Re: How to break const

[Timon Gehr]

On 06/18/2012 05:15 PM, Mehrdad wrote:

On Monday, 18 June 2012 at 15:11:00 UTC, Timon Gehr wrote:

On 06/18/2012 04:55 PM, Mehrdad wrote:

Identical calls giving identical results? What?


import std.stdio;
struct S
{
         this(int a)
         {
                 this.a = a;
                 this.increment = { return this.a++; };
         }
         int a;
         int delegate() pure increment;
         auto oops() const { return this.increment(); }
}
void main()
{
         auto c = immutable(S)(0);
         writeln(c.oops()); // 0
         writeln(c.oops()); // 1
         writeln(c.oops()); // 2
         writeln(c.oops()); // 3
         writeln(c.oops()); // 4
         writeln(c.oops()); // 5
}

Now you have managed to break the type system.
The underlying issue is unrelated to delegates though.

Yeah, I didn't mean to say it's a delegate issue either. That's why the
title was saying "how to break _const_".  Delegates were just a means to
an end. :)


So (**IMHO**) if that's really the case, we should really spend some
time fixing the /design/ of const before the implementation...

This is mostly about the design of object initialisation.

good idea or no?

Certainly.