Update
This commit is contained in:
danrega
@@ -1736,137 +1736,208 @@ The following examples show the retrieval of type information. Instead of the ex
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comes in handy, too.
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```abap
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"Getting a reference to a type description object of a type.
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"i.e. getting an instance of a type description class.
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"To do so, the static methods of the class CL_ABAP_TYPEDESCR can be used.
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"As shown below, the type decription object can be used to create data
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"objects dynamically. Note that instances of classes are not covered.
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"------------------------------------------------------------------------
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"---------------- Getting general type information ----------------------
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"------------------------------------------------------------------------
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"Type for which information should be retrieved
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TYPES elem_type TYPE c LENGTH 5.
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"Getting references to type description objects of a type ...
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"... using the cl_abap_typedescr=>describe_by_name method.
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"In this case, the name of the types are used.
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"The following examples cover elementary, structured and
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"internal table types.
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TYPES elemtype TYPE n LENGTH 3.
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TYPES structype TYPE zdemo_abap_carr.
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TYPES strtabtype TYPE string_table.
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"The reference in the type description object references an
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"object from one of the classes CL_ABAP_ELEMDESCR, CL_ABAP_ENUMDESCR,
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"CL_ABAP_REFDESCR, CL_ABAP_STRUCTDESCR, CL_ABAP_TABLEDESCR,
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"CL_ABAP_CLASSDESCR, or CL_ABAP_INTFDESCR. You may want to check the
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"content of the type description objects in the debugger.
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DATA(tdo_by_name_elem) = cl_abap_typedescr=>describe_by_name( 'ELEMTYPE' ).
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DATA(tdo_by_name_struc) = cl_abap_typedescr=>describe_by_name( 'STRUCTYPE' ).
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DATA(tdo_by_name_itab) = cl_abap_typedescr=>describe_by_name( 'STRTABTYPE' ).
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"Inline declarations are handy to avoid helper variables such as
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"in the following example.
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DATA tdo_by_name_elem_helper TYPE REF TO cl_abap_typedescr.
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tdo_by_name_elem_helper = cl_abap_typedescr=>describe_by_name( 'ELEMTYPE' ).
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"... using the cl_abap_typedescr=>describe_by_data method.
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"In this case, the data objects are provided.
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"The examples cover an elementary data object, a structure and and
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"internal table.
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DATA elemdobj TYPE elemtype.
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DATA strucdobj TYPE structype.
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DATA tabledobj TYPE strtabtype.
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DATA(tdo_by_data_elem) = cl_abap_typedescr=>describe_by_data( 'ELEMTYPE' ).
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DATA(tdo_by_data_struc) = cl_abap_typedescr=>describe_by_data( 'STRUCTYPE' ).
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DATA(tdo_by_data_itab) = cl_abap_typedescr=>describe_by_data( 'STRTABTYPE' ).
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"... using the cl_abap_typedescr=>describe_by_data_ref method
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"In this case, a data reference variable is used.
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"Note: As a result, the method returns a reference that points to
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"an object in one of the classes CL_ABAP_ELEMDESCR, CL_ABAP_ENUMDESCR,
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"CL_ABAP_REFDESCR, CL_ABAP_STRUCTDESCR, or CL_ABAP_TABLEDSECR.
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DATA dref1 TYPE REF TO i.
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dref1 = NEW #( ).
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"Data reference pointing to CL_ABAP_ELEMDESCR
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DATA(tdo_by_dref1) = cl_abap_typedescr=>describe_by_data_ref( dref1 ).
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"Data reference pointing to CL_ABAP_TABLEDSECR
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DATA(dref2) = NEW string_table( ).
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DATA(tdo_by_dref2) = cl_abap_typedescr=>describe_by_data_ref( dref2 ).
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"... using the cl_abap_typedescr=>describe_by_data_ref method
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"In this case, an object reference variable is used.
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DATA oref TYPE REF TO zcl_demo_abap_objects.
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oref = NEW #( ).
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DATA(tdo_by_oref) = cl_abap_typedescr=>describe_by_object_ref( oref ).
