Module: CachedAttr::ClassMethods

Defined in:
lib/cached_attr.rb

Instance Method Summary collapse

Instance Method Details

#cached_attr(name, options = {}, &block) ⇒ Object

Defines an attribute on the including class.

Parameters:

  • name (Symbol) —

    the name of the attribute

  • options (Hash) (defaults to: {}) —

    options

Options Hash (options):

  • :writer (Object) —

    if set to true, also define a writer method for the property

  • :ttl (Object) —

    the time to live for a value. Ignored if nil or false

  • :method (Object) —

    the method to call if no block is given



33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
 
# File 'lib/cached_attr.rb', line 33

def cached_attr(name, options = {}, &block)
  default_opts = {
      :writer => false,
      :method => false,
      :ttl => false
  }
  opts = default_opts.merge(options)

  class_eval do
    internal_retrieve_method = "__internal_retrieve_#{name}".to_sym
    define_method(internal_retrieve_method) do
      if block.nil?
        val = self.send(opts[:method])
      else
        val = self.instance_exec(&block)
      end
      cached_attributes_store[name][:invoke_count] += 1
      val
    end
    internal_init_method = "__internal_init_#{name}".to_sym
    define_method(internal_init_method) do |val = nil|
      unless cached_attributes_store.has_key?(name)
        cached_attributes_store[name] = {:call_count => 0, :invoke_count => 0}
        if val.nil?
          cached_attributes_store[name][:value] = self.send(internal_retrieve_method)
          cached_attributes_store[name][:expires] = Time.now + opts[:ttl] if opts[:ttl]

        else
          cached_attributes_store[name][:value] = val
        end
      end
      cached_attributes_store[name]
    end


    define_method("_#{name}_reset!".to_sym) do
      cached_attributes_store.delete(name)
    end

    define_method("_#{name}_expires".to_sym) do
      self.send(internal_init_method)[:expires]
    end

    define_method("_#{name}_call_count".to_sym) do
      self.send(internal_init_method)[:call_count]
    end

    define_method("_#{name}_invoke_count".to_sym) do
      self.send(internal_init_method)[:invoke_count]
    end

    define_method(name) do

      cache_val = self.send(internal_init_method)

      if opts[:ttl] && cache_val[:expires] && Time.now > cache_val[:expires]
        cache_val[:value] = self.send(internal_retrieve_method)
        cache_val[:expires] = Time.now + opts[:ttl]
      end

      cache_val[:call_count] = cached_attributes_store[name][:call_count] + 1
      cache_val[:value]
    end

    if opts[:writer]
      define_method("#{name}=") do |val|
        self.send(internal_init_method, val)
      end
    end
  end

end