Re: Second class nil? Strong and weak nils in tables?

[PA <petite.abeille@...>]

On Oct 27, 2007, at 23:50, Duck wrote:

[This topic should be promoted to meta-thread status as it simply 
refuses to die :P]

> That's exactly my point. That code is the clear and natural way to use 
> {...}, but it also breaks whenever any of the args in ... is nil.

For reference purpose, the canonical way to enumerate variable length 
arguments in 5.1 is with 'select':

for anIndex = 1, select( '#', ... ) do
    local aValue = select( anIndex, ... )
    -- do something with value
end

> Converting a list into a table is lossy, precisely because you can't 
> have explicit nils in tables.

Table size needs to be recorded explicitly in that case:

local someArguments = { n = select( '#', ... ), ... }

for anIndex = 1, someArguments.n do
    local aValue = someArguments[ anIndex ]
    -- do something with value
end

unpack( someArguments, 1, someArguments.n )

Which looks suspiciously like the pre-5.1 way of doing things as Rici 
Lake humorously pointed out:

<Digression>
If this seems like a reversion to Lua 4 and the old 'n'
field, so be it.... you could use a different key if you liked
</Digression>

http://lua-users.org/lists/lua-l/2007-06/msg00452.html