Hi there! A lot of the answers to your questions are at least implied
in the Fine Manual
(https://docs.python.org/3/library/functions.html#super), but it's not
very clear and written more for precision than comprehension. Here's my
attempt at explaining :-)
On 16/07/2019 11:08, אורי wrote:
Hi,
1. When we use super() in Python 3, we don't pass it the first argument
(self). Why?
Actually the first argument to super() isn't self, it's the class that
we want the superclass of. The *second* argument is self. In the
normal course of using super() inside a class method, these arguments
will almost always be the class itself and the instance the method was
called on. Since that's almost always the case, the compiler offers us
a short-cut: omit the "cls" and "self" and the compiler will fill them
in for us. That way we don't have to repeat ourselves and risk
mis-typing something.
What happens if the first argument is not self?
The first argument of what? I'm not sure what you're getting at here.
I think it would make more sense to use something like
self.super().__init__(*args, **kwargs) or something like this.
That would mean either forbidding classes to have a method named "super"
or accepting that users' classes could completely screw up inheritance
for their subclasses.
2. I want to override a function called build_suite in an inherited class.
The function receives an argument "test_labels" which I want to change (I
define it if it's not defined), but I don't do anything with the argument
"extra_tests". Is it possible to include "extra_tests" in *args, **kwargs
Yes.
and how?
Don't list it in your parameters :-)
def build_suite(self, test_labels=None, *args, **kwargs):
...
return super().build_suite(test_labels=test_labels, *args, **kwargs)
I think maybe they will release another version in the future
without "extra_tests", or with additional arguments, and I don't want to
have to change my code then.
With a shim layer like this, your chances of getting away with making no
changes to your code when an API you use changes are rather small.
--
Rhodri James *-* Kynesim Ltd
--
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