X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=moose-class%2Fslides%2Findex.html;h=6c0e0b0cdf7d566016517118d200fe90af3307e5;hb=f28e0a12c2f3f8d2380386202bd2d35fee215086;hp=ea20e486eae08452ebe2f580efbbcf9b052caf49;hpb=bd857054d0772af174d9ca4c76ac138dde5eb976;p=gitmo%2Fmoose-presentations.git
diff --git a/moose-class/slides/index.html b/moose-class/slides/index.html
index ea20e48..6c0e0b0 100644
--- a/moose-class/slides/index.html
+++ b/moose-class/slides/index.html
@@ -40,7 +40,7 @@ img#me05 {top: 43px;left: 36px;}
@@ -208,7 +219,7 @@ use Moose;
- AKA advice
- "Before foo(), do this first"
- - "Do this after foo()
+ - "Do this after foo()"
- "Put this code around foo()"
@@ -235,7 +246,10 @@ after 'foo'
my @return =
$self->$real_foo( @_, bar => 42 );
- return ( @return, 'modify return values' );
+ return (
+ @return,
+ 'modify return values'
+ );
};
@@ -262,7 +276,7 @@ has weight => (
);
# kaboom
-Person->new( weight => 'fat' );
+Person->new( weight => 'heavy' );
@@ -284,11 +298,11 @@ use Moose;
has blog_uri => (
is => 'rw',
isa => 'URI',
- handles => { 'blog_hostname' => 'host' },
+ handles => { 'blog_host' => 'host' },
);
-$person->blog_hostname;
-# really calls $person->blog_uri->host
+$person->blog_host;
+# really calls $person->blog_uri->host
@@ -829,6 +843,16 @@ has last_name => (
);
+
+
More Why Moose?
+
+
+ - Less code == fewer bugs
+ - Moose is well-tested, test your own code, not Moose
+ - Focus on what, not how
+
+
Part 1: Moose Classes
@@ -869,8 +893,8 @@ use Moose;
BUILDARGS
- - Takes
@_, returns a hash reference of attribute names/value
- - Accepts a hash or hashref; throws otherwise
+ - Processes
new's @_, returns a hash reference of attribute name/value pairs
+ - Accepts a hash or hashref; errors otherwise
- Provide your own for other cases
- Always call
$class->SUPER::BUILDARGS(@_) as a fallback!
@@ -885,10 +909,9 @@ use Moose;
sub BUILDARGS {
my $class = shift;
- if ( @_ == 1 && ! ref $_[0] ) {
+ if ( @_ == 1 && ! ref $_[0] ) {
return { ssn => $_[0] };
}
-
return $class->SUPER::BUILDARGS(@_);
}
@@ -925,11 +948,37 @@ sub BUILD {
+
Object Construction a la Moose
+
+
Person->new(@_)
+
+
+ - Calls
Person->BUILDARGS(@_) to turn @_ into a hashref
+ - Blesses a reference
+ - Populates attributes based on the hashref from #1
+ - Calls
$new_object->BUILDALL($constructor_args)
+
... which calls all BUILD methods
+ - Returns the object
+
+
+
The Object is Opaque
+
+
+ - Technically it's a hash reference
+ - If you ever treat it as one you are doing it wrong!
+ - Moose probably provides a feature to do what you need
+
+
DEMOLISH
- Like
DESTROY, but Moose makes sure all DEMOLISH methods in a hierarchy are called
- Called in normal inheritance order, children to parents
+ - Never called by you, only by Perl itself
@@ -938,6 +987,8 @@ sub BUILD {
extends is sugar for declaring parent classes- Also ensures metaclass compatibility between parent and child
+ - Do not
use base
package Employee;
@@ -991,6 +1042,7 @@ extends 'LWP';
override is another method modifier- An alternative to Perl's
SUPER::
+ - Declares your intent to override a method
@@ -1002,12 +1054,13 @@ use Moose;
extends 'Person';
-override work => sub {
+override work => sub {
my $self = shift;
- die "Pay me first" unless $self->got_paid;
- super();
-};
+ die "Pay me first"
+ unless $self->got_paid;
+ super();
+};
@@ -1016,7 +1069,8 @@ use Moose;
- Mostly like
$self->SUPER::work(@_)
- But cannot change
@_!
- - Binds the parent's method at compile time
+ - Binds the parent's method correctly at compile time
+ - Parent determined by checking
Child->meta()->superclasses()
package Person;
use Moose;
-__PACKAGE__->meta->make_immutable;
+__PACKAGE__->meta->make_immutable;
@@ -1163,12 +1231,17 @@ use Moose;
Exercises
# cd exercises
-$ perl bin/prove -lv t/00-prereq.t
-Missing anything? Install it. (see tarballs/)
+# perl bin/prove -lv t/00-prereq.t
+
+# perl install-moose (if needed)
+
+## Read the instructions in t/01-classes.t
# perl bin/prove -lv t/01-classes.t
+# edit lib/Person.pm and lib/Employee.pm
+
Iterate til this passes all its tests
-
Roles Can Have State and Behavior
+
Roles - State and Behavior
package HasPermissions;
use Moose::Role;
-
# state
has access_level => ( is => 'rw' );
@@ -1199,7 +1271,8 @@ sub can_access {
my $self = shift;
my $required = shift;
- return $self->access_level >= $required;
+ return $self->access_level
+ >= $required;
}
package Person;
use Moose;
-with 'HasPermissions';
+with 'Printable';
Classes Consume Roles
-
my $person = Person->new(
- first_name => 'Kenichi',
- last_name => 'Asai',
+package Person;
+
+sub as_string { $_[0]->first_name() }
+
+...
