Actually, that code isn't doing what you think. One way to see is to just add "use strict" to it. You'll get:
Global symbol "$x" requires explicit package name
A more fun way is:
sub foo {
my $x= $_[0] if ! defined $x;
print "(@_):", ++$x, " ";
undef $x if @_ && shift;
}
foo($_) for( 0,0,5,4,3,0,5,0,4,0,3 );
print $/, $x= 10, $/;
foo($_) for( 0,0,5,4,3,0,5,0,4,0,3 );
print $/;
which produces:
(0):1 (0):1 (5):6 (4):5 (3):4 (0):1 (5):6 (0):1 (4):5 (0):1 (3):4
10
(0):1 (0):2 (5):3 (4):1 (3):1 (0):1 (5):2 (0):1 (4):2 (0):1 (3):2
The $x in "if !defined $x" is the global $main::x because
my variables can't be used until after the
end of the statement in which they were declared.
So your code is always initializing the lexical $x in your subroutine because you have never defined the global $main::x that you are checking against.
-
tye
(but my friends call me "Tye")
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