A state defines a value that an attribute can be in after being transitioned 0 or more times. States can represent a value of any type in Ruby, though the most common (and default) type is String.
In addition to defining the machine's value, a state can also define a behavioral context for an object when that object is in the state. See StateMachine::Machine#state for more information about how state-driven behavior can be utilized.
Calls a method defined in this state's context on the given object. All arguments and any block will be passed into the method defined.
If the method has never been defined for this state, then a NoMethodError will be raised.
# File lib/state_machine/state.rb, line 210 def call(object, method, method_missing = nil, *args, &block) if machine.states.matches?(object, name) && context_method = methods[method.to_sym] # Method is defined by the state: proxy it through context_method.bind(object).call(*args, &block) else # Dispatch to the superclass since the object either isn't in this state # or this state doesn't handle the method method_missing.call if method_missing end end
Defines a context for the state which will be enabled on instances of the owner class when the machine is in this state.
This can be called multiple times. Each time a new context is created, a new module will be included in the owner class.
# File lib/state_machine/state.rb, line 181 def context(&block) machine_name = machine.name # Evaluate the method definitions context = StateContext.new(self) context.class_eval(&block) context.instance_methods.each do |method| methods[method.to_sym] = context.instance_method(method) # Calls the method defined by the current state of the machine context.class_eval def #{method}(*args, &block) self.class.state_machine(#{machine_name.inspect}).states.fetch(#{name.inspect}).call(self, #{method.inspect}, lambda {super(*args, &block)}, *args, &block) end, __FILE__, __LINE__ + 1 end # Include the context so that it can be bound to the owner class (the # context is considered an ancestor, so it's allowed to be bound) machine.owner_class.class_eval { include context } context end
Generates a human-readable description of this state's name / value:
For example,
State.new(machine, :parked).description # => "parked" State.new(machine, :parked, :value => :parked).description # => "parked" State.new(machine, :parked, :value => nil).description # => "parked (nil)" State.new(machine, :parked, :value => 1).description # => "parked (1)" State.new(machine, :parked, :value => lambda {Time.now}).description # => "parked (*)
# File lib/state_machine/state.rb, line 128 def description description = name ? name.to_s : name.inspect description << " (#{@value.is_a?(Proc) ? '*' : @value.inspect})" unless name.to_s == @value.to_s description end
Draws a representation of this state on the given machine. This will create a new node on the graph with the following properties:
label - The human-friendly description of the state.
width - The width of the node. Always 1.
height - The height of the node. Always 1.
shape - The actual shape of the node. If the state is a final state, then "doublecircle", otherwise "ellipse".
The actual node generated on the graph will be returned.
# File lib/state_machine/state.rb, line 230 def draw(graph) node = graph.add_node(name ? name.to_s : 'nil', :label => description, :width => '1', :height => '1', :shape => final? ? 'doublecircle' : 'ellipse' ) # Add open arrow for initial state graph.add_edge(graph.add_node('starting_state', :shape => 'point'), node) if initial? node end
Determines whether there are any states that can be transitioned to from this state. If there are none, then this state is considered final. Any objects in a final state will remain so forever given the current machine's definition.
# File lib/state_machine/state.rb, line 103 def final? !machine.events.any? do |event| event.branches.any? do |branch| branch.state_requirements.any? do |requirement| requirement[:from].matches?(name) && !requirement[:to].matches?(name, :from => name) end end end end
Transforms the state name into a more human-readable format, such as "first gear" instead of "first_gear"
# File lib/state_machine/state.rb, line 115 def human_name(klass = @machine.owner_class) @human_name.is_a?(Proc) ? @human_name.call(self, klass) : @human_name end
Generates a nicely formatted description of this state's contents.
For example,
state = StateMachine::State.new(machine, :parked, :value => 1, :initial => true) state # => #<StateMachine::State name=:parked value=1 initial=true context=[]>
# File lib/state_machine/state.rb, line 250 def inspect attributes = [[:name, name], [:value, @value], [:initial, initial?], [:context, methods.keys]] "#<#{self.class} #{attributes.map {|attr, value| "#{attr}=#{value.inspect}"} * ' '}>" end
Determines whether this state matches the given value. If no matcher is configured, then this will check whether the values are equivalent. Otherwise, the matcher will determine the result.
For example,
# Without a matcher state = State.new(machine, :parked, :value => 1) state.matches?(1) # => true state.matches?(2) # => false # With a matcher state = State.new(machine, :parked, :value => lambda {Time.now}, :if => lambda {|value| !value.nil?}) state.matches?(nil) # => false state.matches?(Time.now) # => true
# File lib/state_machine/state.rb, line 172 def matches?(other_value) matcher ? matcher.call(other_value) : other_value == value end
The value that represents this state. This will optionally evaluate the original block if it's a lambda block. Otherwise, the static value is returned.
For example,
State.new(machine, :parked, :value => 1).value # => 1 State.new(machine, :parked, :value => lambda {Time.now}).value # => Tue Jan 01 00:00:00 UTC 2008 State.new(machine, :parked, :value => lambda {Time.now}).value(false) # => <Proc:0xb6ea7ca0@...>
# File lib/state_machine/state.rb, line 143 def value(eval = true) if @value.is_a?(Proc) && eval if cache_value? @value = @value.call machine.states.update(self) @value else @value.call end else @value end end
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