This is a follow-up to my
last post, where I talked about central classes to keep type declarations for an application.
Of course, I do the same thing for constants. I have for instance a class to keep some very central date constants:
class ZCL_ABAP_DATE_CONSTANTS definition
public
final
create public .
public section.
constants maximum_date type d value '99991231'.
constants first_day_of_year type string value '0101'.
constants last_day_of_year type string value '1231'.
constants minimum_date type d value '00010101'.
protected section.
private section.
ENDCLASS.
Unfortunately things do not work as they do for type classes. I found out, that you can access constants of a class only using the public class and the static operator
=>:
* Working
call_method( zcl_abap_date_constants=>maximum_date ).
However, if I create a short cut using a variable, it doesn't work (although this works for the types - strange):
data date_constants type ref to zcl_abap_date_constants.
data common_types type ref to zcl_abap_common_types.
" Working for types
data binary_table type common_types->binary_table.
" Not working for constants --> syntax error
call_method( date_constants->maximum_date ).
A workaround could be instantiate the class using the variable:
class app definition.
public section.
methods constructor.
methods main.
private section.
data date_constants type ref to ZCL_ABAP_DATE_CONSTANTS.
endclass.
class app implementation.
method constructor.
date_constants = new #( ).
endmethod.
method main.
cl_demo_output=>display( date_constants->maximum_date ).
endmethod.
endclass.
But as
maxfreck pointed out, it's also possible to keep the constant class abstract and inherit a local class from it:
class constants definition final inheriting from zcl_abap_date_constants.
endclass.
* Working
call_method( constants=>maximum_date ).