+
+my $person = Person->new(
+ first_name => 'Kenichi',
+ last_name => 'Asai',
access_level => 42,
);
-print $person->full_name
- . ' has '
- . $person->can_access(42)
- ? 'great power'
- : 'little power';
+$person->print();
@@ -1269,7 +1344,9 @@ print $person->full_name
package Person;
use Moose;
-with 'Printable';
+
with 'Printable';
+
+sub as_string { $_[0]->first_name() }
@@ -1280,6 +1357,8 @@ use Moose;
with 'Printable';
+sub as_string { $_[0]->first_name() }
+
has has_been_printed => ( is => 'rw' );
sub print {
@@ -1300,7 +1379,7 @@ sub print {
# or ...
-if ( Person->meta->does('Printable') ) { ... }
+Person->meta->does_role('Printable')
@@ -1360,69 +1439,17 @@ use Moose;
-
Method Aliasing
-
-
package FragileDancer;
-use Moose;
-
-with 'IsFragile' =>
- { alias =>
- { break => 'break_bone' } },
- 'CanBreakdance' =>
- { alias =>
- { break => 'break_it_down' } };
-
-
- - Renames the roles' methods
- - Still conflicts, need to
exclude as well
-
-
-
Method Exclusion
-
-
package FragileDancer;
-use Moose;
-
-with 'IsFragile' =>
- { alias =>
- { break => 'break_bone' },
- exclude => 'break' },
- 'CanBreakdance' =>
- { alias =>
- { break => 'break_dance' },
- exclude => 'break' };
-
-
And then ...
-
-
package FragileDancer;
-use Moose;
-
-sub break {
- my $self = shift;
-
- $self->break_dance;
- if ( rand(1) < 0.5 ) {
- $self->break_bone;
- }
-}
-
-
Still Full of Fail
+
Conflicts Are a Smell
- - Roles are also about semantics!
- - We've fulfilled the letter and lost the spirit
+ - Roles are about semantics!
- Roles have a meaning
- - Think twice before blindly aliasing and excluding methods!
+ - Method name conflicts smell like bad design
-
Hot Role-on-Role Action
+
Roles With Roles
package Comparable;
use Moose::Role;
@@ -1431,7 +1458,7 @@ requires 'compare';
-
Hot Role-on-Role Action
+
Roles With Roles
package TestsEquality;
use Moose::Role;
@@ -1440,7 +1467,7 @@ with 'Comparable';
sub is_equal {
my $self = shift;
- return $self->compare(@_) == 0;
+ return $self->compare(@_) == 0;
}
@@ -1478,11 +1505,11 @@ with 'HasSubProcess';
Delayed Conflict
-
package StateOfTexas;
+ package SysadminAssassin;
with 'Killer';
- StateOfTexas must implement its own executeSysadminAssassin must implement its own execute- But loading the
Killer role by itself does not cause an error
@@ -1510,7 +1537,7 @@ use Moose;
with 'HasSize';
-has size => ( is => 'ro' );
+has size => ( is => 'ro' );
@@ -1524,7 +1551,7 @@ requires 'size';
package Shirt;
use Moose;
-has size => ( is => 'ro' );
+has size => ( is => 'ro' );
with 'HasSize';
@@ -1546,9 +1573,9 @@ with 'HasSize';
package Comparison;
use Moose;
-has [ 'left', 'right' ] => (
- is => 'ro',
- does => 'Comparable',
+has [ 'left', 'right' ] => (
+ is => 'ro',
+ does => 'Comparable',
);
@@ -1563,8 +1590,9 @@ has [ 'left', 'right' ] => (
use Moose::Util qw( apply_all_roles );
-my $fragile_person = Person->new( ... );
-apply_all_roles( $fragile_person, 'IsFragile' );
+my $fragile_person = Person->new( ... );
+apply_all_roles( $fragile_person,
+ 'IsFragile' );
- Does not change the
Person class
@@ -1636,8 +1664,6 @@ requires 'compare';
Real Examples
- - Column and ColumnAlias both do ColumnLike
- - ColumnLike things can be used in certain parts of queries
- All queries do HasWhereClause
- Select does Comparable and Selectable (for subselects)
- A where clause requires its components to do Comparable
@@ -1718,8 +1744,8 @@ has first_name => (
required => 1,
);
-Person->new( first_name => undef ); # ok
-Person->new(); # kaboom
+Person->new( first_name => undef ); # ok
+Person->new(); # kaboom
@@ -1727,7 +1753,7 @@ Person->new(); # kaboom
- Attributes can have defaults
- - Simple non-referecne scalars (number, string)
+ - Simple non-reference scalars (number, string)
- Subroutine reference
- A builder method
@@ -1768,7 +1794,7 @@ has bank => (
-
Default as a Subroutine Reference
+
Subroutine Reference Default
- Called as a method on the object
@@ -1812,7 +1838,8 @@ has packages => (
use Moose;
my $highlander_bank =
- Bank->new( name => 'Spire FCU' );
+ Bank->new(
+ name => 'Clan MacLeod Trust' );
has bank => (
is => 'rw',
@@ -1824,7 +1851,8 @@ has bank => (
Builder
