deepak’s gists

deepak / ar_add_on_attr_or_base.rb

Created January 6, 2011 11:46

ActiveRecord rails 2.3.9 patch to add an error on the attribute or base otherwise

	# ActiveRecord rails 2.3.9 patch to add an error on the attribute or base otherwise
	module ActiveRecord
	class Errors
	def add_on_attr_or_base(attribute, message = nil, options = {})
	if @base.respond_to?(attribute)
	add(attribute, message, options)
	else
	ActiveRecord::Base.logger.warn "attribute #{attribute} does not exist so we are adding on base"
	add_to_base(message)
	end

deepak / thread_kill.rb

Created January 14, 2011 09:24

Thread#kill works as a script but not in irb

	t = Thread.new { kill }
	puts t.inspect

	# irb eval's code. but then this works as a script but does not work in irb
	# eval "t = Thread.new { kill }; puts t.inspect"

	__END__

	runs successfully when run as a script ie. ruby <filename>
	#<Thread:0x1dc5090 dead>

deepak / thread_join_args.block_and_safe.rb

Created January 14, 2011 09:53

Thread#join will block until the thread exists. We can also pass a timeout to Thread#join. an upper bound for blocking the join call

	#!/usr/bin/env ruby
	# USAGE: ruby <file.rb>

	threads = []
	threads << Thread.new { sleep 10; puts "one" }
	# does not work
	# /tmp/bar.rb:12: undefined local variable or method `kill' for main:Object (NameError)
	# from /tmp/bar.rb:18:in `join'
	# from /tmp/bar.rb:18
	# from /tmp/bar.rb:18:in `each'

deepak / raggi_queue.txt

Created January 14, 2011 11:42

	# https://github.com/rubygems/rubygems-mirror/blob/master/lib/rubygems/mirror/pool.rb
	# also check
	require 'thread'

	class MirrorPool
	def initialize(size)
	@size = size
	@queue = Queue.new
	end

deepak / [TRIVIAL] thread_join_and_status.rb

Created January 14, 2011 12:12

[TRIVIAL] the thread becomes dead after we get the value. also we can pass a timeout value to Thread#join and try to join afterwards

	t = Thread.new { sleep 5; puts 1 }
	puts "status: #{t.status} on #{t.inspect}"
	t.join(1)
	puts "status: #{t.status} on #{t.inspect}"
	t.join(1)
	puts "status: #{t.status} on #{t.inspect}"
	t.join(1)
	puts "status: #{t.status} on #{t.inspect}"
	t.join(1)
	puts "status: #{t.status} on #{t.inspect}"

deepak / exception_handeling.rb

Created January 19, 2011 06:22

Benchmarking exception handeling in ruby.

	# throwing and catching an exception is worse than returning a simple type
	# maybe it is because exceptions have to maintain the backtrace
	# hypothesis: if the code throwing an exception is nested deep then the perf hit will be larger
	# as the backtrace will be bigger
	# the java and lisp communities have had discussions on exceptions before.
	# The LISP guys are smug about the exception handling in their language. dunno why but they are smug about
	# everything. smug lisp weenies...

	require 'benchmark'

deepak / if_case_benchmark.rb

Created January 20, 2011 10:41

benchmark btw if and case statements in ruby

	# asked by dhruvasagar on irc
	# http://stackoverflow.com/questions/2547059/delphi-performance-case-versus-if
	require 'benchmark'

	SO_MUCH = 10_000
	X = 'f'

	# 8 cases
	Benchmark.bmbm do \|x\|
	x.report("case") do

deepak / ruby_core_classes_extend.rb

Created January 21, 2011 07:18

	# is it a bad idea to override ruby core classes
	# ex:
	# 1. overriding functions which almost do the same thing. breaks the principle of surprise. we override
	# Array#size but Array#length is the older definition.
	# 2. overriding array so that the default position starts at 1 rather than 0 and other included modules
	# like Emumerator#each just work. We can do it but it seems very cumbersome and fragile.

	# some good practices given at: http://www.ruby-forum.com/topic/214157
	# do not override core classes, either:
	# 1. add it to the metaclass of the specific object

deepak / groovy_it_operator.rb

Created January 21, 2011 10:31

groovy it operator in ruby

	# goes in an infinite loop. does not work

	class Array
	def each(&blk)
	enum = to_enum
	if block_given?
	it = enum.next
	blk.eval("it=args")
	yield
	else

deepak / wget-list.sh

Created January 24, 2011 06:48

wget-list: manage the list of downloaded files

	#!/bin/sh
	# wget-list: manage the list of downloaded files

	# invoke wget-list without arguments

	# http://www.linux.com/feature/59457
	# http://ubuntuforums.org/showthread.php?t=672074
	# http://www.lifehack.org/articles/lifehack/make-your-idle-computer-work-for-you.html
	# http://decafbad.net/projects/scripts
	# http://www.google.co.in/search?q=wget+queue&ie=utf-8&oe=utf-8&aq=t&rls=com.ubuntu:en-US:unofficial&client=firefox-a

Deepak Kannan deepak