DSLs in Ruby through metaprogramming

DSL-uri in Ruby prin metaprogramming

DSL • Domain Speciﬁc Language • subroutine (Assembler) • procedure (Fortran, Pascal, C) • objects, messages (C++, Java) • DSLs (Lisp, Smalltalk, Ruby)

Classes vs Objects • Object Oriented programming • Ruby object model • Class => objects • metaclass?

Objects State + Behavior => Object

State + Behavior @name: “Fred” fred say_name() attack(player)

Methods @name: “Fred” Monster fred say_name() method table attack(player)

Calling methods @name: “Fred” Monster fred say_name() class attack(player) fred.say_name()

self • current object • default receiver • @ivar

Metaprogramming Changing self

Changing self • self = blah • object.method • class • Module#class_eval • Object#instance_eval

object.method(param) • self <= object • look up method in self.class • invoke method

value: “fred” String monster capitalize() class

Inheritance Object super: class: frozen?() value: “fred” String super: monster class: class capitalize()

Object super: class: frozen?() String super: class: capitalize() anonymous super: value: “fred” class: monster class: say_name()

Object super: Ghost class: class: • metaclass frozen?() • eigenclass String • singleton class super: class: capitalize() anonymous super: value: “fred” class: monster class: say_name()

Ruby Classes Objects

Ruby Classes

Changing self

Anonymous classes

Class methods There is no spoon...

Class methods

Object Class super: super: class: class: frozen?() new() anonymous super: super: class: class: Monster methods... say_name()

Changing self

Module#class_eval

Object#instance_eval

Module#class_eval

module NiftyDSL

One more thing...

DSLs in Ruby through metaprogramming

by Cluj.rb on Nov 12, 2010

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