从迭代器调用迭代对象

Question

如何从迭代块调用迭代对象？

# "self" is an Object, and not an iterating object I need.
MyClass.some.method.chain.inject{|mean, i| (mean+=i)/self.size}

我的意思是我需要这样做：

@my_object = MyClass.some.method.chain
@my_object.inject{|mean, i| (mean+=i)/@my_object.size}

Answer 1

这个答案是 James Kyburz 的 的副本回答类似问题

Ruby 中没有 this，最接近的是 self。

以下是一些可以帮助您的示例

#example 1 not self needed numbers is the array

numbers = [1, 2, 3]

numbers.reduce(:+).to_f / numbers.size

# example 2 using tap which gives access to self and returns self
# hence why total variable is needed

total = 0
[1, 2, 3].tap {|a| total = a.reduce(:+).to_f / a.size }

# instance_eval hack which accesses self, and the block after do is an expression 
# can return the average without an extra variable

[1, 2, 3].instance_eval { self.reduce(:+).to_f / self.size } # => 2.0

到目前为止我更喜欢示例 1