Class: Linked::Item

Inherits:
Object
  • Object
show all
Includes:
Listable
Defined in:
lib/linked/item.rb

Overview

This is the default implementation of a listable object

This class implements a listable value object that wraps an arbitrary value an can be with other listable items.

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Listable

#after, #before, #in_chain?, #initialize_copy, #item, #next, #prev, #take

Methods included from Mutable

#append, #delete, #delete_after, #delete_before, #prepend

Constructor Details

#initialize(value = nil) ⇒ Item

Creates a new item. If a list is given the item will be considered a part of that list and appended to the end of it.

Parameters:

  • value (Object) (defaults to: nil) —

    an arbitrary object to store with the item.



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# File 'lib/linked/item.rb', line 21

def initialize(value = nil)
  @value = value
  super()
end

Instance Attribute Details

#value ⇒ Object

The Item can hold an arbitrary object as its value and it will stay with the item.

Returns:

  • (Object) —

    any object that is stored in the item.



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# File 'lib/linked/item.rb', line 15

def value
  @value
end

Instance Method Details

#==(other) ⇒ true, false Also known as: eql?

Item equality is solely determined by tha value. If the other object responds to #value, and its value is equal (#==) to this value, the objects are considered equal.

Parameters:

  • other (#value, Object) —

    any object.

Returns:

  • (true, false) —

    true if the value of the given object is equal to the item value.



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# File 'lib/linked/item.rb', line 47

def ==(other)
  return false unless other.respond_to? :value
  value == other.value
end

#freeze ⇒ self

Freezes the value, as well as making the item itself immutable.

Returns:

  • (self) 


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# File 'lib/linked/item.rb', line 64

def freeze
  value.freeze
  super
end

#hash ⇒ Integer

Uses the hash value of the item value.

Returns:

  • (Integer) —

    a fixnum that can be used by Hash to identify the item.



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# File 'lib/linked/item.rb', line 57

def hash
  value.hash
end

#initialize_dup(source) ⇒ item

Calling #dup on an item returns a copy that is no longer connected to the original item chain. The value will also be copied.

Parameters:

  • source (Item) —

    the item to copy.

Returns:

  • (item) —

    a new Item.



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# File 'lib/linked/item.rb', line 31

def initialize_dup(source)
  @value = begin
             source.value.dup
           rescue TypeError
             source.value
           end
  super
end

#inspect ⇒ String

The default #inspect method becomes very cluttered the moment you start linking objects together. This implementation fixes that and only shows the class name, object id and value (if set).

Returns:

  • (String) —

    a string representation of the list item.



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# File 'lib/linked/item.rb', line 74

def inspect
  return yield(self).to_s if block_given?
  value ? object_identifier + " value=#{value.inspect}" : object_identifier
end