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From: evans@decvax.DEC.COM (Marc Evans)
Newsgroups: comp.os.vms,comp.windows.x
Subject: Re: XtAddInput and VMS DEC Windows
Message-ID: <487@decvax.decvax.dec.com.UUCP>
Date: 26 Dec 90 13:51:24 GMT
References: <1990Nov20.184509.3252@objy.com> <52.2772c5f0@xmws.uucp>
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Reply-To: evans@decvax.DEC.COM
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Organization: Synergytics
Lines: 43

In article <52.2772c5f0@xmws.uucp>, baxter@xmws.uucp writes:
|> In article <1990Nov20.184509.3252@objy.com>, ricks@prefect.objy.com (Rick L. Spickelmier) writes:
|> > I'm trying to get XtAddInput to work on VMS with the input 
|> > coming from a pipe connected to a subprocess (created with
|> 	stuff deleted
|> > I just hang...  Does anybody use XtAddInput under VMS?  
|> 
|> Yes
|> 
|> > Is it with a subprocess via pipes?  
|> 
|> No 
|> 
|> I did a presentation on this at DECUS six months ago... get ahold of
|> the VAX Sig session notes from someone for the New Orleans Decus last spring.
|> 
|> You CANN'T DO IT with PIPES...  Which are ONLY SIMULATED on VMS. 
|> 
|> You need control of read completion from the mailbox that the pipe really is...
|> 
|> You _MUST_ do this in a VMS specific way, i.e. You MUST use the VMS QIO 
|> Mechansim and you must do it asynchonously... so that XtMainEventLoop will 
|> still have control...
|> 
|> The source argument to XtAddInput is really a VMS event flag number...
|> THIS is the key!!!!!

[...]

This brings up an interesting problem. DEC claims that VMS is going to be POSIX.1
compliant in a future version. DEC also claims that full binary backward compatibility
will be preserved. Now then, according to the X specification for XtAddInput, on
POSIX compliant systems, the source argument must be a valid file descriptor. How is
VMS going to deal with this situation? One of the two claims will have to be dropped,
at least from my perspective. Any comments?

- Marc

-- 
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Marc Evans - WB1GRH - evans@decvax.DEC.COM  | Synergytics     (603)635-8876
      Unix and X Software Contractor        | 21 Hinds Ln, Pelham, NH 03076
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