READ-ONLY attribute vs GETTER methods

By | February 22, 2011 | ABAP Objects, OO Concepts, Performance | 10,677 | 6

READ-ONLY is something different for the people who have worked on the OOP in the past. Like JAVA doesn’t have the read only addition. So, there is a hot discussion going on in SAP ABAP Objects world, why READ-ONLY is there and what is the purpose of it. Let’s unleash the READ-ONLY (and its power over GETTER methods).

As good Object Oriented Programming suggests, we should hide our attributes from the outside world and let them allow to access only with the PUBLIC methods. These methods are:

  • SETTER – To set the data to the attribute. Usually, this method has the single parameter and typically that is named as VALUE. Implementation of the method sets the respective attribute from the parameter value. So, we should use the naming convention as SET_attr( ).
  • GETTER – To retrieve the value from the attribute. This method should have the single parameter and typically it would be VALUE as type RETURNING. Implementation of this method, passes the attribute value to the caller in the parameter. As we name the SETTER methods, we should name the GETTER methods as GET_attr( ).
  • Now, let’s see what is the READ-ONLY:
    READ-ONLY is the addition to the PUBLIC attributes. This allows the caller to access the attribute, but doesn’t allow it to change the value. Refer keyword documentation on READ-ONLY on SAP Help at: READ-ONLY addition

    Caller can simply access the variable directly with proper operator. Like this:

    *& Developer : Naimesh Patel
    *& Purpose   : READ-ONLY Demo
    REPORT  ztest_np.
    CLASS lcl_example DEFINITION.
        DATAv_speed TYPE READ-ONLY.
          constructor IMPORTING speed TYPE i.
    ENDCLASS.                    "lcl_example DEFINITION
      METHOD constructor.
        me->v_speed speed.
      ENDMETHOD.                    "constructor
    ENDCLASS.                    "lcl_example IMPLEMENTATION

      DATAo_test TYPE REF TO lcl_example.
      CREATE OBJECT o_test
          speed 10.
    * o_test->v_speed = 100.    " Syntax Error
      WRITE'Accessing V_SPEED:'o_test->v_speed.

    In simple terms, we can reduce the amount of coding by using the READ-ONLY operator rather than creating GET_attr( ) methods for each methods.

    GETTER vs READ-ONLY Performance: Who wins?
    I tried to create this sample program to find out which is better. Here is the code lines:

    *& Developer : Naimesh Patel
    *& Purpose   : READ-ONLY vs GETTER Performance
    REPORT  ztest_np.
        DATAv_speed TYPE READ-ONLY.
        METHODSget_speed RETURNING value(returnTYPE i.
        METHODSset_speed IMPORTING value TYPE i.
    ENDCLASS.                    "lcl_car DEFINITION

      METHOD get_speed.
        return v_speed.
      ENDMETHOD.                    "get_speed
      METHOD set_speed.
        v_speed value.
      ENDMETHOD.                    "set_speed
    ENDCLASS.                    "lcl_Car IMPLEMENTATION

      DATAo_bmw TYPE REF TO lcl_car.
      CREATE OBJECT o_bmw.
      DATAlv_speed TYPE i.
      DATAlv_temp TYPE i.

      DATAlv_flag TYPE flag,
            lv_sta_time TYPE timestampl,
            lv_end_time TYPE timestampl,
            lv_diff_w   TYPE DECIMALS 5,
            lv_diff_f   LIKE lv_diff_w,
            lv_save     LIKE lv_diff_w.

    * Getter Performance
      GET TIME STAMP FIELD lv_sta_time.
      DO 1000 TIMES.
        o_bmw->set_speedsy-index ).
        lv_temp lv_temp + o_bmw->get_speed).
      GET TIME STAMP FIELD lv_end_time.
      lv_diff_w lv_end_time lv_sta_time.
      WRITE/(15'With getter'lv_diff_w.


    * READ-ONLY Performance
      GET TIME STAMP FIELD lv_sta_time.
      DO 1000 TIMES.
        o_bmw->set_speedsy-index ).
        lv_temp lv_temp + o_bmw->v_speed.
      GET TIME STAMP FIELD lv_end_time.
      lv_diff_f lv_end_time lv_sta_time.
      WRITE/(15'With READ-ONLY'lv_diff_f.

    * Saved time
      lv_save lv_diff_w lv_diff_f.
      WRITE/(15'Saved time'lv_save.

    When I ran the report, it showed that we can save around 67% of time while using the READ-ONLY compared to GETTER( ) method. When GETTER( ) method take about 100% time, direct attribute access finishes job in about 33% time. This should be useful when we are designing complex system, which uses too many GETTER methods.

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    Naimesh Patel{271 articles}

    I'm SAP ABAP Consultant for more than a decade. I like to experiment with ABAP especially OO. I have been SDN Top Contributor.
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    • Thank you for the excellent blog including the test program. I tried in in our sandbox system. The results can be verified as
      With getter 0,00086
      With READ-ONLY 0,00026
      Saved time 0,00060

      Now looking at the numbers I think it is useful in performance-sensitive processes when you need every single grain of speed. In most cases you will do more than read an attribute a thousand times. For every single command that I add to the 1000-times-DO, the relative performance gain will get a lot smaller. For one Million loops, we will gain one second.

      To stay consistent with object-oriented philosophy, keep programs sources reusable and maintenance-friendly, I will clearly prefer the getter method.

      But still good to know.


    • Thanks Clemens.

      One more point to consider:
      Since we can't use the chaining statement to pass result of one method to subsequent method – as it is in Java – till 702 EhP2. It is little cumbersome to write the code to get the result from one method to helper variables and than pass this to next method. I'll update the post with this consideration too.

      Naimesh Patel

    • Anonymous

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    • Jens

      Hi Naimesh,

      First of all i would like to say Thank You for this webside with really great content!

      Regarding your upper post I disagree with yours and the SAP recommendation to prefer to use the attributes as public with the read-only addition. OK, it might be useful in high availability scenarios where every microsecond is needed and where you are not able to scale the performance by adding new hardware or buffer scenarios but in normal case and regular project conditions the information hiding and good design principles knock out the performance issue.

      You would like to read the entries of an itab which is provided as public attribute in a class. To assure that the itab is filled you need to call first the access methods which fulfill it with records or you implement the update of the itab in the class- / constructor.

      Both ways have negative impact to the design or performance. The way by using the access method makes it more complicated for the user to use the class services because he needs to know about the sequence dependency of the class. The second way forces a source access to all needed sources at the creation time of the class which maybe has bad performance and overhead (do i need really all source accesses for my current concerns?).

      If i masquerade the implementation by using a getter method i am able to use mechanisms like lazy initialization to access the sources at the time i really need them or to process pre- or post conditions which the user does not need to know.

      The main intention of my post is the support the principle to keep it simple, stupid. The user of my service classes shall be able to deal with it as easy as possible without needing to know something about the internal design or suffering by a long creation process.

      Cheers and go ahead with your great articles,


    • Hello Jens,

      I’m glad that you like the content of the site.

      Valid Point. I almost agree with you to use the GETTER methods instead of the READ-ONLY addition. It comes in handy when you can’t do the method chaining and need to use lot of helper variables to get the values from the GETTER methods before ABAP 702.

      Naimesh Patel

    • Roushan Kumar

      Such a nice site sir…… it is very useful for a new comer in abap like me , have passion about abap….

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