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Re^2: Perl oddities (s/// doesn't DWIM in map)

by Roy Johnson (Monsignor)
on Mar 01, 2005 at 20:18 UTC ( #435597=note: print w/replies, xml ) Need Help??

in reply to Re: Perl oddities (s/// doesn't DWIM in map)
in thread Perl oddities

A related oddity is that map can modify its input, in addition to generating output. That leads to the pitfall of
my @new = map { s/foo/bar/; $_ } @old; # @old is modified along with @new! # should be my @new = map { s/foo/bar/; $_ } map {$_} @old;
If map couldn't modify its input, the whole "map in a void context" debate might never have happened. for would be used for modifying input, map would be used for generating new output. Of course, it's a tradeoff, giving up some liberty for safety.

Caution: Contents may have been coded under pressure.

Replies are listed 'Best First'.
Re^3: Perl oddities (s/// doesn't DWIM in map)
by ikegami (Pope) on Mar 01, 2005 at 22:59 UTC
    my @new = map { local $_ = $_; s/foo/bar/; $_ } @old; also avoids the problem. Probably faster than using two maps, too. Still ugly, unfortunately.
Re^3: Perl oddities (s/// doesn't DWIM in map)
by Aristotle (Chancellor) on Nov 19, 2005 at 09:02 UTC

    I write that as

    s/foo/bar/ for my @new = @old;

    Makeshifts last the longest.

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