我正在尝试编写一个插件,以下列方式为ActiveRecord中的某些方法添加别名:
class Foo < ActiveRecord::Base
include MyOwnPlugin
acts_as_my_own_plugin :methods => [:bar]
def bar
puts 'do something'
end
end
插件内部:
module MyOwnPlugin
def self.included(base)
base.class_eval do
extend ClassMethods
end
end
module ClassMethods
def acts_as_my_own_plugin(options)
options[:methods].each do |m|
self.class_eval <<-END
alias_method :origin_#{m}, :#{m}
END
end
end
end
end
这种方法不起作用,因为当运行#acts_as_my_own_plugin时,Foo #bar尚未定义,因为它尚未运行。
放置acts_as_my_own_plugin:methods =&gt; [:bar] AFTER 条形函数声明将起作用。但这并不漂亮。
我希望能够将acts_as_my_own_plugin置于类定义之上,就像大多数插件一样。
是否有其他方法可以满足这种条件?
答案 0 :(得分:5)
永远记住:Ruby中几乎所有内容都有回调。
尝试以下方法:
module MyOwnPlugin
def self.included(base)
base.extend(ClassMethods)
end
module ClassMethods
# gets called from within the models
def acts_as_my_own_plugin(options)
# store the list of methods in a class variable and symbolize them
@@methods = []
options[:methods].each { |method| @@methods << method.to_sym }
end
# callback method. gets called by ruby if a new method is added.
def method_added(name_of_method)
if @@methods.include?(name_of_method)
# delete the current method from our @@methods array
# in order to avoid infinite loops
@@methods.delete(name_of_method)
#puts "DEBUG: #{name_of_method.to_s} has been added!"
# code from your original plugin
self.class_eval <<-END
alias_method :origin_#{name_of_method}, :#{name_of_method}
def #{name_of_method}
puts "Called #{name_of_method}"
origin_#{name_of_method}
end
END
end
end
end
end
# include the plugin module in ActiveRecord::Base
# in order to make acts_as_my_own_plugin available in all models
ActiveRecord::Base.class_eval do
include MyOwnPlugin
end
# just call acts_as_my_own_plugin and define your methods afterwards
class Foo < ActiveRecord::Base
acts_as_my_own_plugin :methods => [:bar]
def bar
puts 'do something'
end
end
我希望这很有用。你可以用Ruby做的疯狂事情真是太酷了;)
如果要允许在调用acts_as_my_own_plugin
之前和之后定义方法,则需要再次更改代码以允许此操作。然而,困难的部分已经完成。
免责声明:已经使用Ruby 1.8.7进行了测试。可能无法使用Ruby 1.9。*。