Re: [Caml-list] Safe Obj.magic container ?

[David Teller <David.Teller@univ-orleans.fr>]

On Wed, 2008-02-27 at 12:23 +0100, Tom Primožič wrote:
> The following are my experience and guesses, nothing
> scientific/official/thoroughly tested:
>         1. can I assume that this is always going to work if u is
>         'a.'a   ?
> 
> Well, there is no type 'a.'a. You can have:
> type u = { everything: 'a . 'a }

That's actually what I meant.

> but this presupposes that values of type u are blocks
> (heap-allocated). Therefore, if you cast a boolean (true) to type u,
> and then try to access the everything field of the "new" value, you
> will get a segfault.

Ok.

> 
>         3. assuming the answer to 1. is No, is there a type u or a
>         simple
>         manipulation which should work for any type t ? Or perhaps
>         just for
>         polymorphic variants ?
> 
> type u = int
> this will work for any type. You can even do pointer manipulation with
> it (adding and subtracting even numbers of bytes).
>
> Sorry everybody.

Er... I can't quite figure if it's a joke.

>  - Tom

Cheers,
 David

-- 
David Teller
 Security of Distributed Systems
  http://www.univ-orleans.fr/lifo/Members/David.Teller
 Angry researcher: French Universities need reforms, but the LRU act brings liquidations.