- - A method name which returns the default
+ - A method name
+ - When called, this method returns the default value
-
Lazy, Good for Nothing Attributes
+
Lazy, Good for Nothin' Attributes
- Normally, defaults are generated during object construction
@@ -1897,7 +1926,8 @@ has bank => (
use Moose;
has shoe_size => (
- is => 'ro',
+ is => 'ro',
+ required => 1,
);
has shoes => (
is => 'ro',
lazy => 1,
- builder => '_build_shoes',
+ builder => '_build_shoes',
);
sub _build_shoes {
my $self = shift;
return Shoes->new(
- size => $_[0]->shoe_size );
+ size => $self->shoe_size );
}
@@ -1980,16 +2010,16 @@ has account => (
package Person;
use Moose;
-has shoe_size => (
+has shoe_size => (
is => 'ro',
init_arg => 'foot_size',
);
-Person->new( shoe_size => 13 );
+Person->new( shoe_size => 13 );
my $person =
- Person->new( foot_size => 13 );
-print $person->shoe_size;
+ Person->new( foot_size => 13 );
+print $person->shoe_size;
@@ -1998,12 +2028,12 @@ print $person->shoe_size;
package Person;
use Moose;
-has shoes => (
+has shoes => (
is => 'ro',
init_arg => undef,
);
-Person->new( shoes => Shoes->new );
+Person->new(
shoes => Shoes->new );
@@ -2097,7 +2127,7 @@ use Moose;
has first_name => (
reader => 'get_first_name',
- writer => 'set_first_name,
+ writer => 'set_first_name',
);
@@ -2113,7 +2143,7 @@ has first_name => (
);
- - Can also mix-and-match
+ - Can also mix-and-match
is and explicit names
@@ -2150,6 +2180,13 @@ has first_name => (
Attributes can have a default or builder
Attributes with a default or builder can be lazy
Attributes can have a clearer and/or predicate
+
+
+
+
+
Basic Attributes Summary
+
+
- An attribute's constructor name can be changed with
init_arg
- A subclass can alter its parents' attributes
- Attribute accessor names can be changed
@@ -2164,7 +2201,8 @@ has first_name => (
Exercises
# cd exercises
-# perl bin/prove -lv t/03-basic-attributes.t
+# perl bin/prove -lv \
+ t/03-basic-attributes.t
Iterate til this passes all its tests
- Apply to an existing method
- - ... from a parent class, the current class, or a role
+ - ... that comes from a parent class, the current class, or a role
- Roles can provide modifiers that are applied at composition time
-
What is a Method Modifier
+
What Are Method Modifiers For?
- "Inject" behavior
- Add behavior to generated methods (accessors, delegations)
- - Provide roles which modify existing behavior
+ - Added from a role, can modify existing behavior
-
Other Uses Example
+
More Modifier Examples
has password => (
is => 'rw',
clearer => 'clear_password',
);
-
has hashed_password => (
is => 'ro',
builder => '_build_hashed_password',
clearer => '_clear_hashed_password',
);
-
after clear_password => sub {
my $self = shift;
$self->_clear_hashed_password;
@@ -2317,8 +2354,7 @@ after clear_password => sub {
$self->$orig(
$self->_munge_insert(@_) );
- $new_user->_assign_uri;
-
+ $new_user->_assign_uri;
return $new_user;
};
Modifier Order
- - Before runs order from last to first
+ - Before runs in order from last to first
- After runs in order from first to last
- Around runs in order from last to first
@@ -2382,6 +2418,7 @@ around run => sub {
- Inverted
super
- From least- to most-specific
+ - Like Mason's autohandler feature
- Grandparent to parent to child
- Not allowed in roles
@@ -2390,19 +2427,21 @@ around run => sub {
Augment and Inner
-
package Document;
+ package Document;
sub xml { '<doc>' . inner() . '</doc>' }
package Report;
extends 'Document';
-
-augment xml => { title() . inner() . summary() };
+augment xml =>
+ sub { my $self = shift;
+ $self->title() . inner() . $self->summary() };
package TPSReport;
extends 'Report';
-
-augment xml => { tps_xml() . inner() };
+augment xml =>
+ sub { my $self = shift;
+ $self->tps_xml() . inner() };
@@ -2481,7 +2520,8 @@ extends 'Report';
Exercises
# cd exercises
-# perl bin/prove -lv t/04-method-modifiers.t
+# perl bin/prove -lv \
+ t/04-method-modifiers.t
Iterate til this passes all its tests
Part 5: Types
-
-
Part 6: Advanced Attributes
-
-
-
Weak References
+
A Type System for Perl
- - A weak reference lets you avoid circular references
- - Weak references do not increase the reference count
+ - Sort of ...
