On Sat, Jun 26, 2021 at 5:09 AM Guido van Rossum email@example.com wrote:
On Fri, Jun 25, 2021 at 11:42 AM Chris Angelico firstname.lastname@example.org wrote:
On Sat, Jun 26, 2021 at 4:20 AM Guido van Rossum email@example.com wrote:
On Fri, Jun 25, 2021 at 8:22 AM Bluenix firstname.lastname@example.org wrote:
I am not fully aware of how ssl.SSLContext is used, but adding __slots__ would prevent this. You would see an error similar to: AttributeError: 'MyClass' object has no attribute 'my_attribute'
That's a reasonable solution, except that it's not backwards compatible. It's possible that there is code out there that for some reason adds private attributes to an SSLContext instance, and using __slots__ would break such usage. (They could perhaps fix their code by using a dummy subclass, but that could well become a non-trivial change to their code, depending on where they get their SSLContext instances.)
So unless there's evidence that nobody does that, we're stuck with the status quo. I'm adding Christian Heimes to the thread in case he has a hunch either way.
Another possible solution - although I'm not sure how practical this would be - would be to have __init__ accept only specific keyword arguments. You could do something like:
ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT, minimum_version=ssl.PROTOCOL_TLSv1_1)
and it would work, but if you misspell "minimum_version", it would error out. That's actually what I expected it to do, based on the signature; but it doesn't, it simply ignores the argument. Not actually sure what it does with kwargs.
But that's not what the OP wrote -- his code used an attribute assignment. It looks like SSLContext just throws the *args and **kwds away. You *must* set the attribute. I don't know why it has *args and **kwds at all -- maybe so that you can subclass it and define an __init__ that takes those?
It all seems a mystery to me. I've never used this directly -- I've always just used urllib's default for https URLs.
Yeah - my first thought on reading the OP's issue was "hmm, can't you just use kwargs and get them validated?", but it doesn't validate. So this would require both changing the SSLContext class *and* the calling code. Unideal, but less backward incompatible than __slots__ would be.