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"------------------------------------------------------------------------
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"--- Getting more detailed information by programmatically accessing ----
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"--- the attributes -----------------------------------------------------
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"------------------------------------------------------------------------
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"------------------------------------------------------------------------
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"--- Examples using a type description object for an elementary type ----
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"------------------------------------------------------------------------
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DATA(elem_kind) = tdo_by_name_elem->kind. "E (elementary)
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DATA(elem_absolute_name) = tdo_by_name_elem->absolute_name. "Check in the debugger for such a local type
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DATA(elem_relative_name) = tdo_by_name_elem->get_relative_name( ). "ELEMTYPE
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DATA(elem_is_ddic_type) = tdo_by_name_elem->is_ddic_type( ). "has the value abap_false
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"Getting more information using type-specific type description classes (e.g. cl_abap_elemdescr for elementary
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"types, as shown in the hierarchy tree above)
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"Using casts, you can access special attributes (i.e. the properties of the respective types).
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"Creating a data reference variable to hold the reference to
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"the type description object
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DATA type_descr_obj_elem TYPE REF TO cl_abap_elemdescr.
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DATA ref_elemdescr TYPE REF TO cl_abap_elemdescr.
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ref_elemdescr = CAST #( tdo_by_name_elem ).
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"Using the older cast operator ?= (which is not used in the examples)
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ref_elemdescr ?= tdo_by_name_elem.
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"Retrieving type information by creating an instance of a type description
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"class. As the name implies, the describe_by_name method expects the name
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"of the type. In the following example, the reference to the type object is
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"assigned using a downcast to the reference variable of type CL_ABAP_ELEMDESCR
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"created above.
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type_descr_obj_elem = CAST #( cl_abap_typedescr=>describe_by_name( 'ELEM_TYPE' ) ).
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"Alternatives using inline declaration
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DATA(ref_elemdescr2) = CAST cl_abap_elemdescr( tdo_by_name_elem ).
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"Using method chaining, you can omit extra declarations
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DATA(ref_elemdescr3) = CAST cl_abap_elemdescr( cl_abap_typedescr=>describe_by_name( 'ELEMTYPE' ) ).
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DATA(elem_abs_name) = CAST cl_abap_elemdescr( cl_abap_typedescr=>describe_by_name( 'ELEMTYPE' ) )->absolute_name.
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"Implementing a check before the cast to the type-specific type description class
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IF tdo_by_name_elem IS INSTANCE OF cl_abap_elemdescr.
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DATA(ref_elemdescr4) = CAST cl_abap_elemdescr( tdo_by_name_elem ).
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ENDIF.
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"Using the older cast operator ?=
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type_descr_obj_elem ?= cl_abap_typedescr=>describe_by_name( 'ELEM_TYPE' ).
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"Some examples for more detailed information that is accessible after
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"the cast. Check the options after the object component selector ->.
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DATA(elem_output_length) = ref_elemdescr->output_length. "3
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"The following method checks compatibility of a specified data object
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DATA(elem_applies1) = ref_elemdescr->applies_to_data( elemdobj ). "has the value abap_true
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DATA test_dobj TYPE c LENGTH 3.
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DATA(elem_applies2) = ref_elemdescr->applies_to_data( test_dobj ). "has the value abap_false
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"Inline declarations are handy to avoid helper variables.
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DATA(type_descr_obj_inl_1) = CAST cl_abap_elemdescr(
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cl_abap_typedescr=>describe_by_name( 'ELEM_TYPE' ) ).
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"-----------------------------------------------------------------
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"--- Examples using a type description object for a structure ----
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"-----------------------------------------------------------------
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DATA ref_structdescr1 TYPE REF TO cl_abap_structdescr.
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ref_structdescr1 = CAST #( tdo_by_name_struc ).
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"You may want to check the type description object in the debugger.
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"Various methods/attributes provide you with detailed information.
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"The following examples show a selection:
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"Kind/Type kind/Output length
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DATA(kind) = type_descr_obj_inl_1->kind. "E (elementary)
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DATA(type_kind) = type_descr_obj_inl_1->type_kind. "C
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DATA(output_length) = type_descr_obj_inl_1->output_length. "5
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"Check examples before making the cast
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"The examples also use inline declaration.
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CASE TYPE OF tdo_by_name_struc.
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WHEN TYPE cl_abap_structdescr.
