How Does Short Circuit Evaluation Optimize Conditional Expressions in Go?

Short Circuit Evaluation in Go: Order of Boolean Expressions

In Go, like many other programming languages, short circuit evaluation is implemented within conditional expressions. This means that nested boolean expressions are evaluated in a certain order, optimizing performance in specific cases.

Consider the following code:

if error != nil || someFunc() || otherFunc() {
    return
}

If the error in the above expression is not nil, Go will immediately return without calling someFunc() or otherFunc(). This is because || is a short-circuiting operator. If the first subexpression (error) evaluates to true, the result of the overall expression is known to be true regardless of the outcome of the subsequent subexpressions.

In another example:

if !isValidQueryParams(&queries) || r == nil || len(queries) == 0 {
    return
}

Since short circuit evaluation is in effect, if isValidQueryParams() returns false, Go will immediately return without checking if r is nil or if the queries list is empty. This approach helps reduce unnecessary computations.

Therefore, when optimizing performance in such scenarios, you should consider the potential cost of each function call and place them in an order that leverages short circuit evaluation. Go will evaluate expressions from left to right, and as soon as the overall result (true or false) is determined, the remaining expressions will not be evaluated.

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