+ - Variables are not typed
+ - Attributes can have types
+ - MooseX modules let you define method signatures
-
Circular Reference Illustrated
-
-
my $foo = {};
-my $bar = { foo => $foo };
-$foo->{bar} = $bar;
+
Components of a Moose Type
- - Neither
$foo nor $bar go out of scope
- (until the program exits)
+ - A type is a name and a constraint
+ - Types have a hierarchy
+ - Constraints are cumulative from parents
+ - Types can have associated coercions
-
Weakening Circular References
+
Built-in Type Hierarchy
-
use Scalar::Util qw( weaken );
+
+Any
+Item
+ Bool
+ Maybe[`a]
+ Undef
+ Defined
+ Value
+ Str
+ Num
+ Int
+ ClassName
+ RoleName
+
+
+
Built-in Type Hierarchy
-
- - When
$bar goes out of scope, $foo->{bar} becomes undef
-
+
+(Item)
+ (Defined)
+ (Value)
+ Ref
+ ScalarRef
+ ArrayRef[`a]
+ HashRef[`a]
+ CodeRef
+ RegexpRef
+ GlobRef
+ FileHandle
+ Object
+
-
Circular References in Attributes
+
Bool
-
package Person;
-use Moose;
+ True
+ 1
-has name => ( is => 'ro' );
-has friend => ( is => 'rw' );
+ False
+ 0
+'0'
+''
+undef
-my $alice = Person->new( name => 'Alice' );
-my $bob = Person->new( name => 'Bob' );
-$bob->friend($alice);
-$alice->friend($bob);
+
+ - Like Perl's
if ($foo)
+
-
The Fix
+
Value (and subtypes)
-
package Person;
-use Moose;
+
+ Value is true when ! ref $thingValue and Str are effectively the same, but Str is more expressiveNum is true when a $scalar looks like a number- An overloaded object which numifies does not pass the
Num constraint!
+ - Perl 5's overloading is hopelessly broken
+
+
+
ClassName and RoleName
-my $alice = Person->new( name => 'Alice' );
-my $bob = Person->new( name => 'Bob' );
-$bob->friend($alice);
-$alice->friend($bob);
+
+ - A string with a package name
+ - The package must already be loaded
+
-
Under the Hood
+
Parameterizable Types
- - A
weak_ref attribute calls weaken ...
+ - What does
ArrayRef[`a] mean?
+ s/`a/Int/ (or Str or ...)- When you use it you can write ...
- - during object construction
- - when the attribute is set via a writer
+ ArrayRef (== ArrayRef[Item])ArrayRef[Str]ArrayRef[MyTypeName]ArrayRef[HashRef[Maybe[Int]]]
-
Triggers
+
Maybe[`a]
- - A code reference run after an attribute is set
- - Like an
after modifier, but makes intentions clearer
+ - Maybe means either the named type or
undef
+ Maybe[Int] accepts integers or undef
+
Gross
+
+
Type Union
-
after salary_level => {
- my $self = shift;
- return unless @_;
- $self->clear_salary;
-};
+
+ - This or that (or that or ...)
+ Int | ArrayRef[Int]- But use a coercion instead when possible
+ - Or use a
role_type, duck_type, or anything not a union
+ - A union is often a code smell
+
-
Use a Trigger Instead
+
Making Your Own Types
-
Cleaner
+
use Moose::Util::TypeConstraints;
- has salary_level => (
- is => 'rw',
- trigger => sub { $_[0]->clear_salary },
+subtype 'PositiveInt',
+ as 'Int',
+ where { $_ > 0 },
+ message
+ { "The value you provided ($_)"
+ . " was not a positive int." };
+
+has size => (
+ is => 'ro',
+ isa => 'PositiveInt',
);
-
Delegation
+
Automatic Types
- - Attributes can be objects
- - Delegation transparently calls methods on those objects
+ - Moose creates a type for every Moose class and role
+ - Unknown names are assumed to be classes
-
Delegation Examples
+
Automatic Types
-
package Person;
+ package Employee;
+use Moose;
-has lungs => (
- is => 'ro',
- isa => 'Lungs',
- handles => [ 'inhale', 'exhale' ],
-);
+has manager => (
+ is => 'rw',
+ isa => 'Employee',
+);
-
- - Creates
$person->inhale and ->exhale methods
- - Internally calls
$person->lungs->inhale
-
+has start_date => (
+ is => 'ro',
+ isa => 'DateTime',
+);
-
Why Delegation?
