const(FAQ)

[Kevin Bealer]

Koroskin Denis Wrote:

> Slightly modifying your example...
> 
> Looks like a bug to me:
> 
> import std.stdio;
> 
> void set(inout int key, int value)
> {
>      key = value;
> }
> 
> class Square {
>      private int _area = -1;
>      private int _width = 0;
> 
>      public this(int width)
>      {
>          _width = width;
>      }
> 
>      public const int area()
>      {
>          if (_area == -1) {
>              //_area = _width*_width;      // we cannot change variable  
> value direcly
>              set(_area, _width*_width);    // but we can do it _indirectly_  
> ???
>                                            // it means that _all_ variables  
> are mutable!
>          }
>          return _area;
>      }
> }
> 
> int main(string[] args)
> {
>      const Square c = new Square(10);
>      writefln(c.area());
> 
>      return 0;
> }

Maybe I'm missing something but checking your code in the version of dmd that I currently have (2.007), the compiler says:

Error: cast(int)(this._area) is not an lvalue

Kevin