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Roberto Ierusalimschy kirjoitti 17.2.2009 kello 19:01:


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:


And all of that can easily be done using token modifiers.

Case solved?  :)

(this must be the longest surviving thread in lua-list history)

-asko





 do local finalized f, g = ...
   ...
 end

But the do-end is not part of the syntax.

-- Roberto