PRAGMA action


Function
This action enables/disables a transfer IN OUT parameters of the procedure by a reference.
Declaration
 PRAGMA "ENABLE_INOUT_BY_REF"
 
  PRAGMA "DISABLE_INOUT_BY_REF"

Description
The action is meaningful only when you use a procedure with IN OUT parameters (a structure type) in context of object Event. It is unimportant for RPC procedures.

When CALL action is executed, the action PRAGMA "ENABLE_INOUT_BY_REF" ensures the real parameter, which inputs to the procedure via its formal parameter, will not be copied to the formal parameter of procedure. It means the formal parameter represents a reference to the real parameter.

Basically, CALL action creates a copy of the real parameter and uses it as the formal parameter. It causes:

  1. A procedure call copies the procedure values uselessly (it is slower).
  2. The formal parameter is "separated" from the real parameter.
PRAGMA "ENABLE_INOUT_BY_REF" ensures the formal parameter is "a reference" to the real parameter and the value is not copied. The procedure call is faster.
Example
 PROCEDURE Proc1(RECORD (SD.Data) _data)
 .
 .
 _data[1]^Col  :=2
 .
 .
 .
 .
 END Proc1
 
 BEGIN
  PRAGMA "ENABLE_INOUT_BY_REF"
  RECORD (SD.Data) _rec
  REDIM _rec [2]
 
  _rec[1]^Col  :=0
 
  CALL Proc1(_rec)
 
 END

 
An application of PRAGMA "ENABLE_INOUT_BY_REF" action:
The formal parameter _data is the real parameter _rec.
When you write _data[1]^Col := 2, the value "2" is assigned to the real parameter _rec[1]^Col.

An application of CALL action (PRAGMA "ENABLE_INOUT_BY_REF" action is not used):
The formal parameter _data is an absolute copy of the real parameter _rec.
When you write _data[1]^Col := 2, the value "2" is assigned to the formal parameter _data.
After CALL proc1(_rec) is executed, the formal parameter _data will be copied to the real parameter _rec.

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