如何使用图示和可选的散列同时以限定在红宝石的方法？ [英] How to define a method in ruby using splat and an optional hash at the same time?

问题描述

我可以这样定义一个方法：

I am able to define a method like this:

def test(id, *ary, hash_params)
  # Do stuff here
end

但是这使得 hash_params 参数强制性的。这些不工作之一：

But this makes the hash_params argument mandatory. These don't work either:

def t(id, *ary, hash_params=nil)  # SyntaxError: unexpected '=', expecting ')'
def t(id, *ary, hash_params={})   # SyntaxError: unexpected '=', expecting ')'

有没有一种方法，使之选？

Is there a way to make it optional?

推荐答案

您不能这样做。你必须考虑关于Ruby如何能够确定哪些属于 *元，哪些属于可选的哈希值。由于红宝石无法了解你的心思，上面的参数组合（图示+可选）是不可能为它在逻辑上解决。

You can't do that. You have to think about how Ruby would be able to determine what belongs to *ary and what belongs to the optional hash. Since Ruby can't read your mind, the above argument combination (splat + optional) is impossible for it to solve logically.

您要么重新安排你的论点：

You either have to rearrange your arguments:

def test(id, h, *a)

在这种情况下， ^ h 将不可选的。或则手动编程：

In which case h will not be optional. Or then program it manually:

def test(id, *a)
  h = a.last.is_a?(Hash) ? a.pop : nil
  # ^^ Or whatever rule you see as appropriate to determine if h
  # should be assigned a value or not.

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