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Functions, procedures and return values

Separates returned values from routine effects.

Functions, procedures and return valuesAdvPL

01 · OVERVIEW

Overview

A function can be called as a statement with its return discarded; that changes neither its declaration nor its effects. RETURN ends the current routine and can explicitly return Nil when no useful value exists. Here a helper calculates a value while the editorial entry only displays it. Display success is not write confirmation. (Sources: refs. 1–1.)

03 · PRACTICAL EXAMPLE

Commented example

#Include "Protheus.ch"
User Function Ed411()
    // The helper return participates in the expression.
    ConOut(cValToChar(Double411(4)))
Return Nil
Static Function Double411(nValue)
Return nValue*2

Expected result

Displays 8; main routine returns Nil. Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.

BEST PRACTICES

Document return and effects separately; test every exit path.
Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.

Functions, procedures and return values

Overview

Commented example

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