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Sat Dec 22 00:30:00 2012

Slides for the talk beginning-perl at lpw-2009

BEGINning
Perl

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mst

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perl(1)

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Beginning
Perl

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BEGINning
Perl

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BEGIN
CHECK
INIT
END

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BEGIN

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lasts until
your main.pl
starts to run

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use

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  BEGIN {
    require Module;
    Module->import;
  }

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  use strict;
  use warnings;

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  $^H
  ${^WARNING_BITS}

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  strict->import

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affects
compilation
scope

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  use Moose;

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prototypes

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  sub (&)

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Try::Tiny

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  try {
    ...
  } catch {
    ...
  };

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Moose::Util::TypeConstraints

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  type MyType
    => where { $_ =~ /mine/ };

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sub binding

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  foo()

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binds at
compile
time

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... so
you can
delete it

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namespace::clean

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  use Scalar::Util qw(blessed);
  use namespace::clean;

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  delete ${Module::}{blessed};

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CORE::GLOBAL

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autodie

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Fatal

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  open my $fh, '<', $file
    or die "Argh: $!";

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*CORE::GLOBAL::open

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  use autodie;
  open my $fh, '<', $file;

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use feature

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  given ($foo) {
    when (/bar/) {
      ...
    }
    default {
      ...
    }
  }

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  use 5.012; # strict!

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source
filter

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Switch.pm

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ARGH

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Smart::Comments

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NOT
ARGH

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 ### Debug output here

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Devel::Declare

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screw with
the parser

-

  method foo ($bar) {
    warn $bar;
  }

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TryCatch

-

  try {
    ...
  } catch (FileException $e) {
    ...
  }

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PerlX::MethodCallWithBlock

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  $obj->iterate(3) {
    warn "hello! ".$_[0];
  };

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autobox

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screw with
the semantics

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  [ 1, 2, 3 ]->each(sub {
    print "$_\n";
  });

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  @stuff->grep(sub {
    $_ % 2
  });

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accessor
building

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  *{"${pkg}::${name}"}
    = sub { ... };

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closures
eval

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Moose

-

metaclass

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metaclass
metamethod
metaattribute

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  has foo => (
    is => 'rw',
    trigger => sub { ... }
  );

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compiled
accessors

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pay only
for what
you use

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MooseX::Declare

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  class MyClass is MyBaseClass
    with MyRole {

      method my_method (Str $arg) {

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pluggable
design

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CatalystX::Declare

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  sub update :Chained('load_object')
    :PathPart('edit') :CaptureArgs(0) {

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  controller MyController {

    action update under 'load_object' as 'edit' {

-

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IPW

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Web::Simple

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prototypes
sub binding
CORE::GLOBAL

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Mike
Whitaker

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Devel::Declare

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Dante's
Inferno

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used to
being
satan

-

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what if I
don't use
any of them?

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not
using
code

-

but
first

-

let's shave
a yak

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  foo(..., sub { ... }, ...);

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how do I
cache that?

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B::Deparse

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closures

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Data::Dump::Streamer

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closures

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record
refs

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  local *Data::Dumper::_dump

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Data::Visitor

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  $save{refaddr($ref)}
    = '$input->[1]';

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dump with
filter

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  if (exists $save{refaddr($ref)}) {

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  {
    string => "foo",
    code => undef
  }

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  $structure->{code}
    = $input->[1];

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  my $__captures = {
    "\$attr_trigger" => \undef,
    "\$attr_name" => \"foo"
  };

  # fixup code for external references
  $__captures->{"\$attr_trigger"} = \((\@_)->[6]);

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  my $orig = MyModule->can('name');
  *MyModule::name = sub {
    <track refs in @_ here>
    $orig->(@_);
  };

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  local *MyExporter::import = sub {
    $orig_import->(@_);
    <override imports here>
  };

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  name('foo', sub { $bar }, 'baz');

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  has foo => (
    is => 'rw',
    trigger => sub { ... }
  );

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shaving
a moose

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wrap Moose::import

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warp Moose::import

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track calls
to has

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repeated
string eval
is SLOW

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BUT

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Class::MOP::Method::Generated
sub _eval_closure {

-

  my ($self, $lexicals, $code) = @_;

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PadWalker
closed_over

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save captures
save source

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One1.txt
dump1.txt

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make_immutable

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  sub MooseX::Antlers::ImmutableHackFor
    ::NameOfClass::make_immutable {

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  *meta = sub { $hack_class }

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 *has = sub { ($replay_has{$_[0]}->(@_) }

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there's
a pattern
here

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  use MooseX::Antlers::StealImport
    Moose => {
      meta => sub { $hack_class },
      has => sub { ($replay_has{$_[0]}->(@_) }
    };

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  no MooseX::Antlers::StealImport
    qw(Moose);

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One2.txt
dump2.txt

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metaclass

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what if
we need
it later?

-

don't pay
for what you
don't use

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__DATA__

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  no warnings 'redefine';
  *One::meta = sub {
    my $meta_code = do {
      local $/; <One::DATA>
    };
    local $@;
    my $meta = eval $meta_code;
    die $@ if $@;
    $meta;
  };

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dump3.txt

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end
result?

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Data::Dump::Streamer

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  foreach my $method (qw(new DESTROY foo)) {
    is(
      $compiled_src{$method}, $orig_src{$method},
      "${method} restored ok"
    );
  }

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character
identical

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same for the
metaclass

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One3.txt

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  io('One.pmc') <
    MooseX::Antlers::Compiler
      ->load_with_compiler('One')
      ->compiled_source

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net
gain?

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  $ time perl t/lib/One.pm 
  real    0m1.213s
  $ time perl -Ilib One.pmc
  real    0m0.089s

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questions?

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  git://git.shadowcat.co.uk
       /gitmo
       /MooseX-Antlers.git

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#moose
#moose-dev

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thank
you