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Date: Fri, 10 Jul 2015 12:43:55 -0700 (PDT)
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Subject: Re: If not Ada, what else...
From: Patrick Noffke <patrick.noffke@gmail.com>
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Xref: news.eternal-september.org comp.lang.ada:26751
Date: 2015-07-10T12:43:55-07:00
List-Id: <comp.lang.ada>

On Friday, July 10, 2015 at 2:10:44 PM UTC-5, David Botton wrote:
> > I may be missing something here, but I don't see where Ada's type system
> > is that much better than C++'s,
> 
> So in C++ you can create new incompatible types with various ranges, use them for array indexes, true enums? 
> 

In C++11 you have enum class which makes an enum its own type.  You can still cast it to the class type, but you can't willy-nilly use it as an int as with the old-style enum.

This generates an error:

    enum class Junk : int
    {
        One, Two, Three
    };

    int a = Junk::One; // error:  cannot convert to int

Where this is allowed:

    int a = (int) Junk::One;

But there's nothing to prevent you from using the old style.  Even -Wold-style-cast doesn't generate a warning for this:

    enum Junk
    {
        One, Two, Three
    };

    int a = One;

(I guess because it's not technically a C cast -- enum really is just an int.)

I'm curious -- how would you create incompatible types with different ranges in C++?  AFAIK the language itself or the standard library don't provide that.

Pat