What does “select((select(s),$|=1)[0])” do in Perl?

Question

I\'ve seen some horrific code written in Perl, but I can\'t make head nor tail of this one:

select((select(s),$|=1)[0])

It\'s in some netwo

Answer 1

In another venue, I once proposed that a more comprehensible version would be thus:

for ( select $fh ) { $| = 1; select $_ }

This preserves the compact idiom’s sole advantage that no variable needs be declared in the surrounding scope.

Or if you’re not comfortable with $_, you can write it like this:

for my $prevfh ( select $fh ) { $| = 1; select $prevfh }

The scope of $prevfh is limited to the for block. (But if you write Perl you really have no excuse to be skittish about $_.)