Method: DataMapper::Hook::ClassMethods#register_hook

Defined in:
lib/dm-core/support/hook.rb

#register_hook(target_method, scope) ⇒ Object

Registers a method as hookable. Registering hooks involves the following process

  • Create a blank entry in the HOOK Hash for the method.

  • Define the methods that execute the before and after hook stack. These methods will be no-ops at first, but everytime a new hook is defined, the methods will be redefined to incorporate the new hook.

  • Redefine the method that is to be hookable so that the hook stacks are invoked approprietly.



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# File 'lib/dm-core/support/hook.rb', line 165

def register_hook(target_method, scope)
  if scope == :instance && !method_defined?(target_method)
    raise ArgumentError, "#{target_method} instance method does not exist"
  elsif scope == :class && !respond_to?(target_method)
    raise ArgumentError, "#{target_method} class method does not exist"
  end

  hooks = hooks_with_scope(scope)

  if hooks[target_method].nil?
    hooks[target_method] = {
      # We need to keep track of which class in the Inheritance chain the
      # method was declared hookable in. Every time a child declares a new
      # hook for the method, the hook stack invocations need to be redefined
      # in the original Class. See #define_hook_stack_execution_methods
      :before => [], :after => [], :in => self
    }

    define_hook_stack_execution_methods(target_method, scope)
    define_advised_method(target_method, scope)
  end
end