+
Subtype Shortcuts - class_type
-
- - Reduce the number of classes exposed
- - Re-arrange class internals -
- turn a method into an attribute with delegation
- - Provide convenenience methods
-
-
use Moose::Util::TypeConstraints;
+class_type 'DateTime';
-
-
Moose's handles Parameter
+
-
- - Accepts many arguments ...
-
- - Array reference - list of methods to delegate as-is
- - Hash reference - map of method names
- - Regex - delegates all matching methods
- - Role name - delegates all methods in the role
- - Sub reference - does something complicated ;)
-
-
-
-
subtype 'DateTime',
+ as 'Object',
+ where { $_->isa('DateTime') },
+ message { ... };
+
-
Array Reference
+
Subtype Shortcuts - role_type
-
- - Takes each method name and creates a simple delegation from the delegating class to the delegatee attribute
-
+
use Moose::Util::TypeConstraints;
+role_type 'Printable';
+
+
+
+
subtype 'Printable',
+ as 'Object',
+ where
+ { Moose::Util::does_role(
+ $_, 'Printable' ) },
+ message { ... };
-
Hash Reference
+
Subtype Shortcuts - duck_type
-
- - Mapping of names in the delegating class to the delegatee class
-
+
use Moose::Util::TypeConstraints;
+duck_type Car => qw( run break_down );
-
package Person;
-use Moose;
+
-has account => (
- is => 'ro',
- isa => 'BankAccount',
- handles => {
- receive_money => 'deposit',
- give_money => 'withdraw',
- },
-);
+
subtype 'Car',
+ as 'Object',
+ where { all { $_->can($_) }
+ qw( run break_down ) },
+ message { ... };
-
Hash Reference Detailed
+
Subtype Shortcuts - enum
-
handles => {
- receive_money => 'deposit',
- give_money => 'withdraw',
- },
+
use Moose::Util::TypeConstraints;
+enum Color => qw( red blue green );
-
- $person->receive_money = $person->account->deposit$person->give_money = $person->account->withdraw
+
+
+
my %ok = map { $_ => 1 }
+ qw( red blue green );
+
+subtype 'Color'
+ as 'Str',
+ where { $ok{$_} },
+ message { ... };
-
Regex
+
Anonymous Subtypes
package Person;
-use Moose;
-has name => (
- is => 'ro',
- isa => 'Name',
- handles => qr/.*/,
+my $posint =
+ subtype as 'Int', where { $_ > 0 };
+
+has size => (
+ is => 'ro',
+ isa => $posint,
);
- - Creates a delegation for every method in the Name class
- - Excludes
meta and methods inherited from Moose::Object
+ - Shortcuts have anonymous forms as well
-
Role Name
+
Coercions
-
package Auditor;
-use Moose::Role;
+ use Moose::Util::TypeConstraints;
-sub record_change { ... }
-sub change_history { ... }
+subtype 'UCStr',
+ as 'Str',
+ where { ! /[a-z]/ };
+
+
Coercions
+
+
coerce 'UCStr',
+ from 'Str',
+ via { uc };
+
+has shouty_name => (
+ is => 'ro',
+ isa => 'UCStr',
+ coerce => 1,
+);
+
+
Coercion Examples
+
+
subtype 'My::DateTime',
+ as class_type 'DateTime';
+
+coerce 'My::DateTime',
+ from 'HashRef',
+ via { DateTime->new( %{$_} ) };
+
+coerce 'My::DateTime',
+ from 'Int',
+ via { DateTime->from_epoch(
+ epoch => $_ ) };
+
+
+ - Use coercion to inflate a value
+
+
+
Coercion Examples
+
+
coerce 'ArrayRef[Int]',
+ from 'Int',
+ via { [ $_ ] };
+
+
+ - Instead of union -
Int | ArrayRef[Int]
+
+
+
Using Types with Attributes
+
+
package Person;
+
+has height => (
+ is => 'rw',
+ isa => 'Num',
+);
+
+has favorite_numbers => (
+ is => 'rw',
+ isa => 'ArrayRef[Int]',
+ coerce => 1,
+);
+
+
More Droppings
+
+
+ Moose::Util::TypeConstraints also needs cleanup
+
+
package Person;
+
+use Moose;
+use Moose::Util::TypeConstraints;
+
+subtype ...;
+
+no Moose;
+no Moose::Util::TypeConstraints;
+
+
Questions So Far?
+
+
+
+
Exercises
+
+
# cd exercises
+# perl bin/prove -lv t/05-types.t
+
+Iterate til this passes all its tests
+
+
Typed Methods (Low-tech)
+
+
package Person;
+use MooseX::Params::Validate qw( validated_list );
+
+sub work {
+ my $self = shift;
+ my ( $tasks, $can_rest ) =
+ validated_list(
+ \@_,
+ tasks =>
+ { isa => 'ArrayRef[Task]',
+ coerce => 1 },
+ can_rest =>
+ { isa => 'Bool',
+ default => 0 },
+ );
+ ...
