Re: LuaJIT2 bug: 'mytable[mystring] or 0' wrongly 0

[Jim Pryor <lists+lua@...>]

On Mon, Nov 16, 2009 at 10:29:10PM -0200, Roberto Ierusalimschy wrote:
> > > BTW: You'll get better performance if you don't fill the rd[]
> > > array backwards. It degrades into a hash table in this case.
> > 
> > That probably also applies to plain Lua.
> 
> It degrades into a hash while it is being filled, but when it finishes
> I think the result is always a pure array. (I proved this some time
> ago, but I am not sure the algorithm is still exactly the same.)


Do you mean if I do this:

    tbl = {[2]=20,[3]=30,[4]=40}
    -- now tbl is all hash
    
    tbl[1]=10

At the last step an array part big enough to hold 4 elements will be
created, and all the pairs formerly in the hash part will be removed
from there and copied over to the array part?

-- 
Profjim
profjim@jimpryor.net