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 Post subject: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Tue Jan 14, 2014 12:51 pm 
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Real Name: Frederick D. S. "Rick" Marshall
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This is the very first MDC Type A extension we are applying to our Revised MUMPS Draft Standard (RMDS). It explains what the initial values should be for the intrinsic special variables $DEVICE, $IO, $KEY, $PRINCIPAL, $TEST, $X, and $Y when a MUMPS process is first created, which MUMPS 1995 is silent about.

This proposal was proposed and sponsored by Jon Diamond and developed within MDC Subcommittee 15, Programming Structures. The MDC approved this extension at its 20 June 1993 meeting in Washington, DC, by a vote of thirty-seven in favor, none opposed, and four abstentions.

I will post the extension document itself tomorrow, once we fix a small bug with Mumpster that's currently blocking me from doing so.

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Frederick D. S. "Rick" Marshall, VISTA Expertise Network, 819 North 49th Street, Suite 203, Seattle, Washington 98103, (206) 465-5765, rick dot marshall at vistaexpertise dot net
"The hidden harmony is best." - Heraclitus of Ephesus


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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Tue Jan 14, 2014 8:12 pm 
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Here's the extension itself, in Adobe Portable Document Format.


Attachments:
File comment: MDC X11/1994-5 Initialising Intrinsics
MDC 1994-5 Initialising Intrinsics 20131029 toad.pdf [178.29 KiB]
Downloaded 334 times

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Frederick D. S. "Rick" Marshall, VISTA Expertise Network, 819 North 49th Street, Suite 203, Seattle, Washington 98103, (206) 465-5765, rick dot marshall at vistaexpertise dot net
"The hidden harmony is best." - Heraclitus of Ephesus
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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Wed Jan 15, 2014 1:52 am 
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Location: Australia
Real Name: Ray Newman
Began Programming in MUMPS: 01 Jul 1976
I'll give a definate response as to MUMPS V1 current state in a few days. I'm currently on holidays and a little short of time.

Ray


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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Wed Jan 15, 2014 8:51 am 
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Location: Russia, Moscow
Real Name: Eugene Karataev
Began Programming in MUMPS: 10 Mar 1997
MiniM has been checked OK. Initializations of intrinsics already use this conventions, no changes required.

Eugene


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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Sat Jan 18, 2014 1:24 am 
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Real Name: Ray Newman
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MUMPS V1.64 conforms to the initialisation of the specified intrinsic special variables.

Ray Newman


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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Fri Jan 31, 2014 12:25 pm 
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I'm glad both MiniM and MUMPS V1 have this extension handled.

Our next step for this extension will be to upgrade the MUMPS Validation Suite to check for these initial values.

And, of course, as additional implementors join us, we'll be very interested in hearing about their implementation of this extension.

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Frederick D. S. "Rick" Marshall, VISTA Expertise Network, 819 North 49th Street, Suite 203, Seattle, Washington 98103, (206) 465-5765, rick dot marshall at vistaexpertise dot net
"The hidden harmony is best." - Heraclitus of Ephesus


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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Sat Feb 01, 2014 8:56 pm 
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Location: Watsonville, CA (USA)
Real Name: Greg Woodhouse
Began Programming in MUMPS: 01 Oct 1992
Okay, I'm a little confused by the language here. It seems to be saying that if $IO is initialized to anything but the empty string, that value is not useable. ( meaning it cannot be USEd ?). Is the idea that if $ IO=$P that device is already implicitly in use. What happens as a result of U $ IO in this case? If no error occurs, is it really true that the device is not useable? If an error occurs, what would it be, and is this really desirable ?


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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Sat Feb 01, 2014 10:06 pm 
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Greg, as you will see when I publish MDC Type A Extension X11/2014-1 Effect of CLOSE $IO, implementations differ a lot in their handling of the current and principal device at the boundary cases, such as process creation and when $IO is closed.

The current proposal is half of a pair that together fix device handling to allow two coherent choices out of the range of coherent and incoherent behaviors the implementations allowed. One choice is to have a principal device, open it, and use it, which sets $IO = $PRINCIPAL. The other choice is not to have a principal device, in which case $IO = "" so you know how to test for this case, and $PRINCIPAL is set to whatever the implementor feels like, since that gives them more leeway to innovate in this case.

So, if $IO = $PRINCIPAL, you can safely USE $IO, but if $IO = "", then you cannot safely USE $IO.

Does that make sense?

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Frederick D. S. "Rick" Marshall, VISTA Expertise Network, 819 North 49th Street, Suite 203, Seattle, Washington 98103, (206) 465-5765, rick dot marshall at vistaexpertise dot net
"The hidden harmony is best." - Heraclitus of Ephesus


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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Sun Feb 02, 2014 12:37 pm 
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Yes. That is reasonable behavior.


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 Post subject: Re: 1. X11/1994-5, Initialising Intrinsics
PostPosted: Sun Feb 02, 2014 12:52 pm 
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In standardizing, there is often this balancing act between wanting to converge on a common standard versus wanting to support the existing implementations who have trail-blazed with the language. The result is that sometimes the standard ends up encoding these choices that represent the reasonable range of options the implementors staked out. That's certainly the case here.

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"The hidden harmony is best." - Heraclitus of Ephesus


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