If we are using too many conditional IF, ELSEIF or ELSE statements it will impact performance. We can think of using a switch statement instead of multiple if-else if possible, or refactor code to reduce number of IF, ELSEIF and ELSE statements. Sometimes called "complexity cyclomatic". MATCH-CASE statement has a performance advantage over if – else.

Functional rules

one variable must be used maximum twice in IF / ELSEIF / ELSE statements at the same level - WARNINGs :
IF and ELSEIF statements use explicitly variable names !
ELSE statements use implicity variable names !
one variable must be used maximum twice in IF / ELSEIF / ELSE statements at differents hierarchical levels
we can assume that if one variable is used three times or more, we should :
use a MATCH-CASE statement instead
or refactor the code if possible

Non compliant Code Example

Non-compliant, because nb is used 4 times : - 2 explicit times in IF statements - 2 implicit times in ELSE statements

index = 1
nb = 2
...
if nb == 0:
    nb = index
elif nb == 1:
    nb = index * 2
elif nb == 2:
    nb = index * 3
else:
    nb = -1
return nb

Compliant Code Example

MATCH-CASE statement solution + refactor solution

index = 1
nb = 2
...
match nb:
    case 0:
        nb = index * (nb + 1)
    case 1:
        nb = index * (nb + 1)
    case 2:
        nb = index * (nb + 1)
    case _:
        nb = -1
return nb