如何在 ruby​​ 中获取调用者对象名称？

Question

经常会从不同的对象A、B、C调用同一个方法X。是否可以从方法X内部获取调用者对象（A、B、C）的名称

例如：

class Sample
  def method
    # what needs to be done here?
  end
end

n1 = Sample.new
n2 = Sample.new

n1.method #=> expected output is to print n1
n2.method #=> expected output is to print n2

Answer 1

不，这不起作用。成像以下：

n1 = Sample.new
n2 = n1

n2.method #=> ambiguous, both n1 and n2 would be valid

您可以为您的实例分配一个名称：

class Sample
  attr_accessor :name
end

n1 = Sample.new
n1.name = :n1

n2 = Sample.new
n2.name = :n2


n1.name #=> :n1
n2.name #=> :n2

Answer 2

正如其他人所说，直接使用object_id 很可能是更好的方法。

无论如何，沿着这条线的东西可能适用于你的情况：

class Sample
  def method(&b)
    eval("local_variables.select {|v| eval(v.to_s).object_id == #{object_id}}", 
         b.binding)
  end
end

n1 = Sample.new
n2 = Sample.new
n3 = n2

p n1.method {}         #=> [:n1]
p n2.method {}         #=> [:n2, :n3]
p Sample.new.method {} #=> []

它返回当前范围内引用被调用对象的所有（局部）变量。如果您的每个对象都被一个变量引用，这可能 成为你正在寻找的东西。

Neil Slater 建议：您也可以使用 gem binding_of_caller 来简化 转移绑定：

require 'binding_of_caller'

class Sample
  def method
    binding.of_caller(1).eval(
      "local_variables.select {|v| eval(v.to_s).object_id == #{object_id}}"
    )
  end
end

n1 = Sample.new
n2 = Sample.new
n3 = n2

p n1.method         #=> [:n1]
p n2.method         #=> [:n2, :n3]
p Sample.new.method #=> []

（使用 gem 的 0.7.2 版测试）。

Answer 3

任何对象都可以通过它的object_id来识别：

class Sample
  def method
    puts self.object_id
  end
end

n1 = Sample.new
n2 = Sample.new

puts n1.object_id
n1.method

puts n2.object_id
n2.method

--output:--
2152302060
2152302060
2152302040
2152302040

变量名...没那么多。

Answer 4

只返回self 应该可以工作，

这是一个例子：

class Sample
  attr_accessor :name
  def method
    puts self  
    puts self.name  
  end
end

n1 = Sample.new
n1.name = "Bangalore"
n2 = Sample.new
n2.name = "Chennai"


n1.method #=> expected output is to print n1
n2.method #=> expected output is to print n2


-------
Output: 
#<Sample:0x7f492f62c030> # n1 object
Bangalore # n1.name 
#<Sample:0x7f492f62bec8> # n2 object
Chennai #n2.name