in reply to Confused by a couple of idioms

"o|c|out=s" => \my $csv creates $csv at this point as a lexical variable and assigns a reference to it to (I assume) this hash value.

$csv and $xls = $csv; tests if $csv is true, and if it is, assigns its value to $xls.

It's the same as: $csv && ( $xls = $csv );.

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Re^2: Confused by a couple of idioms
by ateague (Monk) on Feb 21, 2019 at 22:27 UTC

    Here is the code in question in context; it is part of Getopt::Long

    use Getopt::Long qw( :config bundling noignorecase passthrough );
GetOptions (
    "help|?"    => sub { usage 0; },
    "V|version" => sub { print "$cmd [$VERSION]\n"; exit 0; },
    "man"       => sub { exec "pod2man $0 | nroff -man"; },
    "info"      => sub { require Pod::Usage;
                         Pod::Usage::pod2usage (VERBOSE => 2);
                         exit;
                         },
 
    "o|c|out=s" => \my $csv,
    "i|s|in=s"  => \my $xls,
    "f|force!"  => \my $opt_f,
 
    "A|all!"    => \my $opt_a,
    "N|no-pfx!" => \my $opt_N,
    ) or usage 1;

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    It is assigning the value from the -o, -c, or --out switches to the $csv lexical variable that it is defining in-line

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Re^2: Confused by a couple of idioms
by nysus (Parson) on Feb 21, 2019 at 23:54 UTC

    Yeah, I just never knew you could put a backslash before "my." I've never seen that. Is that basically shortcut for: 

    my $csv;

%hash = { key => $csv };

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    $PM = "Perl Monk's";
    $MCF = "Most Clueless Friar Abbot Bishop Pontiff Deacon Curate Priest Vicar";
    $nysus = $PM . ' ' . $MCF;
    Click here if you love Perl Monks

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