Re: Inclusion of lpack in Lua? Suggestions for Lua's unpack()

[David Manura <dm.lua@...>]

On Sun, Jan 17, 2010 at 1:37 AM, Majic wrote:
> Perl's pack() and unpack() functions for dissecting binary
> streams.  ... but it is my opinion that something like this will
> become necessary with the inclusion of bitlib in 5.2.

These are very useful functions.  It's a fundamental need to
(en/de)code some binary stream.  The need also comes up in FFI [1] and
was also mentioned in a similar way in LuaJIT.  I wouldn't go as far
to call them "necessary" as in impossible not to have since you can
write them in Lua, and some programs using bitops might not use
packing/unpacking (but do most?).  One would also need to decide which
encodings to support (128-bit floats?)

[1] http://alien.luaforge.net/

> I also wanted to suggest that instead of relying on the length operator, it
> could return all values in general.  Something like:
>   local sample = { ['key'] = 'value', 'value2' } unpack(sample) would
>   yield: return 'value', 'value2'

Keys are unordered, unless you impose an ordering like next or
__pairs.  It's not clear to me that such an implementation of unpack
would return elements in the order I would need them in.  What is the
use case for this?