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AttributeError: 'super' object has no attribute ... #549
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You must import I see I have to change something in the documentation, this should be mentioned in PyObjC's introduction but it isn't. Background: PyObjC's proxy for Cocoa classes dynamically looks for methods as needed, both for performance reasons and because Cocoa classes can change at runtime without a way to cheaply detect this. Because of this the I've written a PEP that tries to fix this PEP 447, but now think this is too complex and that a better solution is possible. I haven't gotten around to fully flesh out a proposal for that though (and in any case, such a proposal would end up in Python 3.13 at the earliest). |
Can |
this still fails with pyobjc 9.1.1 and import AppKit
import objc
print(objc.__version__)
class Sub(AppKit.NSObject):
def init(self):
print("init")
self = objc.super().init()
return self
s = Sub.alloc().init()
|
Yes, you can. |
That's because you really have to use import AppKit
import objc
from objc import super
print(objc.__version__)
class Sub(AppKit.NSObject):
def init(self):
print("init")
self = super().init()
return self
s = Sub.alloc().init() |
thanks for the explanation! |
In my case, this was baffling to discover, because it looked like it worked correctly locally in local & alias builds for me, but then failed in release builds. I wonder if it would be possible to at least have a linter for this somehow, if a clearer error when using the wrong |
I'm afraid not. I've considered changing the type of the |
A linter is possible, but not something I can work on in the short term. |
There now is some documentation. Leaving the issue open for now to look into linter possibilities. |
Hmmm... Because of the way calls to argument less super is implemented in CPython it might be possible to detect this at runtime. In particular: there will be a Something that could be good enough (in if "__classcell__" in class_dict:
if "__module__" in class_dict:
mod = sys.modules[class_dict["__module__"]]
if not hasattr(mod, "super") or mod.super is not objc.super:
warnings.warn("Objective-C subclass uses super() but super is not objc.super", ...) Probably with configuring the used warning to always report. The code above is completely untested at this time. |
import objc
NSObject = objc.lookUpClass("NSObject")
class MyObject(NSObject):
def init(self):
self = super().init()
if self is None:
return None
self.a = 42
return self $ python3 a.py
/a.py:5: ObjCSuperWarning: Objective-C subclass uses super(), but super is not objc.super
class MyObject(NSObject): |
This adds a new warning ``objc.ObjCSuperWarning`` and uses that to warning about class definitions that use argumentless super in Objective-C subclasses without binding ``super`` to ``objc.super``.
Changeset d6e9b63 warns about using the wrong That's not entirely ideal because the warning will mostly be invisible when using a tool like py2app to create a standalone application, but makes it a lot easier to detect the issue (and this also found a recent bug in the PyObjC testsuite itself...) |
super! thanks |
Describe the bug
Calling
super()
in a subclasses of NSObject (like a NSView) triggers an error.Platform information
this worked fine in pyobjc 9.0.1
thanks!!
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