3 ms·

The answer is a qualified "yes". Because not only can it no longer participate in multiple inheritance, but it is very prone to misbehaving silently when used i

The answer is a qualified "yes". Because not only can it no longer participate in multiple inheritance, but it is very prone to misbehaving silently when used in such a manner, even for experienced Python users. I say qualified because whether or not the bug warrants fixing is another matter. It's more warranted for public-facing APIs than internal code, since it's less practical for downstream users to modify your code. In your internal code, if your team knows about the issue or just avoids multiple inheritance altogether, or if you have some kind of static analysis to check class hierarchies for you, it might be safe to avoid. (Just listing some considerations that I can think of. There might be more.) My overall point though was just to illustrate one particular example of a flaw that catches even experienced Python developers off-guard, let alone beginners.

pansa2 6y ago
> every class should always call super().__init__() For this to work, should every class also have an __init__ method that accepts zero arguments?
- mehrdadn 6y ago
  That's an excellent question and this opens the door to another another interesting discussion. I don't have the energy for that unfortunately, but to reply to your comment: it's not really important that it succeeds per se. Drastically increasing the likelihood of an error is good enough. What's important is that it mitigates the chances of introducing a bug silently.
  - glyph 6y ago
    There’s no error in the original example; in Python, the ability to participate in inheritance diamonds with arbitrary other classes is a feature which must be explicitly documented and maintained. James Knight wrote a really good piece on this many years ago: https://fuhm.net/super-harmful/ https://fuhm.net/super-harmful/ The solution is just to avoid inheritance. It’s full of terrible pitfalls in most languages, but Python more than most.

pansa2 6y ago

> every class should always call super().__init__() For this to work, should every class also have an __init__ method that accepts zero arguments?

mehrdadn 6y ago
That's an excellent question and this opens the door to another another interesting discussion. I don't have the energy for that unfortunately, but to reply to your comment: it's not really important that it succeeds per se. Drastically increasing the likelihood of an error is good enough. What's important is that it mitigates the chances of introducing a bug silently.
- glyph 6y ago
  There’s no error in the original example; in Python, the ability to participate in inheritance diamonds with arbitrary other classes is a feature which must be explicitly documented and maintained. James Knight wrote a really good piece on this many years ago: https://fuhm.net/super-harmful/ https://fuhm.net/super-harmful/ The solution is just to avoid inheritance. It’s full of terrible pitfalls in most languages, but Python more than most.