Re[2]: idea of vision of blueprint of ROADMAP of Lua core

[Gunnar Zötl <gz@...>]

Adam wrote:
ADM> Wim Couwenberg wrote:
>> -  function environments (see (1) below)

I consider those to be a meta-mechanism, allowing to do some
interesting stuff by working around the lexical scoping. Lexical 
scoping is a good_thing[tm], but as lua relies on meta-mechanisms, a
controlled way around that does help in implementing things that would
be tough to do without. The use for packages is an example.

>> -  coroutines (is there *anyone* at all who agrees??  :-)  )

ADM> They're fantastic (albeit not essential) as iterators.  Apart from
ADM> that I don't use them myself, as attractive as they are from a
ADM> 'computer science' angle.

I do use them for all sorts of things. Maybe that's a consequence of
having worked on a system with only cooperative multitasking for quite some
time, subsequently getting used to that sort of thing. They are
excessively handy for implementing lightweight multitasking within an
application.

>> -  mutable upvalues (see (2) below)

ADM> I rely on mutable closures for a few things.  I'd be sad if they

me, too.

>> -  proxy constructions

Did I miss something? I thought this proxy stuff was not part of the
language, but rather a common lua pattern.

 >> And some pluses:
 >>
 >> +  __pairs metamethod

ADM> Although this would be academically pleasing and the lack of
ADM> such a metamethod seems like an obvious hole in proxy tables
ADM> etc, in real life I seem to be living quite comfortably without.

I'd like that. A need for iterating through all values accessible
through a table that inherits from another table by means of
metatables made me implement a __pairs metamethod myself. However, the
necessary modifications to the pairs() function can be done from
within lua, so there is not really a need for this. Still, I'm all in
favor of this. 

 >> +  __settable, __gettable metamethods

ADM> Doing what exactly?

As I see it, those are meant to be counterparts to __index and
__newindex, with the difference that they intercept accesses to values
already defined in the table. With those one could get rid of the
proxy constructions. I have no opinion on that, as the proxy approach
works reasonably well for me.

have a nice day,

Gunnar