Re: [ANN] Lua 5.4.0 (work1) now available

[Rodrigo Azevedo <rodrigoams@...>]

Warning: I'm just rambling here!

2018-03-13 16:43 GMT-03:00 Roberto Ierusalimschy <roberto@inf.puc-rio.br>:

> for k,v in pairs(t) do print(k, v) end
1       nil
2       nil
3       nil
4       nil

I think we're going to need a considerable amount of time to understand these "nils" everywhere. But, could the (new) undef syntax

 

  t[i] = undef     -- remove a key from a table 

  t[i] == undef    -- test whether a table has a key
  t[i] ~= undef    -- test whether a table has a key

Any other use of 'undef' gives a syntax error.

be tied to the removal of the key/values, if possible (not referenced by something)? maybe, to put the key/value in a high priority (newest always) generation (from the new generational gc), such that we could have a more deterministic memory management. Then, the (new) syntax could be extended to non-tables

a = function(x) return x end

a = undef

as a hint for the gc.

--

Rodrigo Azevedo Moreira da Silva