Re: Disallowing Pre-Defined Operations

["Samuel T. Harris" <samuel_t_harris@Raytheon.com>]

"Charles H. Sampson" wrote:
> 
>      During the deliberations that led to Ada 95, was a mechanism for
> disallowing the pre-defined operations of a type considered?  By "disal-
> lowing" I mean some way of informing the compiler that an attempt to use
> a certain pre-defined operation is a compile-time error.  Did anyone
> even ask for it?  (Obviously I didn't, even though I've thought since
> the mid-eighties that it would be a useful capability to have.)
> 

One could use a derived type and overload the undesired operators
to simply raise some appropriate exception. Perhaps Operation_Error.
That will give you runtime checks on "improper" usage.

As to compile time checks, one can develop an ASIS program
which hunts for the offending operators. You can even
create you own pragma to denote which operators are not
to be referenced. Other compilers may complain about
an unsupported or unrecognized pragma, but they should
allow compilation. The ASIS program can recognize such
pragmas and use them to key in on which operators
should not be used.

-- 
Samuel T. Harris, Principal Engineer
Raytheon, Aerospace Engineering Services
"If you can make it, We can fake it!"