doubt help SAP Library Objects

[Former Member]

I don´t understand the next paragraph (help SAP Library)

link sap library

Is there a error? CREF1 to

CREF3

?
If it could not be so,why CREF2?

"The effect of the assignment statement is to copy the reference from

CREF1 to CREF2

. As a result, the reference in CREF3 also points to the object C_COUNTER<1>. No more references point to the object C_COUNTER<2>, and it is automatically deleted by the garbage collection. The internal name C_COUNTER<2> is now free again."

[Former Member]

escuse me, the link is :

<a href="http://help.sap.com/saphelp_nw70/helpdata/en/73/f6b832b3fd11d194f20000e8353423/content.htm">http://help.sap.com/saphelp_nw70/helpdata/en/73/f6b832b3fd11d194f20000e8353423/content.htm</a>

[naimesh_patel]

I think there isn't any error.

I have tried to explain this.

start-of-selection.

  CREATE OBJECT: cref1, cref2.
"  creates CREF1 .. value = {O:3*PROGRAM=ZTEST_NPCLASS=C1} - first reference
"  creates CREF2 .. vlaue = {O:4*PROGRAM=ZTEST_NPCLASS=C1} - second reference
"  CREF3 .. value = *** illegal reference ***

  move cref2 to cref3.
"  creates CREF1 .. value = {O:3*PROGRAM=ZTEST_NPCLASS=C1}
"  creates CREF2 .. vlaue = {O:4*PROGRAM=ZTEST_NPCLASS=C1}
"  CREF3 .. value = {O:4*PROGRAM=ZTEST_NPCLASS=C1}
" Values of the CREF3 has been set from CREF2 even if we have definition like DATA: cref3 like cref1.

  clear cref2.
" CREF2 .. VALUE = *** illegal reference ***  
" CREF3 .. VALUE = {O:4*PROGRAM=ZTEST_NPCLASS=C1}
" second reference is not yet free because CREF3 is holding that

  cref3 = cref1.
"  creates CREF1 .. value = {O:3*PROGRAM=ZTEST_NPCLASS=C1}
"  creates CREF2 .. VALUE = *** illegal reference ***  
"  CREF3 .. value = {O:3*PROGRAM=ZTEST_NPCLASS=C1}
" second reference is free now.. so, garbage collector will take care of it
  write: 'bye'.

Regards,

Naimesh Patel

[Former Member]

Hi abapers,

thank you for you attention.

I have debuger the next code:

REPORT  zcu04_prueba.

CLASS counter DEFINITION.
 PUBLIC SECTION.
  DATA A TYPE I.
  METHODS: increment.

ENDCLASS.

CLASS counter IMPLEMENTATION.
 METHOD increment.
   A = A + 1.
 ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.

 DATA: cref1  TYPE REF TO counter,
           cref2  TYPE REF TO counter,
           cref3  LIKE cref1.

1º):

cref1 = 0<>

cref2 = 0<>

cref3 = 0<>

CREATE OBJECT: cref1, cref2.

2º):

cref1 = 9

MOVE cref2 TO cref3.

3º):

cref1 = 9

CLEAR cref2.

4º):

cref1 = 9

cref3 = cref1.

4º):

cref1 = 9

http://help.sap.com/saphelp_nw70/helpdata/en/73/f6b832b3fd11d194f20000e8353423/content.htm

I don´t understand the next sentence (help SAP Library)

"

The effect of the assignment statement is to copy the reference from CREF1 to CREF2

. As a result, the reference in CREF3 also points to the object C_COUNTER<1>. No more references point to the object C_COUNTER<2>, and it is automatically deleted by the garbage collection. The internal name C_COUNTER<2> is now free again."

I don´t understand. I think that the sentence:

"

The effect of the assignment statement is to copy the reference from CREF1 to CREF3

is the correct.

Why it is no correct?

Thanks.

Cordial greetings

[uwe_schieferstein]

Hello Lopez

You are right. There is obviously a mistake in the description of the sample.

Regards

Uwe

[uwe_schieferstein]

Hello Lopez

To clarify the question I have pasted the coding here:

DATA: cref1  TYPE REF TO c_counter,
          cref2  TYPE REF TO c_counter,
          cref3  LIKE CREF1.

CREATE OBJECT: cref1, cref2.  " 'pointers' for both instances exist

MOVE cref2 TO cref3.               " cref2 and cref3 point to the same instance

CLEAR cref2.                           " cref3 still filled -> still pointers to both instances exist

cref3 = cref1.                           " cref3 points no longer to instance<2> but instance<1>
                                              " Thus, there is no pointer to instance<2> anymore
                                              " instance<2> will be removed by garbage collector

Regards

Uwe