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>getattr(self, name) > ... This can be useful for catching and redirecting common misspellings ... I can think of only one good reason to redirect spel

>__getattr__(self, name) > ... This can be useful for catching and redirecting common misspellings ... I can think of only one good reason to redirect spelling errors, and that's if you are a widely-used library and you want to support both "color" and "colour" (and similar Britishisms). Other than that, you're just asking for a headache.

chernevik 15y ago
I am but an egg . . . and while I agree this stuff is great, it is magic and I think it helps to write code so your usage is explicit. Sometimes all that's needed is a hint that something is Not Normal, so the code reader is alerted to look carefully. A test showing Foo(4) * Bar('grandma') == 'nice' can at least flag and often explain whatever mysteries you've created. If you don't put the tests in doc strings with doc tests, at least put a reference to them in the module so the reviewer knows to look for them. Stuff like __getattr__ is particularly tricky. I also try to end __getattr__ code with an AttributeException, which I find really helps debugging. I like using this to dispatch calls to objects better built to fill them, but I try to do so explicitly within the __getattr__ code to give reviewers a clue as to what's going on. For example, I'll check the attribute name against a list before passing it on to the target object. Even if I intent to pass _everything_ to a target, I'll first check the target for the passed attribute with getattr(target, attribute name, False), so that failed passthroughs stay with the object calling them. (You can generate messages indicating the problem -- "Can't find 'RIAA' in object 'Nice'" and pass those to an AttributeException.) Ideally any string validly usable as an instance attribute should be findable somewhere in the code by grep.
jules 15y ago
It would be perhaps be useful to throw an error saying "X object has no attribute Y, did you mean Z instead?".
- steve-howard 15y ago
  That's probably a better idea. In either case being "liberal in what you accept" is a discredited software practice.
  - mhansen 15y ago
    being "liberal in what you accept" is a discredited software practice. What? When did that get discredited?
    - steve-howard 15y ago
      Not entirely discredited; I spoke too strongly. It's not a good idea to be more liberal than the situation calls for; here's a discussion on the subject: http://programmers.stackexchange.com/questions/12401/be-liberal-in-what-you-accept-or-not http://programmers.stackexchange.com/questions/12401/be-libe...

>__getattr__(self, name) > ... This can be useful for catching and redirecting common misspellings ... I can think of only one good reason to redirect spel

chernevik 15y ago

I am but an egg . . . and while I agree this stuff is great, it is magic and I think it helps to write code so your usage is explicit. Sometimes all that's needed is a hint that something is Not Normal, so the code reader is alerted to look carefully. A test showing Foo(4) * Bar('grandma') == 'nice' can at least flag and often explain whatever mysteries you've created. If you don't put the tests in doc strings with doc tests, at least put a reference to them in the module so the reviewer knows to look for them. Stuff like __getattr__ is particularly tricky. I also try to end __getattr__ code with an AttributeException, which I find really helps debugging. I like using this to dispatch calls to objects better built to fill them, but I try to do so explicitly within the __getattr__ code to give reviewers a clue as to what's going on. For example, I'll check the attribute name against a list before passing it on to the target object. Even if I intent to pass _everything_ to a target, I'll first check the target for the passed attribute with getattr(target, attribute name, False), so that failed passthroughs stay with the object calling them. (You can generate messages indicating the problem -- "Can't find 'RIAA' in object 'Nice'" and pass those to an AttributeException.) Ideally any string validly usable as an instance attribute should be findable somewhere in the code by grep.

jules 15y ago

It would be perhaps be useful to throw an error saying "X object has no attribute Y, did you mean Z instead?".

steve-howard 15y ago
That's probably a better idea. In either case being "liberal in what you accept" is a discredited software practice.
- mhansen 15y ago
  being "liberal in what you accept" is a discredited software practice. What? When did that get discredited?
  - steve-howard 15y ago
    Not entirely discredited; I spoke too strongly. It's not a good idea to be more liberal than the situation calls for; here's a discussion on the subject: http://programmers.stackexchange.com/questions/12401/be-liberal-in-what-you-accept-or-not http://programmers.stackexchange.com/questions/12401/be-libe...