[ANN] stdlib 38 released

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[ANN] stdlib 38 released

Gary V. Vaughan
General Lua Libraries

I am happy to announce release 38 of stdlib.

stdlib's home page is at http://rrthomas.github.io/lua-stdlib

This fixes a few oversights in the transfer from getopt to optparse,
plus a few assorted long standing bugs, and quite a few speed ups in
the object system and elsewhere.  Upgrading is recommended for all
users of v35 and newer.

* Noteworthy changes in release 38 (2014-01-30) [stable]

** New features:

 - The separator parameter to `std.string.split` is now optional.  It
   now splits strings with `%s+` when no separator is specified.  The
   new implementation is faster too.

 - New `std.object.mapfields` method factors out the table field copying
   and mapping performed when cloning a table `_init` style object. This
   means you can call it from a function `_init` style object after
   collecting a table to serve as `src` to support derived objects with
   normal std.object syntax:

       Proto = Object {
         _type = "proto"
         _init = function (self, arg, ...)
           if type (arg) == "table" then
             mapfields (self, arg)
           else
             -- non-table instantiation code
           end
         end,
       }
       new = Proto (str, #str)
       Derived = proto { _type = "Derived", ... }

 - Much faster object cloning; `mapfields` is in imperative style and
   makes one pass over each table it looks at, where previous releases
   used functional style (stack frame overhead) and multiple passes over
   input tables.

   On my 2013 Macbook Air with 1.3GHz Core i5 CPU, I can now create a
   million std.objects with several assorted fields in 3.2s.  Prior to
   this release, the same process took 8.15s... and even release 34.1,
   with drastically simpler Objects (19SLOC vs over 120) took 5.45s.

 - `std.object.prototype` is now almost an order of magnitude faster
   than previous releases, taking about 20% of the time it previously
   used to return its results.

 - `io.warn` and `io.die` now integrate properly with `std.optparse`,
    provided you save the `opts` return from `parser:parse` back to the
    global namespace where they can access it:

       local OptionParser = require "std.optparse"
       local parser = OptionParser "eg 0
Usage: eg
"
       _G.arg, _G.opts = parser:parse (_G.arg)
       if not _G.opts.keep_going then
         require "std.io".warn "oh noes!"
       end

    will, when run, output to stderr: "eg: oh noes!"

** Bug fixes:

 - Much improved documentation for `optparse`, so you should be able
   to use it without reading the source code now!

 - `io.warn` and `io.die` no longer output a line-number when there is
   no file name to append it to.

 - `io.warn` and `io.die` no longer crash in the absence of a global
   `prog` table.

 - `string.split` no longer goes into an infinite loop when given an
   empty separator string.

 - Fix `getmetatable (container._functions) == getmetatable (container)`,
   which made tostring on containers misbehave, among other latent bugs.

 - `_functions` is never copied into a metatable now, finally solving
   the conflicted concerns of needing metatables to be shared between
   all objects of the same `_type` (for `__lt` to work correctly for one
   thing) and not leaving a dangling `_functions` list in the metatable
   of cloned objects, which could delete functions with matching names
   from subsequent clones.

Install it with LuaRocks, using:

    luarocks install stdlib 38

Until the rocks are available from the official repository in a few days,
you can install directly from the stdlib release branch, with:

    $ luarocks install \
    http://raw.github.com/rrthomas/lua-stdlib/release-v38/stdlib-38-1.rockspec