在我的问题上进行扩展(ruby/rails: extending or including other modules), 使用我现有的解决方案,最好的方法是确定我的模块是否已经被包含?
目前我所做的是,在每个模块上定义实例方法,这样当它们被包含时,方法就会可用。然后我只是在父模块中添加了一个捕获器(method_missing()
),以便我可以捕获它们是否已被包含。我的解决方案代码如下:
module Features
FEATURES = [Running, Walking]
# include Features::Running
FEATURES.each do |feature|
include feature
end
module ClassMethods
# include Features::Running::ClassMethods
FEATURES.each do |feature|
include feature::ClassMethods
end
end
module InstanceMethods
def method_missing(meth)
# Catch feature checks that are not included in models to return false
if meth[-1] == '?' && meth.to_s =~ /can_(\w+)\z?/
false
else
# You *must* call super if you don't handle the method,
# otherwise you'll mess up Ruby's method lookup
super
end
end
end
def self.included(base)
base.send :extend, ClassMethods
base.send :include, InstanceMethods
end
end
# lib/features/running.rb
module Features::Running
module ClassMethods
def can_run
...
# Define a method to have model know a way they have that feature
define_method(:can_run?) { true }
end
end
end
# lib/features/walking.rb
module Features::Walking
module ClassMethods
def can_walk
...
# Define a method to have model know a way they have that feature
define_method(:can_walk?) { true }
end
end
end
在我的模型中,我有:
# Sample models
class Man < ActiveRecord::Base
# Include features modules
include Features
# Define what man can do
can_walk
can_run
end
class Car < ActiveRecord::Base
# Include features modules
include Features
# Define what man can do
can_run
end
然后我就可以
Man.new.can_walk?
# => true
Car.new.can_run?
# => true
Car.new.can_walk? # method_missing catches this
# => false
我写的对吗?还有更好的方式吗?
object.class.include? Module
。 - makhanrespond_to?
来检查一个方法是否可用。 - Lesleh