Signal

Base class for all signals

Attributes

Attribute	Type	Description
receivers	list = []	Internal list of registered receiver metadata, including lookup keys, weak references to receivers and senders, and asynchronicity flags.
lock	threading.Lock = threading.Lock()	A threading lock used to ensure thread-safe access when modifying receivers or clearing the sender cache.
use_caching	boolean = False	Boolean flag that determines whether to cache the resolved receivers for each distinct sender to improve performance.
sender_receivers_cache	WeakKeyDictionary or dict = {}	A mapping of senders to their resolved receivers, implemented as a WeakKeyDictionary if caching is enabled.
_dead_receivers	boolean = False	Internal flag indicating that the receivers list contains dead weak references that need to be cleaned up.

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Constructor

Signature

def Signal(
    use_caching: boolean = False
) - > None

Parameters

Name	Type	Description
use_caching	boolean = False	If set to True, the signal will cache the receivers for each distinct sender to improve performance on subsequent sends.

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Methods

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connect()

@classmethod
def connect(
    receiver: callable,
    sender: object,
    weak: boolean,
    dispatch_uid: hashable
) - > null

Connect receiver to sender for signal.

Parameters

Name	Type	Description
receiver	callable	A function or instance method that will be called when the signal is emitted; must accept keyword arguments.
sender	object	The specific object from which the receiver should respond to events, or None to listen to all senders.
weak	boolean	Whether to use weak references to the receiver to allow it to be garbage collected automatically.
dispatch_uid	hashable	A unique identifier to prevent the same receiver from being subscribed multiple times.

Returns

Type	Description
null

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disconnect()

@classmethod
def disconnect(
    receiver: callable,
    sender: object,
    dispatch_uid: hashable
) - > boolean

Disconnect receiver from sender for signal.

Parameters

Name	Type	Description
receiver	callable	The registered receiver function or method to remove from the signal's dispatch list.
sender	object	The registered sender from which the receiver should be disconnected.
dispatch_uid	hashable	The unique identifier of the specific receiver instance to disconnect.

Returns

Type	Description
boolean	True if a receiver was successfully disconnected, False otherwise.

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has_listeners()

@classmethod
def has_listeners(
    sender: object
) - > boolean

Checks if there are any active receivers currently connected to the signal for a given sender.

Parameters

Name	Type	Description
sender	object	The object emitting the signal to check for associated listeners.

Returns

Type	Description
boolean	True if at least one synchronous or asynchronous listener is registered for the sender.

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send()

@classmethod
def send(
    sender: object,
    **named: dict
) - > list

Send signal from sender to all connected receivers.

Parameters

Name	Type	Description
sender	object	The object initiating the signal dispatch.
**named	dict	Arbitrary keyword arguments passed directly to every connected receiver.

Returns

Type	Description
list	A list of tuple pairs containing the receiver and its corresponding response value.

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asend()

@classmethod
def asend(
    sender: object,
    **named: dict
) - > list

Send signal from sender to all connected receivers in async mode.

Parameters

Name	Type	Description
sender	object	The object initiating the signal dispatch.
**named	dict	Arbitrary keyword arguments passed directly to every connected receiver.

Returns

Type	Description
list	A list of tuple pairs containing the receiver and its corresponding response value, resolved asynchronously.

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send_robust()

@classmethod
def send_robust(
    sender: object,
    **named: dict
) - > list

Send signal from sender to all connected receivers catching errors.

Parameters

Name	Type	Description
sender	object	The object initiating the signal dispatch.
**named	dict	Arbitrary keyword arguments passed directly to every connected receiver.

Returns

Type	Description
list	A list of tuple pairs containing the receiver and either its response or the Exception instance if it failed.

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asend_robust()

@classmethod
def asend_robust(
    sender: object,
    **named: dict
) - > list

Send signal from sender to all connected receivers catching errors.

Parameters

Name	Type	Description
sender	object	The object initiating the signal dispatch.
**named	dict	Arbitrary keyword arguments passed directly to every connected receiver.

Returns

Type	Description
list	A list of tuple pairs containing the receiver and either its response or the Exception instance if it failed, resolved asynchronously.

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