[GUI] CGA standard

Alastair Reid alastair@reid-consulting-uk.ltd.uk
Sun, 16 Mar 2003 20:45:18 +0000

Krasimir Angelov <ka2_mail@yahoo.com> writes:
> I am under the impression that there is a consensus of all points
> mentioned [below] but they have to be specified in the standard.

My impression differs on 3 of the 4 points.
> Summary:
> - CGA should use callback functions for event handling

The concensus does seem to be that this is readily implemented and can
be used to implement the other styles of interface being proposed.

> - All primitives should be thread safe

There seems to be some disagreement over this and strong arguments for
considering requiring single-threaded use.  (There are also strong
arguments for requiring thread-safety.)

> - Calling whoever of the primitives should not block the concurrent
>   threads. An exception can be done only for the primitives who are
>   executed in a very short constant time

This decision is contingent on a multithreaded design.

> - For each event there should be two functions: register and unregister

My understanding is that there should be one function 'register' which
returns an 'unregister' action as part of its result.  This neatly
avoids the problem of needing equality tests on functions
(semantically difficult) or hacks to get around this lack.

Alastair Reid                 alastair@reid-consulting-uk.ltd.uk  
Reid Consulting (UK) Limited  http://www.reid-consulting-uk.ltd.uk/alastair/