FUNCTIONUnder review

FieldBlock

FieldBlock( cField ) --> bRet

Creates a block for reading or assigning a field.

FieldBlockAdvPL

01 · OVERVIEW

Overview

A FieldBlock block reads when evaluated without a value and assigns when supplied a value. Not every Eval is harmless reading. A missing field can allow block creation and fail only on evaluation. This GitHub adaptation checks field and record position, evaluates without a write value and keeps EDTRB context during creation and evaluation. It reports value type rather than registration data. EDTRB is an already-open owned test alias; ED_COD, when used, is a length-10 character field in the teaching schema. (TOTVS, n.d., ref. 1)

02 · SYNTAX

Syntax

FieldBlock( cField ) --> bRet

Parameters

cField

CharacterRequired

Existing field name in the alias.

Return value

Field-access block; definition errors can return Nil.

03 · PRACTICAL EXAMPLE

Commented example

#Include "Protheus.ch"

User Function Ed383()
    Local bRead
    Local xValue
    If Select("EDTRB") > 0
        If EDTRB->(FieldPos("ED_COD")) > 0 .And. !EDTRB->(Eof())
            bRead := EDTRB->(FieldBlock("ED_COD"))
            // No second argument: do not assign the field.
            xValue := EDTRB->(Eval(bRead))
            ConOut(ValType(xValue))
        EndIf
    EndIf
Return Nil

Expected result

With prepared schema/record, expected type C without assignment. Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.

BEST PRACTICES

Use only an owned test table with known schema. Qualify the alias, check record position and manage context changes under the caller contract.
Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.