+}
+
+
Typed Methods (High-tech)
+
+
package Person;
+
+use MooseX::Method::Signatures;
+
+method work ( ArrayRef[Task] :$tasks,
+ Bool :$can_rest = 0 ) {
+ my $self = shift;
+
+ ...
+}
+
+
Digression: The Type Registry
+
+
+ - Types are actually
Moose::Meta::TypeConstraints objects
+ - Stored in an interpreter-global registry mapping names to objects
+
+
+
Danger!
+
+
+ - Coercions are attached to type objects
+ - Therefore also global
+ - Name conflicts between modules!
+ - Coercion conflicts between modules!
+
+
+
Namespace Fix
+
+
+ - Use some sort of pseudo-namespacing scheme
+ - Never coerce directly to a class name, or to built-in types
+
+
+
Namespace Fix
+
+
use Moose::Util::TypeConstraints;
+subtype 'MyApp::Type::DateTime',
+ as 'DateTime';
+
+coerce 'MyApp::Type::DateTime',
+ from 'HashRef',
+ via { DateTime->new( %{$_} ) }
+
+has creation_date => (
+ is => 'ro',
+ isa => 'MyApp::Type::DateTime',
+ coerce => 1,
+);
+
+
Namespace Fix
+
+
subtype 'MyApp::Type::ArrayOfInt',
+ as 'ArrayRef[Int]';
+
+coerce 'MyApp::Type::ArrayOfInt',
+ from 'Int',
+ via { [ $_ ] };
+
+
Namespace Fix Pros and Cons
+
+
+ - Relatively simple
+ - Already built into Moose
+ - Conflates type and module namespaces
+ - Type names are strings, so typos are easy to make and may be hard to find
+
+
+
MooseX::Types
+
+
package MyApp::Types;
+
+use MooseX::Types
+ -declare => [ qw( ArrayOfInt ) ];
+use MooseX::Types::Moose
+ qw( ArrayRef Int );
+
+subtype ArrayOfInt,
+ as ArrayRef[Int];
+
+coerce ArrayOfInt
+ from Int,
+ via { [ $_ ] };
+
+
MooseX::Types
+
+
package MyApp::Account;
+
+use MyApp::Types qw( ArrayOfInt );
+
+has transaction_history => (
+ is => 'rw',
+ isa => ArrayOfInt,
+);
+
+
MooseX::Types
+
+
+ - Type names are exported functions, catches typos early
+ - Types must be pre-declared
+ - Types are stored with namespaces internally, but you use short names
+ - Import existing Moose types as functions from
MooseX::Types::Moose
+ - Still need string names for things like
ArrayRef['Email::Address']
+
+
+
MooseX::Types Pros and Cons
+
+
+ - Catches typos at compile time
+ - Automatic namespacing
+ - One more thing to install and learn
+ - Every name is typed twice (declared and then defined)
+ - Still stuck with strings when referring to class or role names
+ - Coercion gotcha from earlier still applies to types exported from
MooseX::Types::Moose
+
+
+
Recommendation
+
+
+ - Use
MooseX::Types
+ - Compile time error catching and automatic namespacing are huge wins
+ - Docs from
Moose::Util::TypeConstraints are 98% compatible with MooseX::Types anyway
+ - A function exported by a type library works wherever a type name would
+
+
+
Questions?
+
+
+
+
Part 6: Advanced Attributes
+
+
+
+
Weak References
+
+
+ - A weak reference lets you avoid circular references
+ - Weak references do not increase the reference count
+
+
+
Circular Reference Illustrated
+
+
my $foo = {};
+my $bar = { foo => $foo };
+$foo->{bar} = $bar;
+
+
+ - Neither
$foo nor $bar go out of scope
+ (until the program exits)
+
+
+
Weakening Circular References
+
+
use Scalar::Util qw( weaken );
+
+my $foo = {};
+my $bar = { foo => $foo };
+$foo->{bar} = $bar;
+weaken $foo->{bar}
+
+
+ - When
$bar goes out of scope, $foo->{bar} becomes undef
+
+
+
Circular References in Attributes
+
+
package Person;
+use Moose;
+
+has name => ( is => 'ro' );
+has friend => ( is => 'rw' );
+
+my $alice = Person->new( name => 'Alice' );
+my $bob = Person->new( name => 'Bob' );
+$bob->friend($alice);
+$alice->friend($bob);
+
+
The Fix
+
+
package Person;
+use Moose;
+
+has name => ( is => 'ro' );
+has friend => ( is => 'rw',
+ weak_ref => 1 );
+
+my $alice = Person->new( name => 'Alice' );
+my $bob = Person->new( name => 'Bob' );
+$bob->friend($alice);
+$alice->friend($bob);
+
+
Under the Hood
+
+
+ - A
weak_ref attribute calls weaken ...
