deepak

p = Proc.new { foo = 12; p local_variables }

# why is the two different?
# what is the meaning of "_" variable
p.call #["_", "p", "foo"]
p.binding.eval("local_variables") #["_", "p"]

deepak

# either use the cli option
# ruby -C /this/dir chdir.rb

# or explicitly set in code. this has some options - 
# missing a gotcha check 'the ruby programming language' book
#puts "=== Dir.chdir: #{Dir.chdir(File.expand_path('..',__FILE__))}"

puts "=== Dir.pwd: #{Dir.pwd}"

deepak

# thanks to banister
# functions are better as they have a different scope - keep the scope under control

str = "hello world"
arr = (1..100).to_a

def foo(str)
  Proc.new { str.size }.binding.eval("local_variables + instance_variables") 
end

deepak

> ruby -v
ruby 1.8.7 (2010-04-19 patchlevel 253) [x86_64-linux], MBARI 0x6770, Ruby Enterprise Edition 2010.02

> ri method_added
More than one method matched your request. You can refine
your search by asking for information on one of:

     Kernel::method_added, Kernel::method_added, Module#method_added,
     Numeric#singleton_method_added,
     Shell::CommandProcessor::method_added, Object::method_added,

deepak

=begin
<raggi> 	anyone know if there's a term that describes what the defined? keyword does?	12:44 PM
 <raggi> 	i asked my guys today if they could describe waht it does, and was ofc met mostly with silence, i know i can describe it, but i'm not sure i know of a term that means the same thing	12:44 PM
 <dkannan> 	raggi: type of slot - not a term as such	12:46 PM
 <raggi> 	dkannan: that's not what defined? is	12:46 PM
 <raggi> 	dkannan: try doing: defined?((1;1))	12:46 PM
 <dkannan> 	raggi: ok	12:47 PM
 <dkannan> 	raggi: some more: defined?(1); defined?(Fixnum); defined?(Object.new); defined?(o = Object.new);	12:51 PM
 <dkannan> 	raggi: it is like how the interpreter sees the world.	12:56 PM
 <dkannan> 	raggi: how does interpreter dry-run sound?	12:56 PM

deepak

#dkannan: 	raggi: just copy-pasted the whole thing	1:04 PM
#raggi: 	the defined?(o = something) is basically a bug i think	1:05 PM
#raggi; 	not 100% on that, but i think it's an AST bug, you can do a similar thing in other ways	1:06 PM
#raggi: 	(that is, you can make local variables come into existence without assigning to them)

# short-circuit
puts defined? foo
false && (foo = "will this be assigned")
puts defined? foo
puts foo.inspect

deepak

#!/usr/bin/env ruby
# profiling Array#push and Array#<< using ruby-prof gem

# BUG: why does "Array#<<" not show-up on the profiler but "Array#push" does

begin
  require "ruby-prof"
rescue LoadError
  require "rubygems"
  require "ruby-prof"

deepak

# in ruby 1.9.2-p0
require 'test/unit'

class Foo < String
end

class ObSpace < Test::Unit::TestCase
  def setup
    @m = "hello"
    @n = Foo.new("hello")

deepak

# -*- coding: utf-8 -*-
# $ ruby -vw foobar.rb 
# ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]
# foobar.rb:1: syntax error, unexpected tINTEGER
# def 1.hello
#      ^
# foobar.rb:3: syntax error, unexpected keyword_end, expecting $end

class Object
  def metaclass

deepak

chunk, bacon = *["chunky", "bacon"]
puts "#{chunk} #{bacon}" #=> chunky bacon

*chunk_bacon = "chunky", "bacon"
puts chunk_bacon.inspect #=> ["chunky", "bacon"]

puts Proc.new {|*_|  _.inspect }.call([12,20]) #=> "[[12, 20]]" 

# can be used to collect multiple arguments in one
puts Proc.new {|*_|  _.inspect }.call(12,20)   #=> "[12, 20]"