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.

Basic Example

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

Hash Conversion Example

hash = {:a => {:b => 23, :d => {:e => "abc"}}, :f => [{:g => 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 = Mash.new
mash.author!.name = "Michael Bleigh"
mash.author # => <Mash name="Michael Bleigh">

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 53

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 149

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])
  else
    default(method_name, *args, &blk)
  end
end

Instance Method Details

#[](key) {|value| ... } ⇒ Object

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 69

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

#[]=(key, value) ⇒ Object

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 78

def []=(key,value) #:nodoc:
  regular_writer(convert_key(key), convert_value(value))
end

#deep_merge(other_hash) ⇒ 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 106

def deep_merge(other_hash)
  dup.deep_update(other_hash)
end

#deep_update(other_hash) ⇒ 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 113

def deep_update(other_hash)
  other_hash.each_pair do |k,v|
    key = convert_key(k)
    if regular_reader(key).is_a?(Mash) and v.is_a?(::Hash)
      regular_reader(key).deep_update(v)
    else
      regular_writer(key, convert_value(v, true))
    end
  end
  self
end

#delete(key) ⇒ Object 



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# File 'lib/hashie/mash.rb', line 90

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

#dup ⇒ Object

Duplicates the current mash as a new mash.



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# File 'lib/hashie/mash.rb', line 96

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

#id ⇒ Object

:nodoc:



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# File 'lib/hashie/mash.rb', line 60

def id #:nodoc:
  key?("id") ? self["id"] : super
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 84

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

#key?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hashie/mash.rb', line 100

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

#regular_dup ⇒ Object 



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

alias_method :regular_dup, :dup

#regular_reader ⇒ Object 



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# File 'lib/hashie/mash.rb', line 64

alias_method :regular_reader, :[]

#regular_writer ⇒ Object 



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

alias_method :regular_writer, :[]=

#respond_to?(method_name) ⇒ 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 144

def respond_to?(method_name)
  return true if key?(method_name)
  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 129

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 135

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