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 # =>

Constant Summary

ALLOWED_SUFFIXES =
%w(? ! = _)

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

- (Mash) initialize(source_hash = nil, default = nil, &blk)

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 66

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

- (Object) method_missing(method_name, *args, &blk)



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# File 'lib/hashie/mash.rb', line 200

def method_missing(method_name, *args, &blk)
  return self.[](method_name, &blk) if key?(method_name)
  suffixes_regex = ALLOWED_SUFFIXES.join
  match = method_name.to_s.match(/(.*?)([#{suffixes_regex}]?)$/)
  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)
  end
end

Instance Method Details

- (Object) custom_reader(key) {|value| ... } 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 86

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

- (Object) custom_writer(key, value, convert = true) 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 95

def custom_writer(key, value, convert = true) #:nodoc:
  regular_writer(convert_key(key), convert ? convert_value(value) : value)
end

- (Object) deep_merge(other_hash, &blk) 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 144

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

- (Object) deep_update(other_hash, &blk) 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 151

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

- (Object) delete(key)



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# File 'lib/hashie/mash.rb', line 125

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

- (Object) dup

Duplicates the current mash as a new mash.



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# File 'lib/hashie/mash.rb', line 131

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

- (Object) fetch(key, *args)



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# File 'lib/hashie/mash.rb', line 121

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

- (Object) id

:nodoc:



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# File 'lib/hashie/mash.rb', line 73

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

- (Object) initializing_reader(key)

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 104

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

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

Returns:

  • (Boolean)


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# File 'lib/hashie/mash.rb', line 135

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

- (Boolean) prefix_method?(method_name)

Returns:

  • (Boolean)


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# File 'lib/hashie/mash.rb', line 195

def prefix_method?(method_name)
  method_name = method_name.to_s
  method_name.end_with?(*ALLOWED_SUFFIXES) && key?(method_name.chop)
end

- (Object) regular_dup



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# File 'lib/hashie/mash.rb', line 129

alias_method :regular_dup, :dup

- (Object) replace(other_hash)



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# File 'lib/hashie/mash.rb', line 182

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

- (Boolean) respond_to?(method_name, include_private = false)

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 190

def respond_to?(method_name, include_private = false)
  return true if key?(method_name) || prefix_method?(method_name)
  super
end

- (Object) shallow_merge(other_hash)

Performs a shallow_update on a duplicate of the current mash



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# File 'lib/hashie/mash.rb', line 169

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

- (Object) shallow_update(other_hash)

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



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# File 'lib/hashie/mash.rb', line 175

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

- (Object) type

:nodoc:



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# File 'lib/hashie/mash.rb', line 77

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

- (Object) underbang_reader(key)

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 112

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