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DATA(ref_structdescr2) = CAST cl_abap_structdescr( tdo_by_name_struc ).
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WHEN OTHERS.
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...
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ENDCASE.
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"In the following example, the type properties are retrieved
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"without cast. The data object has the type ref to
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"cl_abap_typedescr. See the hierarchy tree above.
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"The reference in the type description object references an
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"object from one of the classes CL_ABAP_ELEMDESCR, CL_ABAP_ENUMDESCR,
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"CL_ABAP_REFDESCR, CL_ABAP_STRUCTDESCR, CL_ABAP_TABLEDSECR,
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"CL_ABAP_CLASSDESCR, or CL_ABAP_INTFDESCR.
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"In the following case, it is CL_ABAP_ELEMDESCR.
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"Note that in most of the following examples, the explicit
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"cast is included when retrieving a reference to the type
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"description object.
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TYPES another_elem_type TYPE n LENGTH 3.
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DATA(type_descr_obj_inl_2) = cl_abap_typedescr=>describe_by_name( 'ANOTHER_ELEM_TYPE' ).
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DATA(ref_structdescr3) = COND #( WHEN tdo_by_name_struc IS INSTANCE OF cl_abap_structdescr
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THEN CAST cl_abap_structdescr( tdo_by_name_struc ) ).
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"More types
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"Structured data type (here, using the name of a database table)
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DATA(type_descr_obj_struc) = CAST cl_abap_structdescr(
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cl_abap_typedescr=>describe_by_name( 'ZDEMO_ABAP_CARR' ) ).
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"More details accessible after the cast
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DATA(struc_kind) = ref_structdescr1->struct_kind. "F (flat)
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"The following attribute returns a table with component information, such as
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"the component names and type kinds.
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DATA(struc_components) = ref_structdescr1->components.
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"The following method also returns a table with component information. In this case,
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"more information is returned such as type description objects of each component and more.
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DATA(struc_components_tab) = ref_structdescr1->get_components( ).
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"Various attributes/methods available for detailed information
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"Kind
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DATA(struc_kind) = type_descr_obj_struc->kind. "S
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"-----------------------------------------------------------------------
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"--- Examples using a type description object for an internal table ----
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"-----------------------------------------------------------------------
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DATA ref_tabledescr1 TYPE REF TO cl_abap_tabledescr.
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ref_tabledescr1 = CAST #( tdo_by_name_itab ).
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"Cast with inline declaration (for a change)
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DATA(ref_tabledescr2) = CAST cl_abap_tabledescr( tdo_by_name_itab ).
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"Getting components of the structure (e.g. the component names
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"and type description objects for the individual components)
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DATA(comps_struc) = type_descr_obj_struc->get_components( ).
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"Another internal table as an example
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DATA itab TYPE SORTED TABLE OF zdemo_abap_carr WITH UNIQUE KEY carrid.
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DATA(ref_tabledescr3) = CAST cl_abap_tabledescr( cl_abap_typedescr=>describe_by_data( itab ) ).
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"The follwing attribute also lists the component names and types
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"(but not the type desription objects as is the case above)
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DATA(comps_struc2) = type_descr_obj_struc->components.
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DATA(itab_table_kind) = ref_tabledescr3->table_kind. "O (sorted table)
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DATA(itab_has_unique_key) = ref_tabledescr3->has_unique_key. "has the value abap_true
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"Returns a table with the names internal table keys
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DATA(itab_table_key) = ref_tabledescr3->key. "carrid
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"Returns a table with a description of all table keys, e.g.
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"all components of a key, key kind (U, unique, in the example case),
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"information whether the key is the primary key etc.
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DATA(itab_keys) = ref_tabledescr3->get_keys( ).
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"If you want to get information about the line type, e.g. finding out about
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"the component names, another cast is required.
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"First, getting a reference to the type description object for the structured type.
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DATA(itab_comp_ref) = ref_tabledescr3->get_table_line_type( ).
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"Then, performing a cast to access the component information as shown above.
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DATA(itab_line_info) = CAST cl_abap_structdescr( itab_comp_ref ).
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DATA(itab_comps1) = itab_line_info->components.
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DATA(itab_comps2) = itab_line_info->get_components( ).
