Re: Why use C++?

[Georg Bauhaus <rm.dash-bauhaus@futureapps.de>]

On 12.08.11 21:51, Jed wrote:

> I like the semantic also (not the syntax though). I still don't have a
> feel for the scope of the desired (your) semantics and the compiler
> implementation effort requited though. So far, I'm clear on "ranged
> integers + size attribute".

As others have argued, and as has come out of the study
mentioned earlier, the language should allow specifying types
by referring to those properties of the solution that
are descriptive of the envisioned type's properties.  That's
rarely int alone, but rather what the programmer has in mind.

Sorry, I can't present to you a complete and consistent summary
of the world's programmers' ideas about whole number types in
their programs, other than in the negative: they are rarely covered
by int, as is exemplified in this thread.

A positive addition: we already have alternative ways of
declaring types and they lead to exactly as efficient
programs.

These types are an interesting challenge, anyway.  A few compiler
writers have done some homework and decided that cyclic types (beyond
wrapping ones such as unsigned int) would be nightmarish to
implement.  At least efficiently, IIUC.

But do they have to implement all kind of ideas, or should
a language just offer building blocks for the type system?
For example, offer a set membership operation, one that can
no just be tacked onto operator=, but such that the compiler
can infer things systematically, guided by standard rules
whenever it meets =.

Is there a way, for example, to define a type system
that  keeps HALT out of  operator=?


> So, a control panel on top of the low-level things. (4GL vs. 3GL).

int refers only to what the C++ standard has to say about
minimal properties of int.  Simply being more specific about what
values I have in mind is far, far away from a 4GL language.
Even WRT GL time.  The idea is at least as old as 3GL, and
has been implemented long ago.
The difference in concept between int and integer types flowing
from programmer's specification need not be huge:
Writing "int" gives permissions to the implementation, so do
"n1 .. n2" etc. Only that a C++ compiler cannot but conflate
the value set the programmer had in mind and the  value set
that happens to be that of int in a given implementation.