学步园

编辑器通过 Rtti 还能够调用一个类的方法, 也能读取或设置其属性值.
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unit Unit1;

interface

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

type
TForm1 = class(TForm)
Button1: TButton;
Button2: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
end;

{自定义的类}
TMyClass = class(TComponent)
public
procedure msg(const str: string);
function Add(const a,b: Integer): Integer;
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

uses Rtti;

{ MyClass 类的实现 -----------------------------------------------------------}

procedure TMyClass.msg(const str: string);
begin
MessageDlg(str, mtInformation, [mbYes], 0);
end;

function TMyClass.Add(const a, b: Integer): Integer;
begin
Result := a + b;
end;

//通过 Rtti 的手段使用 TMyClass 类的方法 --------------------------------------
procedure TForm1.Button1Click(Sender: TObject);
var
obj: TMyClass;
t: TRttiType;
m1,m2: TRttiMethod;
r: TValue; //TRttiMethod.Invoke 的返回类型
begin
t := TRttiContext.Create.GetType(TMyClass);

{获取 TMyClass 类的两个方法}
m1 := t.GetMethod('msg'); {procedure}
m2 := t.GetMethod('Add'); {function}

obj := TMyClass.Create(Self); {调用需要依赖一个已存在的对象}

{调用 msg 过程}
m1.Invoke(obj, ['Delphi 2010']); {将弹出信息框}

{调用 Add 函数}
r := m2.Invoke(obj, [1, 2]); {其返回值是个 TValue 类型的结构}
ShowMessage(IntToStr(r.AsInteger)); {3}

obj.Free;
end;

//通过 Rtti 的手段修改并获取 TMyClass 类的属性 --------------------------------
procedure TForm1.Button2Click(Sender: TObject);
var
obj: TMyClass;
t: TRttiType;
p: TRttiProperty;
r: TValue;
begin
obj := TMyClass.Create(Self);

t := TRttiContext.Create.GetType(TMyClass);

p := t.GetProperty('Name');
p.SetValue(obj, 'NewName');

r := p.GetValue(obj);
ShowMessage(r.AsString); {NewName}

obj.Free;
end;

end.
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回复下面的问题：如何设置枚举值：
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procedure TForm1.Button3Click(Sender: TObject);
var
t: TRttiType;
p: TRttiProperty;
r: TValue;
begin
t := TRttiContext.Create.GetType(TButton);

p := t.GetProperty('Align');
p.SetValue(Button1, TValue.FromOrdinal(TypeInfo(TAlign), Ord(alLeft)));

r := p.GetValue(Button1);
ShowMessage(IntToStr(r.AsOrdinal)); {3}
end;

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