[GROUPED] [LINKCOUNTED] [STREAMED] DATASET( struct )

This form is only used as a Value Type for passing parameters, specifying function return types, or defining a SET OF datasets. If GROUPED is present, the passed parameter must have been grouped using the GROUP function. The LINKCOUNTED and STREAMED keywords are primarily for use in BEGINC++ functions or external C++ library functions.

Example:

MyRec := {STRING1 Letter};
SomeFile := DATASET([{'A'},{'B'},{'C'},{'D'},{'E'}],MyRec);
         
//Passing a DATASET parameter
FilteredDS(DATASET(MyRec) ds) := ds(Letter NOT IN ['A','C','E']);
                  //passed dataset referenced as "ds" in expression
          
OUTPUT(FilteredDS(SomeFile));

//*****************************************************************
// The following example demonstrates using DATASET as both a
// parameter type and a return type
rec_Person := RECORD
  STRING20 FirstName;
  STRING20 LastName;
END;

rec_Person_exp := RECORD(rec_Person)
  STRING20 NameOption;
END;

rec_Person_exp xfm_DisplayNames(rec_Person l, INTEGER w) :=
    TRANSFORM
  SELF.NameOption :=
           CHOOSE(w,
                  TRIM(l.FirstName) + ' ' + l.LastName,
                  TRIM(l.LastName) + ', ' + l.FirstName,
                  l.FirstName[1] + l.LastName[1],
                  l.LastName);
  SELF := l;
END;

DATASET(rec_Person_exp) prototype(DATASET(rec_Person) ds) :=
     DATASET( [], rec_Person_exp );

DATASET(rec_Person_exp) DisplayFullName(DATASET(rec_Person) ds) :=
     PROJECT(ds, xfm_DisplayNames(LEFT,1));

DATASET(rec_Person_exp) DisplayRevName(DATASET(rec_Person) ds) :=
     PROJECT(ds, xfm_DisplayNames(LEFT,2));

DATASET(rec_Person_exp) DisplayFirstName(DATASET(rec_Person) ds) :=
     PROJECT(ds, xfm_DisplayNames(LEFT,3));

DATASET(rec_Person_exp) DisplayLastName(DATASET(rec_Person) ds) :=
     PROJECT(ds, xfm_DisplayNames(LEFT,4));

DATASET(rec_Person_exp) PlayWithName(DATASET(rec_Person) ds_in,
                                     prototype PassedFunc,
                                     STRING1 SortOrder='A',
                                     UNSIGNED1 FieldToSort=1,
                                     UNSIGNED1 PrePostFlag=1) := FUNCTION
  FieldPre := CHOOSE(FieldToSort,ds_in.FirstName,ds_in.LastName);
  SortedDSPre(DATASET(rec_Person) ds) :=
      IF(SortOrder='A',
         SORT(ds,FieldPre),
         SORT(ds,-FieldPre));
  InDS := IF(PrePostFlag=1,SortedDSPre(ds_in),ds_in);
  
  PDS := PassedFunc(InDS); //call the passed function parameter
         
  FieldPost := CHOOSE(FieldToSort,
                      PDS.FirstName, 
                      PDS.LastName,
                      PDS.NameOption);
  SortedDSPost(DATASET(rec_Person_exp) ds) :=
        IF(SortOrder = 'A',
          SORT(ds,FieldPost),
          SORT(ds,-FieldPost));
      
  OutDS := IF(PrePostFlag=1,PDS,SortedDSPost(PDS));
  RETURN OutDS;
END;

    //define inline datasets to use.
ds_names1 := DATASET( [{'John','Smith'},{'Henry','Jackson'},
                       {'Harry','Potter'}], rec_Person );
ds_names2 := DATASET( [ {'George','Foreman'},
                        {'Sugar Ray','Robinson'},
                        {'Joe','Louis'}], rec_Person );
          

//get name you want by passing the appropriate function parameter:
s_Name1 := PlayWithName(ds_names1, DisplayFullName, 'A',1,1);
s_Name2 := PlayWithName(ds_names2, DisplayRevName, 'D',3,2);
a_Name := PlayWithName(ds_names1, DisplayFirstName,'A',1,1);
b_Name := PlayWithName(ds_names2, DisplayLastName, 'D',1,1);
OUTPUT(s_Name1);
OUTPUT(s_Name2);
OUTPUT(a_Name);
OUTPUT(b_Name);