On Tue, 14 Aug 2018 10:58:17 +0200, Frank Millman wrote:
>> > I have an abstract class ClassA with a number of concrete
>> > sub-classes. ClassA has a method which invokes 'self.method_b()'
>> > which is defined separately on each sub-class. Pylint complains that
>> > "Instance of 'ClassA' has no 'method_b' member".
[...]
> I do mean a lot of methods, not classes. I don't have any problem adding
> the lines. It is just that, before I starting using pylint, it had not
> occurred to me that there was any problem with my approach. If an
> experienced python programmer was reviewing my code, would they flag it
> as 'bad style'?
*shrug*
I wouldn't necessarily call it *bad*, but perhaps *not-quite good* style.
I think its fine for a small projects and quick scripts, especially if
they're written and maintained by a single person for their own use.
Perhaps not so much for large projects intended for long-term use with
continual development.
If there really are a lot of such missing methods, I'd consider writing
something like this:
class A:
def __init__(self, ...):
...
# === process abstract methods en masse ===
for name in "method_a method_b method_c method_d".split():
@abstractmethod
def inner(self):
raise NotImplementedError
inner.__name__ = name
# This is okay, writing to locals works inside the class body.
locals()[name] = inner
del inner, name # Clean up the class namespace.
def concrete_method_a(self):
...
although to be honest I'm not sure if that would be enough to stop PyLint
from complaining.
--
Steven D'Aprano
"Ever since I learned about confirmation bias, I've been seeing
it everywhere." -- Jon Ronson
--
https://mail.python.org/mailman/listinfo/python-list
