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| -rw-r--r-- | perl6.html.markdown | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/perl6.html.markdown b/perl6.html.markdown index b5a25a41..54feeee7 100644 --- a/perl6.html.markdown +++ b/perl6.html.markdown @@ -193,6 +193,15 @@ sub mutate($n is rw) { say "\$n is now $n !"; } +my $m = 42; +mutate $m; # $n is now 43 ! + +# This works because we are passing the container $m to mutate. If we try +# to just pass a number instead of passing a variable it won't work because +# there is no container being passed and integers are immutable by themselves: + +mutate 42; # Parameter '$n' expected a writable container, but got Int value + # If what you want a copy instead, use `is copy`. # A sub itself returns a container, which means it can be marked as rw: |