Keith Watanabe * NET 2.0

Using qw for an array ref:

[qw(item1 item2 item3 item4)];

Extracting parts of a split list

my ($item1, $item2, $item3) = (split(/s+/, $str))[2,4,5];

Converting An Array To Key-Value Pairs For A Hash

my @list = qw(key1 val1 key2 val2 key3 val3 key4 val4);
my %h = %{+{@list}};

Calling a function inside of a quoted element

Very useful when you don't want to end a quote or heredoc.

my $var = "hello @{[getName()]}n";

Checking if the correct number of parameters are passed into a subroutine

sub func {
  die unless @_ == 4;
}

Using A Lookup Table To Quickly Validate If Arguments Exist

Good for checking input.

sub validate {
  my %args = (arg1 => 1, arg2 => 1, arg3 => 1, arg4 => 1);
  return exists $args{$_};
}

Converting a subroutine's arrayref argument to an array

some_func("arg1", "arg2", ['item1', ['item2'], ['item3'], ['item4']);

sub some_func {
  my $arg1 = shift;
  my $arg2 = shift;
  my @items = @{shift()};
  print "$_n" for @items;
}

Dynamic Subroutines With Hashrefs

Nice technique when you want to create callbacks and require that the function calls are a little dynamic (for instance, when you don't know what function you might need to call).

my $h = { progname => 'some_func' };
eval "$h->{progname}('David')";

sub some_func {
  print "Hello $_[0]n";
}

Getting Local Time in Epoch Seconds

use Time::Local;
my $sec = timelocal( (localtime)[0..5] );

Efficient File Slurping

open (FILE, $dir) || die $!;
my $file = do { local $/; <FILE> };
close (FILE);

Getting All Files in A Directory

opendir( DIR, $dir ) || die $!;
my @segdirs = grep { !/^./ } readdir( DIR );
closedir( DIR );

Better Inheritance in Perl

use base(Path::MyClass);

Creating A Basic Constructor

sub new {
  my ($class, %args) = @_;
  my $self = {};
  bless $self, ref $class || $class;
}

Creating A Singleton Instance

Using the constructor from above:

sub instance {
  my $class = shift;
  strict 'refs';
  my $instance = ${"$class::_instance"};
  defined $$instance ? $$instance : ( $$instance = $class->new( @_ ) );
}