2009/4/10 Philippe Marschall <philippe.marschall at gmail.com>:
> 2009/4/10 Ralph Johnson <johnson at cs.uiuc.edu>:
>>> A very interesting article that anyone interested in the topic must
>>> read: "What To Know Before Debating Type Systems"
>>> http://www.pphsg.org/cdsmith/types.html
>>
>> i disagree that "strong typing" doesn't mean anything.  Weak typing
>> means "has a type system but it is easy to get around it".  Strong
>> typing means "has a type system and you can't get around it easily".
>> Strong typing certainly does NOT mean compile-time typing.
>>
>> I agree that "dynamic" (checked at run-time) vs. "static" (checked at
>> compile-time) is what is important.  C and Fortran have weak static
>> type systems.  Java has a strong static type system, but only because
>> casts are checked at run-time, i.e. the static type system has holes
>> in it but the run-time system patches those holes.  Smalltalk has a
>> strong dynamic type system; there is no way to run a method on an
>> object that it doesn't belong to.
>
> #valueWithReceiver:arguments:?
>
Right. But. Is given method is part of standard?
IMO this is a dirty hack, which could crash the VM, if primitive
doesn't checking receiver & method class compatibility.

A secure VM could reject implementing primitive at all, and then as a
workaround, all you can do is temporarily compile&install given method
in receiver's class and only then send a message.

There are many cases, when bypassing a message lookup semantics is
undesirable and ignoring the intents of developer. For instance, a
transparent proxy will not function correctly for such cases.
Also squeak already having some optimization, a limited set of
selectors, which are bypassing lookup (#class #== ).
But again, this is implementation detail. IMO, in most standard/pure
form, a language implementation should not provide a ways, how you can
bypass a message lookup semantics.

> Cheers
> Philippe
>
>



-- 
Best regards,
Igor Stasenko AKA sig.