Re: Unnecessary New Closures

[roberto@... (Roberto Ierusalimschy)]

> I'm curious about a problem I encountered with this:
> 
> table.sort(sometable, function(a, b) return a[1] < b[1] end);
> 
> If this is executed repeatedly this creates a new closure every time.
> Because, as I understand it, this function is compiled as a prototype
> with no upvalues, why is a new closure created every time? Seems
> unnecessary, let alone inefficient. Would it not be possible for the
> lua compiler to just get the reference to the function (closure) and
> pass it?

Unfortunately not :(  The compiler has no way to know whether the
closure is "escaping" through 'table.sort' (e.g., being stored in
global variables), and each new closure may have its own independent
environment.

-- Roberto