ruby-打印变量名及其值

当然有可能!

我的解决方案按对象测试var对象ID标识: http://codepad.org/V7TXRxmL
它被束缚在束缚的传球风格中…
尽管它只适用于局部变量,但是可以很容易地使其成为“通用的”,添加使用其他范围变量列表方法,如 instance_variables 等。

# the function must be defined in such a place 
# ... so as to "catch" the binding of the vars ... cheesy
# otherwise we're kinda stuck with the extra param on the caller
@_binding = binding
def write_pair(p, b = @_binding)
  eval("
    local_variables.each do |v| 
      if eval(v.to_s + \".object_id\") == " + p.object_id.to_s + "
        puts v.to_s + ': ' + \"" + p.to_s + "\"
      end
    end
  " , b)
end

# if the binding is an issue just do here:
# write_pair = lambda { |p| write_pair(p, binding) }

# just some test vars to make sure it works
username1 = "tyndall"
username  = "tyndall"
username3 = "tyndall"

# the result:
write_pair(username)
# username: tyndall

如果可以使用符号而不是变量名,可以这样做:

def wp (s, &b)
  puts "#{s} = #{eval(s.to_s, b.binding)}"
end

使用中:

irb(main):001:0> def wp (s, &b)
irb(main):002:1>   puts "#{s} = #{eval(s.to_s, b.binding)}"
irb(main):003:1> end
=> nil
irb(main):004:0> var = 3
=> 3
irb(main):005:0> wp(:var) {}
var = 3

请注意,必须通过空块 {} 或者它无法获取绑定来计算符号。

我做了一个 vim 宏:

" Inspect the variable on the current line (in Ruby)
autocmd FileType ruby nmap ,i ^"oy$Iputs "<esc>A: #{(<esc>"opA).inspect}"<esc>

将要检查的变量单独放在一行上,然后键入 ,i (逗号,然后是i)在正常模式下。它变成这样:

foo

进入这个:

puts "foo: #{(foo).inspect}"

这很好,因为它没有任何外部依赖项(例如,您不必加载库来使用它)。

这是一个简单的解决方案:

  def bug string
    puts string + eval(string)
  end

这是更易读的:

 def bug string
    puts '#' * 100
    puts string + ': ' + eval(string).inspect
 end

因此调用它:

bug "variable"

如果需要携带实际变量,则必须键入两次,然后才能以内联方式进行。因此:

puts "variable: #{variable}"

基于以前与符号和绑定相关的答案…如果将变量名作为符号传递给您(谁不喜欢删除多余的击键呢?!试试这个:

def wp(var_name_as_sym)
  # gets caller binding, which contains caller's execution environment
  parent_binding = RubyVM::DebugInspector.open{|i| i.frame_binding(2) }
  # now puts the symbol as string + the symbol executed as a variable in the caller's binding
  puts %Q~#{var_name_as_sym.to_s} = #{eval("#{var_name_as_sym.to_s}.inspect", parent_binding)}~
end

aa=1
bb='some bb string'
os = OpenStruct.new(z:26, y:25)

控制台输出:

> wp :aa
aa = 1
=> nil
> wp :bb
bb = "some bb string"
=> nil
> wp :os
os = #<OpenStruct z=26, y=25>
=> nil

使用Ruby 2.2.2P95

(信贷) banister 对于 getting binding 调用上下文)

在Ruby中不能真正获得变量的名称。但是你可以这样做:

data = {"username" => "tyndall"}

甚至

username = "tyndall"
data = {"username", "password", "favorite_color"}
data.each { |param|
   value = eval(param)
   puts "#{param}: #{value}"
}

def write_pair var, binding
  puts "#{ var } = #{ eval(var, binding)}"
end


username = "tyndall"
write_pair "username", binding

这看起来很奇怪,因为绑定从未被定义过,但它是有效的。从 Ruby: getting variable name :

binding()方法提供一个绑定对象,该对象记住 调用方法时的上下文。然后通过一个绑定 在eval()中,它计算该上下文中的变量。

一定要传递一个字符串,而不是变量。

# make use of dynamic scoping via methods and instance vars
@_binding = binding
def eval_debug(expr, binding = @_binding)
   "#{expr} => #{eval(expr, binding)}"
end

# sample invocation:
x = 10
puts eval_debug "x"
puts eval_debug "x**x"