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# =======================
# Spell: Pattern Dispatch
# =======================

# Select which methods to call based on their names.

$x = 0

class C
  def my_first_method

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# =================
# Spell: Open Class
# =================

# Modify an existing class.

class String
  def my_string_method
    "my method"
  end

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# =======================
# Spell: Object Extension
# =======================

# Define Singleton Methods by mixing a module into an object’s eigenclass.

obj = Object.new

module M
  def my_method

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# ================
# Spell: Nil Guard
# ================

# Override a reference to nil with an “or.”

x = nil
y=x || "avalue" # =>"avalue"

# For more information: http://www.pragprog.com/titles/ppmetr/metaprogramming-ruby

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# ================
# Spell: Namespace
# ================

# Define constants within a module to avoid name clashes.

module MyNamespace
  class Array
    def to_s
      "my class"

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# ======================
# Spell: Named Arguments
# ======================

# Collect method arguments into a hash to identify them by name.

def my_method(args)
  args[:arg2]
end

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# ==================
# Spell: Monkeypatch
# ==================

# Change the features of an existing class.

"abc".reverse # => "cba"

class String
  def reverse

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# ===================
# Spell: Mimic Method
# ===================

# Disguise a method as another language construct.

def BaseClass(name)
  name == "string" ? String : Object
end

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# =============================
# Spell: Lazy Instance Variable
# =============================

# Wait until the first access to initialize an instance variable.

class C
  def attribute
    @attribute = @attribute || "some value"
  end

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# ====================
# Spell: Kernel Method
# ====================

# Define a method in module Kernel to make the method available to all objects.

module Kernel
  def a_method
    "a kernel method"
  end