[lazarus] Setting a value using RTTI
SMiller1 at stvgb.org
Fri Dec 1 14:19:43 EST 2000
If you are going to add a
procedure SetProp(Instance: TObject; const PropName: string;const Value: string);
can you add a
procedure SetSetProp(Instance: TObject; Index : Intger;const Value: string);
That way I don't have to do a thing! :-)
I have TComponentInterface setup to set Boolean, Integers, Floats, Methods and strings. The functions seem to work but setting certain properties seems to fail.
I successfully set a Method so that was pretty cool.
>>> michael.vancanneyt at wisa.be 12/01/00 07:44AM >>>
On Fri, 1 Dec 2000, Shane Miller wrote:
> Question for all:
> Using RTTI howdo I set a property value?
> In my source code for TComponentInterface.SetPropbyName
> I get the PPropinfo record for the property VISIBLE and
> I check the Setproc variable. It's <> nil so I need
> to call it somehow. I have a TMySetProc type that is a
> Procedure (const value) of Object;
> In TComponentInterface I have a variable MySetProc of type TMySetProc. I assign MySetProc by....
> MySetProc := TMySetProc(SetProc^);
> then I call it
> It crashes. Thoughts?
The correct way to do this is using setordprop:
procedure SetOrdProp(Instance : TObject;PropInfo : PPropInfo; Value : Longint);
You could do like this;
// Easy access function:
function GetPropInfo(Instance: TObject; const PropName: string): PPropInfo;
Result := GetPropInfo(Instance.ClassType, PropName);
Only use the SetXXXprop functions to set properties, don't start looking in
the propinfo records.
I will enhance the typinfo unit ASAP, so functions of the kind
procedure SetSetProp(Instance: TObject; const PropName: string;const Value: string);
are available. They were introduced in Delphi 5 as well; you could then
use these functions.
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