Re: 'Valid, subtypes and constraint checking - Thanks

["Robert I. Eachus" <rieachus@comcast.net>]

Peter Amey wrote:

> Thanks to all the responders.  The advice is consistent and useful.  In 
> deference to Jean-Pierre, I withdraw the adjective "horrible" for the 
> use of unchecked conversion!

The right name for Unchecked_Conversion is 
It_is_the_programmer's_job_to_do_some_checking_on_this_Conversion.

But the apostrophe would have made it an attribute. ;-)

Seriously the right place to use Unchecked_Conversion is when you, the 
programmer need to do some type checking, and nowhere else.

For completeness, Unchecked_Deallocation should be 
Assume_that_there_are_no_other_valid_copies_of_this_access_value.

In both cases, the compiler is not promising the user it won't do any 
checking, or will free the memory pointed to by the access value. The 
purpose of these units is to allow the programmer to assert something to 
the compiler.

-- 
                                        Robert I. Eachus

"Quality is the Buddha. Quality is scientific reality. Quality is the 
goal of Art. It remains to work these concepts into a practical, 
down-to-earth context, and for this there is nothing more practical or 
down-to-earth than what I have been talking about all along...the repair 
of an old motorcycle."  -- from Zen and the Art of Motorcycle 
Maintenance by Robert Pirsig