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Subject: Re: macLib semantics should be documented somewhere
From: Andrew Johnson <[email protected]>
To: Benjamin Franksen <[email protected]>
Cc: [email protected]
Date: Thu, 22 Aug 2013 13:01:45 -0500
Hi Ben,

On 08/22/2013 09:00 AM, Benjamin Franksen wrote:
We recently compiled msi (a patched version but that is not the point here)
with R3.14.12.2 and stumbled over the "recursive" and "undefined" keywords
that the macLib seems to insert when expanding, respectively, recursive or
undefined macros.

They're not really keywords as such because they are not specifically recognized in the input text. The scoped macro syntax allows you to declare or define sub-macros after the name and/or default value inside the macro body, and I made use of that syntax to add those two words as markers. The strings ",recursive" or ",undefined" are appended to the macro body when those conditions are detected during expansion; they will ignored if the generated text is subsequently passed through macLib again with the macro properly defined (macLib parses them as a sub-macro that just hasn't been given a value).

I remembered this being talked about on tech-talk at one
time but I could not find the thread in the archives. So I tried to find
documentation about this somewhere. I looked into the Application Developer's
Guide, the release notes, and the file macLibREADME in the sources, all to no
avail. We even looked at the changeset comments using the bazaar web interface
(3.14 branch). It appears this change was introduced along with the
introduction of scoping in the macLib, but the comment did not say so.

Correct, mea culpa (obviously!).

Anyway, the main intent of this message is not to complain, but rather to
(politely) request that some documentation for the macLib is added somewhere,
ideally in the Application Developer's Guide (which already contains a section
on the macLib but only lists the exported procedures). The macLibREADME is
probably a good starting point, but it would need to be updated to include the
latest changes.

The documentation needs to be moved into the libCom chapter of the Application Developers Guide. There is a Launchpad bug against the guide https://bugs.launchpad.net/epics-appdev/+bug/641365 which says exactly this, although it didn't go into detail about what needs to be added until now.

I'll see what I can do. Maybe we could move all EPICS development to Mars where the day is 40 minutes longer than on Earth...

- Andrew
--
Advertising may be described as the science of arresting the human
intelligence long enough to get money from it. -- Stephen Leacock

Replies:
Re: macLib semantics should be documented somewhere Benjamin Franksen
References:
macLib semantics should be documented somewhere Benjamin Franksen

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