UninitializedDeallocWarning: NSNotification object with postNotification_ is empty and wont work

[leifadev]

Problem

Having trouble making a notification come up. I believe I am getting the warning because the object x I am making in the first place is empty as from print statements. After the failed attempt too, no print statements would show up again too.

Cocoa.NSNotification.alloc().init_() is supposed to be an empty notification called by Cocoa.NSNotificationCenter.alloc().postNotification_(x), but it doesn't work and I get the UninitializedDeallocWarning error below:

Code

@objc.IBAction
def helplink_(self, url):
  x = Cocoa.NSNotification.alloc().init_()
  Cocoa.NSNotificationCenter.alloc().postNotification_(x)

Error

PycharmProjects/shoutout/main.py:77: UninitializedDeallocWarning: leaking an 
uninitialized object of type NSNotificationCenter
  x = Cocoa.NSNotification.alloc().init_()

Here is working code for launching a NSURL string object...

x = Cocoa.NSURL.alloc().initWithString_(self.gitUrl)
Cocoa.NSWorkspace.alloc().openURL_(x)

I am confused on how I can solve this, I will try to figure out a way to use other ones besides postNotification: or initWithName:object:userInfo:, etc. Any help on what I am doing wrong?

[ronaldoussoren]

PyObjC maps Objective-C's method calls directly into Python. Because of this object creation is a two step process, an explicit version of Python's __new__ and __init__ methods, for example:

obj = NSObject.alloc().init()

Leaving out the call to an init* method results in a partially initialised object, hence the UninitializedDeallocWarning. And alternative to using the two-step construction proces is to use one of the factory methods on a class (such as Cocoa.NSArray.array()).

In your particular case the call to postNotification_ uses the wrong pattern, it should be something like this:

@objc.IBAction
def helplink_(self, url):
    x = Cocoa.NSNotification.alloc().init() # Or probably    x = Cocoa.NSNotification.notificationWithName_object_("hi", 42) 
    Cocoa.NSNotificationCenter.defaultCenter().postNotification_(x) 

BTW. I intent to add more pythonic object creation in a future version, hopefully this year. See #275 for the basic idea.

[leifadev]

BTW. I intent to add more pythonic object creation in a future version, hopefully this year. See #275 for the basic idea.

What do you mean by exactly making it more pythonic? Meaning allowing things ot be simplified in certain ways, super or subclassing stuff?

P.S. Also, I made a discord server for people to talk and get support about this, it has a simple open-source wiki with tickets for people to add good info. https://dsc.gg/pyobjc

If you think it would be helpful you can link it somewhere, or otherwise ill invite someone separately if I help them I dont know

[leifadev]

Sadly after I wrote the above comment, I got this error:

/Users/ddd/PycharmProjects/shoutout/main.py:73: UninitializedDeallocWarning: leaking an uninitialized object of type NSConcreteNotification

However with x = Cocoa.NSNotification.notificationWithName_object_("hi", 42), it passed and registered at the memory address as a NSConcreteNotification object here: NSConcreteNotification 0x1001df2f0 {name = hi; object = 42}

However, no notification showed up sadly