Re: A question re meaning/use of the "for ... use ..."

[Keith Thompson <kst-u@mib.org>]

"Randy Brukardt" <randy@rrsoftware.com> writes:
> "Jeffrey Carter" <spam@spam.com> wrote in message
> news:H1Hsd.1987$yr1.256@newsread3.news.pas.earthlink.net...
>> Stephen Leake wrote:
>>
>> > There is no standard attribute that returns the internal
>> > representation specified by the enumeration representation clause.
>> > However, GNAT provides the non-standard 'Enum_Rep for this purpose.
>>
>> I have no problem with 'Pos returning the abstract position number, but
>> do think something like GNAT's 'Enum_Rep should be standard, along with
>> a conversion the other way, equivalent to 'Val ('Enum_Val?).
>
> The ARG discussed this long ago, and concluded that such a facility isn't
> needed. That's because Unchecked_Conversion provides the needed support.
> Indeed, this is one of the few cases where the result of
> Unchecked_Conversion is defined by the language (using it in this way will
> work on all Ada compilers). There was some discussion about syntax guides
> that prohibit the use of Unchecked_Conversion, but there is a lot of
> discomfort about changing the language just because some people's style
> guides are broken...

How do you portably choose the target type for the Unchecked_Conversion?

The 'Pos attribute returns a result of type universal_integer; there's
no way to make an Unchecked_Conversion return a universal_integer.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
San Diego Supercomputer Center             <*>  <http://users.sdsc.edu/~kst>
We must do something.  This is something.  Therefore, we must do this.