Exception Handling - Classical vs Class-Based

Searchable keywords: exception, RAISING, TRY, CATCH, cx_static_check, cx_dynamic_check, EXCEPTIONS, sy-subrc, class-based exception, classical exception

TOPICS IN THIS FILE

Quick Identification - line 5
Classical Exceptions - line 12
Class-Based Exceptions - line 25
Method Signatures - line 50
Best Practices - line 80
Interface vs Class Methods - line 118

ABAP has two exception handling mechanisms. Using the wrong one causes silent failures.

Quick Identification

Method Signature	Exception Type	Handling Pattern
`EXCEPTIONS exc = 1`	Classical	`sy-subrc` check
`RAISING cx_...`	Class-based	`TRY-CATCH`

Classical Exceptions (Old Style)

Methods declared with EXCEPTIONS in signature:

" Method declaration
class-methods describe_by_name
  importing p_name type any
  returning value(p_descr_ref) type ref to cl_abap_typedescr
  exceptions
    type_not_found.  " <- Classical!

" Calling with classical exception
cl_abap_structdescr=>describe_by_name(
  EXPORTING
    p_name = iv_tabname
  RECEIVING
    p_descr_ref = lo_descr
  EXCEPTIONS
    type_not_found = 1
    OTHERS = 2 ).
IF sy-subrc <> 0.
  " Handle error
ENDIF.

Common classical exception methods:

cl_abap_structdescr=>describe_by_name - type_not_found
cl_abap_tabledescr=>describe_by_name - type_not_found
Many RTTI (Run Time Type Information) methods

Class-Based Exceptions (Modern)

Methods declared with RAISING:

" Method declaration
methods get_ref
  importing p_name type string
  returning value(p_ref) type ref to cl_ci_checkvariant
  raising cx_ci_checkvariant.  " <- Class-based!

" Calling with TRY-CATCH
TRY.
    lo_variant = cl_ci_checkvariant=>get_ref( p_name = lv_variant ).
  CATCH cx_ci_checkvariant INTO DATA(lx_error).
    " Handle error
ENDTRY.

The Mistake to Avoid

WRONG: Using TRY-CATCH for classical exceptions

" This does NOT catch type_not_found!
TRY.
    lo_descr = cl_abap_structdescr=>describe_by_name( iv_name ).
  CATCH cx_root.  " Never reached!
ENDTRY.

CORRECT: Use proper pattern for each type

" Classical - use sy-subrc
cl_abap_structdescr=>describe_by_name(
  EXPORTING p_name = iv_name
  RECEIVING p_descr_ref = lo_descr
  EXCEPTIONS type_not_found = 1 ).
IF sy-subrc <> 0.
  " Handle error
ENDIF.

" Class-based - use TRY-CATCH
TRY.
    lo_obj = cl_ci_checkvariant=>get_ref( lv_name ).
  CATCH cx_root INTO DATA(lx_error).
    " Handle error
ENDTRY.

How to Check Which to Use

Use the view command to check method signature:

abapgit-agent view --objects CL_ABAP_STRUCTDESCR

Look for:

exceptions TYPE_NOT_FOUND → Classical (use sy-subrc)
raising CX_SY_RTTI → Class-based (use TRY-CATCH)

Or search the cheat sheets:

abapgit-agent ref --topic exceptions

Interface vs Class Methods

Interface Methods

Cannot add RAISING clause in the implementing class. Options:

Add RAISING to interface definition
Use TRY-CATCH in the implementation

" Interface definition - can add RAISING here
INTERFACE zif_example.
  methods execute
    importing is_param type data optional
    returning value(rv_result) type string
    raising cx_static_check.
ENDINTERFACE.

" Implementation - CANNOT add RAISING here
CLASS zcl_example DEFINITION.
  INTERFACES zif_example.
ENDCLASS.

CLASS zcl_example IMPLEMENTATION.
  METHOD zif_example~execute.
    " Must handle cx_static_check here with TRY-CATCH
    " or declare it in interface, not here
  ENDMETHOD.
ENDCLASS.

Class Methods

Can add RAISING clause to declare exceptions, allowing caller to handle in one place:

" Class method with RAISING clause
METHODS process_data
  importing iv_data type string
  returning value(rv_result) type string
  raising cx_static_check.

" Caller can handle in one place
TRY.
    lv_result = lo_obj->process_data( iv_data = 'test' ).
  CATCH cx_static_check.
    " Handle exception
ENDTRY.

When to Use Each

Scenario	Recommendation
Multiple callers need to handle exception	Add RAISING to method definition
Exception should be handled internally	Use TRY-CATCH in implementation
Interface method	Add RAISING to interface, or use TRY-CATCH in class

RAISING Clause in Method Calls

The RAISING clause cannot be used in method call statements. It can only be used in method definitions.

" WRONG - syntax error
lo_handler->read( ... ) RAISING cx_dd_ddl_check.

" CORRECT - use TRY-CATCH
TRY.
    lo_handler->read( ... ).
  CATCH cx_dd_ddl_check.
    " Handle error
ENDTRY.

Correct usage in method definitions: abap " Interface/Class method definition METHODS read IMPORTING iv_name TYPE string RAISING cx_static_check. |