On 03/23/10 16:08, John Baldwin wrote:
[snip - looks like a good utility, will probably use it instead of
mergemaster if it gets committed, like the idea about automated updates]
To that end, I wrote a new tool that I think does a decent job of solving
these goals.
Since the issue comes around very rarely, I assume there are not many
people who also get the shivers when they see a shell script (and then a
"posixy" /bin/sh shell script) more than a 100 lines long? :)
Wouldn't it be nice to have a "blessed" (i.e. present-in-base) script
language interpreter with a syntax that has evolved since the 1970-ies?
(with a side-glance to C that *has* evolved since the K&R style).
There was once Perl in base and even though I personally dislike Perl at
least it was a standard of sorts and guaranteed to be there if needed.
Now there are some fairly large chunks of code written in plain shell
script, like mergemaster, freebsd-update, portsup and adduser. I'm not
specifically against shell scripts but (which might just be my personal
opinion) I think they are even less maintainable in the long term than
Perl scripts. I also think the bus factor on good shell script
programmers must be pretty low.
As a possible alternative, or at least to learn about others' opinion on
the subject, I'd like to suggest Lua (http://www.lua.org/).
The reasons:
1) Very light-weight in terms of system integration. Basically, there
are one or two executables and libraries and the libraries can be
discarded if only the interpreter executable is needed and not the
ability to integrate it into C apps. No "libs directories" needed.
Written in C, designed to be easy to invoked from C (from which the
interpreter executable is built on).
This ability to integrate is important because it allows for some nifty
things like implementing "system" commands through C, e.g. a "sysctl()"
function as a wrapper for sysctl(3), or a "GEOM Class" class that wraps
control of GEOM objects.
The basic interpreter executable and the library are ~~ 150 kB each. The
/bin/sh executable is 130 kB.
2) Easy syntax, which even kind of resembles shell scripts in its flow.
Examples: http://lua-users.org/wiki/SampleCode . Unfortunately, its
error handling is not much better than plain C (no "exceptions"). It has
nice C-like formatting (e.g. "%4.2f, %d":format(3.14, 42)) and goodies
like lexical scoping, foreach and coroutines. It's default OOP
implementation is a bit specific (the "tables" and "metatables" system)
but usable.
3) MIT license. Friendly.
What would be gained? I guess what I'm trying to suggest is that a 3000
line shell script (like portsnap, as a random example) could be more
readable, easier to write and maintain were it a 3000 line Lua script.
Thoughts?
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