Difference between “if x” and “if x is not None”

Question

It appears that \"if x\" is almost like short-hand for the longer \"if x is not None\" syntax. Are they functionally identical or are there cases where for a given value of

Answer 1

if x:
    # Evaluates for any defined non-False value of x
if not x:
    # Evaluates for any defined False value of x
if x is None:
    # Evaluates for any instances of None

None is its own type, which happens to be False. "if not x" evaluates if x = None, only because None is False.

There aren't any subtle differences that I know of but there are exact methods to test for use for positivity/negativity in exact situations. Mixing them can work in some situations, but can lead to problems if they're not understood.

if x is True:
    # Use for checking for literal instances of True
if x is False:
    # Use for checking for literal instances of False
if x is None:
    # Use for checking for literal instances of None
if x:
    # Use for checking for non-negative values
if not x:
    # Use for checking for negative values
    # 0, "", None, False, [], (), {} are negative, all others are True