Re: Anybody in US using ADA ? One silly idea..

[Colin_Paul_Gloster@ACM.org (Colin Paul Gloster)]

Timestamped Mon, 03 Feb 2003 10:59:39 +0100,
news:2b9s3vo3bbnaikqd6d4jpppfflfq2kbgfu@4ax.com by
Dmitry A. Kazakov <mailbox@Dmitry-Kazakov.De> contains:

"On Fri, 31 Jan 2003 12:11:03 -0500, Hyman Rosen <hyrosen@mail.com>
wrote:

[..]
>[..] You claim that there is benefit                         
>in requiring that types support unused operations. I                           
>don't see what that benefit is, or where you cut off                           
>the infinite list of possible operations that a type                           
>could conceivably support.                                                     
                                                                                
If you define a type, say, "field". Then you should implement all               
operations of the field."

Yes.

"Otherwise, it is not a field, but a group or           
something else."

Yes.

"So the users of your type would have no delusions               
about it. If it has interface of a group, why to present it as field?"

Indeed. And why if it has operations you do not need, are you
defining this type and using it?

"It is just DbC. Ada gives an example of this approach: when you derive
from an abstract type, the derived non-abstract type has to implement           
all abstract operations, no matter whether some of them will never be           
used. Failure to do that is a *compile-time* error. Same thing with             
C++ templates produces a "valid" program! (Ada generics are safer in            
this respect)"

Having unused procedures (of unknown quality) is not safe.

Timestamped Mon, 03 Feb 2003 17:12:24 +0100,
news:lats3vchsfmpaqiid539c8l7q0293eelcf@4ax.com by
Dmitry A. Kazakov has:

"On Mon, 03 Feb 2003 08:26:33 -0500, Hyman Rosen <hyrosen@mail.com>
wrote:

[..]

>You then                                                                       
>claim that this implicit interface needs to be augmented                       
>with operations that the procedure doesn't need, and then                      
>that types upon which the procedure operates need to have                      
>these useless operations, and that this somehow achieves                       
>safety! I am just baffled.                                                     
                                                                                
They are not useless, they constitute the type. [..]"

There are not used therefore they are useless.