MyFunnyDev

javascript closures

Michał Kuklis — Fri, 25 Jun 2010 05:37:54 +0000

For given content:

  <div id="test0">change mediv>
  <div id="test1">change mediv>
  <div id="test2">change mediv>
  <div id="test3">change mediv>

The code:

 for (var i = 0; i < 4; i++) {
   $('#test' + i).click(function(){
     $(this).html(i);
   });
}

will print (every time any of the elements is clicked):

Here is how this could be solved with the closure:

  for (var i = 0; i < 4; i++) {
    (function (i){
      $('#test' + i).click(function(){
        $(this).html(i);
      });
    })(i);
  }

managing gems with rvm named gem sets

Michał Kuklis — Mon, 31 May 2010 03:20:44 +0000

RVM (Ruby Version Manager) is a tool which lets you install and switch between multiple ruby versions. RVM has also something called Named Gem Sets. This is pretty cool because you can create many different gem sets for different types of apps. Here is how to do it (I assume you have rvm already installed if not check this out):

go to your project folder and create new file called .rvmrc
open .rvmrc and add rvm ruby-version@your-gem-set for example rvm ruby-1.9.1@railsgems
close file and type: rvm gemset create your-gem-set (this will create new set)
type gem list (you should see empty list with no gems installed)

It’s almost as you would start with a fresh system

Clojure syntax

Michał Kuklis — Tue, 02 Feb 2010 05:36:49 +0000

Making a note for myself:

(1 2 3 4) // list
[1 2 3 fred] // vector
{:a 1 :b 2 :c 3}, {1 "a" 2 "b"} // map key/value
#{a b c} // set

dfs in ruby :)

Michał Kuklis — Thu, 14 Jan 2010 05:38:42 +0000

I wrote simple dfs in ruby:

def dfs(node, value, queue)
  return false if node.nil?	
  return true if node.data == value
 
  queue.push node.right unless node.right.nil?
  queue.push node.left unless node.left.nil?	
 
  dfs(queue.pop, value, queue)	
end

for node:

class Node
  attr_accessor :left, :right, :data
end

class variables, class instance variables and instance variables in ruby

Michał Kuklis — Wed, 13 Jan 2010 06:03:22 +0000

This was covered multiple times already. I’ve created this little snippet to remember the difference between different types of variables in ruby:

class A
  @@foo = "class variable of the class A"
  @foo = "class instance variable of the class A"
 
  def instance_method
   @foo = "instance variable of the class A"
  end
 
  def self.class_method1
    # class variables are visible to and shared by the instance and class methods
    @@foo
  end
 
  def self.class_method2
    # class instance variables are visible to and shared by the class methods
    @foo
  end	
end
 
p A.new.instance_method # instance variable of the class A
p A.class_method1 # class variable of the class A
p A.class_method2 # class instance variable of the class A
 
class B < A
  @@foo = "class variable of the class B"
  @foo = "class instance variable of the class B"
end
 
p B.class_method1 # class variable in B
# class variable in A is overwritten by one in B !!!
p A.class_method1 # class variable in B
 
p B.class_method2 # class instance variable of the class B
# class instance variable in A is NOT overwritten by one in B !!!
p A.class_method2 # class instance variable of the class A

anemone with hpricot

Michał Kuklis — Mon, 11 Jan 2010 05:06:32 +0000

Anemone is a pretty cool DSL used for web crawling. I used it with Hpricot to get a feeling for what’s possible. Below is a simple example which crawls and scrappes data from a popular polish real estate website otodom:

require 'rubygems'
require 'sanitize'
require 'anemone'
require 'open-uri'
require 'hpricot'
 
#otodom.pl
Anemone.crawl("http://otodom.pl/index.php?mod=search&act=searchResults&qid=46911208", 
{:storage => Anemone::Storage.PStore("crawl1.pstore")}) do | anemone |
 
  # filter out useless pages
  anemone.focus_crawl do |page|
   page.links.delete_if do |x|
    (x.to_s =~ /mod=search&act=searchResults&qid=/).nil? and
    (x.to_s =~ /[a-zA-Z]+-id[0-9]*\.html$/).nil?
   end
  end
 
  # process details pages
  anemone.on_pages_like(/[a-zA-Z]+-id[0-9]*\.html$/) do | page |
     doc = Hpricot(page.doc)
     price =  doc.at("//strong[@id='offerPrice']")
     location = doc.at("//dl[@class='stripeMe'] > dd")
     desc = doc.at("//div[@id='offerDesc'] > p")
     offer_no = doc.at("//div[@id='offerFoot'] p[@class='toLeft']/span/strong")
     created_at = doc.at("//div[@id='offerFoot'] p[@class='toRight']/span/strong")
     photos = doc.search("//div[@id='imageList']/p/a")
  end
end

Academia vs. Business

Michał Kuklis — Wed, 18 Nov 2009 17:05:02 +0000

blocks, procs and lambdas in ruby

Michał Kuklis — Wed, 18 Nov 2009 04:12:20 +0000

Nice post about block, procs and lambdas in ruby by Robert Sosinski.

changing function’s context in javascript

Michał Kuklis — Sat, 31 Oct 2009 04:24:23 +0000

Today I learned how to change the context of a function in javascript. When we do:

function test() {
  this.foo = "Hello from " + this + " context.";
}
test();
alert(foo); // will show "Hello from [object Window] context.";

foo will belong to the global context. In other words global object foo will be created. We can change the context to some other object by doing:

var otherContext = {};
test.call(otherContext);
alert(otherContext.foo); // will show "Hello from [object Object] context."

In this case foo will belong to otherContext.

Gemcutter & Jeweler

Michał Kuklis — Sat, 17 Oct 2009 05:03:47 +0000

More about gemcutter & jeweler can be found here.

Here are the steps how to publish patched gem cloned from github:

1. Append username to gem name in .gemspec or if you use jeweler open Rakefile and edit Jeweler::Tasks section save it and run:

rake gemspec

2. Build gem with:

gem build

3. Push new gem to gemcutter

gem push