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danrega
2024-06-20 16:58:20 +02:00
parent c2f31ff896
commit fbb576f8e4
4 changed files with 391 additions and 12 deletions
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06_Dynamic_Programming.md
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@@ -1118,6 +1118,21 @@ ENDIF.
"The memory area can also be a dereferenced data reference
ASSIGN dref->* TO <fs>.
"Do not use named data objects in ABAP for Cloud Development because
"you cannot know what data object you get (e.g. a class attribute or a
"local variable). If you want to assign a data object from your local
"scope, it is recommended that you specify the data objects to
"be assigned as components of a structure. Then you can ensure that
"you assign the correct data object dynamically, using the dynamic
"component assignments as shown below.
DATA some_string TYPE string VALUE `hi`.
DATA(some_named_dobj) = 'SOME_STRING'.
"A warning is displayed for the following statement in ABAP for Cloud
"Development.
"ASSIGN (some_named_dobj) TO FIELD-SYMBOL(<fs>).
"------- Assigning components dynamically ------
"You can chain the names with the component selector (-), or, in
"case of reference variables, the object component selector (->).
@@ -1133,8 +1148,8 @@ DATA columnname TYPE string VALUE `COL1`.
ASSIGN st-(columnname) TO <fs>.
"Fully dynamic specification
"If the compiler can fully determine the data object in ASSIGN statements
"in ABAP for Cloud Development, a warning is not issued.
"If the compiler can fully determine the data object in ASSIGN
"statements in ABAP for Cloud Development, a warning is not issued.
ASSIGN ('ST-COL1') TO <fs>.
"Numeric expressions are possible. Its value is interpreted
@@ -1204,6 +1219,39 @@ ASSIGN ('HALLO') TO FIELD-SYMBOL(<eu>) ELSE UNASSIGN.
ASSERT sy-subrc = 0 AND <eu> IS ASSIGNED.
ASSIGN ('DOES_NOT_EXIST') TO <eu> ELSE UNASSIGN.
ASSERT sy-subrc = 4 AND <eu> IS NOT ASSIGNED.
"------- Assigments and casting a dynamically specified type ------
"Pattern: ASSIGN ... TO <fs> CASTING TYPE (type_name).
TYPES: c1 TYPE c LENGTH 1,
c3 TYPE c LENGTH 3,
c10 TYPE c LENGTH 10,
c20 TYPE c LENGTH 20,
str TYPE string.
DATA abc TYPE c LENGTH 26 VALUE 'abcdefghijklmnopqrstuvwxyz'.
DATA(type_names) = VALUE string_table( ( `C1` ) ( `C3` ) ( `C10` ) ( `C20` ) ( `NOPE` ) ( `STR` ) ).
DATA assignment_results TYPE string_table.
FIELD-SYMBOLS <fs> TYPE clike.
LOOP AT type_names INTO DATA(type_name).
TRY.
ASSIGN abc TO <fs> CASTING TYPE (type_name).
assignment_results = VALUE #( BASE assignment_results ( |Type: '{ type_name }'; Assignment result: '{ <fs> }'| ) ).
CATCH cx_root INTO DATA(error).
assignment_results = VALUE #( BASE assignment_results
( |Error! Exception raised: { cl_abap_typedescr=>describe_by_object_ref( error )->get_relative_name( ) }; | &&
|'{ error->get_text( ) }'| ) ).
ENDTRY.
ENDLOOP.
*Content of the assignment_results table:
*Type: 'C1'; Assignment result: 'a'
*Type: 'C3'; Assignment result: 'abc'
*Type: 'C10'; Assignment result: 'abcdefghij'
*Type: 'C20'; Assignment result: 'abcdefghijklmnopqrst'
*Error! Exception raised: CX_SY_ASSIGN_CAST_UNKNOWN_TYPE; 'ASSIGN ... CASTING failed; NOPE is an unknown type'
*Error! Exception raised: CX_SY_ASSIGN_CAST_ILLEGAL_CAST; 'ASSIGN ... CASTING failed: Incompatible type'
```
> **💡 Note**<br>
@@ -1230,7 +1278,7 @@ CREATE DATA dataref TYPE REF TO (some_type).
CREATE DATA dataref TYPE ('\TYPE=STRING').
"Assigning a data object to a field symbol casting a dynamically
"specified type
"specified type as also shown in the example above
TYPES clen5 TYPE c LENGTH 5.
DATA: dobj_c10 TYPE c LENGTH 10 VALUE '1234567890',
some_struct TYPE zdemo_abap_fli.
@@ -2498,7 +2546,7 @@ CLASS zcl_some_class IMPLEMENTATION.
ELSEIF tdo IS INSTANCE OF cl_abap_refdescr.
INSERT |{ tabix } Is instance of cl_abap_refdescr| INTO TABLE str_tab.
"Gettting a reference to the type's type description object using the
"Getting a reference to the type's type description object using the
"describe_by_data_ref, which can be used for data reference variables.
"Note that the dynamic type is evaluated.