Why would a language NOT use Short-circuit evaluation?

Question

Why would a language NOT use Short-circuit evaluation? Are there any benefits of not using it?

I see that it could lead to some performances issues... is that true?

Answer 1

I'd say 99 times out of 100 I would prefer the short-circuiting operators for performance.

But there are two big reasons I've found where I won't use them. (By the way, my examples are in C where && and || are short-circuiting and & and | are not.)

1.) When you want to call two or more functions in an if statement regardless of the value returned by the first.

if (isABC() || isXYZ()) // short-circuiting logical operator
    //do stuff;

In that case isXYZ() is only called if isABC() returns false. But you may want isXYZ() to be called no matter what.

So instead you do this:

if (isABC() | isXYZ()) // non-short-circuiting bitwise operator
    //do stuff;

2.) When you're performing boolean math with integers.

myNumber = i && 8; // short-circuiting logical operator

is not necessarily the same as:

myNumber = i & 8; // non-short-circuiting bitwise operator

In this situation you can actually get different results because the short-circuiting operator won't necessarily evaluate the entire expression. And that makes it basically useless for boolean math. So in this case I'd use the non-short-circuiting (bitwise) operators instead.

Like I was hinting at, these two scenarios really are rare for me. But you can see there are real programming reasons for both types of operators. And luckily most of the popular languages today have both. Even VB.NET has the AndAlso and OrElse short-circuiting operators. If a language today doesn't have both I'd say it's behind the times and really limits the programmer.