CORRESPONDING - Base Form - ABAP Keyword Documentation

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CORRESPONDING - Base Form

Syntax

... { CORRESPONDING dtype|#( [DEEP]
                             [BASE ( base )]
                             struct|{itab [ duplicates]} ) }
  | { CORRESPONDING dtype|#( [BASE ( base )]
                             struct|{itab [ duplicates]}
                             mapping ) } ...

Addition:

... BASE ( base ) ...

Effect

This variant of the component operator CORRESPONDINGconstructs a result with the target type specified using dtype or # from the components of a parameter struct or itab. struct and itab are general expression positions.

If the target type is a structured type, a structure struct must be used as a parameter. The expression creates a structure of the target type. The target structure is either initial or is assigned the value of base after the optional addition BASE as a start value. The target structure is then by default assigned the identically named components of struct in accordance with the rules of MOVE-CORRESPONDING for structures.

If the target type is a table type, an internal table itab must be used as a parameter. The expression creates an internal table of the target type. The target table is either initial or is assigned the value of base after the optional addition BASE as a start value. The target table is then by default assigned the identically named columns of itab in accordance with the rules of MOVE-CORRESPONDING for internal tables using the addition KEEPING TARGET LINES. Here, the addition duplicates can be used to define the behavior with respect to duplicate rows occurring in a target table with unique table keys.

If the addition DEEP is specified, the assignment is made in the same way as with the addition EXPANDING NESTED TABLES of the statement MOVE-CORRESPONDING. A mapping rule mapping can be used to override the matching name assignment rule of MOVE-CORRESPONDING. If a mapping rule is specified, the addition DEEP is set implicitly. It is not allowed to be set explicitly.

Notes

An assignment of structures

struct2 = CORRESPONDING #( struct1 ).

without the addition BASE is not the same as an assignment

MOVE-CORRESPONDING struct1 TO struct2.

In MOVE-CORRESPONDING, all not identically named components in struct2 keep their value. If the result of the constructor expression is assigned, however, they are assigned the value from there. This value is initial for ignored components. This behavior can be overridden using the addition BASE.

In the case of an assignment of a parameter to the target type and its assignment to a data object

dobj = CORRESPONDING type( ... ).

the target object is used directly (for optimization reasons) and a temporary version of the expression is not created and assigned. This is not possible when the target object and parameter are identical and a mapping rule is used. This enables, for example, the content of two components to be switched. In cases like this, a temporary copy of the target object must be created and used and an appropriate syntax warning is produced. This warning can be hidden using a pragma. If this is not detected until runtime, the information needed to create the necessary temporary copy of the target object is missing and runtime error CORRESPONDING_SELF occurs. See the executable example Reflexive Component Assignments.

Example

Assignment of four identically named components of standard table spfli_tab to a temporarily sorted table of type flights on an operand position.

TYPES:
  BEGIN OF flight,
    carrid TYPE spfli-carrid,
    connid   TYPE spfli-connid,
    cityfrom TYPE spfli-cityfrom,
    cityto   TYPE spfli-cityto,
  END OF flight.
TYPES
  flights TYPE SORTED TABLE OF flight WITH UNIQUE KEY carrid connid.

SELECT *
       FROM spfli
       INTO TABLE @DATA(spfli_tab).

cl_demo_output=>display( CORRESPONDING flights( spfli_tab ) ).

Executable Examples

Component Operator for Structures

Component Operator for Internal Tables

Component Operator for Table Expression

Addition

... BASE ( base ) ...

Effect

The addition BASE can be used to specify a start value base for the new structure or internal table. base is a functional operand position in which a database convertible to the target type can be specified.

If the addition BASE is specified, the value of base is assigned to the target structure or target table in accordance with the general assignment rules before the remainder of the expression is evaluated. Here, the addition duplicates after itab can be used to define the behavior with respect to duplicate rows occurring in a target table.

Notes

Unlike the operators NEW and VALUE, parentheses must be placed around base in CORRESPONDING .

Unlike the operators NEW and VALUE, the data type of base is not used in CORRESPONDING to determine a result type specified using #.

The addition BASE can be used with the component operator to replace the statement MOVE-CORRESPONDING as follows:

An assignment of structures

struct2 = CORRESPONDING #( BASE ( struct2 ) struct1 ).

is the same as an assignment

MOVE-CORRESPONDING struct1 TO struct2.

An assignment of internal tables

itab2 = CORRESPONDING #( BASE ( itab2 ) itab1 ).

is the same as an assignment

MOVE-CORRESPONDING itab1 TO itab2 KEEPING TARGET LINES.

Example

Assignment of results of the component operator without and with addition BASE to existing structures of the same content. The value of the component that is not available in the source structure is only retained if BASE is used.

DATA:
  BEGIN OF src,
    a TYPE i VALUE 1,
    b TYPE i VALUE 2,
  END OF src,
  BEGIN OF target1,
    b TYPE i VALUE 11,
    c TYPE i VALUE 12,
  END OF target1.
DATA(target2) = target1.

target1 = CORRESPONDING #( src ).
target2 = CORRESPONDING #( BASE ( target2 ) src ).

cl_demo_output=>new( )->write( target1 )->display( target2 ).