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Python Object-Oriented Python Advanced Objects Constructicons

Posted by Andrew McLane
Andrew McLane
3,385 Points

(books = None) explanation

So a few times when we create args in a method, we put them equal to None. Can someone explain what this does in more detail?

1 Answer

Ryan Cross
Ryan Cross
5,742 Points
Ryan Cross
Ryan Cross
5,742 Points

python doesnt like a mutable parameter. you want an empty list to work with so what about books = [] as a parameter? it doesnt work. read this for why:

http://docs.python-guide.org/en/latest/writing/gotchas/

ericfromportland
ericfromportland
Courses Plus Student 3,400 Points

Ryan, thanks for the info! I was puzzled by exactly the same question, and wondered why I just couldn't pass an empty list in as the parameter (instead of None). I have bookmarked that link! :-)

Cheers, Eric