Apocalypse 12

by Larry Wall
April 16, 2004

Editor's Note: this Apocalypse is out of date and remains here for historic reasons. See Synopsis 12 for the latest information.

• Some of the Problems with Perl 5 OO
  • A little too orthogonal
  • Not quite orthogonal enough
  • Forced non-encapsulation
  • A little too minimal
  • Too much keyword reuse
  • Too difficult to capture metadata
  • Inside-out interfaces
  • Not enough convention
  • Wrong conventions
  • Everything possible, but difficult
• Perl 5 Non-Problems
  • Generating class by running code at compile time
  • There are many roads to polymorphism
  • People using a class shouldn't have to think hard
• Trust in Convention, But Keep Your Powder Dry
• An Easy Example
• Classes
  • Declaration of classes
    • Class traits
  • Use of classes
  • Class name semantics
  • Private classes
• Methods
  • Declaration of methods
  • Use of methods
    • The dot notation
    • The "indirect object" notation
    • Calling private methods
• Class Methods
  • Class invocant
  • Class|object invocant
• Submethods
• Attributes
  • Declaration of attributes
  • Use of attributes
  • Default values

Related Reading Perl 6 Essentials By Allison Randal, Dan Sugalski, Leopold Tötsch Table of Contents Index Sample Chapter Read Online--Safari Search this book on Safari:   Only This Book All of Safari Code Fragments only

• Class Attributes
• Object Construction
  • The default constructor
    • The default cloner
  • CREATE
  • BUILDALL
  • BUILD
  • Eliminating redundancy in constructor calls
• Object Deconstruction
  • DESTROYALL
  • DESTROY
• Dispatch Mechanisms
  • Single dispatch
  • Calling superclasses, and not-so-superclasses
  • Parallel dispatch
  • WALKCLASS and WALKMETH caching
• Multiple Dispatch
  • Declaration of multiple dispatch routines
    • multi sub
    • multi sub * (tradition multimethods)
    • multi method
    • multi submethod
    • multi rule
    • multi submethod BUILD
    • multi method constructors
  • Calling via multiple dispatch
    • Multiple dispatch semantics
    • Single dispatch semantics
    • Indirect objects
  • Meaning of "next METHOD"
  • Making fiends, er, friends
• Overloading
  • Binary ops
• Class Composition with Roles
  • Declaration of roles
    • Parametric types
    • Interfaces
    • Private interfaces
    • Encapsulated attributes
    • Encapsulated private attributes
    • Encapsulated delegation
    • Encapsulated inheritance
  • Use of roles at compile time
    • Conflict resolution
  • Use of roles at runtime (mixins)
• Traits
• Delegation
  • Wildcard delegation
  • Renaming delegated methods
  • Delegation without an attribute
  • Delegation of handlers
  • Hash-based redispatch
  • Relationship to roles
  • Anonymous delegation for ISA emulation
• Types and Subtypes
• Enums
• Open vs. Closed Classes
• Interface Consistency
• Collections of Classes
  • In classes
  • In modules
• Versioning
  • Version declarations
  • Use of version and author wildcards
• Introspection
• Other Non-OO Decisions
  • Exportation
  • The gather/take construct
  • :foo() adverbs
  • Special quoting of identifiers inside curlies going away
  • Vector operators renamed back to "hyper" operators
  • Unary hyper operators now use one quote rather than two
  • $thumb.twiddle no longer requires parens when interpolated
  • The =:= identity operator
  • New grammatical categories
  • Assignment to state variable declaration now does "first" semantics
  • The length() function is gone
  • String positions
  • The new "&" separator in Regexen
• Optional Mandatory Cross-Disciplinary Joke for People Tired of Dogs
• Future Directions
• References...er, Reference...

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