Thanks very much.
I'm studying OcamlP3L system and in its source there is a large use of Obj.magic, so I wanted to know something deeper about it.

Bye,
nicoletta
--- Mar 18/11/08, Dario Teixeira <darioteixeira <at> yahoo.com> ha scritto:
Da: Dario Teixeira <darioteixeira <at> yahoo.com>
Oggetto: Re: "ocaml_beginners"::[] Obj.magic
A: ocaml_beginners <at> yahoogroups.com
Data: Martedì 18 novembre 2008, 16:25

Hi,

> I can't find exhaustive documentation about this

> function. Could somebody explain me its specification?

The first rule of Obj.magic is that you do not talk about

Obj.magic... On a more serious note, Obj.magic is used to

"magically" overrule the type system, allowing you to do

a low-level cast of a type into another. As an example,

try this code in the top-level:

let foo : float = Obj.magic 1;;

Note that this is not a safe type-casting. In fact, on my

machine the above example causes a segfault.

While gurus can certainly find situations where Obj.magic is

indeed useful, I reckon it's almost certain that if you think

you might need Obj.magic, then there must be something wrong

with your design or you are trying to do things which are not

possible within the Ocaml type system.

Cheers,

Dario Teixeira











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