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."}

Constant Summary collapse

DOUBLE_COLON =

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

'::'
USCORE =

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

'_'

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."}

Parameters:

  • o (Adaptable) —

    object to add adapter to

  • block (Proc) —

    optional, evaluated in the context of the adapter (existing or new)

Yield Parameters:

  • adapter (Adapter<self>) —

    the created adapter

  • o (Adaptable) —

    optional, the given adaptable

Returns:

  • (Adapter<self>) —

    an adapter of the same class as the receiver of the call

Raises:

  • (ArgumentError) —

    if the given object o is not adaptable



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# File 'lib/puppet/pops/adaptable.rb', line 94

def self.adapt(o, &block)
  attr_name = self_attr_name
  adapter = if o.instance_variable_defined?(attr_name) && value = o.instance_variable_get(attr_name)
    value
  else
    associate_adapter(create_adapter(o), o)
  end
  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."}

Parameters:

  • o (Adaptable) —

    object to add adapter to

  • block (Proc) —

    optional, evaluated in the context of the new adapter

Yield Parameters:

  • adapter (Adapter<self>) —

    the created adapter

  • o (Adaptable) —

    optional, the given adaptable

Returns:

  • (Adapter<self>) —

    an adapter of the same class as the receiver of the call

Raises:

  • (ArgumentError) —

    if the given object o is not adaptable



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# File 'lib/puppet/pops/adaptable.rb', line 129

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

Parameters:

  • adapter (Adapter) —

    the adapter to associate with the given object o

  • o (Adaptable) —

    the object to adapt

Returns:

  • (adapter) —

    the given adapter



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# File 'lib/puppet/pops/adaptable.rb', line 172

def self.associate_adapter(adapter, o)
  attr_name = :"@#{instance_var_name(adapter.class.name)}"
  o.instance_variable_set(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.

Parameters:

  • o (Adaptable) —

    the object where the adapter should be cleared

Returns:

  • (Adapter) —

    if an adapter was set

  • (nil) —

    if the adapter has not been set



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# File 'lib/puppet/pops/adaptable.rb', line 147

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.

Parameters:

  • o (Adaptable) —

    The object to adapt. This implementation ignores this variable, but a specialization may want to initialize itself differently depending on the object it is adapting.

Returns:

  • (Adapter<self>) —

    instance of the subclass of Adapter receiving the call



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# File 'lib/puppet/pops/adaptable.rb', line 163

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.

Parameters:

  • o (Adaptable) —

    object to get adapter from

Returns:

  • (Adapter<self>) —

    an adapter of the same class as the receiver of #get

  • (nil) —

    if the given object o has not been adapted by the receiving adapter

Raises:

  • (ArgumentError) —

    if the object is not adaptable



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# File 'lib/puppet/pops/adaptable.rb', line 69

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.

Parameters:

  • name (String) —

    the fully qualified name of a class

Returns:

  • (String) —

    the name with all ‘::’ replaced by ‘_’



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

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

.self_attr_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 for the name of this instance. The name is created by calling Adapter#instance_var_name and then cached.

Returns:

  • (String) —

    the instance variable name for name



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

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