Signal Functions

The urwid.*_signal() functions use a shared Signals object instance for tracking registered and connected signals. There is no reason to instantiate your own Signals object.

urwid.connect_signal(obj, name, callback, user_arg=None)

Signals.connect(obj, name, callback, user_arg=None)

Parameters:

• obj (object) – the object sending a signal
• name (signal name) – the signal to listen for, typically a string
• callback (function) – the function to call when that signal is sent
• user_arg – optional additional argument to callback, if None no arguments will be added

When a matching signal is sent, callback will be called with all the positional parameters sent with the signal. If user_arg is not None it will be sent added to the end of the positional parameters sent to callback.

urwid.disconnect_signal(obj, name, callback, user_arg=None)

Signals.disconnect(obj, name, callback, user_arg=None)

This function will remove a callback from the list connected to a signal with connect_signal().

urwid.register_signal(sig_cls, signals)

Signals.register(sig_cls, signals)

Parameters:

• sig_class (class) – the class of an object that will be sending signals
• signals (signal names) – a list of signals that may be sent, typically each signal is represented by a string

This function must be called for a class before connecting any signal callbacks or emiting any signals from that class’ objects

urwid.emit_signal(obj, name, *args)

Signals.emit(obj, name, *args)

Parameters:

• obj (object) – the object sending a signal
• name (signal name) – the signal to send, typically a string
• *args – zero or more positional arguments to pass to the signal callback functions

This function calls each of the callbacks connected to this signal with the args arguments as positional parameters.

This function returns True if any of the callbacks returned True.