Re: [screen-devel] alias support for GNU Screen

[Micah Cowan]

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Steve Kemp wrote:
>   I've recently put together a few new features and updates
>  for GNU Screen, in a (transient?) fork called tscreen[0].  This
>  is primarily because I've always had the belief that GNU Screen
>  was not being actively developed - but also because there are
>  things that I personally would like to see added, changed, or
>  dropped.

Hi Steve!

I had the opportunity to look tscreen over yesterday (mainly, just
reading the FAQ and feature list), when Tony Bernard pointed it out to
the list yesterday. I'm guessing that's probably also how you came to
post here, from queries generated from that post. :)

You're not wrong about active development. Screen development has been
pretty much languishing for the last couple of years. It has recently
picked up the pace; I recently joined as co-maintainer, and Sadrul Habib
Chowdhury has recently joined development, making prodigious efforts in
implementing bugfixes and small features.

But from the beginning, I made it clear that my limited free time, and
priority of focus on GNU Wget, would mostly mean I'd be limited to
administrative roles; managing the bug tracker and project tools more
than active development. Meanwhile, Sadrul's pace has been limited
recently by the demands of educational institutions. ;)

...in short, development _has_ picked up. But it's still struggling, and
it's probably open to debate whether it's "active". :)

Nevertheless, development is taking place, and we're open to patch
suggestions and such.

>   One of the most interesting new features is the ability to
>  define aliases.  In my current implementation there are two
>  kinds of aliases:
> 
>     1.  Mere synonyms.
>     2.  Constant calls to other functions with a list of arguments.

AFAICT, (1) is a subset of (2)? Unless you mean that you would be unable
to follow on those arguments with additional arguments.

>   In terms of implementation the code is pretty straightforward, and
>  some of the actual details show through.  We maintain a global linked
>  list of aliases.

A hash or self-balancing tree could be more scalable, of course.

I thought I remembered seeing something about a limit of 20 to the total
number of aliases yesterday, but I don't see that any more, and the code
doesn't show that. Am I crazy, or was that there yesterday? :)

BTW, GNU Screen now has tilde expansion as well, but only for one
command (I forget which one). The logic, IIRC, is currently inline to
that function, rather than farmed out for use by other functions.

At the moment we're in feature freeze, preparing the sources for
eventual release. Probably in a couple of days I'll set up a new branch
(or perhaps a separate repository) to hold changes targeted for after
the release. William Pursell has contributed a number of patches to
bring in the use of autoconf; that would go in there as well.

Bringing in the use of autoconf also means we could start taking
advantage of gnulib facilities, which already has several useful mapping
structures (trees and hashes) we could avail ourselves of.

- --
Micah J. Cowan
Programmer, musician, typesetting enthusiast, gamer.
GNU Maintainer: wget, screen, teseq
http://micah.cowan.name/
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