🚀 go-pugleaf

In article <3173E842.7D17@willows.com>, Tarang Deshpande
<tarang@willows.com> wrote:

> HASDI RODZMANN HASHIM wrote:
> > 
> > If you have a choice, do you want the parethesis pair over the caster
> > (C-style) or over the castee (Pascal-style)? eg...
> > 
> > a = (int)b; /* cast to int */
> > a = int(b); /* allowable in C++ */
> > 
> 
> 
> I would prefer the Pascal style where the parenthesis go around the
> thing being casted.  This is so that the cast looks like a function
> and it then seems consistent when overriding the cast operator.

On the one hand, I prefer the "C" style cast because it is explicit that a
cast is taking place, whereas the functional style requires you to know
whether the function is a cast function or not. Since casting is an
important thing to know about in a statically typed language (ignoring
RTTI for this discussion), I prefer the emphasis on casting; I think it
makes code more readable.

On the other hand, the functional style emphasizes that some function may
actually be called, and that that function may do significantly more than,
for example, sign extension. However, I was just reading "Item 5: Be wary
of user-defined conversion functions" in Scott Meyers' More Effective C++,
and he basically concludes that you should never define cast operator
functions in a class because they can be called unexpectedly (unless, of
course, you really really want to :-).

Instead of either solution, I prefer the Dylan approach: there is a
function "as()" that takes a type parameter and an object parameter and
returns an object of the specified type, created using the object
parameter. It looks like this:

  foo := as(<type>, bar);

The thing I like about this is that "as()" is defined as part of the
language (like, say "new" in C++), so you always know that you are
performing a cast, but  it also indicates that a function is, or may, be
called. Of course, C++ can't currently handle this approach because it
doesn't have values that represent types. Perhaps RTTI provides this
solution?

-- 
Chris Page        | Internet chain letters, advertisements and SPAMs suck...
Don't Panic!      | 
page@best.com     |                   Cut it out! :-P