From: Clemens Hintze <c.hintze@...>
Date: 2000-12-04T20:40:01+09:00
Subject: [ruby-talk:6798] Dump locals during debugging (was: Re: using join())

>>>>> "Joseph" == Joseph McDonald <joe@vpop.net> writes:

(...)

    Joseph> Here's a prob I just tumbled into.  During debugging it
    Joseph> would be cool to do something like:

(...)

    Joseph> but I can't seem to get the objects name.

Sorry to be pedantic here, but there are no object names in
Ruby. Every variable is merely a place where a reference to a certain
object is stored. That place is named in your code with a variable
name.

Strictly spoken, the Ruby compiler would be free to discard every
variable name after compilation of your code if not necessary for
debugging purposes.

It looks more like:

    +- text -+               +-------+
    | <addr>-+-------------> | world |
    +--------+               +-------+

Where the "world" is an instance of class String. You see, objects
doesn't have names!

But I often use following extension during debugging:

  class Binding
    def info_locals(*args)
      vars = eval("local_variables", self)
      vars &= args unless args.empty?
      vars.each { |v| puts %(#{v} --> #{eval(v, self).inspect}) }
    end
  end

After 'require'ing I can use it as following:

  a = 12
  b = 14
  o = Object.new
  
  class Foo
    def initialize
      @v = 24
    end
  end
  
  f = Foo.new
  
  urls = ["hello", "world"]
  text = "world!"

  puts "All:"
  binding.info_locals                
  puts "\nOnly selected ones:"	     
  binding.info_locals "urls", "text"

and get then:

All:
a --> 12
b --> 14
o --> #<Object:0x4021e9bc>
f --> #<Foo:0x4021cc70 @v=24>
urls --> ["hello", "world"]
text --> "world!"

Only selected ones:
urls --> ["hello", "world"]
text --> "world!"


HTH,
\cle