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"Kind of structure
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DATA(struct_kind) = type_descr_obj_struc->struct_kind. "F (flat)
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"----------------------------------------------------------------------
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"--- Examples using a type description object for a data reference ----
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"----------------------------------------------------------------------
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DATA ref_refdescr1 TYPE REF TO cl_abap_refdescr.
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TYPES type_ref_i TYPE REF TO i.
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DATA(tdo_ref) = cl_abap_typedescr=>describe_by_name( 'TYPE_REF_I' ).
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ref_refdescr1 = CAST #( tdo_ref ).
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DATA(ref_refdescr2) = CAST cl_abap_refdescr( tdo_ref ).
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"Internal table type
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TYPES tab_type TYPE SORTED TABLE OF zdemo_abap_carr
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WITH UNIQUE KEY carrid.
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"Getting a reference to the type description object of a type used to
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"type the reference
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DATA(ref_type) = ref_refdescr1->get_referenced_type( ).
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DATA(ref_abs_name) = ref_refdescr1->get_referenced_type( )->absolute_name. "\TYPE=I
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DATA(type_descr_obj_tab) = CAST cl_abap_tabledescr(
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cl_abap_typedescr=>describe_by_name( 'TAB_TYPE' ) ).
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"-------------------------------------------------------------------------
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"--- Examples using a type description object for an object reference ----
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"-------------------------------------------------------------------------
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DATA ref_oref1 TYPE REF TO cl_abap_objectdescr.
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ref_oref1 = CAST #( tdo_by_oref ).
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"See the hierarchy of type description classes. You may also use
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"cl_abap_classdescr.
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DATA(ref_oref2) = CAST cl_abap_classdescr( tdo_by_oref ).
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"Kind
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DATA(tab_kind) = type_descr_obj_tab->kind. "T
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"Returns a table with information about the class attributes
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DATA(class_attributes) = ref_oref1->attributes.
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"The following method returns more information than the attribute
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"below (e.g. key kind, i.e. if it is a unique key, etc.)
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DATA(tab_keys) = type_descr_obj_tab->get_keys( ).
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DATA(tab_keys2) = type_descr_obj_tab->key.
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"Returns a table with information about the methods such as
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"parameters, visibility and more
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DATA(class_methods) = ref_oref1->methods.
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"Getting internal table components
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"The method get_table_line_type returns a variable of type ref to
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"cl_abap_datadescr. This way you can retrieve the table components.
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"Method chaining is useful here.
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DATA(tab_comps) = CAST cl_abap_structdescr(
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type_descr_obj_tab->get_table_line_type( ) )->get_components( ).
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"Returns a table with information about the interfaces implemented
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DATA(class_intf) = ref_oref1->interfaces.
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"Reference type
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TYPES ref_str TYPE REF TO string.
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DATA(type_descr_obj_ref) = CAST cl_abap_refdescr(
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cl_abap_typedescr=>describe_by_name( 'REF_STR' ) ).
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"Can class be instantiated
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DATA(class_is_inst) = ref_oref1->is_instantiatable( ). "has the value abap_true
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"Returns the type description object of the referenced type
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DATA(ref_type) = type_descr_obj_ref->get_referenced_type( ).
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"Using an interface
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DATA(tdo_intf) = cl_abap_typedescr=>describe_by_name( 'ZDEMO_ABAP_OBJECTS_INTERFACE' ).
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DATA ref_iref TYPE REF TO cl_abap_intfdescr.
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ref_iref = CAST #( tdo_intf ). "cl_abap_objectdescr is also possible
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"Getting the absolute type name
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DATA(ref_type_abs_name) =
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type_descr_obj_ref->get_referenced_type( )->absolute_name. "\TYPE=STRING
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"Kind/Type kind
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DATA(ref_kind) = type_descr_obj_ref->kind. "R
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DATA(ref_type_type_kind) =
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type_descr_obj_ref->get_referenced_type( )->type_kind. "g (string)
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"Getting a reference to a type description object of an existing
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"data object. Instead of referring to the name of a type, referring
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"to a data object here. The relevant method is describe_by_data.
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"Elementary data object
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DATA dobj_elem TYPE i.
