231 lines
11 KiB
XML
231 lines
11 KiB
XML
<?xml version="1.0" encoding="UTF-8" ?>
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<class name="Callable" version="4.1" 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 method or a standalone function.
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</brief_description>
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<description>
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[Callable] is a built-in [Variant] type that represents a function. It can either be a method within an [Object] instance, or a standalone function not related to any object, like a lambda function. Like all [Variant] types, it can be stored in variables and passed to other functions. It is most commonly used for signal callbacks.
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[b]Example:[/b]
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[codeblocks]
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[gdscript]
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func print_args(arg1, arg2, arg3 = ""):
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prints(arg1, arg2, arg3)
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func test():
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var callable = Callable(self, "print_args")
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callable.call("hello", "world") # Prints "hello world ".
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callable.call(Vector2.UP, 42, callable) # Prints "(0, -1) 42 Node(node.gd)::print_args".
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callable.call("invalid") # Invalid call, should have at least 2 arguments.
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[/gdscript]
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[csharp]
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// Default parameter values are not supported.
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public void PrintArgs(Variant arg1, Variant arg2, Variant arg3 = default)
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{
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GD.PrintS(arg1, arg2, arg3);
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}
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public void Test()
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{
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// Invalid calls fail silently.
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Callable callable = new Callable(this, MethodName.PrintArgs);
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callable.Call("hello", "world"); // Default parameter values are not supported, should have 3 arguments.
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callable.Call(Vector2.Up, 42, callable); // Prints "(0, -1) 42 Node(Node.cs)::PrintArgs".
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callable.Call("invalid"); // Invalid call, should have 3 arguments.
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}
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[/csharp]
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[/codeblocks]
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In GDScript, it's possible to create lambda functions within a method. Lambda functions are custom callables that are not associated with an [Object] instance. Optionally, lambda functions can also be named. The name will be displayed in the debugger, or when calling [method get_method].
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[codeblock]
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func _init():
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var my_lambda = func (message):
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print(message)
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# Prints Hello everyone!
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my_lambda.call("Hello everyone!")
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# Prints "Attack!", when the button_pressed signal is emitted.
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button_pressed.connect(func(): print("Attack!"))
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[/codeblock]
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[b]Note:[/b] Methods of native types such as [Signal], [Array], or [Dictionary] are not of type [Callable] in order to avoid unnecessary overhead. If you need to pass those methods as [Callable], use a lambda function as a wrapper.
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[codeblock]
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func _init():
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var my_dictionary = { "hello": "world" }
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# This will not work, `clear` is not a callable.
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create_tween().tween_callback(my_dictionary.clear)
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# This will work, as lambdas are custom callables.
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create_tween().tween_callback(func(): my_dictionary.clear())
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[/codeblock]
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</description>
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<tutorials>
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</tutorials>
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<constructors>
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<constructor name="Callable">
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<return type="Callable" />
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<description>
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Constructs an empty [Callable], with no object nor method bound.
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</description>
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</constructor>
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<constructor name="Callable">
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<return type="Callable" />
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<param index="0" name="from" type="Callable" />
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<description>
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Constructs a [Callable] as a copy of the given [Callable].
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</description>
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</constructor>
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<constructor name="Callable">
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<return type="Callable" />
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<param index="0" name="object" type="Object" />
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<param index="1" name="method" type="StringName" />
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<description>
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Creates a new [Callable] for the method named [param method] 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="bind" qualifiers="vararg const">
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<return type="Callable" />
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<description>
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Returns a copy of this [Callable] with one or more arguments bound. When called, the bound arguments are passed [i]after[/i] the arguments supplied by [method call]. See also [method unbind].
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[b]Note:[/b] When this method is chained with other similar methods, the order in which the argument list is modified is read from right to left.
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</description>
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</method>
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<method name="bindv">
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<return type="Callable" />
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<param index="0" name="arguments" type="Array" />
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<description>
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Returns a copy of this [Callable] with one or more arguments bound, reading them from an array. When called, the bound arguments are passed [i]after[/i] the arguments supplied by [method call]. See also [method unbind].
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[b]Note:[/b] When this method is chained with other similar methods, the order in which the argument list is modified is read from right to left.
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</description>
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</method>
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<method name="call" qualifiers="vararg const">
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<return type="Variant" />
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<description>
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Calls the method represented by this [Callable]. Arguments can be passed and should match the method's signature.
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</description>
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</method>
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<method name="call_deferred" qualifiers="vararg const">
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<return type="void" />
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<description>
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Calls the method represented by this [Callable] in deferred mode, i.e. at the end of the current frame. Arguments can be passed and should match the method's signature.
