Question

我在搜索哈希值时遇到问题，我的值是方法。我只是不想运行graph_draw(g, vertex_text=g.vertex_properties["name"], ...)匹配密钥的方法。

plan_type

目前，如果我将“bar”作为def method(plan_type, plan, user) { foo: plan_is_foo(plan, user), bar: plan_is_bar(plan, user), waa: plan_is_waa(plan, user), har: plan_is_har(user) }[plan_type] end传入，则每个方法都会运行，我怎样才能只运行plan_type方法？

Answer 1

这个变种怎么样？

def method(plan_type, plan, user)
  {
    foo: -> { plan_is_foo(plan, user) },
    bar: -> { plan_is_bar(plan, user) },
    waa: -> { plan_is_waa(plan, user) },
    har: -> { plan_is_har(user) }
  }[plan_type].call
end

使用lambdas或procs是一种让事情变得懒惰的好方法，因为只有当他们收到方法call时才执行它们

因此，您可以使用->（lambda literal）作为轻量级包装器，可能需要大量计算，call只能在需要时使用。

Answer 2

一个非常简单的解决方案：

<强>代码

def method(plan_type, plan=nil, user)
  m =
  case plan_type
  when "foo" then :plan_is_foo
  when "bar" then :plan_is_bar
  when "waa" then :plan_is_waa
  when "har" then :plan_is_har
  else nil
  end

  raise ArgumentError, "No method #{plan_type}" if m.nil?
  (m==:plan_is_har) ? send(m, user) : send(m, plan, user)
end

您当然可以使用哈希而不是case语句。

示例

def plan_is_foo plan, user "foo's idea is to #{plan} #{user}" end def plan_is_bar plan, user "bar's idea is to #{plan} #{user}" end def plan_is_waa plan, user "waa's idea is to #{plan} #{user}" end def plan_is_har user "har is besotted with #{user}" end

method "foo", "marry", "Jane" #=> "foo's idea is to marry Jane" method "bar", "avoid", "Trixi at all costs" #=> "bar's idea is to avoid Trixi at all costs" method "waa", "double-cross", "Billy-Bob" #=> "waa's idea is to double-cross Billy-Bob" method "har", "Willamina" #=> "har is besotted with Willamina" method "baz", "Huh?" #=> ArgumentError: No method baz

使用方法值搜索ruby中的哈希值

2 个答案: