Trey Harris trey-at-lopsa.org |Perl 6| wrote:
In 5.10, given seems to copy its argument, whereas for aliases it. (I
haven't looked at the code; maybe it's COW-ing it.) If you add a
C<say "Value is now $foo";> to the end of the below program, and then
change C<for> to C<given> and run the program with values of $foo less
than 500 or greater than 1000, you'll see the difference: with C<for>,
the value remains changed after the block, with C<given> it is not.
I do not believe this distinction is true in Perl 6, is it?
Trey
Correct. In S04,
"
If you rely on C<$_> as the implicit parameter to a block,
then C<$_> is considered read/write by default. That is,
the construct:
for @foo {...}
is actually short for:
for @foo <-> $_ {...}
so you can modify the current list element in that case.
"
Are you saying that Perl 5.10 has given/when ? Or is that the CPAN
module that basically rewrites the entire file?
--John
