红宝石+运算符是怎么做的? [英] How does ruby do the + operator?

问题描述

Ruby不支持像variable++这样的递增变量.我看到了以下行为:

Ruby does not support incrementing variables like variable++. I saw this behaviour that:

2 ++ 4

给出6.实际上，两个变量之间的任意数量的+符号都被视为一个单独的+.红宝石如何管理它?既然ruby做到了，那可以作为++运算符不可用的原因吗?

gives 6. In fact, any number of + signs between two variables are treated as one single +. How does ruby manage that? And since ruby does that, can it be taken as the reason for the unavailability of the ++ operator?

推荐答案

此:

2 ++ 4

解析为:

2 + (+4)

所以第二个+是一元加号.添加更多加号只会添加更多一元+运算符，因此:

so the second + is a unary plus. Adding more pluses just adds more unary + operators so:

2 ++++++ 4

被视为:

2 + (+(+(+(+(+(+4))))))

如果在Fixnum中提供了+@方法:

class Fixnum
  def +@
    puts 'unary +'
    self
  end
end

然后您甚至可以看到它的发生:

then you can even see it happen:

> 2 ++ 4
unary +
 => 6 

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