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Python Python Basics (2015) Logic in Python Weighing Your Options

Posted by Robert Peters
Robert Peters
3,728 Points

Python, is vs ==

Does anyone know which is more secure to use for checking if a variable is None in Python, A == None or A is None, couldn't tell which was being referred to at the end of the vid. And if possible, give a (VERY) simple explanation as to how the other creates a security flaw? I realise that may be well beyond me, for now, but... curiosity.

3 Answers

Robert Peters
Robert Peters
3,728 Points

cheers pal, yeah its a pretty good description thanks. maybe I misunderstood him in that he didn't mean it's actually 'unsafe' to use the ==, just that it's 'safer' to use 'is' in these circumstances as in it's 'correct'. Thanks for the help

Idan Melamed
Idan Melamed
16,285 Points
Idan Melamed
Idan Melamed
16,285 Points

From this stackoverflow thread:

Quoting Python's Coding Style Guidelines - PEP-008 (jointly defined by Guido himself), Comparisons to singletons like None should always be done with is or is not, never the equality operators.

I'm still not exactly sure why this is preferable then ==...

diegoholt
diegoholt
1,076 Points
diegoholt
diegoholt
1,076 Points

Yeah I'd love some clarification here too!