Class: Dagger::Default

Inherits:
Object
  • Object
show all
Defined in:
lib/dagger/default.rb

Overview

Default value generator for a dictionary

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(dictionary, cached: false, rule_prefix: '_default') ⇒ Default

Initialize a default value generator for a dictionary

:call-seq:

new(dictionary) => Dagger::Default
new(*, cached: false)
new(*, rule_prefix: '_default')



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# File 'lib/dagger/default.rb', line 14

def initialize(dictionary, cached: false, rule_prefix: '_default')
  @dictionary = dictionary
  @cached = cached
  @rule_prefix = KeyTree::Path[rule_prefix]
  @default_proc = ->(tree, key) { generate(tree, key) }
  @locks = Set[]
end

Instance Attribute Details

#cached=(value) ⇒ Object (writeonly)

Sets the attribute cached

Parameters:

  • value —

    the value to set the attribute cached to.



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# File 'lib/dagger/default.rb', line 31

def cached=(value)
  @cached = value
end

#default_proc ⇒ Object (readonly)

Returns the value of attribute default_proc.



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# File 'lib/dagger/default.rb', line 22

def default_proc
  @default_proc
end

Instance Method Details

#cached? ⇒ Boolean

Verify state of caching of future values

:call-seq:

cached? => bool

Returns:

  • (Boolean) 


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# File 'lib/dagger/default.rb', line 28

def cached?
  !(!@cached)
end

#generate(tree, key) ⇒ Object

Generate a default value for a key, possibly caching the result in the tree. Raises a KeyError f the default value cannot be generated.

:call-seq:

generate(tree, key) => value || KeyError



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# File 'lib/dagger/default.rb', line 39

def generate(tree, key)
  key = KeyTree::Path[key] unless key.is_a? KeyTree::Path
  raise %(deadlock detected: "#{key}") unless @locks.add?(key)

  return result = process(key) unless cached?
  tree[key] = result unless result.nil?
ensure
  @locks.delete(key)
end