For a list of settings of Dutch and Belgium mobile network operators see this page.

Câmara de Lobos

Paul da Serra

Pico do Arieiro

The third highest peak on the island (1818 meters).

North Madeira

In order to enable sorting I first modify the get_paged_list function of the PersonModel class:

function get_paged_list($limit = 10, $offset = 0, $order_column = '', $order_type = 'asc'){
	if (empty($order_column) || empty($order_type))
		$this->db->order_by('id','asc');
	else
		$this->db->order_by($order_column, $order_type);
	return $this->db->get($this->tbl_person, $limit, $offset);
}

The index function of the person controller must be modified as well. I changed the following parts:

• Function parameters
• Get ordering from URI
• Call to model
• Table header

function index($offset = 0, $order_column = 'id', $order_type = 'asc'){
	// checks
	if (empty($offset)) $offset = 0;
	if (empty($order_column)) $order_column = 'id';
	if (empty($order_type)) $order_type = 'asc';
	//TODO: check for valid column
 
	// load data
	$persons = $this->personModel->get_paged_list($this->limit, $offset, $order_column, $order_type)->result();
 
	// generate pagination
	$this->load->library('pagination');
	$config['base_url'] = site_url('person/index/');
	$config['total_rows'] = $this->personModel->count_all();
	$config['per_page'] = $this->limit;
	$config['uri_segment'] = 3;
	$this->pagination->initialize($config);
	$data['pagination'] = $this->pagination->create_links();
 
	// generate table data
	$this->load->library('table');
	$this->table->set_empty(" ");
	$new_order = ($order_type == 'asc' ? 'desc' : 'asc');
	$this->table->set_heading(
		'No',
		anchor('person/index/'.$offset.'/name/'.$new_order, 'Name'),
		anchor('person/index/'.$offset.'/gender/'.$new_order, 'Gender'),
		anchor('person/index/'.$offset.'/dob/'.$new_order, 'Date of Birth (dd-mm-yyyy)'),
		'Actions'
	);
	$i = 0 + $offset;
	foreach ($persons as $person){
		$this->table->add_row(++$i, $person->name, strtoupper($person->gender)=='M'? 'Male':'Female', date('d-m-Y',strtotime($person->dob)),
			anchor('person/view/'.$person->id,'view',array('class'=>'view')).' '.
			anchor('person/update/'.$person->id,'update',array('class'=>'update')).' '.
			anchor('person/delete/'.$person->id,'delete',array('class'=>'delete','onclick'=>"return confirm('Are you sure want to delete this person?')"))
		);
	}
	$data['table'] = $this->table->generate();
 
	// load view
	$this->load->view('personList', $data);
}

Updated June 29th 2010 thanks to Stephen.

The only problem now is pagination doesn’t work any more. As far as I know there is no solution to pass the ordering parameter to CodeIgniter’s pagination class. I think the best solution is to implement your own pagination class. Maybe I’ll discuss that in another post.

The first step is download and install the latest version of NUnit since older versions are not compatible with .NET 4. NUnit version 2.5.5 can be downloaded here.

Now go to Tools -> External Tools:

I think this screen shot explains itself very well. Now its possible to add this external command to a tool bar. To do so go to View -> Toolbars -> Customize:

Press the New button and enter a name. Now open the Commands tab and add the external command (usually External Command 1 when you don’t have any other external commands) to the toolbar:

When clicking the NUnit button in the new toolbar the NUnit GUI starts and loads your test suite.

Canon

Nikon (Nikkor)

Sigma

Tamron

Tokina

References

• Sigma abbreviations
• Overclockers.com.au – Lens Specifications Explained
• Photographers Resource – Tamron Lens Codes
• WonderfulPhotos.com – Photography Acronyms
• Tokina lens catalog
• ParkCameras.com – DSLR Camera Lenses and Abbreviations

*#*#INFO#*#*

In numbers:

*#*#4636#*#*

I have tested this on my HTC Desire (Android 2.1 and 2.2) and in an emulator (Android 2.1). The following screen is shown:

Service menu

In Phone Information you can see some information about the phone, current network and data connection (modify settings or pressing buttons is at your own risk!):

Phone information

For more information about these settings and other menu items see this post.

Update August 15 2010:

In Android 2.2 the service menu is extended with Wifi information.

Watir

First download and install Ruby. If you are familiar with Eclipse, Aptana is a nice web development plugin (see this simple installation tutorial). If you don’t know how to use Ruby, Bas has a nice article about getting started with Ruby.

The second step is install Watir. You can try these examples to see what Watir does.

