Re: Proposed change to BC iterator parameters

[Jeffrey Carter <spam@spam.com>]

Robert A Duff wrote:

> Anyway, the key point of "limited" is that you can't copy things.  The
> "=" issue is a more minor one, I think.

My point exactly.

> Jeffrey Carter <spam@spam.com> writes:

>>In hindsight, it would have been better to eliminate the "limited"
>>reserved word completely, and use instead
>>
>>type T is private;
>>-- Same as Ada's "limited private"
>>
>>type T is private with ":=";
>>-- Assignment defined; "=" not; no Ada equivalent
>>
>>with the capability of defining "=" for either type.
 >
> Here, I think you're talking about regular private types in
> packages (as opposed to generic formals).  One idea is to say:

I was thinking about both.

> Unfortunately, the Ada compiler does not understand the comment, "-- For
> use only in the package body!".  You say above, ``with the capability of
> defining "=" for either type.''  But it's not trivial to make that "="
> be the predefined one.

If we had a syntax like that I described, there would be no predefined 
"=" for either kind of type.

One can think about all kinds of constraints on types, such as the 
integer types you mentioned. It would be nice to have unconstrained 
arrays with a fixed lower bound*:

type String_From_1 is array (Positive range 1 .. <>) of Character;

I don't expect to see major changes of this sort. Where do you stop? 
Should you allow arrays with a fixed upper bound?

* Ada sort of has this:

type String_From_1 (Length : Natural) is record
    Value : String (1 .. Length);
end record;

-- 
Jeff Carter
"Perfidious English mouse-dropping hoarders."
Monty Python & the Holy Grail
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