From: Trans <transfire@...>
Date: 2005-10-02T05:26:46+09:00
Subject: Re: ideas for an RCR: variable locality


Eric Mahurin wrote:
> --- Trans <transfire@gmail.com> wrote:
>
> > And a way to share vars from the above scope specifically:
> >
> >   z = lambda [
> >      share :x
> >   ]
>
> I was hoping to not bring in any type of variable declaration
> syntax (like perl's my/our/local) into play.

I undertsnad but then you start getting into more syntax hacks like {
|x,y; z|...  }. That;s even worse. At least the above is simple and
clear.

> I was also
> thinking that this type of block would have no write access to
> the variables in the surrounding scope (block would need to
> return data instead).

Yes, I am too. You'd have to use #share to open a variable up.

> You could give read-only access when the
> block accesses one of its variables not yet assigned to (get
> the value from the containing scope):
>
> x = 1+2
> z = lambda {{
>   # becomes equivalent to y = (x=3) when compiled
>   y = x
> }}

That's cool. So you'd really only need a way to "send it out". hmmm..
#share cuold work for that, it's would then be more like #return
instead of a declaration.

> Hopefully this could be done in such a way so that once that
> block is created it doesn't need access to its containing scope
> anymore and you don't have to worry about the block preventing
> GCing stuff in that scope (as you do with normal blocks).
> Although you wouldn't be able to get the Binding of this type
> of block, you would still want to have a way to get the file,
> line, (and column?) of where the block was created.
>
> > Since hash and block share literal deliminators, it only
> > seems fair
> > that array do the same ;-)
>
> But [] is also an operator and {} is not.  To use [] for a
> different type of block, you'd have to differentiate between it
> and the [] operator based on spacing - which I think is bad.

That's true. But hey let's open up {} as an operator too. I'm not
afraid of the spacebar! Besides I never put spaces before my []
operators anyway, and really who does?

T.