Question

A friend (fellow low skill level recreational python scripter) asked me to look over some code. I noticed that he had 7 separate statements that basically said.

if ( a and b and c):
    do something

the statements a,b,c all tested their equality or lack of to set values. As I looked at it I found that because of the nature of the tests, I could re-write the whole logic block into 2 branches that never went more than 3 deep and rarely got past the first level (making the most rare occurrence test out first).

if a:
    if b:
        if c:
    else:
        if c:
else:
    if b:
        if c:
    else:
        if c:

To me, logically it seems like it should be faster if you are making less, simpler tests that fail faster and move on.
My real questions are

1) When I say if and else, should the if be true, does the else get completely ignored?

2) In theory would

if (a and b and c)

take as much time as the three separate if statements would?

Answer 1

if statements will skip everything in an else bracket if it evaluates to true. It should be noted that worrying about this sort of problem, unless it’s done millions of times per program execution, is called “premature optimization” and should be avoided. If your code is clearer with three if (a and b and c) statements, they should be left in.