Multi-consumer multi-producer dispatching mechanism
Multiple-producer-multiple-consumer signal-dispatching
dispatcher is the core of the PyDispatcher system, providing the primary API and the core logic for the system.
Module attributes of note:
- Any – Singleton used to signal either “Any Sender” or
- “Any Signal”. See documentation of the _Any class.
- Anonymous – Singleton used to signal “Anonymous Sender”
- See documentation of the _Anonymous class.
connections – { senderkey (id) : { signal : [receivers...]}}
Connect receiver to sender for signal
messages/signals/events. Receivers must be hashable objects.
if weak is True, then receiver must be weak-referencable (more precisely saferef.safeRef() must be able to create a reference to the receiver).
Receivers are fairly flexible in their specification, as the machinery in the robustApply module takes care of most of the details regarding figuring out appropriate subsets of the sent arguments to apply to a given receiver.
signal – the signal to which the receiver should respond
if Any, receiver will receive any signal from the indicated sender (which might also be Any, but is not necessarily Any).
Otherwise must be a hashable Python object other than None (DispatcherError raised on None).
sender – the sender to which the receiver should respond
if Any, receiver will receive the indicated signals from any sender.
if Anonymous, receiver will only receive indicated signals from send/sendExact which do not specify a sender, or specify Anonymous explicitly as the sender.
Otherwise can be any python object.
returns None, may raise DispatcherTypeError
Disconnect receiver from sender for signal
receiver – the registered receiver to disconnect signal – the registered signal to disconnect sender – the registered sender to disconnect weak – the weakref state to disconnect
disconnect reverses the process of connect, the semantics for the individual elements are logically equivalent to a tuple of (receiver, signal, sender, weak) used as a key to be deleted from the internal routing tables. (The actual process is slightly more complex but the semantics are basically the same).
Get list of all receivers from global tables
This gets all receivers which should receive the given signal from sender, each receiver should be produced only once by the resulting generator
Get list of receivers from global tables
This utility function allows you to retrieve the raw list of receivers from the connections table for the given sender and signal pair.
Normally you would use liveReceivers( getReceivers( ...)) to retrieve the actual receiver objects as an iterable object.
Filter sequence of receivers to get resolved, live receivers
This is a generator which will iterate over the passed sequence, checking for weak references and resolving them, then returning all live receivers.
Send signal from sender to all connected receivers.
signal – (hashable) signal value, see connect for details
sender – the sender of the signal
if Any, only receivers registered for Any will receive the message.
if Anonymous, only receivers registered to receive messages from Anonymous or Any will receive the message
Otherwise can be any python object (normally one registered with a connect if you actually want something to occur).
Return a list of tuple pairs [(receiver, response), ... ]
if any receiver raises an error, the error propagates back through send, terminating the dispatch loop, so it is quite possible to not have all receivers called if a raises an error.
Send signal only to those receivers registered for exact message
sendExact allows for avoiding Any/Anonymous registered handlers, sending only to those receivers explicitly registered for a particular signal on a particular sender.
Error types for dispatcher mechanism
Bases: exceptions.KeyError, ars.lib.pydispatch.errors.DispatcherError
Error raised when unknown (sender,signal) set specified
Bases: exceptions.TypeError, ars.lib.pydispatch.errors.DispatcherError
Error raised when inappropriate signal-type specified (None)
Module implementing error-catching version of send (sendRobust)
Send signal from sender to all connected receivers catching errors
signal – (hashable) signal value, see connect for details
sender – the sender of the signal
if Any, only receivers registered for Any will receive the message.
if Anonymous, only receivers registered to receive messages from Anonymous or Any will receive the message
Otherwise can be any python object (normally one registered with a connect if you actually want something to occur).
Return a list of tuple pairs [(receiver, response), ... ]
if any receiver raises an error (specifically any subclass of Exception), the error instance is returned as the result for that receiver.
Robust apply mechanism
Provides a function “call”, which can sort out what arguments a given callable object can take, and subset the given arguments to match only those which are acceptable.
Refactored “safe reference” from dispatcher.py
Bases: object
‘Safe’ and reusable weak references to instance methods
BoundMethodWeakref objects provide a mechanism for referencing a bound method without requiring that the method object itself (which is normally a transient object) is kept alive. Instead, the BoundMethodWeakref object keeps weak references to both the object and the function which together define the instance method.
weakSelf – weak reference to the target object
weakFunc – weak reference to the target function
Return a weak-reference-like instance for a bound method
reference, must have <im_self> and <im_func> attributes and be reconstructable via:
target.<im_func>.__get__( target.<im_self> )
which is true of built-in instance methods.
Return a safe weak reference to a callable target