Re: Creating several types from a base type and conversion

[Simon Wright <simon@pushface.org>]

Ken Roberts <alisonken1@gmail.com> writes:

> So the next question is how to convert between CharWord/BaseWord?

Possibly using Ada.Unchecked_Conversion. Hidden inside a function with a
helpful-in-six-months name.

It takes very little time to compile code nowadays, I'd strongly suggest
you start with the basics (e.g. BaseWord) and build up from there,
checking as you go (there are a _lot_ of syntax errors in your example
code).

You can't say

    type DataWord is new BaseWord with record
        Upper : array 00 .. 8#77777# of Boolean;
        Lower : array 00 .. 8#77777# of Boolean;
    end record;

because BaseWord isn't a tagged type, and even if it was you don't want
to add extra information, you're looking for an alternative view.
And that's not the syntax for an array declaration.
And you can't declare an anonymous array in a record.
And that's two large arrays (I think you're aiming for representations).

----------

I was wondering whether an Unchecked Union (ARM B.3.3[1]) might serve,
but (30) says "The use of an unchecked union to obtain the effect of an
unchecked conversion results in erroneous execution".

[1] http://www.ada-auth.org/standards/rm12_w_tc1/html/RM-B-3-3.html