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Yegor Bugayenko
18 August 2015
Why Many Return Statements Are a Bad Idea in OOP
This debate
is very old, but I have something to say too. The question
is whether a method may have multiple return
statements or always
just one. The answer may surprise you: In a pure object-oriented
world, a method must have a single return
statement and nothing else.
Yes, just a return
statement and that’s it. No other operators
or statements. Just return
. All arguments in favor of multiple
return
statements go against the very idea of object-oriented programming.
This is a classical example:
public int max(int a, int b) {
if (a > b) {
return a;
}
return b;
}
The code above has two return
statements, and it is shorter than this one
with a single return
:
public int max(int a, int b) {
int m;
if (a > b) {
m = a;
} else {
m = b;
}
return m;
}
More verbose, less readable, and slower, right? Right.
This is the code in a pure object-oriented world:
public int max(int a, int b) {
return new If(
new GreaterThan(a, b),
a, b
);
}
What do you think now? There are no statements or operators. No if
and no >
.
Instead, there are objects of class If
and GreaterThan
.
This is a pure and clean object-oriented approach.
However, Java doesn’t have that. Java (and many other pseudo OOP languages)
gives us operators like if
, else
, switch
, for
, while
, etc. instead
of giving built-in classes, which would do the same. Because of that, we continue
to think in terms of procedures and keep talking about whether
two return
statements are better than one.
If your code is truly object-oriented, you won’t be able to have more than
one return
. Moreover, you will have nothing except a return
in each method.
Actually, you will have only two operators in the entire
software—new
and return
. That’s it.
Until we’re there, let’s stick with just one return
and at least try to look
like pure OOP.