiers="const">
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<return type="Object" />
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<description>
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Returns the object emitting this signal.
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</description>
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</method>
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<method name="get_object_id" qualifiers="const">
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<return type="int" />
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<description>
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Returns the ID of the object emitting this signal (see [method Object.get_instance_id]).
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</description>
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</method>
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<method name="has_connections" qualifiers="const">
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<return type="bool" />
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<description>
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Returns [code]true[/code] if any [Callable] is connected to this signal.
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</description>
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</method>
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<method name="is_connected" qualifiers="const">
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<return type="bool" />
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<param index="0" name="callable" type="Callable" />
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<description>
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Returns [code]true[/code] if the specified [Callable] is connected to this signal.
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</description>
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</method>
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<method name="is_null" qualifiers="const">
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<return type="bool" />
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<description>
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Returns [code]true[/code] if this [Signal] has no object and the signal name is empty. Equivalent to [code]signal == Signal()[/code].
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</description>
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</method>
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</methods>
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<operators>
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<operator name="operator !=">
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<return type="bool" />
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<param index="0" name="right" type="Signal" />
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<description>
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Returns [code]true[/code] if the signals do not share the same object and name.
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</description>
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</operator>
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<operator name="operator ==">
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<return type="bool" />
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<param index="0" name="right" type="Signal" />
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<description>
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Returns [code]true[/code] if both signals share the same object and name.
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</description>
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</operator>
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</operators>
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</class>
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