Path: utzoo!utgpu!water!watmath!clyde!att!rutgers!mailrus!ncar!boulder!stan!garya
From: garya@stan.com (Gary Aitken)
Newsgroups: comp.windows.x
Subject: Re: Request for Object-Oriented extension to XEvents (long)
Message-ID: <269@stan.com>
Date: 19 Oct 88 16:18:04 GMT
References: <161@tityus.UUCP> <8810181510.AA25050@EXPO.LCS.MIT.EDU>
Organization: Solbourne Computer Inc., Longmont, Co.
Lines: 29

>  It seems that all you'd be saving would be a hash table lookup.

True.  But in an application with a lot of windows (and let's face it,
many real applications are going to have hundreds of them), duplicating
the hash table is going to gobble up a lot of memory.  I'm guessing it
will gobble a lot more memory than the cells wasted for those windows
which won't have a "user_data" field specified for them, but someone
should probably do some analysis of this before going forward with a
proposal.

>  You'd probably want to have it obey the same swapping rules as
>  properties.  But, whether or not an application would choose to be unportable
>  and store a real pointer in it depends on the semantics of setting the user
>  data field. 

I don't think this is true.  Just as the event mask is associated with
a particular client, and used only by that client, so is the proposed
data field.  The server would only carry it as baggage, with no inter-
pretation, and would return it in the same form it was presented.  If the
server chose to swap bytes for some reason, it would be obligated to swap
them back when generating the returned event structure.

>  For example, is there a user data field for every client for every window?

I think the answer is yes, which means all the ChangeWindowAttributes 
problems go away.

-- Gary Aitken
        ncar!boulder!stan!garya