class Hashie::Mash
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 = {: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">
Under Bang Example¶ ↑
mash = Mash.new mash.author # => nil mash.author_ # => <Mash> mash.author_.name # => nil mash = Mash.new mash.author_.name = "Michael Bleigh" (assigned to temp object) mash.author # => <Mash>
Constants
- ALLOWED_SUFFIXES
Public Class Methods
# File lib/hashie/mash.rb, line 62 def self.load(path, options = {}) @_mashes ||= new return @_mashes[path] if @_mashes.key?(path) fail ArgumentError, "The following file doesn't exist: #{path}" unless File.file?(path) parser = options.fetch(:parser) { Hashie::Extensions::Parsers::YamlErbParser } @_mashes[path] = new(parser.perform(path)).freeze end
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.
# File lib/hashie/mash.rb, line 87 def initialize(source_hash = nil, default = nil, &blk) deep_update(source_hash) if source_hash default ? super(default) : super(&blk) end
Public Instance Methods
Assigns a value to a key
# File lib/hashie/mash.rb, line 187 def assign_property(name, value) self[name] = value end
Retrieves an attribute set in the Mash. Will convert any key passed in to a string before retrieving.
# File lib/hashie/mash.rb, line 99 def custom_reader(key) default_proc.call(self, key) if default_proc && !key?(key) value = regular_reader(convert_key(key)) yield value if block_given? value end
Performs a #deep_update on a duplicate of the current mash.
# File lib/hashie/mash.rb, line 162 def deep_merge(other_hash, &blk) dup.deep_update(other_hash, &blk) end
Recursively merges this mash with the passed in hash, merging each hash in the hierarchy.
# File lib/hashie/mash.rb, line 169 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 && self.key?(k) custom_writer(key, value, false) end end self end
# File lib/hashie/mash.rb, line 139 def delete(key) super(convert_key(key)) end
# File lib/hashie/mash.rb, line 254 def dig(*keys) super(*keys.map { |key| convert_key(key) }) end
Duplicates the current mash as a new mash.
# File lib/hashie/mash.rb, line 149 def dup self.class.new(self, default) end
play nice with ActiveSupport Array#extract_options!
# File lib/hashie/mash.rb, line 244 def extractable_options? true end
# File lib/hashie/mash.rb, line 135 def fetch(key, *args) super(convert_key(key), *args) end
This is the bang method reader, it will return a new Mash if there isn't a value already assigned to the key requested.
# File lib/hashie/mash.rb, line 118 def initializing_reader(key) ck = convert_key(key) regular_writer(ck, self.class.new) unless key?(ck) regular_reader(ck) end
# File lib/hashie/mash.rb, line 153 def key?(key) super(convert_key(key)) end
# File lib/hashie/mash.rb, line 226 def method_missing(method_name, *args, &blk) return self.[](method_name, &blk) if key?(method_name) name, suffix = method_name_and_suffix(method_name) case suffix when '='.freeze assign_property(name, args.first) when '?'.freeze !!self[name] when '!'.freeze initializing_reader(name) when '_'.freeze underbang_reader(name) else self[method_name] end end
# File lib/hashie/mash.rb, line 221 def prefix_method?(method_name) method_name = method_name.to_s method_name.end_with?(*ALLOWED_SUFFIXES) && key?(method_name.chop) end
# File lib/hashie/mash.rb, line 205 def replace(other_hash) (keys - other_hash.keys).each { |key| delete(key) } other_hash.each { |key, value| self[key] = value } self end
# File lib/hashie/mash.rb, line 211 def respond_to_missing?(method_name, *args) return true if key?(method_name) suffix = method_suffix(method_name) if suffix true else super end end
another ActiveSupport method, see issue #270
# File lib/hashie/mash.rb, line 249 def reverse_merge(other_hash) self.class.new(other_hash).merge(self) end
Performs a #shallow_update on a duplicate of the current mash
# File lib/hashie/mash.rb, line 192 def shallow_merge(other_hash) dup.shallow_update(other_hash) end
Merges (non-recursively) the hash from the argument, changing the receiving hash
# File lib/hashie/mash.rb, line 198 def shallow_update(other_hash) other_hash.each_pair do |k, v| regular_writer(convert_key(k), convert_value(v, true)) end self end
# File lib/hashie/mash.rb, line 72 def to_module(mash_method_name = :settings) mash = self Module.new do |m| m.send :define_method, mash_method_name.to_sym do mash end end end
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.
# File lib/hashie/mash.rb, line 126 def underbang_reader(key) ck = convert_key(key) if key?(ck) regular_reader(ck) else self.class.new end end
# File lib/hashie/mash.rb, line 143 def values_at(*keys) super(*keys.map { |key| convert_key(key) }) end
Protected Instance Methods
# File lib/hashie/mash.rb, line 261 def method_name_and_suffix(method_name) method_name = method_name.to_s if method_name.end_with?(*ALLOWED_SUFFIXES) [method_name[0..-2], method_name[-1]] else [method_name[0..-1], nil] end end
# File lib/hashie/mash.rb, line 270 def method_suffix(method_name) method_name = method_name.to_s method_name[-1] if method_name.end_with?(*ALLOWED_SUFFIXES) end