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DATA(ty_des_obj_el) = CAST cl_abap_elemdescr(
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cl_abap_typedescr=>describe_by_data( dobj_elem ) ).
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"Structure
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DATA dobj_struc TYPE zdemo_abap_carr.
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DATA(ty_des_obj_struc) = CAST cl_abap_structdescr(
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cl_abap_typedescr=>describe_by_data( dobj_struc ) ).
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"Internal table
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DATA dobj_itab TYPE TABLE OF zdemo_abap_carr WITH EMPTY KEY.
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DATA(ty_des_obj_itab) = CAST cl_abap_tabledescr(
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cl_abap_typedescr=>describe_by_data( dobj_itab ) ).
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"Reference variable
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DATA dref_var TYPE REF TO string.
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DATA(ty_des_obj_dref) = CAST cl_abap_refdescr(
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cl_abap_typedescr=>describe_by_data( dref_var ) ).
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DATA(ref_intf_attr) = ref_iref->attributes.
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DATA(ref_intf_meth) = ref_iref->methods.
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DATA(ref_intf_attr_objdescr) = CAST cl_abap_objectdescr( tdo_intf )->attributes.
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```
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Excursions:
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@@ -1935,11 +2006,12 @@ DATA(type_descr_obj) = CAST cl_abap_structdescr(
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cl_abap_typedescr=>describe_by_name( 'SOME_STRUC_TYPE' ) ).
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```
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The focus here is on using RTTC methods such as `get...`.
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The focus here is on using RTTC methods such as `get...`. It is recommended that you use the `get` method instead of the `create` method.
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```abap
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"Creating type description objects using ...
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"... elementary data types
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"----------------------------------------------------------------------
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"--- Creating type description objects using elementary data types ----
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"----------------------------------------------------------------------
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"Conceptually, all elementary, built-in ABAP types already
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"exist and can be accessed by the corresponding get_* methods.
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"In ADT, click CTRL + space after cl_abap_elemdescr=>...
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@@ -1965,7 +2037,9 @@ DATA(tdo_elem_p) = cl_abap_elemdescr=>get_p( p_length = 3
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"DATA(tdo_elem_string_2) = CAST cl_abap_elemdescr(
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" cl_abap_typedescr=>describe_by_name( 'STRING' ) ).
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"... structured data types
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"----------------------------------------------------------------------
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"--- Creating type description objects using structured data types ----
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"----------------------------------------------------------------------
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"They are created based on a component description table.
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"A structured type such as the following shall be created dynamically
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@@ -1990,13 +2064,14 @@ DATA(tdo_struc) = cl_abap_structdescr=>get(
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( name = 'D' type = cl_abap_elemdescr=>get_p( p_length = 4
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p_decimals = 3 ) ) ) ).
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"... internal table types
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"---------------------------------------------------------------------
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"--- Creating type description objects using internal table types ----
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"---------------------------------------------------------------------
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"Note: Specifying the line type is mandatory, the rest is optional.
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|
||||
"An internal table type such as the following shall be created dynamically
|
||||
"using a type description object.
|
||||
TYPES std_tab_type_std_key TYPE STANDARD TABLE OF string
|
||||
WITH DEFAULT KEY.
|
||||
TYPES std_tab_type_std_key TYPE STANDARD TABLE OF string WITH DEFAULT KEY.
|
||||
|
||||
"Creating a type description object using RTTC method
|
||||
"Not specifying the other optional parameters means that the
|
||||
@@ -2008,8 +2083,7 @@ DATA(tdo_tab_1) = cl_abap_tabledescr=>get(
|
||||
"Another internal table type for which more parameter specifications
|
||||
"are needed. The following internal table type shall be created using
|
||||
"a type description object.
|
||||
TYPES so_table_type TYPE SORTED TABLE OF zdemo_abap_flsch
|
||||
WITH UNIQUE KEY carrid connid.
|
||||
TYPES so_table_type TYPE SORTED TABLE OF zdemo_abap_flsch WITH UNIQUE KEY carrid connid.
|
||||
|
||||
"Creating a type description object using RTTC method
|
||||
"The following example also demonstrates how comfortably constructor
|
||||
|
||||
Reference in New Issue
Block a user