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danrega
2025-01-28 16:06:42 +01:00
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06_Dynamic_Programming.md
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@@ -319,6 +319,7 @@ FIELD-SYMBOLS:
<simple> TYPE simple, "Elementary data type including enumerated types and
"structured types with exclusively character-like flat components
<object> TYPE REF TO object. "object can only be specified after REF TO; can point to any object
"The types REF TO object and REF TO data are considered complete types.
"Data objects to work with
DATA: BEGIN OF s,
@@ -428,6 +429,7 @@ ASSIGN s-structure TO <simple>.
ASSIGN s-xl1 TO <simple>.
"ASSIGN s-tab_ha TO <simple>.
s-oref = NEW cl_system_uuid( ).
ASSIGN s-oref TO <object>.
```
@@ -459,15 +461,20 @@ ASSIGN s-oref TO <object>.
#### Declaring Data Reference Variables
``` abap
"Example declarations of data reference variables with static types.
"The static types can be complete or generic (but only data can be used).
"Note that they do not yet point to a data object. At this stage,
"initial reference variables contain null references.
"The following example shows a selection of declaration options with data reference
"variables with static types. The static types can be complete or generic (but
"only data can be used).
"Note that the variables do not yet point to a data object. At this stage,
"initial reference variables contain null references.
DATA num type i.
DATA: ref_a TYPE REF TO i, "Complete data type
ref_b TYPE REF TO some_dbtab, "Complete data type
ref_c LIKE REF TO some_data_object,
ref_b TYPE REF TO zdemo_abap_carr, "Complete data type
ref_c LIKE REF TO num,
ref_d TYPE REF TO data, "Generic data type
ref_e LIKE ref_a. "Referring to an existing data reference variable
ref_e LIKE ref_a, "Referring to an existing data reference variable
ref_f TYPE TABLE OF REF TO i, "Reference table, complete data type
ref_g TYPE TABLE OF REF TO data. "Reference table, generic data type
```
As shown below, instead of the explicit declaration, inline declarations are also possible.
@@ -1047,6 +1054,7 @@ DATA(idx) = line_index( dref->*[ ('CARRID') = 'LH' ] ).
Some example contexts of using data references are as follows:
*Overwriting data reference variables*:
``` abap
DATA dref TYPE REF TO data.
dref = NEW i( 1 ).
@@ -1108,6 +1116,7 @@ READ TABLE fli_tab INDEX 1 REFERENCE INTO DATA(rt_ref).
```
*Data reference variables as part of structures and internal tables*:
``` abap
"Unlike field symbols, data reference variables can be used as
"components of structures or columns in internal tables.
@@ -1129,6 +1138,19 @@ APPEND struc TO itab.
itab[ 1 ]-ref->* = 123.
```
*Internal tables of type REF TO data can contain any data references*:
```abap
DATA it_ref TYPE TABLE OF REF TO data.
"Such a table can hold any data type
it_ref = VALUE #( ( NEW i( 3 ) ) "Elementary type
( NEW string( `hello` ) ) "Elementary type
( NEW zdemo_abap_flsch( carrid = 'XY' connid = '1234' ) ) "Structured type
( NEW string_table( ( `a` ) ( `b` ) ( `c` ) ) ) "Table type
).
```
> **✔️ Hint**<br>
> When to actually use either a field symbol
or a data reference variable? It depends on your use case. However, data
@@ -2309,8 +2331,7 @@ ENDCLASS.
### Dynamic Method Calls
- The following code snippet shows dynamically specifying method calls.
- The following code snippet shows dynamically specifying method calls. Find three example classes below the syntax pattern snippet.
- The snippet covers methods. Dynamic method calls require `CALL METHOD` statements.
- Find an example of a dynamic function module call - as another example of [procedure](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenprocedure_glosry.htm "Glossary Entry") calls - in the [Program Flow Logic](./13_Program_Flow_Logic.md#function-module-example) cheat sheet.
@@ -2359,7 +2380,14 @@ CALL METHOD class=>(meth) PARAMETER-TABLE ptab.
"The addition EXCEPTION-TABLE for exceptions is not dealt with here.
```
**Example class 1**
**Click to expand the expandable sections for example code**
<details>
<summary>🟢 Example class 1</summary>
<!-- -->
<br>
The following example class explores dynamic method calls with simple methods. You can create a demo class called `zcl_demo_abap` and copy and paste the following code. Once activated, you can choose *F9* in ADT to run the class. The example is not designed to display output in the console.
@@ -2547,8 +2575,16 @@ CLASS zcl_demo_abap IMPLEMENTATION.
ENDCLASS.
```
</details>
<br>
<details>
<summary>🟢 Example class 2</summary>
<!-- -->
<br>
**Example class 2**
The following simplified example highlights several things in the context of a dynamic method call example:
- Dynamic method call and assigning actual parameters to formal parameters statically
@@ -2624,6 +2660,110 @@ CLASS zcl_demo_test IMPLEMENTATION.
ENDCLASS.
```
</details>
<br>
<details>
<summary>🟢 Example class 3</summary>
<!-- -->
<br>
The following example demonstrates dynamic method calls with methods defined in interfaces.
<table>
<tr>
<td> Class include </td> <td> Code </td>
</tr>
<tr>
<td>
Global class
</td>
<td>
``` abap
CLASS zcl_demo_abap DEFINITION
PUBLIC
FINAL
CREATE PUBLIC .
PUBLIC SECTION.
INTERFACES if_oo_adt_classrun.
PROTECTED SECTION.
PRIVATE SECTION.
ENDCLASS.
CLASS zcl_demo_abap IMPLEMENTATION.
METHOD if_oo_adt_classrun~main.
"Creating an instance of the local class that implements
"an interface
DATA(oref) = NEW lcl( ).
"Static method call
DATA(number) = oref->lif~get_number( ).
out->write( number ).
"Dynamic method call
"Note the uppercase.
TRY.
CALL METHOD oref->('lif~get_number') RECEIVING number = number.
out->write( number ).
CATCH cx_sy_dyn_call_illegal_method INTO DATA(error).
DATA(error_text) = error->get_text( ).
out->write( error_text ).
ENDTRY.
CALL METHOD oref->('LIF~GET_NUMBER') RECEIVING number = number.
out->write( number ).
ENDMETHOD.
ENDCLASS.
```
</td>
</tr>
<tr>
<td>
CCIMP include (*Local Types* tab in ADT)
</td>
<td>
``` abap
INTERFACE lif.
METHODS get_number RETURNING VALUE(number) TYPE i.
ENDINTERFACE.
CLASS lcl DEFINITION.
PUBLIC SECTION.
INTERFACES lif.
ENDCLASS.
CLASS lcl IMPLEMENTATION.
METHOD lif~get_number.
number = cl_abap_random_int=>create( seed = cl_abap_random=>seed( )
min = 1
max = 1000 )->get_next( ).
ENDMETHOD.
ENDCLASS.
```
</td>
</tr>
</table>
</details>
<p align="right"><a href="#top">⬆️ back to top</a></p>
### Dynamic Function Module Calls