+
+ - during object construction
+ - when the attribute is set via a writer
+
+
+
+
+
Triggers
+
+
+ - A code reference run after an attribute is set
+ - Like an
after modifier, but makes intentions clearer
+
+
+
Gross
+
+
after salary_level => {
+ my $self = shift;
+ return unless @_;
+ $self->clear_salary;
+};
+
+
Use a Trigger Instead
+
+
Cleaner
+
+
has salary_level => (
+ is => 'rw',
+ trigger =>
+ sub { $_[0]->clear_salary },
+);
+
+
Trigger Arguments
+
+
+ $self$new_value$old_value - if one exists
+
+
Delegation
+
+
+ - Attributes can be objects
+ - Delegation transparently calls methods on those objects
+
+
+
Delegation Examples
+
+
package Person;
+
+has lungs => (
+ is => 'ro',
+ isa => 'Lungs',
+ handles => [ 'inhale', 'exhale' ],
+);
+
+
+ - Creates
$person->inhale and ->exhale methods
+ - Internally calls
$person->lungs->inhale
+
+
+
Why Delegation?
+
+
+ - Reduce the number of classes exposed
+ - Re-arrange class internals -
+ turn a method into an attribute with delegation
+ - Provide convenenience methods
+
+
+
Moose's handles Parameter
+
+
+ - Accepts many arguments ...
+
+ - Array reference - list of methods to delegate as-is
+ - Hash reference - map of method names
+ - Regex - delegates all matching methods
+ - Role name - delegates all methods in the role
+ - Sub reference - does something complicated ;)
+
+
+
+
+
Array Reference
+
+
+ - 1-to-1 mapping
+ - Takes each method name and creates a simple delegation from the delegating class to the delegatee attribute
+
+
+
Hash Reference
+
+
+ - Mapping of names in the delegating class to the delegatee class
+
+
+
package Person;
+use Moose;
+has account => (
+ is => 'ro',
+ isa => 'BankAccount',
+ handles => {
+ receive_money => 'deposit',
+ give_money => 'withdraw',
+ },
+);
+
+
Hash Reference Detailed
+
+
handles => {
+ receive_money => 'deposit',
+ give_money => 'withdraw',
+ },
+
+
+ $person->receive_money = $person->account->deposit$person->give_money = $person->account->withdraw
+
+
Regex
+
+
package Person;
+use Moose;
+
+has name => (
+ is => 'ro',
+ isa => 'Name',
+ handles => qr/.*/,
+);
+
+
+ - Creates a delegation for every method in the Name class
+ - Excludes
meta and methods inherited from Moose::Object
+
+
+
Role Name
+
+
package Auditor;
+use Moose::Role;
+sub record_change { ... }
+sub change_history { ... }
+
+package Account;
+use Moose;
has history => (
is => 'ro',
@@ -2748,6 +3340,120 @@ has history => (
+
Native Delegation
+
+
+ - Delegate to unblessed Perl types
+ - Scalar, array or hash ref, etc
+ - Treat Perl types as objects
+ - Still uses
handles
+ - Pretend that native Perl types have methods
+
+
+
Native Delegation - Array(Ref)
+
+
+ - Methods include:
+
+ pushshiftelements - returns all elementscountis_empty- quite a few more
+
+
+
+
+
Native Delegation - Array(Ref)
+
+
package Person;
+use Moose;
+has _favorite_numbers => (
+ traits => [ 'Array' ],
+ is => 'bare',
+ isa => 'ArrayRef[Int]',
+ default => sub { [] },
+ init_arg => undef,
+ handles =>
+ { favorite_numbers => 'elements',
+ add_favorite_number => 'push',
+ },
+);
+
+
Native Delegation - Array(Ref)
+
+
my $person = Person->new();
+
+$person->add_favorite_number(7);
+$person->add_favorite_number(42);
+
+print "$_\n"
+ for $person->favorite_numbers;
+
+# 7
+# 42
+
+
Native Delegation
+
+
+ - Native types are ...
+
+ - Number -
add, mul, ...
+ - String -
append, chop, ...
+ - Counter -
inc, dec, ...
+ - Bool -
set, toggle, ...
+ - Hash -
get, set, ...
+ - Array - already saw it
+ - Code -
execute and execute_method
+
+
+
+
+
Curried Delegation
+
+
+ - A delegation with some preset arguments
+ - Works with object or Native delegation
+
+
+
Curried Delegation
+
+
package Person;
+use Moose;
+has account => (
+ is => 'ro',
+ isa => 'BankAccount',
+ handles => {
+ receive_100 =>
+ [ 'deposit', 100 ]
+ give_100 =>
+ [ 'withdraw', 100 ]
+ },
+);
+
+
Curried Delegation
+
+
$person->receive_100;
+# really is
+$person->account->deposit(100);
+
Traits and Metaclasses
@@ -2772,7 +3478,7 @@ has history => (
Traits and Metaclasses
- - Can add/alter/remove attribute parameter (from
has)
+ - Can add/alter/remove an attribute parameter (from
has)
- Can change behavior of created attribute
@@ -2790,7 +3496,6 @@ has ssn => (
isa => 'Str',
label => 'Social Security Number',
);
-
print Person->meta
->get_attribute('ssn')->label;
@@ -2809,7 +3514,6 @@ has ssn => (
isa => 'Str',
label => 'Social Security Number',
);
-
print Person->meta
->get_attribute('ssn')->label;
@@ -2832,33 +3536,261 @@ print Person->meta
Use weak_ref to avoid circular references
Use trigger to do an action post-attribute write
Use delegations to hide "internal" objects
+ Use native delegations to treat Perl types as objects
Traits and metaclasses let you extend Moose's core attribute features
-
Questions?
