理解 Delphi 的类(十一) - 深入类中的方法[2] - 关于覆盖与重定义

//标准的覆盖是这样的
TBass = class
  procedure Proc; virtual; {或用 dynamic}
end;

TChild = class(TBass)
  procedure Proc; override;
end;


//以下几种情况属于重定义, 其中例 3-5 还会有编译提示

{例1}
TBass = class
  procedure Proc;
end;

TChild = class(TBass)
  procedure Proc;
end;

{例2}
TBass = class
  procedure Proc;
end;

TChild = class(TBass)
  procedure Proc; virtual;
end;

{例3}
TBass = class
  procedure Proc; virtual;
end;

TChild = class(TBass)
  procedure Proc; virtual;
end;

{例4}
TBass = class
  procedure Proc; virtual;
end;

TChild = class(TBass)
  procedure Proc;
end;

{例5}
TBass = class
  procedure Proc; virtual;
end;

TChild = class(TBass)
  procedure Proc; dynamic;
end;

{上面这五种情况我们尽量不要使用}


//方法重定义时, 避免编译提示的办法

{办法1: 使用 reintroduce 指示字}
TBass = class
  procedure Proc; virtual;
end;

TChild = class(TBass)
  procedure Proc; reintroduce;
end;

{办法2: 使用编译器指令}
TBass = class
  procedure Proc; virtual;
end;

{$WARNINGS OFF}
TChild = class(TBass)
  procedure Proc; virtual;
end;
{$WARNINGS ON}