Re: Perl::Critic says don't modify $_ in list functions and other things

Here's the problem with your approach:

my @a = qw( a b c );
my @b = map { $_ = uc($_); $_ } @a;
say "@a";  # A B C     <-- You clobbered @a!!!
say "@b";  # A B C
[download]

Use List::MoreUtils's apply instead of map.

my @a = qw( a b c );
my @b = apply { $_ = uc($_);} @a;
say "@a";  # a b c
say "@b";  # A B C
[download]

Comment on Re: Perl::Critic says don't modify $_ in list functions and other things Select or Download Code

Replies are listed 'Best First'.
Re^2: Perl::Critic says don't modify $_ in list functions and other things by Your Mother (Archbishop) on Jul 09, 2020 at 08:40 UTC
I hope I’m not being obtuse and about to embarrass myself but… `# Why this? my @b = apply { $_ = uc($_);} @a; # Instead of this, or a more verbose version of it? my @b = map uc, @a;` [download]	[reply] [d/l]
Re^3: Perl::Critic says don't modify $_ in list functions and other things by AnomalousMonk (Archbishop) on Jul 09, 2020 at 14:34 UTC
I'll take the liberty of answering for ikegami and guess that `my @b = apply { $_ = uc($_);} @a;` is just a quick example of the use of `apply` put together to be consistent with the preceding code `my @b = map { $_ = uc($_); $_ } @a;` which was itself just a quick example put together to demonstrate a particular problem. I'd be very surprised if ikegami suggested it \| either for production code. Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]
Re^3: Perl::Critic says don't modify $_ in list functions and other things by ikegami (Patriarch) on Jul 12, 2020 at 14:40 UTC
Of course, but the OP isn't actually using `$_ = uc($_)`, and your solution wouldn't help the OP. `$_ = uc($_)` is just a placeholder for a large block of code that possibly modifies `$_`.	[reply] [d/l] [select]