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From: garya@stan.com (Gary Aitken)
Newsgroups: comp.windows.x
Subject: Re: Request for Object-Oriented extension to XEvents
Message-ID: <272@stan.com>
Date: 20 Oct 88 14:51:18 GMT
References: <161@tityus.UUCP> <267@stan.com> <5626@blia.BLI.COM>
Organization: Solbourne Computer Inc., Longmont, Co.
Lines: 30

>  should there be n pointers passed?  ...

Agreed, the generalization from 1 pointer to 2 could go on expanding
and should send up all sorts red flags...  I like the idea of an
arbitrary number of bits (chars?), client definable.  The server would
then accept/return something like:
        short int     n_bytes ;   /* # bytes in client info */
              char    *client_data ;
However, this then gets a bit contorted because the arbitrary data has
to go down the wire.

As you point out, the client could easily have an arbitrarily complex
structure it needed to keep track of, and it is trying to use the server
to give it a hint (no, better than that, an exact map) to which structure
to use.  Since this is client specific data, it seems a bit strange to
use the server as a cache for it, which is the effect of storing an
arbitrary number of bits.  I'll withdraw my earlier plea for more than
one pointer, and say one is enough.  If the client has complex structures,
it can ask the server to accept/return a ptr to the structure.  In this
model, it SHOULD be a pointer, not an arbitrary string of bits.

The main problem with cacheing a pointer is that if the dispatch mechanism
reallocates its tables when it expands them, the cached info is wrong.
The client will have deal with that problem itself.

>  ... calling this an "object-oriented" extension is a mistake."

Agreed.  I don't care what you call it.  The point is, ANY application
is going to go through some dispatch mechanism after calling XNextEvent,
and any information the server can provide to speed it up by reducing a
duplication of function on the client side would be a help.