Dear Aaron,
Please suggest me if I am wrong.
Singleton is not suitable to me. I got several const objects of same class.
Best Regards
leigh
----- Original Message -----
From: Aaron Scott-Boddendijk <[EMAIL PROTECTED]>
To: Multiple recipients of list delphi <[EMAIL PROTECTED]>
Sent: Sunday, May 07, 2000 1:15 PM
Subject: Re: [DUG]: Declare const object
> > This method is currently I use. But I am not happy about that. Because I
> > want that variable to be logical const, no one should modify it. I want
> > compiler automatic tell me it is an error if in my code I try to modify
the
> > value.
>
> You can create a field in your object as a property and have the Class
treated as
> a singleton (only one copy of the class ever exists)...
>
> unit X;
>
> interface
> const
> MyClassDefaultValue = 0;
>
> type
> TMyClass = class(TObject)
> private
> FAValue :Integer;
> // Declared as private to indicate intended use as a singleton
although
> // 'Create' will still be available as public due to its
declaration on TObject.
> constructor Create(AVAlue :Integer);
> public
> property AValue :Integer read FAValue;
> end;
>
> // Singleton access function ... This could equally be declared as a
public
> // class method of TMyClass.
> function MyClass :TMyClass;
>
> implementation
>
> var
> _MyClass :TMyClass;
>
> function MyClass :TMyClass;
> begin
> // if this is the first invocation then the singleton instance will be
created.
> if _MyClass=nil then _MyClass := TMyClass.Create(MyClassDefaultValue);
> result := _MyClass;
> end;
>
> constructor TMyClass.Create(AValue :Integer);
> begin
> inherited Create;
> FAValue := AValue;
> end;
>
> initialization
> finalization
> // Release the Singleton instance if one exists.
> _MyClass.Free;
> end.
>
> --
> Aaron@home
>
>
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