b.santos/abap-cheat-sheets
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Update

Browse Source
This commit is contained in:
danrega
2023-12-22 16:32:38 +01:00
parent 3290f1fd47
commit 88eaaa6f31
6 changed files with 66 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files

80
06_Dynamic_Programming.md
View File

@@ -118,27 +118,34 @@ Once the memory area is assigned, you can work with the content.
``` abap
"Some data object declarations to be used
DATA: num TYPE i,
struc TYPE zdemo_abap_fli, "Demo database table
tab TYPE string_table.
DATA: num TYPE i,
struc TYPE zdemo_abap_fli, "Demo database table
itab_str TYPE string_table,
itab_fli TYPE TABLE OF zdemo_abap_fli WITH EMPTY KEY.
APPEND INITIAL LINE TO itab_fli.
"Declaring field symbols with complete types
FIELD-SYMBOLS: <fs_i> TYPE i,
<fs_struc> TYPE zdemo_abap_fli,
<fs_tab> TYPE string_table.
<fs_struc> TYPE zdemo_abap_fli,
<fs_tab> TYPE string_table.
"Declaring field symbols with generic type
FIELD-SYMBOLS <fs_gen> TYPE data.
"Assigning data objects to field symbols
"Note: In this case, the field symbols have an appropriate type.
"Using field symbols with a static type
ASSIGN num TO <fs_i>.
ASSIGN struc TO <fs_struc>.
ASSIGN tab TO <fs_tab>.
ASSIGN num TO <fs_gen>. "Could be any of the data objects
ASSIGN itab_str TO <fs_tab>.
"Using field symbol with a generic type
ASSIGN num TO <fs_gen>.
ASSIGN itab_fli TO <fs_gen>.
ASSIGN itab_fli[ 1 ] TO <fs_gen>.
"Assigning components
ASSIGN struc-carrid TO <fs_gen>.
ASSIGN itab_fli[ 1 ]-connid TO <fs_gen>.
"Inline declaration is possible, too. The type
"is automatically derived.
"Inline declaration (the field symbol has the type data)
ASSIGN num TO FIELD-SYMBOL(<fs_inl>).
"CASTING addition for matching types of data object and field
@@ -167,6 +174,8 @@ ASSIGN chars TO <fs2> CASTING LIKE chars_l4.
> IF <fs> IS ASSIGNED.
>   ...
> ENDIF.
>
> DATA(check) = COND #( WHEN <fs> IS ASSIGNED THEN `assigned` ELSE `not assigned` ).
> ```
>- Using the statement `UNASSIGN`, you can explicitly remove the assignment of the field symbol. A `CLEAR` statement only initializes the value.
> ``` abap
@@ -485,6 +494,8 @@ IF ref_carr IS BOUND.
  ...
ENDIF.
DATA(ref_bound) = COND #( WHEN ref_carr IS BOUND THEN ref_carr->carrid ELSE `is not bound` ).
"Explicitly removing a reference
"However, the garbage collector takes care of removing the references
"automatically once the data is not used any more by a reference.
@@ -500,10 +511,8 @@ ref_int->* = 123.
"Generic type
DATA ref_generic TYPE REF TO data.
ref_generic = NEW i( ).
"In older ABAP releases, CREATE DATA statements were needed.
CREATE DATA ref_generic TYPE i.
ref_generic = NEW i( ). "Syntax in modern ABAP
CREATE DATA ref_generic TYPE i. "Syntax for older ABAP releases
"As mentioned above, the content of anonymous data objects can only be
"accessed using dereferenced data variables and field symbols.
@@ -542,7 +551,7 @@ dref = NEW i( 2 ).
``` abap
"This snippet shows that three data references are created
"with the same reference variable. Storing them in an internal table
"using the TYPE TABLE OF REF TO prevents the overwriting.
"using the type TYPE TABLE OF REF TO prevents the overwriting.
DATA: dref TYPE REF TO data,
itab TYPE TABLE OF REF TO data,
@@ -582,6 +591,10 @@ LOOP AT fli_tab REFERENCE INTO DATA(ref).
ref->carrid = ...
...
ENDLOOP.
"More statements are available that assign content to a data reference variable,
"for example, READ TABLE.
READ TABLE fli_tab INDEX 1 REFERENCE INTO DATA(rt_ref).
```
*Data reference variables as part of structures and internal tables*:
@@ -737,7 +750,7 @@ ASSIGN iref->('IN_STR') TO <fs>.
"Assigning static attributes
"All visible static attributes in classes and interfaces can be assigned
"In the following example, a class and an interface is specified statically,
"In the following example, a class and an interface are specified statically,
"and the attributes are specified dynamically.
ASSIGN zcl_demo_abap_objects=>('PUBLIC_STRING') TO <fs>.
ASSIGN zdemo_abap_objects_interface=>('CONST_INTF') TO <fs>.
@@ -752,8 +765,21 @@ ASSIGN ('ZDEMO_ABAP_OBJECTS_INTERFACE')=>('CONST_INTF') TO <fs>.
"Further dynamic syntax options are possible, for example,
"specifying the memory area after ASSIGN with a writable expressions
"because the operand position after ASSIGN is a result position
"because the operand position after ASSIGN is a result position.
ASSIGN NEW zcl_demo_abap_objects( )->('PUBLIC_STRING') TO <fs>.
