如何从其TRttiType实例化一个类? [英] How do I instantiate a class from its TRttiType?

问题描述

我想创建一个以其类名作为字符串的表单，

I want to create a form given its class name as a string, which has been asked about before, but instead of calling GetClass, I want to use Delphi's new RTTI feature.

有了这个代码，我有了一个 TRttiType ，但是我不知道如何实例化它.

With this code, I've got a TRttiType, but I don't know how to instantiate it.

var
  f:TFormBase;
  ctx:TRttiContext;
  lType:TRttiType;
begin
  ctx := TRttiContext.Create;
  for lType in ctx.GetTypes do
  begin
    if lType.Name = 'TFormFormulirPendaftaran' then
    begin
      //how to instantiate lType here?
      Break;
    end;
  end;
end;

我也尝试过 lType.NewInstance ，但是没有运气.

I've also tried lType.NewInstance with no luck.

推荐答案

您必须转换 TRttiType 到 TRttiInstanceType 类，然后使用 GetMethod 函数.

You must cast the TRttiType to the TRttiInstanceType class and then invoke the constructor using the GetMethod function.

尝试此示例

var
  ctx:TRttiContext;
  lType:TRttiType;
  t : TRttiInstanceType;
  f : TValue;
begin
  ctx := TRttiContext.Create;
  lType:= ctx.FindType('UnitName.TFormFormulirPendaftaran');
  if lType<>nil then
  begin
    t:=lType.AsInstance;
    f:= t.GetMethod('Create').Invoke(t.MetaclassType,[nil]);
    t.GetMethod('Show').Invoke(f,[]);
  end;
end;

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