Re: table.getn in Lua 5.0.2/3

[Stefan Brantschen <sbr@...>]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 14 Sep 2006, at 17:37, David Given wrote:

> As soon as you start setting numeric elements to nil, or even if you
> start setting them beyond the end of the array, then it's not a valid
> array any more and all these things start producing undefined  
> behaviour.

All true. But as long as you know what you're doing, arrays with  
holes can be handled just well (cf. also PIL II, p16). For example, a  
table representing breakpoints in a file in a debugger, like

breakpoints = {some_file_name = {2 = true, 25 = true}, other_file = ..}

is just handy. Of course, you need to be aware that certain operators  
and functions don't work correctly. But sometimes you _want_ to set a  
numerically indexed table element to nil, and not use table.remove()  
- -- see the above example.

Lua 5.1 also has new function table.maxn() that works with arrays  
with holes.

With regards
- - Stefan


-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.3 (Darwin)

iQEVAwUBRQo35TqiXtt/m8NcAQIFrwgAqO8fgrkgLyYmwHiXPc1UOdu+afn89V89
fpDUSXasvFA6relYtK07fySTLC3DldmKWadGfNNK1tcpFggIJTc5R+zzuy4Ys+0V
Rh1fCQmaYF9+c993kjVcJZkUxVG7de80eH9dqK9MlgJ5bqh9rcCiSVn2rgXwqzJH
EblFu09WBEsEWHgCI3bNTuGMyB/mqD3uusCPnhpMqkBN8AXoIYEqrNOyDC0c5sIw
Hq+xc9Qoq/YBokgY5rOoLJ2vK4AqYbBmIm5Pgpf79UNnFAFcSyxjmm2u9zTxC2Ce
n7tCflZRhquOXTl9q6dWTmIuyLBecq5QaqlAX7n0D/KdPKqZGZ9McQ==
=Jo97
-----END PGP SIGNATURE-----