saferef.safeRef() doesn't update BoundMethodWeakref.deletionMethods

[z-tux-mind]

Thank you for this great library, it is of great help for event-driven apps 😊

Calling again saferef.safeRef(object, newOnDeleteCallback) results in setting the BoundMethodWeakref.deletionMethods to [newOnDeleteCallback] instead of [oldOnDeleteCallback, newOnDeleteCallback].

I think this is caused by a wrong usage of __new__. Objects returned by __new__ are consequently passed to __init__.
Therefore, __init__ is re-run when another reference is created, which is not the intended behaviour as the code is written.

pydispatcher/pydispatch/saferef.py

Line 70 in 5119d46

def __new__( cls, target, onDelete=None, *arguments,**named ):

A simple solution would be to check if the instance has already been initialised in __init__:

def __init__(self, ...):
    if hasattr(self, 'deletionMethods'): return

Also, another change I would add is:

# in __new__
if onDelete is not None:
    current.deletionMethods.append( onDelete)
# in __init__
self.deletionMethods = [onDelete] if onDelete is not None else []

Thank you for your time and great help!

[mcfletch]

Sorry, been working on paying work rather intently. I'm taking off time next month, so should be able to look into this then.