Re: [jamboost] container.jam question

From: Vladimir Prus (ghost_at_[hidden])
Date: 2002-07-03 09:43:37

Rene Rivera wrote:

> >One other thought if that doesn't seem apporpriate for what you need... to
> >do the unwrapping I'd add another accessor like this:
> >
> >l0 = [ $(l).get-at 0 ] ;
> >ECHO $(l0[1]) ;
> >
> >A better name than "get-at" would be good though.
>
> OK, both are implemented and tested now :-)
>
> Couldn't think of a better name than get-at.

Oh... that's "get-at" I was interested in. Now, in function returing two 
lists I'd write

return [ new list [ new list $(l1) ] [ new list $(l2) ] ;

and at call site:

t = [ some-rule ] ;
x1 = [ $(t).get-at 0 ] ;
for e in $(x1) ....

Great! This is certainly better than separating the two lists with "@" and 
manually unpacking them. 

I've have two nits, though. You better document that the 'list' class uses 
1-based numbering ("mimics std::list" made me though differently), and 
document the new 'get-at' method, as well as 'at', now that is accepts 
several indices. 

BTW, I'm really thinking that $(l[0]) should result in error. Jam's checking 
for errors in variable expansion is rather sloppy.

I'm also not sure about the name "list". It causes confusion with jam's 
lists. Can we use a different name, something like "tuple", or "vector"?

- Volodya