Metadata in Ruby- -
# assume a scene: some user-names are invalid
# when derive a concrete User implementation class
# we wish simply annotate which names should be forbidden in this class
require "active_support/class_inheritable_attributes"
class User
include ClassInheritableAttributes
def initialize(name, age)
invalid_names = self.class.get_invalid_names # invoke class method
if(invalid_names != nil)
invalid_names.each do |name_symbol|
invalid_name = name_symbol.to_s
if(invalid_name == name)
raise "Cannot use this name : " + name
end
end
end
@name = name
@age = age
end
class <<self
# class method can be used to set up meta-data
def invalid_names(*names)
write_inheritable_array("invalid_names", names)
end
# and meta-data would be read via class method
def get_invalid_names
read_inheritable_attribute("invalid_names")
end
end
end
class UserImpl < User
invalid_names :fuck, :damn # meta-data passed in as Symbols
end
u1 = UserImpl.new("Gigix", 24) # will success
begin
u2 = UserImpl.new("fuck", 24) # will raise a RuntimeError
rescue RuntimeError => e
end
u3 = User.new("fuck", 24) # will success, User class not forbid any name
- 作者： 透明 2005年08月29日, 星期一 11:22
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你可以使用这个链接引用该篇日志 http://publishblog.blogdriver.com/blog/tb.b?diaryID=943050
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- 评论人：w da
Tue Aug 30 06:28:48 CST 2005
wer e
- 评论人：daquan
Mon Aug 29 19:35:15 CST 2005
sorry，没看清意图就评论了，原来是禁止非法名字的:)
- 评论人：daquan
Mon Aug 29 19:32:19 CST 2005
代码里面也不该有脏字儿吧
