I'm quite new to Python (and its duck typing), but am currently working on a Python project that needs serious refactoring. In a for loop, I need to discriminate between items of a list based on their type, and call functions defined in the derived class. What is the Python way of doing this? Consider this: from typing import List class A: def __init__(self): pass class B(A): def my_function(self): print("I'm of type B.") collection: List[A] = [A(), B(), A(), B(), B()] # select only the B items and call their specific function for object in [item for item in collection if isinstance(item, B)] object.my_function() # <- no help from the IDE here In that last line, object is expected to be of type A. Since type hinting the loop variable is not allowed, I could introduce a more specific variable, because I already did the type checking: for object in [item for item in collection if isinstance(item, B)] b: B = object # a "sort-of" cast b.my_function() # <- IDE recognizes b to be of type B I'd like to only use the means provided by Python itself, not PyCharm or similar tools. Is there a better way of achieving type hinting support besides introducing a type-hinted extra variable? Continue reading...
