Re: Typing in Ada

[Dave Thompson <david.thompson1@worldnet.att.net>]

On Tue, 01 Jun 2004 01:09:41 GMT, "Peter C. Chapin"
<pchapin@sover.net> wrote:

> tmoran@acm.org wrote in news:_KOuc.24339$IB.6225@attbi_s04:
> 
> >   How would you do in C the equivalent of
<snip>
> Are you asking me to show you symbolic polynomical manipulation code in C? 
> I don't understand how that bears on the question of how strongly typed C 
> is. In any case your example uses features like generic instantiation and 
> operator overloading that could be more directly mapped to C++. Would you 
> say that C++ is more strongly typed than C?
> 
Slightly. In C enum types simply are integer types; in C++ they are
distinct, though it will silently convert an enum _to_ an integer (not
the reverse). And C++ makes character literals type char instead of
type int, so overloading on that type has some hope of being usable. 
(Although char still is, and promotes as, an integer type.)

And it does not allow silent conversions _from_ pointer-to-void (which
is the moral equivalent of System.Address) to other (data) pointers.
(This is actually a specific case of not allowing conversions "down"
the class hierarchy, which in general does not apply to C.)

And finally, though people don't always think of it as typing, C++
requires the "new" style declaration of routines/methods with
parameters specified so calls, and pointers-to-function (and pmfs) if
used, can be fully checked*; C supports this but also allows the old
K&R1 FORTRANish function-of-you-must-know-the-args. For that matter,
C++ and C99, unlike C89 and earlier, no longer have implicit
declarations of functions, as taking unspecified arguments and
returning int; this isn't really a typing issue, as an implicitly
declared function actually has the same type, and gets the same
(limited) checking, as an equivalent explicit declaration, but lack of
a visible, checkable, and modifiable declaration makes it seem so.

* except for varargs -- and C++ default arguments and overloading
allow better alternatives in many cases to varargs.

- David.Thompson1 at worldnet.att.net