Testing a simple website

For one of my school projects I had to write a simple test for one of the function of this online calculator. In this tutorial we will test the GCF and LCM function. Start with creating a new Ruby script containing the right requirements and a test case class:

require 'watir'
require 'test/unit'
 
class TC_LCM_GCD < Test::Unit::TestCase
 def test_lcm_gcd
  # ...
 end
end

In order to let Watir start a new browser add the following to the test_lcm_gcd function:

Watir::Browser.default = "ie"
b = Watir::Browser.start("http://www.calcenstein.com/calc/0416.php") # GCF and LCM

If you want to use Firefox for testing, change “ie” to “firefox” and don’t forget to install the plugin. The second line starts a new browser window.

Our goal is to let Watir insert two values (the ‘First Value’ and ‘Second Value’ input field), and then press the ‘Solve’ button. In order to do so we need to know the name or id (or value in some cases) of the input fields and the ‘Solve’ button. Instead of looking at the source I can recommend to use the Firebug add-on for Firefox, and use the inspect function. The ‘First Value’ input is named ‘a’, and the ‘Second Value’ input is named ‘b’. We want to set ‘a’ to 30 and ‘b’ to 45:

b.text_field(:name, "a").set "30"
b.text_field(:name, "b").set "45"

When these values are set, Watir must press the ‘Solve’ button. It appears this button doesn’t have a name or id, so get it by value and execute the click action:

b.button(:value, "Solve").click

Now the click action is executed and the result is printed in the other two input fields (named ‘lcmA’ and ‘gcdA’). Like in all other test cases, the result must be verified. The correct result is LCM = 90 and GCF = 15, so use assertions to check the values:

assert(b.text_field(:name, "lcmA").value == "90")
assert(b.text_field(:name, "gcdA").value == "15")

This simple test case is now complete. The test output should be something like this:

Loaded suite My_test_suite
Started
.
Finished in 5.579 seconds.

1 tests, 2 assertions, 0 failures, 0 errors

Implicit conversion

Implicit conversion (or coercion) is automatic type conversion by the compiler. In C# it does not require a special syntax because the type conversion is safe and no data will be lost. In the following example the value of an integer is stored in a long. This is safe because an integer is 4 bytes (on a 32 bit computer), and a long is 8 bytes. So every value that fits in an integer fits in a long. For a complete conversion table see this page.

int i = 12345678;
long l = i;

It is also possible to cast a derived class to a base class without using a special syntax.

Explicit conversion

Instead of implicit conversion explicit conversion (or casting) is not done by the compiler. It is explicitly defined in the application (i.e. it requires a cast operator). There is a possible risk of losing data when the source and destination have a different size or when the source is converted to a base class. Example:

double d = 10.345;
int i = (int)d;

This example will not compile without the explicit cast operator since a double fits not in an integer. Also the value will lose its precision since an integer does not store decimal values. On this page you can find an explicit number conversion table.

User-defined conversion

In C# it is possible to create your own methods for implicit and explicit conversion. For more information see this article.

Helper functions

The .NET framework has various helper functions for conversion. For example System.Convert and the Parse method of various types (e.g. Int32.Parse).

Boxing and unboxing

C# provides a unified type system. All types are derived from the type “object”. It is possible to convert for example an integer to the type object (boxing) and back (unboxing). The is keyword checks if an object is compatible with a specific type. Example:

class Program
{
 static void Main(string[] args)
 {
  int i = 10;
  object o = i; // boxing
  int j = (int) o; // unboxing
  Console.WriteLine(j);
  if (o is int)
  {
   Console.WriteLine("o is an int");
  }
  Console.ReadKey();
 }
}

“Cast” versus “as”

The as operator is often used for type conversion, and it works more or less the same as the cast prefix:

class Program
{
 public class ClassA { }
 
 static void Main(string[] args)
 {
  ClassA a = new ClassA();
  object o = a;
 
  ClassA a2 = (ClassA)o;
  ClassA a3 = o as ClassA;
 }
}

The difference between these two types of conversion is that the first will throw an exception and the second will return null when the conversion is incorrect:

class Program
{
 public class ClassA { }
 
 static void Main(string[] args)
 {
  int i = 5;
  object o = i;
 
  try
  {
   ClassA a2 = (ClassA)o;
  }
  catch (InvalidCastException ex)
  {
   Console.WriteLine(ex.Message);
  }
 
  ClassA a3 = o as ClassA;
  if (a3 == null)
  {
   Console.WriteLine("Incorrect conversion");
  }
  Console.ReadKey();
 }
}

However, this is not the only difference (see this post by Eric Lippert). When you have a user-defined conversion from class A to B, the cast operator (B)A will run the user-defined conversion while the “as” operator will not. The “as” operator will only consider reference, boxing and unboxing conversions. Like Eric says:

• As: “I don’t know if this conversion is legal or not; we’re going to give it a try and see how it goes.”
• Cast: “I am certain that this conversion is legal and I am willing to take a runtime exception if I’m wrong.”
• As: “I want to know what this object *really is*, not what it is convertible to by some representation-changing specially-defined conversion rule.”
• Cast: “Convert this thing using whatever crazy mechanism you need to do to make it work.”

