Re: 'Write attribute vs Write procedure.

[Simon Wright <simon@pushface.org>]

Craig Carey <research@ijs.co.nz> writes:

> So similarly, GNAT.Sockets could be altered so that the comments in it
> suggesting use of Ada 95's X'Read feature, are deleted or discouraged.
> 
> X'Read() has no parameter for diagnostics on what the malfunction was.
> The language can be revised so that X'Read is deleted or else it returns
> error information out directly so that it is available to very next
> line in the source code. If Ada becomes a language where malfunctioning
> programs don't know why, and are really cryptic in describing the
> precise problem (e.g. since code in exception handlers tries to handle too
> many errors), then it could be all made reasonable (insufficiently
> reasonable) by the new style of new unneeded code that seems to do
> ntohing to a single byte but just lose the error info so that the next
> line can't get it (it has to be the line after if the code is in an
> exception handler).

I don't understand this ..

A "simple" solution to your problem (not to mine!) might be to have a
package -- _not_ a revised GNAT.Sockets, please! -- which doesn't deal
with Streams, but with something else.

You still have the option to (for example) encapsulate the data you're
actually interested in in a "datagram" preceded by length information,
so you can read the "datagram" into a Stream_Element_Array and then
internally stream from that (this is the approach we are adopting for
UDP sockets).

> However ACT is saying that customers do not seek big changes in
> GNAT.Sockets.

There is certainly a problem with reading classwide objects from UDP
sockets.