Python if condition and "and"

Question

Python if condition and "and"

 >>> def foo(a):
        print "called the function"
        if(a==1):
            return 1
        else:
            return None
>>> a=1

>>> if(foo(a) != None and foo(a) ==1):
    print "asdf"

called the function
called the function
asdf

Hey. how can i avoid calling the function twice without using an extra variable.

+5

python

boltsfrombluesky Mar 14 '13 at 11:24

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4 answers

how can i avoid calling the function twice without using an extra variable.

Here you can simply replace

if(foo(a) != None and foo(a) ==1):

with

if foo(a) == 1:

foo(a) != Noneis redundant: if foo(a) == 1guaranteed not to be None.

+7

NPE Mar 14 '13 at 11:25

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The following statement

if foo(a) == 1:

will deal with both conditions.

+1

Steve mayne Mar 14 '13 at 11:26

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if foo (a) == 1, then foo (a) will not be None,

so simplify your code:

if foo(a):
    print('asdf')

+1

zds_cn Mar 14 '13 at 11:43

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John la rooy · Accepted Answer · 2013-03-14T11:26:15+0000

You can link comparisons this way

if None != foo(a) == 1:

It works like

if (None != foo(a)) and (foo(a) == 1):

except that it evaluates foo (a) only once.

Python if condition and "and"

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