Module: Prick::EnsureMethods

Defined in:
lib/prick/ensure.rb

Overview

Helper module

Class Method Summary collapse

Class Method Details

.all_extended(c) ⇒ Object 



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# File 'lib/prick/ensure.rb', line 42

def self.all_extended(c)
  c.ancestors
end

.all_included(m) ⇒ Object 



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# File 'lib/prick/ensure.rb', line 38

def self.all_included(m)
  m.singleton_class.included_modules
end

.all_states(c) ⇒ Object 



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# File 'lib/prick/ensure.rb', line 46

def self.all_states(c)
  h = {}
  (all_extended(c) + all_included(c)).reverse.each { |klass|
    h.merge!(klass.instance_variable_get("@ensure_states") || {})
  }
  h
end

.call_method(object, symbol_or_lambda, *args) ⇒ Object 



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# File 'lib/prick/ensure.rb', line 103

def self.call_method(object, symbol_or_lambda, *args)
#     sol_text = symbol_or_lambda.is_a?(Proc) ? "<Proc>" : symbol_or_lambda
#     puts "call_method(#{object.name}, #{sol_text.inspect}, #{args})"

  if symbol_or_lambda.is_a?(Symbol)
    executor = object.method(symbol_or_lambda)
    executor.call(*vargs(executor.arity, args))
  elsif symbol_or_lambda.is_a?(Proc)
    executor = symbol_or_lambda
    executor.call(object, *vargs(executor.arity, args))
  else
    raise Prick::Fail, "Illegal value: #{symbol_or_lambda.inspect}"
  end
end

.ensure(module_or_object, state, expected, *args) ⇒ Object 



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# File 'lib/prick/ensure.rb', line 54

def self.ensure(module_or_object, state, expected, *args)
#     module_or_object_text = module_or_object.is_a?(Module) ? "<module>" : "<object>"
#     puts "ensure_state_impl(#{module_or_object_text.inspect}, #{state.inspect}, #{expected}, #{args.inspect})"

  object = module_or_object
  klass = self.klass(module_or_object)
  value = call_method(object, :"#{state}?", *args)

  if value != expected
    entry = all_states(klass)[state] or
        raise Prick::Error, "Can't find state #{state.inspect}"

    # Handle ensure-pre-conditions recursively
    precondition = (entry.size == 3 ? entry.shift : nil)
    entry.size == 2 or raise "Malformed state entry for #{state.inspect}"
    if precondition && expected # Don't tear down recursively
      case precondition
        when Symbol
          self.ensure(object, precondition, true, *args)
        when Proc
          call_method(object, precondition, *args)
      else
        raise Prick::Fail, "Unexpected value: #{precondition.inspect}"
      end
    end

    method = entry[expected ? 0 : 1]
    case method
      when true # a noop
        ;
      when false # an error
        relation = (expected ? "to" : "from")
        raise Error, "Can't change state #{relation} #{state.inspect}"
      when Symbol # a method
        call_method(object, method, *args)
      when Proc # a lambda
        call_method(object, method, *args)
    else
      raise Error, "Illegal @states entry: #{method.inspect}"
    end
  end
  self # so that you can do 'some = Some.new.ensure_state(:loaded)' in one go
end

.klass(module_or_object) ⇒ Object 



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# File 'lib/prick/ensure.rb', line 34

def self.klass(module_or_object)
 module_or_object.is_a?(Module) ? module_or_object : module_or_object.class
end

.vargs(arity, args) ⇒ Object 



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# File 'lib/prick/ensure.rb', line 98

def self.vargs(arity, args)
  n_args = (arity < 0 ? -(1 + arity) : arity)
  args[0...n_args]
end