为什么不能对类使用运算符重载? [英] Why can I not use operator overloading for classes?

问题描述

我在TDateTime中遇到类运算符的问题.

I'm having a problem with class operators in TDateTime.

type
  TDateTime = class(TObject)
  public
    class operator Add(a: TDateTime; b: TTimeSpan): TDateTime;
    class operator Subtract(a: TDateTime; b: TTimeSpan): TDateTime;
end;

implementation

class operator TDateTime.Add(a: TDateTime; b: TTimeSpan): TDateTime;
begin
  result := TDateTime.Create(a.Ticks + b.Ticks);
end;

class operator TDateTime.Subtract(a: TDateTime; b: TTimeSpan): TDateTime;
begin
  result := TDateTime.Create(a.Ticks - b.Ticks);
end;

错误发生在第四行

E2123预期的过程，功能，属性或VAR

E2123 PROCEDURE, FUNCTION, PROPERTY, or VAR expected

我是为Windows编写的.但是，如果仅适用于.net和iOS，我该如何针对Windows?

I write this for Windows. But if it available only for .net and iOS, how can I do that for Windows?

推荐答案

在Delphi for Windows中，可以仅对记录使用运算符重载，对类不使用.
http://docwiki.embarcadero.com/RADStudio/Rio/en/Operator_Overloading_ (德尔福)

It is possible to use operator overloading only for records, not for classes in Delphi for Windows.
http://docwiki.embarcadero.com/RADStudio/Rio/en/Operator_Overloading_(Delphi)

一些有用的解释

P.S. TDateTime对于用户类型而言是错误的名字.

P.S. TDateTime is bad name for user type.

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