Re: Type Metatables for Table and Userdata - Powerpatch

[Dirk Laurie <dirk.laurie@...>]

2012/12/6 Andrew Starks <andrew.starks@trms.com>:

> I'm struggling with the problem that this is solving. What thing does it do
> that lua does not already do?

I'm hooking onto this remark, but I'm taking into account later posts that
say in effect "first take a look at what `for k,v, in next,t` can do before
demanding semantic changes in `for k,v in t do`".

A table is the only data structure in Lua. It has to do everything for
everybody. But needs differ.

The availability of both pairs and ipairs is a symptom of the fact
that one man's iterator is another man's shmiterator. There are
many other conceivable iterators for one and the same table,
e.g. all pairs _except_ those hit by ipairs, keys only, values only.
Rooting for the reinstatement of `for k,v in t do` in effect says
"the situation in which there is only one right way to traverse
a table is common enough to justify syntax sugar for it".