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ABENABAP_FIELD_SYMBOLS - ABAP FIELD SYMBOLS

Field Symbols

Field symbols are declared using the statement FIELD-SYMBOLS or the declaration operator FIELD-SYMBOL and are either placeholders or symbolic names for existing data objects, or parts of existing data objects to which a memory area can be assigned at program runtime. A field symbol does not reserve physical space in the data area of a program like a data object. Instead, it works as a dynamic identifier of a memory area, where a specific data object or part of an object is located. A field symbol can be used instead of data objects at operand positions of statements. When such a statement is executed, a memory area must be assigned to the field symbol using the statement ASSIGN or the addition ASSIGNING when processing internal tables.

Field symbols can point to almost any data object. A field symbol is similar to a data reference variable dereferenced using ->*. Unlike data reference variables, value semantics are used to access a field symbol Accessing a field symbol is like accessing the named data object or part of the object itself. For data reference variables, however, reference semantics apply.

Field symbols are used for generic work with data objects and for explicit casting of data objects, which is only possible using field symbols.

Use field symbols and data references in appropriate ways

Notes

• Field symbols to which data objects or parts of data objects are assigned in the heap act memory-preserving, like heap references.

• From a technical perspective, the field symbols are implemented by references or pointers, which are comparable to references in data reference variables. A data reference variable is declared in the same way as every other data object and the memory area for the reference it contains is in the data area of the ABAP program. However, the pointer assigned to a field symbol is exclusively managed by the ABAP runtime framework and is located in a memory area, which cannot be accessed directly in an ABAP program.