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[codeblock]
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func _ready():
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grab_focus.call_deferred()
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[/codeblock]
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See also [method Object.call_deferred].
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</description>
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</method>
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<method name="callv" qualifiers="const">
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<return type="Variant" />
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<param index="0" name="arguments" type="Array" />
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<description>
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Calls the method represented by this [Callable]. Unlike [method call], this method expects all arguments to be contained inside the [param arguments] [Array].
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</description>
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</method>
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<method name="get_bound_arguments" qualifiers="const">
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<return type="Array" />
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<description>
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Return the bound arguments (as long as [method get_bound_arguments_count] is greater than zero), or empty (if [method get_bound_arguments_count] is less than or equal to zero).
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</description>
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</method>
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<method name="get_bound_arguments_count" qualifiers="const">
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<return type="int" />
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<description>
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Returns the total amount of arguments bound (or unbound) via successive [method bind] or [method unbind] calls. If the amount of arguments unbound is greater than the ones bound, this function returns a value less than zero.
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</description>
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</method>
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<method name="get_method" qualifiers="const">
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<return type="StringName" />
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<description>
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Returns the name of the method represented by this [Callable]. If the callable is a lambda function, returns the function's name.
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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 on which this [Callable] is called.
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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 this [Callable]'s object (see [method Object.get_instance_id]).
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</description>
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</method>
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<method name="hash" qualifiers="const">
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<return type="int" />
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<description>
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Returns the 32-bit hash value of this [Callable]'s object.
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[b]Note:[/b] [Callable]s with equal content will always produce identical hash values. However, the reverse is not true. Returning identical hash values does [i]not[/i] imply the callables are equal, because different callables can have identical hash values due to hash collisions. The engine uses a 32-bit hash algorithm for [method hash].
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</description>
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</method>
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<method name="is_custom" qualifiers="const">
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<return type="bool" />
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<description>
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Returns [code]true[/code] if this [Callable] is a custom callable. Custom callables are created from [method bind] or [method unbind]. In GDScript, lambda functions are also custom callables.
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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 [Callable] has no target to call the method on.
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</description>
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</method>
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<method name="is_standard" qualifiers="const">
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<return type="bool" />
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<description>
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Returns [code]true[/code] if this [Callable] is a standard callable. This method is the opposite of [method is_custom]. Returns [code]false[/code] if this callable is a lambda function.
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</description>
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</method>
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<method name="is_valid" qualifiers="const">
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<return type="bool" />
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<description>
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Returns [code]true[/code] if the callable's object exists and has a valid method name assigned, or is a custom callable.
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</description>
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</method>
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<method name="rpc" qualifiers="vararg const">
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<return type="void" />
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<description>
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Perform an RPC (Remote Procedure Call). This is used for multiplayer and is normally not available, unless the function being called has been marked as [i]RPC[/i]. Calling this method on unsupported functions will result in an error. See [method Node.rpc].
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</description>
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</method>
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<method name="rpc_id" qualifiers="vararg const">
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<return type="void" />
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<param index="0" name="peer_id" type="int" />
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<description>
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Perform an RPC (Remote Procedure Call) on a specific peer ID (see multiplayer documentation for reference). This is used for multiplayer and is normally not available unless the function being called has been marked as [i]RPC[/i]. Calling this method on unsupported functions will result in an error. See [method Node.rpc_id].
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</description>
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</method>
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<method name="unbind" qualifiers="const">
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<return type="Callable" />
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<param index="0" name="argcount" type="int" />
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<description>
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Returns a copy of this [Callable] with a number of arguments unbound. In other words, when the new callable is called the last few arguments supplied by the user are ignored, according to [param argcount]. The remaining arguments are passed to the callable. This allows to use the original callable in a context that attempts to pass more arguments than this callable can handle, e.g. a signal with a fixed number of arguments. See also [method bind].
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[b]Note:[/b] When this method is chained with other similar methods, the order in which the argument list is modified is read from right to left.
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[codeblock]
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func _ready():
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foo.unbind(1).call(1, 2) # Calls foo(1).
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foo.bind(3, 4).unbind(1).call(1, 2) # Calls foo(1, 3, 4), note that it does not change the arguments from bind.
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[/codeblock]
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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="Callable" />
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<description>
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Returns [code]true[/code] if both [Callable]s invoke different targets.
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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="Callable" />
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<description>
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Returns [code]true[/code] if both [Callable]s invoke the same custom target.
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</description>
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</operator>
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</operators>
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</class>
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