"ELSE UNASSIGN addition
"If ELSE UNASSIGN is specified in the context of dynamic assignments/accesses,
"no memory area is assigned to the field symbol. It is unassigned after
"the ASSIGN statement.
"Note: For the static variant of the ASSIGN statement, i.e. if the memory area
"to be assigned following the ASSIGN keyword is statically specified, the addition
"ELSE UNASSIGN is implicitly set and cannot be used explicitly.
DATA(hallo) = `Hello world`.
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.
```
<p align="right"><a href="#top">⬆️ back to top</a></p>
@@ -909,11 +935,12 @@ READ TABLE itab FROM wa_read USING KEY ('SK') REFERENCE INTO DATA(read_ref).
"Explicitly specifying the key and key values (TABLE KEY addition)
"The component names can also be specified dynamically (which is done in most of the
"following examples for demonstration purposes).
"following examples for demonstration purposes). Note that each component of the table
"key must be specified.
READ TABLE itab WITH TABLE KEY ('SK') COMPONENTS ('COL2') = `aaa` REFERENCE INTO read_ref.
"Specifying the predefined name primary_key explicitly and dynamically
READ TABLE itab WITH TABLE KEY ('PRIMARY_KEY') COMPONENTS ('COL1') = 1 REFERENCE INTO read_ref.
"If the addition COMPONENTS is not specified, the primary table key is used by default.
"If the addition COMPONENTS is not specified, the primary table key is implicitly used.
READ TABLE itab WITH TABLE KEY ('COL1') = 1 REFERENCE INTO read_ref.
"Reading using a free key (WITH KEY addition)
@@ -1181,20 +1208,20 @@ CALL METHOD class=>(meth) PARAMETER-TABLE ptab.
" is of type REF TO data
"The addition EXCEPTION-TABLE for exceptions is not dealt with here.
"Copyable snippet
"Example that uses the PARAMETER-TABLE addition
"Creating an instance by specifying the type statically
"An example class of the cheat sheet repository is used.
DATA(ob_ref) = NEW zcl_demo_abap_objects( ).
DATA(oref1) = NEW zcl_demo_abap_objects( ).
"Calling an instance method
"The method multiplies an integer by 3.
"The calculation result is returned.
DATA(result) = ob_ref->triple( i_op = 2 ). "6
DATA(result) = oref1->triple( i_op = 2 ). "6
"Dynamic equivalent
"Creating an instance of a class by specifying the type
"dynamically
DATA objref TYPE REF TO object.
CREATE OBJECT objref TYPE ('ZCL_DEMO_ABAP_OBJECTS').
DATA oref2 TYPE REF TO object.
CREATE OBJECT oref2 TYPE ('ZCL_DEMO_ABAP_OBJECTS').
"Creating parameter table
DATA(ptab) = VALUE abap_parmbind_tab( ( name = 'I_OP'
@@ -1205,7 +1232,7 @@ DATA(ptab) = VALUE abap_parmbind_tab( ( name = 'I_OP'
value = NEW i( ) ) ).
"Dynamic method call and specifying a parameter table
CALL METHOD objref->('TRIPLE') PARAMETER-TABLE ptab.
CALL METHOD oref2->('TRIPLE') PARAMETER-TABLE ptab.
result = ptab[ name = 'R_TRIPLE' ]-('VALUE')->*. "9
```
@@ -1677,8 +1704,7 @@ CREATE DATA dref_cr TYPE HANDLE tdo_ref.
## More Information
- It is recommended that you also consult section [Dynamic Programming Techniques (F1 docu for standard ABAP)](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abendynamic_prog_technique_gdl.htm) in the ABAP Keyword Documentation since it provides important aspects that should be considered when dealing with dynamic programming in general (e. g. security aspects or runtime error prevention).
- There are even further dynamic programming techniques in the unrestricted language scope such as the
generation or execution of programs at runtime. They are not part of this cheat sheet. Find more details on the related syntax (e. g. `GENERATE SUBROUTINE POOL`, `READ REPORT` and `INSERT REPORT` in the ABAP Keyword Documentation for Standard ABAP: [Dynamic Program Development (F1 docu for standard ABAP)](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abenabap_language_dynamic.htm)
- There are even further dynamic programming techniques in the unrestricted ABAP language scope [Standard ABAP](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abenstandard_abap_glosry.htm) such as the generation or execution of programs at runtime. They are not part of this cheat sheet. Find more details on the related syntax (e. g. `GENERATE SUBROUTINE POOL`, `READ REPORT` and `INSERT REPORT` in the ABAP Keyword Documentation for Standard ABAP: [Dynamic Program Development (F1 docu for standard ABAP)](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abenabap_language_dynamic.htm)
## Executable Example