Signaller

Signals and slots implementation with asyncio support

Slots can be functions, methods or coroutines. Weak references are used by default. If slot is coroutine, it will be scheduled to run asynchronously with asyncio.async() (but you must run event loop by yourself).

You can also run blocking functions asynchronously by specifying force_async=True when connecting signal to slot (it will only apply to that slot) or when creating signal (it will apply to all connected slots). ThreadPoolExecutor with 5 worker threads is used by default, but it can be changed when creating signal with executor argument.

Requirements

• Python >= 3.4

Usage

Example:

import logging
from signaller import Signal, autoconnect

# Enable verbose logging
logging.basicConfig(level=logging.DEBUG)

# Creating signals (you can set signal name, but it is not required,
# signals can be anonymous):
sig_test = Signal('sig_test')

# Connecting signals to slots (uses weak references by default,
# but you can force strong references by specifying weak=False):
def slot(arg):
    print('slot:', arg)

sig_test.connect(slot)
sig_test.connect(lambda arg: print('slot_lambda:', arg), weak=False)

# You can also use decorators for connecting signals to slots:
@sig_test.connect
def slot2(arg):
    print('slot2:', arg)

# And keyword arguments can be specified when using decorators too:
@sig_test.connect(force_async=True)
def slot3(arg):
    print('slot3:', arg)

# You can also use decorators on methods, then signals will be connected to instance
# methods automatically whenever new instance is created. But you must decorate class
# with @autoconnect decorator for autoconnection to work. Class methods and
# static methods are not supported.
@autoconnect
class Cls:
    @sig_test.connect
    def slot4(self, arg):
        print('slot4:', arg)

obj = Cls()

# Slots are automatically disconnected from signals
# when using weak references:
del slot

# Or you can disconnect slots manually:
sig_test.disconnect(slot2)

# Emitting signals (you can send both positional and keyword
# arguments to connected slots):
sig_test.emit('Hello world!')

Output:

INFO:signaller:Connecting signal  to slot 
INFO:signaller:Connecting signal  to slot  at 0x7f3c468c97b8>
INFO:signaller:Connecting signal  to slot 
INFO:signaller:Connecting signal  to slot 
DEBUG:signaller:Marking instance method  for autoconnect to signal 
INFO:signaller:Connecting signal  to slot >
DEBUG:signaller:Object  has been deleted
INFO:signaller:Disconnecting slot  (dead)> from signal 
INFO:signaller:Disconnecting slot  from signal 
INFO:signaller:Emitting signal 
DEBUG:signaller:Calling slot > asynchronously (in executor )
slot3: Hello world!
DEBUG:signaller:Calling slot  at 0x7f3c468c97b8>>
slot_lambda: Hello world!
DEBUG:signaller:Calling slot >>
slot4: Hello world!