Re: Exceptions and out procedure arguments (using GNAT GPL)

[Georg Bauhaus <bauhaus.rm.tsoh@maps.futureapps.de>]

Adam Beneschan wrote:
>
> I'd object to is, say, a procedure that reads a string from a file
> into an OUT parameter, and then raises an exception if the string
> doesn't conform to some syntax.  Then, from the caller's point of
> view, the procedure can *both* return valid (although inferior) output
> *and* raise an exception, which I think would make things difficult to
> understand for someone trying to read the code that calls the
> procedure

The Design by Contract point of view :-)  I.e., you do not use assertions
(and hence exceptions) for handling invalid input; instead, you
use an if statement, or whatever seems equivalent.




-- Georg