Class: Drum::PersistentHash

Inherits:
Object show all
Includes:
Log, YAMLUtils
Defined in:
lib/drum/utils/persist.rb

Overview

A wrapper around a hash that stores values persistently in a YAML.

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Log

#log

Methods included from YAMLUtils

#from_yaml

Constructor Details

#initialize(file_path, value = {}) ⇒ PersistentHash

Creates a new persistent hash.

Parameters:

  • file_path (String) —

    The path to the stored YAML file (may be non-existent).

  • value (Hash) (defaults to: {}) —

    The initial default value, if the file doesn't exist yet or is malformed



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# File 'lib/drum/utils/persist.rb', line 18

def initialize(file_path, value={})
  @file_path = file_path
  begin
    self.load
  rescue StandardError => e
    unless e.is_a?(Errno::ENOENT)
      log.warn "Could not load #{file_path}: #{e.inspect}... creating from scratch"
    end
    @value = value
    self.store
  end
end

Instance Attribute Details

#value ⇒ Hash

Returns The wrapped hash.

Returns:

  • (Hash) —

    The wrapped hash



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# File 'lib/drum/utils/persist.rb', line 10

class PersistentHash
  include Log, YAMLUtils
  attr_reader :value

  # Creates a new persistent hash.
  #
  # @param [String] file_path The path to the stored YAML file (may be non-existent).
  # @param [Hash] value The initial default value, if the file doesn't exist yet or is malformed
  def initialize(file_path, value={})
    @file_path = file_path
    begin
      self.load
    rescue StandardError => e
      unless e.is_a?(Errno::ENOENT)
        log.warn "Could not load #{file_path}: #{e.inspect}... creating from scratch"
      end
      @value = value
      self.store
    end
  end

  # Loads the hash from the file.
  def load
    @value = from_yaml(File.read(@file_path))
  end

  # Saves the hash to the file.
  def store
    File.write(@file_path, @value.to_yaml)
  end

  # Writes a mapping to the hash and stores it on disk.
  #
  # @param [Object] key The key to use.
  # @param [Object] value The value to map the key to.
  def []=(key, value)
    @value[key] = value
    store
  end

  # Reads a mapping from the hash.
  #
  # @param [Object] key The key to use.
  # @return [Object] The value the key is mapped to.
  def [](key)
    @value[key]
  end
end

Instance Method Details

#[](key) ⇒ Object

Reads a mapping from the hash.

Parameters:

  • key (Object) —

    The key to use.

Returns:

  • (Object) —

    The value the key is mapped to.



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# File 'lib/drum/utils/persist.rb', line 54

def [](key)
  @value[key]
end

#[]=(key, value) ⇒ Object

Writes a mapping to the hash and stores it on disk.

Parameters:

  • key (Object) —

    The key to use.

  • value (Object) —

    The value to map the key to.



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# File 'lib/drum/utils/persist.rb', line 45

def []=(key, value)
  @value[key] = value
  store
end

#load ⇒ Object

Loads the hash from the file.



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# File 'lib/drum/utils/persist.rb', line 32

def load
  @value = from_yaml(File.read(@file_path))
end

#store ⇒ Object

Saves the hash to the file.



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# File 'lib/drum/utils/persist.rb', line 37

def store
  File.write(@file_path, @value.to_yaml)
end