RTTI and TDynarray

[Matthew Krasnick]

Matthew Krasnick/NJ/GISLTD 
09/15/2006 09:59 AM

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Delphi-Talk@Elists.Org
cc

Subject
RTTI and TDynarray





I'm looking to use RTTI to get information about an array of a class that 
I'm working on.  I can not seem to return the Dynarray from RTTI, so I 
can't get hold of the contained elements.  As an example I put together a 
test scenario.  I'd appreciate it if anybody could give me a clue as to 
use RTTI with Dynarrays.

In this example I'd like to use RTTI to get information regarding the 
TPersonlist contained in the TPersonListObj class.  Using GetPropValue 
returns back an unassigned variant. 

I came across a function in Soap that seems helpful 
GetDynArrayElTypeInfo(PropInfo^.PropType^,ElementTypeInfo, Dimensions); 
This seems to give me information regarding what's contained in the array, 
but I can't seem to get a handle on the classes so I can get RTTI on the 
contained class.

Any assistance would be greatly appreciated.

Matthew Krasnick
Manager Applications Development


type
  TPerson = class(TComponent)
  private
    FFirstName: string;
    FLastName: string;
    FDOB: TDateTime;
  published
    property FirstName: string read FFirstName write FFirstName ;
    property LastName: string read FLastName write FLastName ;
    property DOB : TDateTime read FDOB write FDOB ;
  end;

  TPersonList = Array of TPerson ;

  TPersonListObj = class(TComponent)
  private
    FPersonList: TPersonlist;
    FCount: integer;
    procedure SetCount(const Value: integer);
    function GetItem(Index: Integer): TPerson;
    procedure SetItem(Index: Integer; const Value: TPerson);
  public
    constructor Create(AOwner: TComponent) ; override ;
    destructor Destroy; override;
    property Items[Index: Integer]: TPerson read GetItem write SetItem ; 
default ;
  published
     property PersonList : TPersonlist read FPersonList write FPersonList 
;
     property Count : integer read FCount write SetCount ;
  end;


procedure TForm1.Button2Click(Sender: TObject);
var
  I, Count: Integer;
  PropInfo: PPropInfo;
  TempList, TempList2: PPropList;
  Data, OutVar : Variant;
 DynArray: Pointer;
 ElemInfo,ElementTypeInfo: PTypeInfo;
  Dims, Dimensions: Integer;
   ArrayName: string ;
   o : pointer ;
   v: Variant ;
begin
  Count := GetPropList(PersonListObj, TempList);
  if Count > 0 then
  begin
    try
      for I := 0 to Count - 1 do
      begin
        PropInfo := TempList^[I];
        if not IsPublishedProp(PersonListObj, PropInfo^.Name) then 
Continue;
        case PropInfo^.PropType^.Kind of
          TKDynArray:
          begin
            // This function returns information regarding the array 
including the class name 
            GetDynArrayElTypeInfo(PropInfo^.PropType^,ElementTypeInfo, 
Dimensions);
//            GetPropInfos(ElementTypeInfo, Templist2);
(*            if GetTypeData(ElementTypeInfo)^.classtype = TKPerson then
          Showmessage('TKPerson');

        // This returns an unassigned variable 
            v:= GetPropValue(PersonListObj,PropInfo^.Name) ;
      end;
    finally
      FreeMem(TempList);
    end;
  end;
end;



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