如何得到一个“动态”对象调用的参考？ [英] How to get a reference to a 'dynamic' object call?

问题描述

好吧，我的问题不是很清楚，但我想要做的是以下内容：

Well, my question is not very clear, but what I want to do is the following:

average = [1, 2, 3].inject(0) { |sum, el| sum + el } / this.size

在code以上不会因为可笑调用的工作这个，但我想要做到的是让一个参照阵列到我打电话注入上。 （在这种情况下[1，2，3]），由于我的无知，在我的红宝石与这个做到了。但是，你能告诉我怎么做是正确的？
是否有可能在所有做没有一个变量引用？

The code above won't work because of the ridiculous call to this, But what I want to accomplish is to get a reference to the array to which I'm calling inject on. (in this case [1, 2, 3]), Given my ignorance in ruby I did it with this. But, Could you please tell me how to do it right? Is it possible at all to do it without a variable reference?

在此先感谢！

推荐答案

有没有这红宝石最近的是自我。

There is no this in ruby the nearest thing is self.

下面是一些例子来帮助你对你的方式。

Here are some examples to help you on your way

#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preFER例如1

So far I prefer example 1

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