- Vytvoril/a D2000 Dev Team, naposledy zmenené mar 08, 2023
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SET AS [DIRECT] action
Function
- a local variable of the ALIAS type,
- an item of a structure of the Object type (reference to an object):
- for local variables of the Record type or typed ALIAS,
- for objects of the Structured variable type.
Declaration
SET dstIdent AS srcIdent [DIRECT]
Parameters
| dstIdent | in | Destination of values and links (value identifier of the ALIAS type (or the Object type in the case of a structure item) row identifier, or whole structure identifier). |
| srctIdent | in | Source of values and links (value identifier of ALIAS type (or Object type in case of a structure item) row identifier, or whole structure identifier). |
The structure type and the size of dstIdent and srcIdent must be identical (otherwise the action generates the error _ERR_RECORD_NO_COMP). Their type may be:
- RECORD,
- ALIAS,
- Object of the Structured variable type
The action sets the values of items from srcIdent_Rec to the values of items in dstIdent_Rec. If the parameter dstIdent_Rec is the reference to a row, then the parameter srcIdent_Rec must be the reference to a row, too. Accordingly, if dstIdent_Rec is the reference to a whole value, srcIdent_Rec must be the reference to a whole value, too.
The action rules are similar to the action SET WITH rules.
- The same function for items of structures of a type other than Object (reference to an object).
- For an item of the Object type, it doesn't assign a value, but changes linked object.
Action allows using row index 0 in following case:
SET dstIdent[0]^Col1 AS srcIdent[0]^Col2 whereby1. dstIdent is local structured variable and Col1 is of the Object type
2. srcIdent is:
- local structured variable and Col2 is of the Object type
- type ALIAS (ALIAS (structDef) _rA) and Col2 is of the Object type
- object type structured variable; it is possible to use the keyword DIRECT
(if Col2 is not type reference to object, DIRECT is obligatory)
Action realizes specified command (SET AS) for all rows of the column.
Hence the sizes of both structures (dstIdent and srcIdent) must be identical.
ALIAS _a INT _i SET _a AS U.INT ; the first test IF U.Int = _a THEN ENDIF ; the second test _i := U.Int IF U.Int = _i THEN ENDIF
The first test for the value equality will be always true, because the local variable _a of ALIAS type is ''pointed'' to the object U.Int.
The result of the second test depends on it, whether the object U.Int has not changed its value since the moment when the value was assigned to _i and the test executed.
Value change:
ALIAS _a SET _a AS U.INT _a := 1
Assignment is interpreted by the script as the assigning the value of 1 to U.Int !!!.
Facilities of a local variable of ALIAS type are identical with items of the Object type
- objects of the Structured variable type,
- local variables of the RECORD type (without the modifier NOALIAS).
For example:
ALIAS _a SET _a AS U.Int _a := 1 ; the first assignment RECORD (SD.RecordDef) _lArr1 SET _lArr1[1]^Object AS U.Int _lArr1[1]^Object := 1 ; the second assignment
The first and also the second assignment has the same effect, in regard of the object U.Int.
Change of pointing an Object type item of a Structured variable type object:
SET SV.Structure[1]^Object AS U.Int
The action will point the item SV.Structurea[1]^Object to the object U.Int. From this moment, the value of the item will be identical with the value of the object U.Int. The assignment:
SV.Structure[1]^Object := 1
It assigns the value of 1 to the object U.Int (analogous to the previous examples).
RECORD (SD.RecordDef) _lArr1 REDIM _lArr1[2] SET _lArr1[1]^Object AS U.Int ; assignment 1 SET _lArr1[2]^Object AS U.Int2 ; assignment 2 SET _lArr1[1]^Object AS _lArr1[2]^Object ; assignment 3
The meaning of the assignments of 1 and 2 is listed above. The meaning of the assignment 3 in the given context identical with the action SET _lArr1[1]^Object AS U.Int2. Or:
SET SV.Structure[1]^Object AS U.Int ; assignment 1 WAIT SET SV.Structure[2]^Object AS U.Int2 ; assignment 2 WAIT SET SV.Structure[1]^Object AS SV.Structure[2]^Object ; assignment 3 WAIT
Analogous to the previous example, the last assignment is identical with the assignment SET SV.Structure[1]^Object AS U.Int2. As you can see from the example, it is copying the reference(s) declared on the right side (the identifier srcIdent).
Such definition does not allow pointing (make a reference) a structure item to another structure item. Therefore, there has been introduced the modifier DIRECT which makes it possible. The action SET AS DIRECT reduces possible types of parameters to these types:
dstIdent - Object type item of a RECORD type local variable, of a local variable ''typed alias'', or of a Structured variable type object.srcIdent - item of a Structured variable type object.
For example:
RECORD (SD.RecordDef) _lArr1 REDIM _lArr1[2] SET _lArr1[1]^Object AS U.Int DIRECT ;assignment 1 SET _lArr1[2]^Object AS U.Int2 DIRECT ;assignment 2 SET _lArr1[1]^Object AS _lArr1[2]^Object DIRECT ;assignment 3 SET _lArr1[1]^Object AS SV.Structure[2]^Int DIRECT ;assignment 4
The assignments 1, 2, 3 are not admissible. The assignment 4 points to the item of the Structured variable type object.
If HOBJ of structured variable only is known, the setting of the reference on its field can be done as follows:
SET _locRec[2]^Object AS (HOBJ, ROW, COL) DIRECT
For example:
; used objects ; SD.Active: Structure definition with one column of Object type. Column name is "Object". ; SV.Active: two line structured variable of SD.Active type RECORD (SD.Active) _b BOOL _bOpenOk ; creating of the reference from the field SV.Active[1]^Object to the field in row 1, column 1 of object with a unique identifier 2131 (HOBJ) ; if object 2131 is not structured variable or row index/column index is outside the range, the action will not be done SET SV.Active[1]^Object AS (2131, 10, 10) DIRECT ; unsuccessful process of previous action will generate Run-Time error WAIT ; creating of the reference from the field _b[1]^Object to the field in row 2, column 1 of the object with unique identifier 24623 (HOBJ) ; unlike the previous example, the object 24623 must be opened _bOpenOk := %OpenRefToObject(24623, @TRUE) IF _bOpenOk THEN SET _b[1]^Object AS (24623, 2, 1) DIRECT ENDIF
!!! The action SET SV.Structure[1]^Object AS U.Int (analogous to the assignment of value to object) is processed by means of the D2000 Server process. It takes an effect later, in dependence on the system load. In the script, using WAIT action allows to wait for its execution!!!
The action allows to change the value of ALIAS type.
ALIAS (SD._System_Redundancy) _aT ALIAS (SD._System_Redundancy) _aT1 SET _aT AS SV._System_Redundancy SET _aT1 AS _aT
The value of ALIAS type can be changed without revision in following way:
BOOL _bOk
ALIAS (SD._System_Redundancy) _aT
INT _hbj
; example 1
_hbj := SV._System_Redundancy\HBJ
SET _aT AS (_hbj)
; example 2
_hbj := %StrToHBJ("SV._System_Redundancy")
_bOk := %OpenRefToObject(_hbj, @TRUE)
SET _aT AS (_hbj)
; or example 3
ALIAS _a
_hbj := %StrToHBJ("SV._System_Redundancy")
_bOk := %OpenRefToObject(_hbj, @TRUE)
SET _a AS (_hbj)
SET _aT AS _a
Related pages:
- Žiadne štítky