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- Subject: Re: state of the Lua nation on resource cleanup
- From: John Belmonte <john@...>
- Date: Tue, 17 Feb 2009 20:59:16 -0500
On Tue, Feb 17, 2009 at 12:01 PM, Roberto Ierusalimschy
>> > What's wrong with Joonas Pihlaja's proposal?
>> > do with f, g = io.open("src.txt","r"), io.open("dst.txt",w")
>> > for l in f:lines() do
>> > ...
>> > g:write(l)
>> > end
>> > end
>> > (Probably with a different syntax...)
>> I've been using it in metalua for a while (syntax "with <var_list> =
>> <values_list> do <scoped_statements> end") for some time, with the
>> convention that the protected variables must have a ":close()" disposal
>> method, and I'm pretty happy with it.
> I do not see why the need for the <scoped_statements>. It would be
> simpler to add only a new form of locals. Something like
> local finalized f, g = ...
> that calls ":close()" (or __gc??) when it goes out of scope. Of course,
> you can (should?) use a conventional do-end around it:
> do local finalized f, g = ...
> But the do-end is not part of the syntax.
I've already enumerated all these options in the original post and
described some trade-offs (point #5). I'm not so concerned about what
syntax is used, just that a solution gets into the language.
...or my answer could be that I already proposed that two years ago
and got ignored :)