Module: Attic::ClassMethods

Defined in:
lib/attic/class_methods.rb

Overview

Adds a few methods for accessing the metaclass of an object. We do this with great caution since the Object class is as global as it gets in Ruby.

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#attic_variables ⇒ Object (readonly)

A list of all the attic variables defined for this class.



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# File 'lib/attic/class_methods.rb', line 10

def attic_variables
  @attic_variables
end

Instance Method Details

#attic(name = nil) ⇒ Object 



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# File 'lib/attic/class_methods.rb', line 34

def attic(name=nil)
  return singleton_class if name.nil?

  name = name.normalize

  self.attic_variables << name unless attic_variable? name

  safe_name = "@_attic_#{name}"
  instance_variable_set(safe_name, name)
rescue TypeError => e
  raise NoSingletonError, name, caller
end

#attic? ⇒ Boolean

A quick way to check if the current object already has a dedicated singleton class. We want to know this because this is where our attic variables will be stored.

Returns:

  • (Boolean) 


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# File 'lib/attic/class_methods.rb', line 15

def attic?
  return false if NoSingletonError.member? self

  # NOTE: Calling this on an object for the first time lazily
  # creates a singleton class for itself. Another way of doing
  # the same thing is to attempt defining a singleton method
  # for the object. In either case, objects that cannot have
  # cannot have a dedicated singleton class (e.g. nil, true,
  # false) will raise a TypeError. We rescue this and add the
  # object to the NoSingletonError list so we don't keep
  # trying to access its singleton class over and over.
  !singleton_class.nil?

rescue TypeError
  # Remember for next time.
  NoSingletonError.add_member self
  false
end

#attic_variable?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/attic/class_methods.rb', line 47

def attic_variable?(name)
  attic_variables.include? name.normalize
end

#attic_variable_get(name) ⇒ Object 



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# File 'lib/attic/class_methods.rb', line 58

def attic_variable_get(name)
  instance_variable_get("@_attic_#{name}")
end

#attic_variable_set(name, val) ⇒ Object 



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# File 'lib/attic/class_methods.rb', line 51

def attic_variable_set(name, val)
  unless attic_variable? name
    attic_variables << name.normalize
  end
  attic.instance_variable_set("@_attic_#{name}", val)
end