Reference to queue

questions
1

How to fix?
How do you know that the link is spoiled without crashing the program?

Q                       &QUEUE 
  CODE      
  InProcedure
  IF Q &= NULL        
    STOP('NULL')
  END
  MESSAGE(RECORDS(Q)) ! GPF
    
InProcedure             PROCEDURE
TestQueue               QUEUE
Var1                      BYTE
                        END
  CODE      
  Q &= TestQueue
2

Hectro,

That is not going to work. The global variable Q holds the address of TestQueue but when InProcedure exits TestQueue goes out of scope and the memory is unallocated.
So Q still has an address assigned but TestQueue doesn’t exist anymore.
I don’t know of anyway to detect that.

Rick

3

Agree with Rick. Instead, why don’t you try this.

!—Global Type
Q QUEUE(),TYPE
Var1 BYTE
END

OuterProcedure PROCEDURE()
LOC:MyQ QUEUE(Q).
CODE
InProcedure(LOC:MyQ)
MESSAGE(RECORDS(LOC:MyQ))

InProcedure PROCEDURE(Q pQ)
CODE
pQ.Var1 = Value
ADD(pQ)

pQ.Var1 = OtherValue
ADD(pQ)

4

I know perfectly well about the scope of variables :slight_smile:
Speech basically, about that that “the foul” reference by means of Clarion to not check up. And any attempt leads to GPF.
It would be nice to have a function in Clarion or be able to handle such an exception.

5

Does any of the SV developers appear here?

6

@bob.ricketts is registered here but I don’t think he is around much. SV are generally only responsive via private contact or the official newsgroups.

On a side note, this was recently posted to the newsgroups:

NEWD()
Versus keeping track of this stuff, sometimes it would be cool if we
could easily check to see if a reference’d object or variable was
declared or new’d.

Is there anything that us mortals can do to detect that?

So far responses are kinda just jokes and H5 jibes though.

7

Hi Brahn - I responded on the NG server with this:

Howdy Brahn -

That one’s a little different. He wants to know if the entity referred
to in the reference actually exists.

  PROGRAM

  MAP
  END

QueueType  Queue,TYPE
Yada1        String(10)
           END

rQ   &QueueType
rQ2  &QueueType

  CODE

  rQ &= NEW QueueType
  rQ2 &= rQ
  Dispose(rQ)
  Message(Choose(NOT rQ &= NULL,'I think rQ still exists!',|
           'rQ is NULL'))
  Message(Choose(NOT rQ2 &= NULL,'I think the rQ2 still exists!',|
           'rQ2 is NULL'))

He wants to be able to verify rQ2, unless I misunderstood.

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