这是方法#to_proc中的错误吗?(Ruby1.8.7)-IsthisabuginMethod#to_proc?(Ruby1.8.7)

Given the following method that takes one argument:

给定以下方法，它只接受一个参数:

def foo(arg); p arg; end

I can call it with an empty array:

我可以用一个空数组来调用它:

foo([])
# prints []

I can also save it as a Method object and call that with an empty array, with the same result:

我也可以将它保存为一个方法对象，并使用一个空数组调用它，得到相同的结果:

method(:foo).call([])
# prints []

However, if I convert the Method object to a Proc and call that with an empty array, I get an ArgumentError:

但是，如果将方法对象转换为Proc，并使用空数组调用它，则会得到一个ArgumentError:

method(:foo).to_proc.call([])
# ArgumentError: wrong number of arguments (0 for 1)
#   from (irb):4:in `foo'
#   from (irb):4:in `to_proc'
#   from (irb):10:in `call'

I expected it to behave the same as the previous two cases. Instead, it seems to be behaving as if I'd written foo(*[]). However, if I call it with a non-empty array, it does behave the way I expected:

我希望它的行为与前两种情况相同。相反，它的行为好像我写了foo(*[])。但是，如果我用非空数组调用它，它的行为确实符合我的预期:

method(:foo).to_proc.call([1])
# prints [1]

So it destructures the argument, but only if the argument happens to be an empty array. And only if I call Method#to_proc.

它会破坏参数，但前提是参数碰巧是空数组。如果我调用方法#to_proc。

Is there a gap in my understanding of how Method or Proc work, or is this a bug?

在我对方法或Proc工作方式的理解上是否存在差距，或者这是一个bug?

I'm running Ruby 1.8.7-p299. I observe the same behaviour in 1.8.6-p399 and 1.8.7-head. However, I don't see it in 1.9.1-p378: there all three forms print [] when called with an empty array.

我运行Ruby 1.8.7-p299。我在1.8.6-p399和1.8.7-head观察到同样的行为。但是，我在1.9.1-p378中没有看到:当使用空数组调用时，这三种表单都打印[]。

1 个解决方案