Re: Lua 5.2 Length Operator and tables (bug?)

[Petite Abeille <petite.abeille@...>]

On Apr 19, 2012, at 12:11 AM, Roberto Ierusalimschy wrote:

> This one does not follow the definition in the manual (where, for
> instance, non-number keys do not interfere with sequences).

yeah, that was intentional in that case… i.e. is it really a pure sequence or not...

To be more literal with the manual, one could reshuffle things a bit, something along these lines:

local function is_seq( aTable )
  for aKey in pairs( aTable ) do
    if type( aKey ) == 'number' and aKey > 0 and aKey == math.floor( aKey ) then
      if aTable[ math.max( aKey - 1, 1 ) ] == nil then
        return false
      end
    end
  end

  return true
end

local aTable = { 1, 2, 3, a = true, b = false }

print( is_seq( aTable ), #aTable )

> true	3

> But the trick 'aKey - 1' is cute :)

:P