RTTI Part 2. Getting object property listing.

Figure 1.

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;

type
TForm1 = class(TForm)
ComboBox1: TComboBox;
Label1: TLabel;
Label2: TLabel;
ComboBox2: TComboBox;
ListBox1: TListBox;
procedure FormCreate(Sender: TObject);
procedure ComboBox1Change(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation
{$R *.DFM}
uses TypInfo;

procedure TForm1.FormCreate(Sender: TObject);
var
tk:TTypeKind;
s:String;
i:integer;
begin
// fill prop types combo
for tk:=Low(TTypeKind) to High(TTypeKind) do
begin
s:=GetEnumName(TypeInfo(TTypeKind),ord(tk));
ComboBox1.Items.Add(s);
end;
ComboBox1.ItemIndex:=1;
// fill objects combo
ComboBox2.Items.Clear;
for i:=0 to ComponentCount-1 do
begin
s:=Components[i].Name;
ComboBox2.Items.Add(s);
end;
ComboBox2.ItemIndex:=0;

ComboBox1Change(Nil);
end;

procedure TForm1.ComboBox1Change(Sender: TObject);
var
i,count:integer;
tk:TTypeKinds;
s:String;
c:TComponent;
pPList:PPropList;
begin
s:=ComboBox1.Text;
i:=GetEnumValue(TypeInfo(TTypeKind),s);
if (i >= Ord(Low(TTypeKind))) and (i <= Ord(High(TTypeKind))) then
tk:=[TTypeKind(i)]
else
tk:=tkAny;
c:=FindComponent(ComboBox2.text);
if Assigned(c) then
begin
pPList:=AllocMem(Sizeof(pPList^));
try
ListBox1.Items.Clear;
count:=GetPropList(c.ClassInfo,tk,pPList);
for i:=0 to count - 1 do
ListBox1.Items.Add(ppList[i].Name);
finally
FreeMem(pPList);
end;
end;
end;

end.

Summary.

The RTTI contains information about every published property of every class. Using the procedures and functions from typInfo.pas you can extract this information at run-time.

Full source code and compiled executable is available at http://www.suite101.com/files/topics/724...
The program is written for Borland Delphi 4, but this code must work under Delphi 3/4/5.
You may experiment with the program for better understanding. I would like to answer any questions that you may have.

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