这有点奇怪,但如果你正在探索 Ruby,那就可以了。
class Person
puts "evaluating Person's body ..."
def self.mega_methods
puts 'in Person#self.mega_methods, about to yield ...'
yield
end
end
class Tom < Person
puts "evaluating Tom's body ..."
print 'Tom.singleton_methods : '; p Tom.singleton_methods
mega_methods do
puts 'in Tom, about to define self.hiya!'
def self.hiya!
puts 'hiYA!'
end
end
print 'Tom.singleton_methods : '; p Tom.singleton_methods
end
Tom.hiya!
执行 :
$ ruby -w t.rb
evaluating Person's body ...
evaluating Tom's body ...
Tom.singleton_methods : ["mega_methods"]
in Person#self.mega_methods, about to yield ...
in Tom, about to define self.hiya!
Tom.singleton_methods : ["mega_methods", "hiya!"]
hiYA!
请注意,按照惯例,方法名称中的感叹号是为销毁方法保留的,例如String#sub!
修改接收器字符串的方法。
另请参阅def `self.function` 名称是什么意思?
一切都是为了自己!
class Person2
def self.mega_methods
print 'in Person2 self='; p self
class << self
print 'in class << self self='; p self
yield
end
end
end
class Tom2 < Person2
mega_methods do
puts "in Tom2, about to define self.hiya! for self=#{self}"
def self.hiya!
puts 'hiYA!'
end
def hi
puts 'hi'
end
end
end
print 'Tom2.singleton_methods : '; p Tom2.singleton_methods
print 'Tom2.instance_methods : '; p Tom2.instance_methods(false)
Tom2.hiya!
Tom2.new.hi
执行 :
$ ruby -w t2.rb
in Person2 self=Tom2
in class << self self=#<Class:Tom2>
in Tom2, about to define self.hiya! for self=Tom2
Tom2.singleton_methods : ["mega_methods", "hiya!"]
Tom2.instance_methods : ["hi"]
hiYA!
hi