Class: Hashie::Mash

Inherits:
Hash
  • Object
show all
Includes:
PrettyInspect
Defined in:
lib/hashie/mash.rb

Overview

Mash allows you to create pseudo-objects that have method-like accessors for hash keys. This is useful for such implementations as an API-accessing library that wants to fake robust objects without the overhead of actually doing so. Think of it as OpenStruct with some additional goodies.

A Mash will look at the methods you pass it and perform operations based on the following rules:

  • No punctuation: Returns the value of the hash for that key, or nil if none exists.
  • Assignment (=): Sets the attribute of the given method name.
  • Existence (?): Returns true or false depending on whether that key has been set.
  • Bang (!): Forces the existence of this key, used for deep Mashes. Think of it as "touch" for mashes.
  • Under Bang (_): Like Bang, but returns a new Mash rather than creating a key. Used to test existance in deep Mashes.

== Basic Example

mash = Mash.new mash.name? # => false mash.name = "Bob" mash.name # => "Bob" mash.name? # => true

== Hash Conversion Example

hash = => {:b => 23, :d => {:e => "abc"}, :f => [=> 44, :h => 29, 12]} mash = Mash.new(hash) mash.a.b # => 23 mash.a.d.e # => "abc" mash.f.first.g # => 44 mash.f.last # => 12

== Bang Example

mash = Mash.new mash.author # => nil mash.author! # =>

mash = Mash.new mash.author!.name = "Michael Bleigh" mash.author # =>

== Under Bang Example

mash = Mash.new mash.author # => nil mash.author_ # => mash.author_.name # => nil

mash = Mash.new mash.author_.name = "Michael Bleigh" (assigned to temp object) mash.author # =>

Instance Method Summary collapse

Methods included from PrettyInspect

#hashie_inspect, included

Methods inherited from Hash

#to_hash, #to_json

Methods included from HashExtensions

#hashie_stringify_keys, #hashie_stringify_keys!, included, #to_mash

Constructor Details

#initialize(source_hash = nil, default = nil, &blk) ⇒ Mash

If you pass in an existing hash, it will convert it to a Mash including recursively descending into arrays and hashes, converting them as well.


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# File 'lib/hashie/mash.rb', line 65

def initialize(source_hash = nil, default = nil, &blk)
  deep_update(source_hash) if source_hash
  default ? super(default) : super(&blk)
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method_name, *args, &blk) ⇒ Object


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# File 'lib/hashie/mash.rb', line 194

def method_missing(method_name, *args, &blk)
  return self.[](method_name, &blk) if key?(method_name)
  match = method_name.to_s.match(/(.*?)([?=!_]?)$/)
  case match[2]
  when "="
    self[match[1]] = args.first
  when "?"
    !!self[match[1]]
  when "!"
    initializing_reader(match[1])
  when "_"
    underbang_reader(match[1])
  else
    default(method_name, *args, &blk)
  end
end

Instance Method Details

#custom_reader(key) {|value| ... } ⇒ Object Also known as: []

Retrieves an attribute set in the Mash. Will convert any key passed in to a string before retrieving.

Yields:

  • (value)

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# File 'lib/hashie/mash.rb', line 85

def custom_reader(key)
  value = regular_reader(convert_key(key))
  yield value if block_given?
  value
end

#custom_writer(key, value) ⇒ Object Also known as: []=

Sets an attribute in the Mash. Key will be converted to a string before it is set, and Hashes will be converted into Mashes for nesting purposes.


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# File 'lib/hashie/mash.rb', line 94

def custom_writer(key,value) #:nodoc:
  regular_writer(convert_key(key), convert_value(value))
end

#deep_merge(other_hash, &blk) ⇒ Object Also known as: merge

Performs a deep_update on a duplicate of the current mash.


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# File 'lib/hashie/mash.rb', line 143

def deep_merge(other_hash, &blk)
  dup.deep_update(other_hash, &blk)
end

#deep_update(other_hash, &blk) ⇒ Object Also known as: deep_merge!, update

Recursively merges this mash with the passed in hash, merging each hash in the hierarchy.


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# File 'lib/hashie/mash.rb', line 150

def deep_update(other_hash, &blk)
  other_hash.each_pair do |k,v|
    key = convert_key(k)
    if regular_reader(key).is_a?(Mash) and v.is_a?(::Hash)
      custom_reader(key).deep_update(v, &blk)
    else
      value = convert_value(v, true)
      value = blk.call(key, self[k], value) if blk
      custom_writer(key, value)
    end
  end
  self
end

#delete(key) ⇒ Object


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# File 'lib/hashie/mash.rb', line 124

def delete(key)
  super(convert_key(key))
end

#dupObject

Duplicates the current mash as a new mash.


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# File 'lib/hashie/mash.rb', line 130

def dup
  self.class.new(self, self.default)
end

#fetch(key, *args) ⇒ Object


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# File 'lib/hashie/mash.rb', line 120

def fetch(key, *args)
  super(convert_key(key), *args)
end

#idObject

:nodoc:


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# File 'lib/hashie/mash.rb', line 72

def id #:nodoc:
  self["id"]
end

#initializing_reader(key) ⇒ Object

This is the bang method reader, it will return a new Mash if there isn't a value already assigned to the key requested.


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# File 'lib/hashie/mash.rb', line 103

def initializing_reader(key)
  ck = convert_key(key)
  regular_writer(ck, self.class.new) unless key?(ck)
  regular_reader(ck)
end

#key?(key) ⇒ Boolean Also known as: has_key?, include?, member?

Returns:

  • (Boolean)

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# File 'lib/hashie/mash.rb', line 134

def key?(key)
  super(convert_key(key))
end

#regular_dupObject


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# File 'lib/hashie/mash.rb', line 128

alias_method :regular_dup, :dup

#replace(other_hash) ⇒ Object


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# File 'lib/hashie/mash.rb', line 181

def replace(other_hash)
  (keys - other_hash.keys).each { |key| delete(key) }
  other_hash.each { |key, value| self[key] = value }
  self
end

#respond_to?(method_name, include_private = false) ⇒ Boolean

Will return true if the Mash has had a key set in addition to normal respond_to? functionality.

Returns:

  • (Boolean)

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# File 'lib/hashie/mash.rb', line 189

def respond_to?(method_name, include_private=false)
  return true if key?(method_name) || method_name.to_s.slice(/[=?!_]\Z/)
  super
end

#shallow_merge(other_hash) ⇒ Object

Performs a shallow_update on a duplicate of the current mash


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# File 'lib/hashie/mash.rb', line 168

def shallow_merge(other_hash)
  dup.shallow_update(other_hash)
end

#shallow_update(other_hash) ⇒ Object

Merges (non-recursively) the hash from the argument, changing the receiving hash


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# File 'lib/hashie/mash.rb', line 174

def shallow_update(other_hash)
  other_hash.each_pair do |k,v|
    regular_writer(convert_key(k), convert_value(v, true))
  end
  self
end

#typeObject

:nodoc:


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# File 'lib/hashie/mash.rb', line 76

def type #:nodoc:
  self["type"]
end

#underbang_reader(key) ⇒ Object

This is the under bang method reader, it will return a temporary new Mash if there isn't a value already assigned to the key requested.


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# File 'lib/hashie/mash.rb', line 111

def underbang_reader(key)
  ck = convert_key(key)
  if key?(ck)
    regular_reader(ck)
  else
    self.class.new
  end
end