Re: [Caml-list] Bless me Father, for I have used Obj.magic

[rixed@happyleptic.org]

-[ Thu, Dec 22, 2011 at 11:07:37PM +0100, Fabrice Le Fessant ]----
> You might one day forget this [Obj.magic], and access the field [t] that
> has not yet been initialized, and get a segfault.

As the only place where this 0 value exists is in the constructor and
it can easily be shown that the function never returns a semi-initialized
t, then this looks quite unprobable here. But I welcome the warning
nonetheless :-)

> My advise would be to first create a dummy [t] record:
> 
> let dummy_t = { operation = (fun _ -> failwith "t not initialized");
>                 some_fields = ... some dummy initializer .. }

Yes, this was my initial intention as well.
Unfortunately, my actual types are much more complex than what's shown
in the example; especially a value of type t2 is quite hairy to construct
and there are lots of operations having lots of complex output types
(records of records of functions of records...) That's why I had this
TODO note in the margin commanding to "build a dummy t to get rid of the
option type" for so long, until I had this terrible idea of using
Obj.magic.