Editing Guard (computer science) (section)

{{Short description|Concept in computer science}}

In [[computer programming]], a '''guard''' is a [[Boolean expression]] that must evaluate to true if the [[Execution (computing)|execution]] of the [[Computer program|program]] is to continue in the branch in question. Regardless of which [[programming language]] is used, a '''guard clause''', '''guard code''', or '''guard statement''' is a check of integrity [[precondition]]s used to avoid errors during execution.

The term '''guard clause''' is a [[Software design pattern]] attributed to [[Kent Beck]] who codified many often unnamed coding practices into named software design patterns, the practice of using this technique dates back to at least the early 1960's. The '''guard clause''' most commonly is added at the beginning of a procedure and is said to "guard" the rest of the procedure by handling edgecases upfront.