Example of Self Reference

Hello experts,
I am totally new to ABAP Objects and was going through a book for the same to learn the concepts.
There is a section of Self Reference in this book. I could not understand this concept by myself. Could you please help me out to explain this thing.
PFB the code that is given in this book to explain Self Reference.
REPORT z_self_reference.
*       CLASS client DEFINITION
CLASS client DEFINITION.
PUBLIC SECTION.
    DATA name(10) TYPE c VALUE 'Master' READ-ONLY.
    METHODS create_server.
ENDCLASS.                    "client DEFINITION
*       CLASS server DEFINITION
CLASS server DEFINITION.
PUBLIC SECTION.
    METHODS acknowledge
     IMPORTING creator TYPE REF TO client.
PRIVATE SECTION.
    DATA name(10) TYPE c VALUE 'Servant'.
ENDCLASS.                    "server DEFINITION
*       CLASS client IMPLEMENTATION
CLASS client IMPLEMENTATION.
METHOD create_server.
    DATA server_ref TYPE REF TO server.
    CREATE OBJECT server_ref.
    CALL METHOD server_ref->acknowledge
      EXPORTING
        creator = me.
ENDMETHOD.                    "create_server
ENDCLASS.                    "client IMPLEMENTATION
*       CLASS server IMPLEMENTATION
CLASS server IMPLEMENTATION.
METHOD acknowledge.
    DATA name TYPE string.
    name = creator->name.
    WRITE: me->name, 'create by', name.
ENDMETHOD.                    "acknowledge
ENDCLASS.                    "server IMPLEMENTATION
DATA client_ref TYPE REF TO client.
START-OF-SELECTION.
CREATE OBJECT client_ref.
CALL METHOD client_ref->create_server.
Thanks,
Mohit Goel.
Edited by: Matt on Apr 8, 2009 10:50 AM

Hi Mohit,
me is used to self reference the attributes and methods of a class within that class.In your program,
within client class implementation, you can use me->name and me->create_server to call the name variable and create_server method in the same class if required.Here me represents "client class".Similarly ,in Server class, you can use me->name and me->acknowledge to call the name variable and acknowledge method in the same class if required.
In your program ,
CALL METHOD server_ref->acknowledge
EXPORTING
creator = me.
is not correct.me is not used as variable . Its only a reference variable.it shoud used me->class attribute(name)/method.
I hope , you could understand the above explanation.
by
Prasad GVK.

Similar Messages

Why do we need a Self Reference "me" to use the components of a class

Hi
I am not clear why do we need a self reference variable "me" to call the components of its own class? when it can be accessed directly as in the following examples?
In my first example below i can call the method display_name directly without creating a reference object or instance of the class within the class.
In the second example i am using the self refernce Write me->name to access the component of a class.
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CLASS egocentric DEFINITION.
PUBLIC SECTION.
    DATA:
     name(10) TYPE c READ-ONLY.
    METHODS set_name.
    METHODS display_name.
ENDCLASS.                    "egocentric DEFINITION
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CLASS egocentric IMPLEMENTATION.
METHOD set_name.
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    CALL method display_name.
ENDMETHOD.                    "write_name
METHOD display_name.
    write: name.
ENDMETHOD.                    "display_name
ENDCLASS.                    "egocentric IMPLEMENTATION
*Global Data
DATA oref TYPE REF TO egocentric.
START-OF-SELECTION.
CREATE OBJECT oref.
CALL METHOD oref->set_name.
CLASS egocentric DEFINITION.
        PUBLIC SECTION.
            DATA:
             name(10) TYPE c VALUE u2018Instructoru2019
READ-ONLY.
             METHODS write_name.
ENDCLASS.
CLASS egocentric IMPLEMENTATION.
        METHOD write_name.
            WRITE me->name.
        ENDMETHOD.
ENDCLASS.
*Global Data
DATA oref TYPE REF TO egocentric.
START-OF-SELECTION.
        CREATE OBJECT oref.
        CALL METHOD oref->write_name.

You can go WIKI and search with ABAP Objects.
Or do the same in 'advanced search' and select a search area. You are bound to find something.
Or this link perhaps:
[abap objects|http://help.sap.com/saphelp_nw70/helpdata/EN/ce/b518b6513611d194a50000e8353423/content.htm]

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regards
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Well lets assume it is a keyword. What i want to know
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<method-handle empty-aggregate="true"/>
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<mapping-class>MWOneToOneMapping</mapping-class>
</mapping>
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<uses-method-accessing>false</uses-method-accessing>
<read-only>false</read-only>
<get-method-handle>
<method-handle empty-aggregate="true"/>
</get-method-handle>
<set-method-handle>
<method-handle empty-aggregate="true"/>
</set-method-handle>
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<private-owned>false</private-owned>
<uses-batch-reading>false</uses-batch-reading>
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Gerd,
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Recursive Self Reference

Hi,
I am trying to do a recursive self reference. Is this the best way of doing it as I keep getting errors?
SQL> CREATE OR REPLACE TYPE type_objtyp AS OBJECT (
2 type_id NUMBER (10),
3 type_name VARCHAR2 (100),
4 sub_type REF type_objtyp
5 )
6 NOT FINAL
7 /
Type created.
SQL> CREATE OR REPLACE TYPE data_objtyp
2 /
Type created.
SQL> CREATE OR REPLACE TYPE data_list_objtyp AS TABLE OF data_objtyp
2 /
Warning: Type created with compilation errors.
SQL> CREATE OR REPLACE TYPE data_objtyp AS OBJECT (
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3 type_ref REF type_objtyp,
4 creation_date DATE,
5 child_list_ref REF data_list_objtyp
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8 /
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SQL>
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type.

