In this post, you will learn about the New keyword, creating objects and calling methods the 7.40 way.
If you are still using CREATE OBJECT and TYPE REF TO always to declare and create objects then you are living in the past. Take a look at what is possible now with the objects.
Suppose you want to create an object for a class ZCL_ABAP, below is the syntax.
DATA(lo_abap) = NEW zcl_abap( ). "New way
This is similar to below piece of code.
DATA lo_abap1 TYPE REF TO lcl_abap. "Old way CREATE OBJECT lo_abap1.
When you have a constructor for the class, you can pass the values within the ( ).
Suppose, you have below class definition and implementation.
CLASS lcl_abap DEFINITION. PUBLIC SECTION. METHODS: constructor IMPORTING iv_user TYPE sy-uname, get_name RETURNING VALUE(rv_name) TYPE char40. PRIVATE SECTION. DATA gv_user TYPE sy-uname. ENDCLASS. CLASS lcl_abap IMPLEMENTATION. METHOD constructor. gv_user = iv_user. ENDMETHOD. METHOD get_name. rv_name = 'Jagdish P'. "This can be a query as well ENDMETHOD. ENDCLASS.
You can create the object as below and use it to call the method.
DATA(lo_abap) = NEW lcl_abap( 'JAGDISHP' ). DATA(lv_name) = lo_abap->get_name( ).
Here, there is only one Importing parameter for the constructor, so a value can be passed without parameter name. When there are multiple parameters in the constructor or the method, we need to specify the name in the call.
DATA(lo_abap) = NEW lcl_abap( iv_user = 'JAGDISHP' iv_type = 'Dialog' ). "only for demo
For reference, below is the old way to do the same thing
DATA lo_abap1 TYPE REF TO lcl_abap. CREATE OBJECT lo_abap1 EXPORTING iv_user = 'JAGDISHP'. CALL METHOD lo_abap->get_name RECEIVING rv_name = lv_name.
Method chaining is not a something that ABAP 7.40 brought in but it is more effective with ABAP 7.40.
Method chaining is not like the chain statement that we use for declaring data with symbol colon [ : ]. It is a way in which you can call a method which is returning something and use that something directly in the code. I know this is confusing, so let us look at an example of how the factory ALV code can be optimized in terms of number of lines using method chaining.
SELECT * FROM sbook INTO TABLE @DATA(bookings). TRY. "Create ALV table object for the output data table cl_salv_table=>factory( IMPORTING r_salv_table = DATA(lo_table) CHANGING t_table = bookings ). "Method chaining lo_table->get_functions( )->set_all( ). lo_table->get_columns( )->set_optimize( ). lo_table->get_display_settings( )->set_striped_pattern( 'X' ). lo_table->display( ). CATCH cx_root. "Handle Error ENDTRY.
Using methods as operands
We use below code to write error after exception is caught.
TRY. ... CATCH cx_root INTO lo_exception. lv_error_txt = lo_exception->get_error_msg( ). WRITE: lv_error_txt. ENDTRY.
The same can we written as below by using method as an operand. This eliminates need of helper variables. Note that this is only possible when the method is a functional method i.e. the method has only Importing and Returning parameters. The returning value is treated as a variable.
TRY. ... CATCH cx_root INTO lo_exception. WRITE: lo_exception->get_error_msg( ). ENDTRY.
This can also be used in conditions.
IF lo_exception->get_error_msg( ) IS NOT INITIAL.
Avoid Type Conflict while calling methods
You can convert the data passed to the method to the type that method needs.
DATA(lo_abap) = NEW lcl_abap( CONV #('JAGDISHP' ) ).
Inline declaration for returning/receiving or importing variables
DATA(lv_name) = lo_abap->get_name( ). OR CALL METHOD lo_abap->get_name RECEIVING rv_name = DATA(lv_name).
Once you get the idea of chaining various statements, the lines of code start to reduce and the code becomes smaller, and easier to maintain.
Yes, it is bit difficult to understand at first, but sooner or later you have to start.
Read about more such ABAP expressions and exciting new syntaxes: ABAP Expressions (7.4+)
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