FUNCTIONUnder review

AEval

AEval( <aArray>, <bBlock>, [nStart], [nCount] ) --> aRet

Executes a block for each element in a range.

AEvalAdvPL

01 · OVERVIEW

Overview

The block receives the element and its index. In multidimensional arrays, a first-level element may be a nested array; AEval does not automatically traverse every cell. Individual block results do not build a new mapped collection: write into a separate destination for that. The example accumulates a sum without modifying source values. (TOTVS, s.d., ref. 1)

02 · SYNTAX

Syntax

AEval( <aArray>, <bBlock>, [nStart], [nCount] ) --> aRet

Parameters

aArray

ArrayRequired

Traversed array.

bBlock

Code blockRequired

Block receiving element and index.

nStart

NumericOptional

First position; default 1.

nCount

NumericOptional

Count from the starting position; defaults through the end.

Return value

Array after the operation; do not assume independent cloning.

03 · PRACTICAL EXAMPLE

Commented example

#Include "Protheus.ch"

User Function EdAeval()
    Local aValues := {10, 20, 30}
    Local nTotal := 0
    // The accumulator is external; no assignments change the array.
    AEval(aValues, {|nValue| nTotal += nValue})
    ConOut(cValToChar(nTotal))
Return Nil

Expected result

Expected result: 60. Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.

BEST PRACTICES

Validate element types before summing external data. Avoid resizing the array during evaluation.
Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.