-
-
-
Exercises
# cd exercises
-# perl bin/prove -lv t/06-advanced-attributes.t
+# perl bin/prove -lv \
+ t/06-advanced-attributes.t
Iterate til this passes all its tests
-
-
Part 7: Introspection
+
+
CYOA
+
+
+ If there is time, keep going ...
+
+
+
+ Otherwise, jump to slide 269 ...
+
-
Part 8: A Tour of MooseX
+ Bonus: A Brief Tour of MooseX
+
+
+
+
Notable MX Modules on CPAN
+
+
+ - Not comprehensive
+ - 177 MooseX distributions on CPAN as of 09/21/2010
+ - Some of them are crap
+
+
+
+
+
Already Mentioned Several
+
+
+ MooseX::NonMoose - best solution for subclassing non-Moose parentsMooseX::Declare - real Perl 5 OOMooseX::FollowPBP and MooseX::SemiAffordanceAccessorMooseX::Params::Validate and MooseX::Method::SignaturesMooseX::Types
+
+
+
+
MooseX::Declare
+
+
use MooseX::Declare;
+use 5.10.0; # for say
+
+class Person {
+ has greeting =>
+ ( is => 'ro', isa => 'Str' );
+
+ method speak {
+ say $self->greeting;
+ }
+}
+
+
+
+
MooseX::Declare
+
+
+ - Still experimental-ish, but seeing more and more use
+ - Not a source filter!
+ - Hooks into the Perl parser rather than filtering all your code
+ - But not supported by
PPI, perltidy, etc. (yet?)
+
+
+
+
+
MooseX::StrictConstructor
+
+
+ - By default, unknown constructor arguments are ignored
+ - MX::StrictConstructor turns these into an error
+
+
+
+
+
MooseX::StrictConstructor
+
+
package Person;
+
+use Moose;
+use MooseX::StrictConstructor;
+
+has name => ( is => 'ro' );
+
+Person->new
+ ( nane => 'Ringo Shiina' ); # kaboom
+
+
+
+
MooseX::Traits
+
+
+ - Combines object construction and role application
+ - Makes it easy to create one-off customized objects
+
+
+
+
+
MooseX::Traits
+
+
package MyApp::Thingy;
+use Moose;
+
+with 'MooseX::Traits';
+
+my $thing =
+ MyApp::Thingy->new_with_traits
+ ( traits => [ 'Foo', 'Bar' ],
+ size => 42 );
+
+
+
+
MooseX::Getopt
+
+
+ - Makes command-line interface programs easy!
+ - Construct an object from CLI arguments
+
+
+
+
+
MooseX::Getopt
+
+
package App::CLI;
+use Moose;
+
+with 'MooseX::Getopt';
+
+has file =>
+ ( is => 'ro', required => 1 );
+has filters =>
+ ( is => 'ro', isa => 'ArrayRef[Str]' );
+
+sub run { ... }
+
+
+
+
MooseX::Getopt
+
+
+ - Then call it like this:
+
+
+
#!/usr/bin/perl
+
+use App::CLI;
+
+App::CLI->new_with_options()->run();
+
+
$ myapp-cli \
+ --file foo \
+ --filters compress \
+ --filters sanitize
+
+
+
+
MooseX::Clone
+
+
package Person;
+
+use Moose;
+with 'MooseX::Clone';
+
+my $person = Person->new;
+my $clone = $person->clone;
+
+
+
+
MooseX::NonMoose
+
+
+ - Highly recommended for subclassing non-Moose parents
+ - Gets all the little annoying details right
+
+
+
+
+
MooseX::Role::Parameterized
+
+
package HasCollection;
+use MooseX::Role::Parameterized;
+parameter type => ( isa => 'Str',
+ default => 'Item' );
+role {
+ my $p = shift;
+
+ my $type =
+ 'ArrayRef[' . $p->type() . ']';
+ has collection =>
+ ( is => 'ro',
+ isa => $type );
+};
+
+
+
+
MooseX::Role::Parameterized
+
+
package Person;
+
+use Moose;
+with HasCollection => { type => 'Int' };
+
+
+
+
Questions?
+
+
+
+
Moose-using Modules
+
+
+ For further reading, a few modules which use Moose ...
+
+
+
+
+
+
-
Part 9: Writing Moose Extensions
+ The End
+ 