ra93013 has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to passing in a regular express and keep getting 

Use of uninitialized value $_ in pattern match (m//) at ./INVALID_FILE
+.pl

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Here's the option I use to pass in the expression 
--pattern '[G|M][0-1][0-9]_(GSP_|VIB_)[0-9]{12}\.log'

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$args{dir}  = $DEFAULT_DIRECTORY unless defined( $args{dir} );
$args{log} =  $DEFAULT_LOG_FILE  unless defined( $args{log} );
$args{pattern} =  $DEFAULT_PATTERN  unless defined( $args{pattern} );
$args{sendto} =  $DEFAULT_SEND_TO  unless defined( $args{sendto} );
$args{help} = 0                  unless defined( $args{help} );
die "$usage\n" if $args{help};

#create new Log::LogLite object
my $log =
  new Log::LogLite( $args{log}, $ERROR_LOG_LEVEL );
print "Pattern Submitted: $args{pattern}\n";

my $pattern_re = m/(?:$args{pattern})/o;
#my $pattern_re = $args{pattern};
print "Pattern: $pattern_re\n";

# Make sure this directory exists
if ( -d $STARTING_DIRECTORY . $args{dir} ) {

        my @files = File::Find::Rule
        ->not_name($pattern_re)
        ->in($STARTING_DIRECTORY . $args{dir});

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Replies are listed 'Best First'.
Re: Uninitialized Value $regex
by toolic (Bishop) on Jun 04, 2015 at 20:23 UTC
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Re: Uninitialized Value $regex
by kcott (Archbishop) on Jun 04, 2015 at 20:34 UTC

    G'day ra93013,

    Your problem is probably this line: 

    my $pattern_re = m/(?:$args{pattern})/o;

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    That's attempting to perform a match (m//) on $_ which isn't set ("uninitialized value $_"). See perlre.

    What you probably want is qr//, not m//. See "Regexp Quote-Like Operators".

    -- Ken

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Re: Uninitialized Value $regex
by Athanasius (Archbishop) on Jun 05, 2015 at 01:56 UTC

    Hello ra93013,

    Just a side note — this:

    $args{dir}     = $DEFAULT_DIRECTORY unless defined( $args{dir} );
$args{log}     = $DEFAULT_LOG_FILE  unless defined( $args{log} );
$args{pattern} = $DEFAULT_PATTERN   unless defined( $args{pattern} );
$args{sendto}  = $DEFAULT_SEND_TO   unless defined( $args{sendto} );
$args{help}    = 0                  unless defined( $args{help} );

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    can be written more succinctly as:

    $args{dir}     //= $DEFAULT_DIRECTORY;
$args{log}     //= $DEFAULT_LOG_FILE;
$args{pattern} //= $DEFAULT_PATTERN;
$args{sendto}  //= $DEFAULT_SEND_TO;
$args{help}    //= 0;

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    See perlop#Logical-Defined-Or.

    Hope that helps,

    Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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      can be written more succinctly ... See perlop#Logical-Defined-Or.

      Yes, but not in perl versions older than 5.10 (released Dec 2007) / 5.9 (released Jul 2007), see perl5100delta /perl590delta. Older perl versions will likely see this as a syntax error. Unfortunately, this little detail is not documented in perlop. For someone new to Perl, perlop must read like defined-or was always present in Perl.

      Alexander

      --
      Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)
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        ... not in perl versions older than 5.10 ...

        In any version of Perl, the command-line  perldoc perlop (and other docs) can be a very welcome local feature sanity check. It's saved me wasted motion more than once.

        The on-line perlop (and on-line documentation in general) is tied to the most recent Perl version and is perhaps a bit overenthusiastic in presenting new features, but even this can be dialed back to previous versions (back to 5.8, IIRC).

        Give a man a fish:  <%-(-(-(-<

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