Module: Gemmy::Patches::HashPatch

Defined in:
lib/gemmy/patches/hash_patch.rb

Overview

Hash patches

Defined Under Namespace

Modules: PersistedHash

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

._autovivified(caller_hash) ⇒ Object 



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# File 'lib/gemmy/patches/hash_patch.rb', line 51

def self._autovivified(caller_hash)
  result = Hash.new { |hash,key| hash[key] = Hash.new(&hash.default_proc) }
  result.deep_merge caller_hash
end

._bury(caller_hash, *args) ⇒ Object

The bury method, taking the input hash as a parameter Used by the Hash#bury instance method



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# File 'lib/gemmy/patches/hash_patch.rb', line 23

def self._bury(caller_hash, *args)
  if args.count < 2
    raise ArgumentError.new("2 or more arguments required")
  elsif args.count == 2
    caller_hash[args[0]] = args[1]
  else
    arg = args.shift
    caller_hash[arg] = {} unless caller_hash[arg]
    _bury(caller_hash[arg], *args) unless args.empty?
  end
  caller_hash
end

Instance Method Details

#autovivified ⇒ Object

Turns a hash into one that’s “autovivified” meaning it’s default values for keys is an empty hash. The result is that you can set nested keys without initializing more than one hash layer.

Usage:

hash = {}.autovivified
hash[:a][:b] = 0
puts hash[:a][:b]
=> 0



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# File 'lib/gemmy/patches/hash_patch.rb', line 47

def autovivified
  Gemmy::Patches::HashPatch._autovivified(self)
end

#bury(*args) ⇒ Object

The opposite of Hash#dig Takes a list of keys followed by a value to set

Example:

a = {a: {b: {}} }
a.bury(:a, :b, :c, 0)
puts a[:a][:b][:c]
=> 0

Source: github.com/dam13n/ruby-bury/blob/master/hash.rb



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# File 'lib/gemmy/patches/hash_patch.rb', line 17

def bury *args
  Gemmy::Patches::HashPatch._bury(self, *args)
end

#persisted(path) ⇒ Object

Sets up a hash to mirror all changes to a database file All nested gets & sets require a list of keys, passed as subsequent args. Instead of [] and []=, use get and set

Everything in the db is contained in a hash with one predefined key, :data. The value is an empty, autovivified hash.

This also makes the caller hash autovivified

Example:

hash = {}.persisted(“db.yaml”) hash.set(:a, :b, 0) # => this writes to disk and memory hash.get(:a, :b) # => reads from memory hash.get(:a, :b, disk: true) # => reads from disk



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# File 'lib/gemmy/patches/hash_patch.rb', line 72

def persisted(path)
  require 'yaml/store'
  Gemmy::Patches::HashPatch._autovivified(self).tap do |hash|
    hash.instance_exec do
      @db = YAML::Store.new path
      @db.transaction do
        @db[:data] = Gemmy::Patches::HashPatch._autovivified({})
      end
    end
    hash.extend Gemmy::Patches::HashPatch::PersistedHash
  end
end