Performance

This article by Emilio Guijarro gives a good explanation about performance of the cast and “as” operator. He concludes the “as” operator is about 5 times faster than the cast operator. The performance is only going to matter in the million number of casts, and then the performance problem is probably why you need so many cast operations.

Why (not) to use “as”

As said before the “as” operator returns null when the conversion is incorrect. When using this piece of code you can not check if the original object was null:

class Program
{
 public class ClassA { }
 
 static void Main(string[] args)
 {
  ClassA a = null;
  object o = a;
 
  try
  {
   ClassA a2 = (ClassA)o;
  }
  catch (InvalidCastException ex)
  {
   Console.WriteLine(ex.Message);
  }
 
  ClassA a3 = o as ClassA;
  if (a3 == null)
  {
   Console.WriteLine("Incorrect conversion");
  }
  Console.ReadKey();
 }
}

This program will write “Incorrect conversion” while the cast conversion didn’t throw an exception. Also the “is” operator does not help in this case since it returns false when the object is null. A correct pattern could be:

if (o == null)
{
 Console.WriteLine("object is null");
}
else
{
 ClassA a3 = o as ClassA;
 if (a3 == null)
 {
  Console.WriteLine("Incorrect conversion");
 }
}

References

• Casting and type conversion – MSDN
• Boxing and unboxing in C# – C-Sharpcorner
• Difference between “as” and “cast” operators – Eric Lippert

Rhino.Mocks.Exceptions.ExpectationViolationException : IMyInterface.MyVoidFunction; Expected #0, Actual #1.

using (_mock.Record())
{
  Expect.Call(_myMock.GetValue("a")).Return("b");
  /* insert expectation for void function here */
}
 
using (_mock.Playback())
{
  // DoSomething calls the mocked object's GetValue function, which returns 'b' when the parameter is 'a'
  // DoSomething also calls a void function which is located in the interface of the mocked object, so this
  // void function must be mocked too, else the test run will fail
  Assert.AreEqual("b", _myObject.DoSomething("a"));
}

When trying to create an expectation for this void function Visual Studio will give a syntax error:

Expect.Call(_myMock.MyVoidFunction()); // Argument '1': cannot convert from 'void' to 'Rhino.Mocks.Expect.Action'

On the internet I found two solutions to fix this problem. The first solution uses a delegate:

Expect.Call(delegate{ _myMock.MyVoidFunction(); });

The second solution uses a lambda:

Expect.Call(() => _myMock.MyVoidFunction());

Now the test will succeed.

Jailkit installation

First I installed Jailkit by using the following commands:

# cd /tmp
# wget http://olivier.sessink.nl/jailkit/jailkit-2.11.tar.gz
# tar -zxvf jailkit-2.11.tar.gz
# cd jailkit-2.11
# ./configure
# make
# make install

Setting up the jail

Now it’s time to set up the jail directory. Jailed users will see this directory as the root directory of the server. I chose to use /home/jail:

# mkdir /home/jail
# chown root:root /home/jail

By using the jk_init command you can set up the jail. In this tutorial the basicshell, netutils, ssh and limited shell are installed:

# jk_init -v /home/jail basicshell
# jk_init -v /home/jail netutils
# jk_init -v /home/jail ssh
# jk_init -v /home/jail jk_lsh

Add a user

Add a new user with a home directory and bash shell, and don’t forget to change the password:

# useradd -d /home/testuser -m testuser -s /bin/bash
# passwd testuser

Now it’s time to jail this user, use the following command:

# jk_jailuser -m -j /home/jail testuser

Your /etc/passwd should contain something like this now:

testuser:x:1003:1004::/home/jail/./home/testuser:/usr/sbin/jk_chrootsh

Enable bash

By using jk_cp the bash libraries are be copied to the jail:

# jk_cp -v -f /home/jail /bin/bash

Now edit the /home/jail/etc/passwd file and make sure it contains something like this:

testuser:x:1003:1004::/home/testuser:/bin/bash

Also make sure the group exists in /home/jail/etc/group:

testuser:x:1004:

Now try to login with testuser. Look for errors in /var/log/auth.log.

Maintenance

By using jk_update updates on the real system can be updated in the jail. A dry-run will show what’s going on:

# jk_update -j /home/jail -d

Without the -d argument the real update is performed. More maintenance operations can be found here.

Troubleshooting

Make sure the jailed user has a home directory in /home/jail/home. If not create one:

# mkdir -p /home/jail/home/testuser
# chown testuser:testuser /home/jail/home/testuser

References

• How to chroot ssh user using Jailkit
• Jailkit howto – ssh only shell in a chroot
• Jailkit howto – creating a regular shell in a chroot jail