Class: Puppet::Pops::Adaptable::Adapter Private

Inherits:
Object
  • Object
show all
Defined in:
lib/puppet/pops/adaptable.rb

Overview

This class is part of a private API. You should avoid using this class if possible, as it may be removed or be changed in the future.

Base class for an Adapter.

A typical adapter just defines some accessors.

A more advanced adapter may need to setup the adapter based on the object it is adapting.

Examples:

Making Duck adaptable

class Duck
  include Puppet::Pops::Adaptable
end

Giving a Duck a nick name

class NickNameAdapter < Puppet::Pops::Adaptable::Adapter
  attr_accessor :nick_name
end
d = Duck.new
NickNameAdapter.adapt(d).nick_name = "Daffy"
NickNameAdapter.get(d).nick_name # => "Daffy"

Giving a Duck a more elaborate nick name

class NickNameAdapter < Puppet::Pops::Adaptable::Adapter
  attr_accessor :nick_name, :object
  def initialize o
    @object = o
    @nick_name = "Yo"
  end
  def nick_name
    "#{@nick_name}, the #{o.class.name}"
  end
  def NickNameAdapter.create_adapter(o)
    x = new o
    x
  end
end
d = Duck.new
n = NickNameAdapter.adapt(d)
n.nick_name # => "Yo, the Duck"
n.nick_name = "Daffy"
n.nick_name # => "Daffy, the Duck"

Using a block to set values

NickNameAdapter.adapt(o) { |a| a.nick_name = "Buddy!" }
NickNameAdapter.adapt(o) { |a, o| a.nick_name = "You're the best #{o.class.name} I met."}

Class Method Summary collapse

Class Method Details

.adapt(o) ⇒ Adapter<self> .adapt(o, {|adapter| block}) ⇒ Adapter<self> .adapt(o, {|adapter, o| block}) ⇒ Adapter<self>

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns an existing adapter for the given object, or creates a new adapter if the object has not been adapted, or the adapter has been cleared.

Examples:

Using a block to set values

NickNameAdapter.adapt(o) { |a| a.nick_name = "Buddy!" }
NickNameAdapter.adapt(o) { |a, o| a.nick_name = "Your the best #{o.class.name} I met."}

Yield Parameters:

  • adapter (Adapter<self>)

    the created adapter

  • o (Adaptable)

    optional, the given adaptable

Raises:

  • (ArgumentError)

    if the given object o is not adaptable


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# File 'lib/puppet/pops/adaptable.rb', line 95

def self.adapt(o, &block)
  attr_name = self_attr_name
  value = o.instance_variable_get(attr_name) if o.instance_variable_defined?(attr_name)
  adapter = value || associate_adapter(create_adapter(o), o)
  if block_given?
    case block.arity
      when 1
        block.call(adapter)
      else
        block.call(adapter, o)
    end
  end
  adapter
end

.adapt_new(o) ⇒ Adapter<self> .adapt_new(o, {|adapter| block}) ⇒ Adapter<self> .adapt_new(o, {|adapter, o| block}) ⇒ Adapter<self>

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Creates a new adapter, associates it with the given object and returns the adapter.

This is used when a fresh adapter is wanted instead of possible returning an existing adapter as in the case of adapt.

Examples:

Using a block to set values

NickNameAdapter.adapt_new(o) { |a| a.nick_name = "Buddy!" }
NickNameAdapter.adapt_new(o) { |a, o| a.nick_name = "Your the best #{o.class.name} I met."}

Yield Parameters:

  • adapter (Adapter<self>)

    the created adapter

  • o (Adaptable)

    optional, the given adaptable

Raises:

  • (ArgumentError)

    if the given object o is not adaptable


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# File 'lib/puppet/pops/adaptable.rb', line 127

def self.adapt_new(o, &block)
  adapter = associate_adapter(create_adapter(o), o)
  if block_given?
    case block.arity
    when 1
      block.call(adapter)
    else
      block.call(adapter, o)
    end
  end
  adapter
end

.associate_adapter(adapter, o) ⇒ adapter

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Associates the given adapter with the given target object


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# File 'lib/puppet/pops/adaptable.rb', line 170

def self.associate_adapter(adapter, o)
  o.instance_variable_set(self_attr_name, adapter)
  adapter
end

.clear(o) ⇒ Adapter?

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Clears the adapter set in the given object o. Returns any set adapter or nil.


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# File 'lib/puppet/pops/adaptable.rb', line 145

def self.clear(o)
  attr_name = self_attr_name
  if o.instance_variable_defined?(attr_name)
    o.send(:remove_instance_variable, attr_name)
  else
    nil
  end
end

.create_adapter(o) ⇒ Adapter<self>

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

This base version creates an instance of the class (i.e. an instance of the concrete subclass of Adapter). A Specialization may want to create an adapter instance specialized for the given target object.


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# File 'lib/puppet/pops/adaptable.rb', line 161

def self.create_adapter(o)
  new
end

.get(o) ⇒ Adapter<self>?

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns an existing adapter for the given object, or nil, if the object is not adapted.

Raises:

  • (ArgumentError)

    if the object is not adaptable


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# File 'lib/puppet/pops/adaptable.rb', line 70

def self.get(o)
  attr_name = self_attr_name
  if o.instance_variable_defined?(attr_name)
    o.instance_variable_get(attr_name)
  else
    nil
  end
end

.instance_var_name(name) ⇒ String

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns a suitable instance variable name given a class name. The returned string is the fully qualified name of a class with '::' replaced by '_' since '::' is not allowed in an instance variable name.


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# File 'lib/puppet/pops/adaptable.rb', line 182

def self.instance_var_name(name)
  name.split(DOUBLE_COLON).join(USCORE)
end

.self_attr_nameString

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns a suitable instance variable name for the name of this instance. The name is created by calling Adapter#instance_var_name and then cached.


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# File 'lib/puppet/pops/adaptable.rb', line 197

def self.self_attr_name
  @attr_name_sym ||= :"@#{instance_var_name(type_name)}"
end

.type_nameString

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns the name of the class, or the name of the type if the class represents an Object type


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# File 'lib/puppet/pops/adaptable.rb', line 188

def self.type_name
  self.name
end