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Postings from April 2011
Consider:
=head3 Non-destructive substitution
The substitution (C<s///>) and transliteration
(C<y///>) operators now support an C</r> option that
copies the input variable, carries out the substitution on
the copy, and returns the result. The original remains unmodified.
my $old = "cat";
my $new = $old =~ s/cat/dog/r;
# $old is "cat" and $new is "dog"
But consider that this has been perfectly normal with different grouping:
NEW: $new = old =~ s/cat/dog/r;
OLD: ($new = $old) =~ s/cat/dog/;
And so has this, actually:
NEW: @new = map { s/cat/dog/r } @old;
OLD: for (@new = @old) { s/cat/dog/ }
It would seem better to give an example of something that wasn't so
trivially done before. For example, this prints "Enlisted" from "unlost":
print ucfirst "unlost" =~ y/aeiouy/yuoiea/r =~ s/$/ed/r;
--tom
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