you can't have a REF to a table type, only to object types. so, instead use a table of REFs:
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Hi,
I created a class in se24 and in method wrote simple addition logic
I created a object in my prog for the class and entered the numbers it works fine.
But when I use ME to reference the method its showing an error ME is not defined by any DATA statemnt
the code is as follows
class zp_class definition load.
PARAMETERS : p_x type i,
             p_y type i.
data : z type i.
CALL METHOD me->zadd
EXPORTING
    v_x    = p_x
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IMPORTING
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write :z .
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regards

Hi ,
me is used to refer the methods and attributes of the same class within the methods of that class only.
This will explain by the folllowing example.
*& Report Z_SIMPLE_CLASS
REPORT z_simple_class.
      CLASS c1 DEFINITION
CLASS c1 DEFINITION.
PUBLIC SECTION.
    DATA: a TYPE i value 3,
              b TYPE i value 4.
    METHODS: m_add exporting a type i
                             b type i,
                      m_sub.
ENDCLASS.                    "c1 DEFINITION
CLASS c1 IMPLEMENTATION.
METHOD m_add.
    DATA c TYPE i.
    c = a + b.
    WRITE: 'c:= ', c.
ENDMETHOD.                    "m_add
METHOD m_sub.
    DATA c TYPE i.
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    a = b.
    c = a - b.
    WRITE: 'c:= ', c.
ENDMETHOD.                    "m_sub
ENDCLASS.                    "c1 IMPLEMENTATION
START-OF-SELECTION.
DATA: cc1 TYPE REF TO c1,
        a1 type i value -4,
        b1 type i value -4.
CREATE OBJECT cc1.
cc1->m_add( importing a = a1 b = b1 ).
write: cc1->a.
write: cc1->b.
by
Prasad G.V.K
Edited by: PRASAD GVK on Jul 21, 2008 3:03 PM

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Issue with self reference on ManyToOne relationship

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private int ID;
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Thanks for the help.
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/* simplified for brevity */
@Entity
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 @Id
 @GeneratedValue(…)
 private Integer id;
 @ManyToOne(…)
 private Record parent;
 @OneToMany(…)
 private Collection<Record> children;
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 for (Record record : records) {
 addRecord(record);
 void addRecord(Record record) {
 // Execute a SELECT to get related record(s).
 // Update the record(s).
 em.persist(record);
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Passing self reference to a method call.

I have classes 'A' & 'B'.
A's method 'M1' calls a B's method 'M2'which takes object of type 'A' as an argument.
Is it possible to use 'this' keyword or do I need to use Class.forName('A')
If not, is there a better way to accomplish the same.
Ex:
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B b = new B().M2(this);
}//end of class
public class B
public Object M2(A a)
}//end of class B
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Class.forName("A") returns an object of type Class, not an object of type A. So it won't work. this would work.

Self reference to the table issue-Query required

Hi,
I have the below query which will give me the result as
select DC.Fullname as Fullname, DSL.Skills as Skills, AdminSC.SkillRatingID as Rating
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Rahul
Crystal Reports / Webi
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Kiran
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You can use LEFT OUTER JOIN with Skills Table like follow query:
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DSL.Skills AS Skills ,
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INNER JOIN dim_Pattern DPS ON DPS.SkillID = DSL.ID
WHERE DPS.PatternTypeID = '2'
sqldevelop.wordpress.com

I am using the Order Analysis Toolkit and want to get more information about the compensation for "Reference Signal Processing", which is scarce in the manuals, the website and the examples installed with the toolkit.

I am using the Order Analysis Toolkit and want to get more information about the compensation for "Reference Signal Processing", which is scarce in the manuals, the website and the examples installed with the toolkit.
In particular, I am analyzing the example "Even Angle Reference Signal Processing (Digital Tacho, DAQmx).vi", whose documentation I am reproducing in the following:
DESCRIPTIONS:
This VI demonstrates how to extract even angle reference signals and remove the slow-roll errors. It uses DAQmx VIs to acquire sound or vibration signals and a digital tachometer signal. This VI includes a two-step process: acquire data at low rotational speed to extract even angle reference; use the even angle reference to remove the errors in the vibration signal acquired at normal operation.
INSTRUCTIONS:
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NOTE: You need to use DSA PXI-447x/PXI-446x and PXI TIO device in a PXI chassis to run this example. The DSA device must be in slot 2 of the PXI chassis.
3. Switch to Extract Even Angle Reference tab. Specify the number of samples to acquire and the # of revs in reference which determines the number of samples in even angle reference. Click Start to take a one-shot data acquisition of the vibration and tachometer signals. After the acquisition, you can see the extracted even angle references in Even Angle Reference.
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1. SVL Scale Voltage to EU.vi
2. OAT Digital Tacho Process.vi
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5. OAT Compensate Even Angle Signal.vi
My question is: How is the synchronization produced at the time of the compensation ? How is it possible to eliminate the errors in a synchronized fashion with respect to the surface of the shaft bearing in mind that I am acquired data at a low rotation speed in order to get the "even angle reference" and then I use it to remove the errors in the vibration signal acquired at normal operation. In this application both operations are made in different acquisitions, therefore the reference of the correction signal is lost. Is it simply compensated without synchronizing ?
Our application is based on FPGA and we need to clarity those aspects before implementing the procedure.
Solved!
Go to Solution.

Hi CracKatoA.
Take a look at the link bellow:
http://forums.ni.com/ni/board/message?board.id=170&message.id=255126&requireLogin=False
Regards,
Filipe Silva

Example of Self Reference

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