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From: "Stefan Monnier" <monnier+lists/caml/news/@tequila.cs.yale.edu>
Newsgroups: lists.caml
Subject: Re: Objects contrib: new URL ...
References: <14183.51513.8527.191081@virtualc5.pa.dec.com> <19990617112633P.garrigue@kurims.kyoto-u.ac.jp> <14185.11632.214915.820706@virtualc5.pa.dec.com>
Date: 17 Jun 1999 14:44:05 -0400
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>>>>> "Fabrice" == Fabrice Le Fessant <fessant@pa.dec.com> writes:
> At the end of this message, you will find a patch to apply on
> patch.cast to raise a Oo.CastFailure exception with the information
> on the file and the line number where the exception was raised.

I have to agree with Jacques:  using a match construct (i.e. `typecase')
rather than a `cast' is cleaner.  It makes it a lot more obvious that the
cast might fail and in the case where you want to deal with several
alternatives, a `typecase' is exactly what you want, whereas using `cast'
would be very awkward (using handlers all over the place).
Of course a `cast' is a little better in the case where you *know* that
it will succeed, but the textual overhead of a `typecase' does not seem
significant.

> (should the compiler allow "x.(-1)" in a program as it currently does?),

No it shouldn't.  And type-systems are being developed that catch those uses
(pushing array bounds checking either to compile-time or (when the analysis is
not powerful enough) to the programmer (to insert the checks by hand)).


	Stefan