从Delphi的子单元访问主表单

Question

我想从一个从main调用的类中访问一个主窗体变量.像这样的东西:

单元1:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs,Unit2, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
  public
  end;
var
  Form1: TForm1;
  Chiled:TChiled;
const
 Variable = 'dsadas';
implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  Chiled.ShowMainFormVariable;
end;

end.

单元2:

unit Unit2;

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

  type
  TChiled = class
  private
  public
    procedure ShowMainFormVariable;
  end;
var
  Form1: TForm1;
implementation

procedure TChiled.ShowMainFormVariable;
begin
  ShowMessage(Form1.Variable);
end;
end.

如果在Unit2中我添加使用Unit1弹出一个圆形错误.

如何使Unit1成为全球？

Answer 1

正如其他答案所述,您应该使用实现部分中的一个单元.

假设你在'unit2'中选择了你在实现中使用'unit1'.那么你需要设计一种机制来告诉'TChiled'如何访问'Form1'.那是因为你没有在'unit2'的接口部分使用'unit1',你不能在接口部分声明'Form1:TForm1'变量.以下只是一种可能的解决方案:

unit2

type
  TChiled = class
  private
    FForm1: TForm;
  public
    procedure ShowMainFormVariable;
    property Form1: TForm write FForm1;
  end;

implementation

uses
  unit1;

procedure TChild.ShowMainFormVariable;
begin
  ShowMessage((FForm1 as TForm1).Variable);
end;

然后在unit1中,您可以在调用TChiled的方法之前设置TChiled的Form1属性:

procedure TForm1.Button1Click(Sender: TObject);
begin
  Chiled.Form1 := Self;
  Chiled.ShowMainFormVariable;
end;