relEval()
 Evaluate a block against the relation in specified work area
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 Prototype

     ERRCODE relEval(
                          AREAP wa,
                          LPDBRELINFO lpdbRelInfo
                       )

 Arguments

     wa is a pointer to self.

     lpdbRelInfo is a pointer to a structure containing information on a
     relation.

 Description

     relEval() performs a relational seek from the parent work area
     referenced by wa to the child work area specified by lpdbRelInfo.

 Default Behavior

     Evaluates the block held in the structure pointed to by
     lpdbRelInfo->itmCobExpr.  The expression resulting from the evaluation
     is placed in wa->valResult and the return code indicates success or
     failure.

     Note:  The selected work area is saved and restored.

     Warning!  If the item held in lpdbRelInfo->itmCobExpr is not a
     code block, a BASE/1004 "No exported method" error is generated.

 Implementation Notes

     .  If any global state necessary for the operation of your driver
        could be modified by the code block in lpdbRelInfo->itmCobExpr (i.e.,
        any CA-Clipper code), you should save that state, call
        SUPER_RELEVAL() and then restore the state.

 Files  Header file is Rdd.api.