RTTI

Former Member — Mon, 26 Mar 2007 09:38:33 GMT

what is RTTI?

what is the significance of CL_ABAP_TYPEDESCR and all its inherited class.

In the instantiation why are these classes protected?

Re: RTTI

Former Member — Mon, 26 Mar 2007 09:57:45 GMT

good

Abbreviation RTTI. Determining data types during program run time.

example->

Here is an example of RTTI. Check whether two data types are identical.

REPORT ...

CLASS conv_exc DEFINITION INHERITING FROM cx_static_check.

ENDCLASS.

PARAMETERS: type1 TYPE c LENGTH 30,

type2 TYPE c LENGTH 30.

DATA: dref1 TYPE REF TO data,

dref2 TYPE REF TO data.

FIELD-SYMBOLS: <data1> TYPE ANY,

<data2> TYPE ANY.

DATA: descr_ref1 TYPE REF TO cl_abap_typedescr,

descr_ref2 TYPE REF TO cl_abap_typedescr,

mess TYPE string.

START-OF-SELECTION.

TRY.

CREATE DATA: dref1 TYPE (type1),

dref2 TYPE (type2).

ASSIGN: dref1->* TO <data1>,

dref2->* TO <data2>.

CATCH cx_sy_create_data_error.

MESSAGE 'Create data error!' TYPE 'I' DISPLAY LIKE 'E'.

LEAVE PROGRAM.

ENDTRY.

...

descr_ref1 = cl_abap_typedescr=>describe_by_data( <data1> ).

TRY.

IF descr_ref1 <> descr_ref2.

RAISE EXCEPTION TYPE conv_exc.

ELSE.

<data2> = <data1>.

ENDIF.

CATCH conv_exc.

CONCATENATE `Assignment from type `

descr_ref2->absolute_name

` to `

descr_ref1->absolute_name

` not allowed!`

INTO mess.

MESSAGE mess TYPE 'I' DISPLAY LIKE 'E'.

ENDTRY.

Examples of RTTI and Objects

REPORT ...

CLASS conv_exc DEFINITION INHERITING FROM cx_static_check.

ENDCLASS.

PARAMETERS: otype1 TYPE c LENGTH 30,

otype2 TYPE c LENGTH 30.

DATA: oref1 TYPE REF TO object,

oref2 TYPE REF TO object.

DATA: descr_ref1 TYPE REF TO cl_abap_typedescr,

descr_ref2 TYPE REF TO cl_abap_typedescr,

mess TYPE string.

START-OF-SELECTION.

TRY.

CREATE OBJECT: oref1 TYPE (otype1),

oref2 TYPE (otype2).

CATCH cx_sy_create_object_error.

MESSAGE 'Create object error!' TYPE 'I' DISPLAY LIKE 'E'.

LEAVE PROGRAM.

CATCH cx_root.

MESSAGE 'Other error!' TYPE 'I' DISPLAY LIKE 'E'.

LEAVE PROGRAM.

ENDTRY.

...

descr_ref1 =

cl_abap_typedescr=>DESCRIBE_BY_OBJECT_REF( oref1 ).

descr_ref2 =

cl_abap_typedescr=>DESCRIBE_BY_OBJECT_REF( oref2 ).

TRY.

IF descr_ref1 <> descr_ref2.

RAISE EXCEPTION TYPE conv_exc.

ELSE.

oref1 = oref2.

ENDIF.

CATCH conv_exc.

CONCATENATE `Assignment from type `

descr_ref2->absolute_name

` to `

descr_ref1->absolute_name

` not allowed!`

INTO mess.

MESSAGE mess TYPE 'I' DISPLAY LIKE 'E'.

ENDTRY.

thanks

mrutyun^

Re: RTTI

uwe_schieferstein — Mon, 26 Mar 2007 10:15:51 GMT

Hello John

If the instantiation of a class is protected or even private then you need to search for <b>static methods</b> within the same class that return an instance of the class or for <b>factory classes</b> (e.g. CL_RECA_MESSAGE_LIST is instantiated using CF_RECA_MESSAGE_LIST).

The significance of RTTI is - at least - twofold:

- Get all relevant information about a (data) object at runtime

- Create any type of data object at runtime (-> hint: TYPE HANDLE statement).

Regards

Uwe

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