我正在尝试在调用特定类的任何方法时获得回调.
覆盖“发送”不起作用.似乎在普通的 Ruby方法调用中不会调用send.以下面的例子为例.
覆盖“发送”不起作用.似乎在普通的 Ruby方法调用中不会调用send.以下面的例子为例.
class Test def self.items @items ||= [] end end
如果我们覆盖Test on Test,然后调用Test.items,则不会调用send.
我正在尝试做什么？
我宁愿不使用set_trace_func,因为它可能会大大减慢速度.
解决方法
使用别名或alias_method：
# the current implementation of Test,defined by someone else
# and for that reason we might not be able to change it directly
class Test
def self.items
@items ||= []
end
end
# we open the class again,probably in a completely different
# file from the definition above
class Test
# open up the Metaclass,methods defined within this block become
# class methods,just as if we had defined them with "def self.my_method"
class << self
# alias the old method as "old_items"
alias_method :old_items,:items
# redeclare the method -- this replaces the old items method,# but that's ok since it is still available under it's alias "old_items"
def items
# do whatever you want
puts "items was called!"
# then call the old implementation (make sure to call it last if you rely
# on its return value)
old_items
end
end
end