Object Watchdog uses existing instance instead of creating new instances

[ghost]

Imagine having the following snippet:

class A(metaclass=ObjectWatchdog):
	def __init__(self, number: int):
		self.number = number

a = A(1)
b = A(2)

What do we expect? We expect a.number == 1 and b.number == 2. However, when printing the a.number we see 2 (!). Adding a print statement before setting the number at initialization level (print(hasattr(self, "number"))) reveals that self.number is already set on instance b.

[yanongena]

Is there a fix for this? I have the same issue which makes the package pretty much useless...
It's a great package but this issue is really a big issue.

[cr0hn]

Not yet. I have the issue in the queue, but other projects with sponsorship have preference

[yanongena]

I've been doing a bit of debugging and think I found the issue.
Because you are replacing the setattr method from a metaclass, you are actually replacing the class function so each instance has the same reference to that method so although we might have different objects, they point to the same function so that's why when setting an attribute on one object, also sets it on the other objects.

I've created my own version which doesn't use metaclass but regular inheritence. This works great.
Just wanted to share, just in case :)

class DataObserver:

    __observableAttrs__ = []
    __observers = []

    def __setattr__(self, key, value):
        self.__dict__[key] = value
        if key in self.__observableAttrs__:
            for observer in self.__observers:
                observer(self, key, value)


    def addObserver(self, fn):
        self.__observers.append(fn)

[idotzang]

This package seems to do exactly what I need, but this is indeed a major issue.
Any timeline to solving this?
Thank you

[saurabh0719]

This package seems to do exactly what I need, but this is indeed a major issue. Any timeline to solving this? Thank you

@idotzang I made a tiny package encapsulating this functionality, it may help - https://github.com/saurabh0719/object-tracker

[cr0hn]

This package seems to do exactly what I need, but this is indeed a major issue.
Any timeline to solving this?
Thank you

Sorry, but currently, I not have so much time to maintain this package, sorry. A PR sounds great :)