有没有办法在delphi中按名称实例化一个类? [英] Is there a way to instantiate a class by its name in delphi?

问题描述

我想实例化一个类，但我只有一个字符串的名称.有办法吗?

I'd like to instantiate a class but I only have its name in a string. Is there a way?

推荐答案

这来自 Delphi 帮助(Delphi 2006，但至少也可从 Delphi 7 获得):

This is from Delphi help (Delphi 2006, but also available from at least Delphi 7):

语法function GetClass(const AClassName: string): TPersistentClass;

Syntax function GetClass(const AClassName: string): TPersistentClass;

说明调用 GetClass 从类名中获取类.此类可用作需要类的例程的参数.在 GetClass 找到它之前，必须先注册 Class.在表单声明(实例变量)中引用的表单类和组件类在表单加载时自动注册.其他类可以通过调用 RegisterClass 或 RegisterClasses 进行注册.

Description Call GetClass to obtain a class from a class name. This class can be used as a parameter to routines that require a class. The Class must be registered before GetClass can find it. Form classes and component classes that are referenced in a form declaration (instance variables) are automatically registered when the form is loaded. Other classes can be registered by calling RegisterClass or RegisterClasses .

这里有一些示例代码.之所以如此有效，只是因为 TButton 是一个 TControl，因此类型转换是有效的.

Here some sample code. Works as such only because TButton is a TControl and therefore the typecast is valid.

procedure TForm1.FormCreate(Sender: TObject);
begin
  RegisterClasses([TButton, TForm]);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  CRef : TPersistentClass;
  AControl : TControl;
begin
  CRef := GetClass('TButton');
  if CRef<>nil then
  begin
     AControl := TControl(TControlClass(CRef).Create(Self));
     with AControl do
     begin
        Parent := Self;
        Width := 50;
        Height := 30;
     end;
  end;
end;

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