Tommy’s stuff: Blog

Remove all children of an element in JavaScript

Mon, 22 Jan 2018 00:00:00 +0000

The DOM API does not provide a function to remove all children of an element. A straightforward way to do this is to remove each child element:

function removeAllChildren(e) {
  while(e.firstChild) {
    e.removeChild(e.firstChild);
  }
}

This works, but there is a faster alternative: select all children using the DOM Range API and delete the contents of the range. This is supported in all modern browsers (in Internet Explorer since version 9).

function removeAllChildren(e) {
  var r = document.createRange();
  r.selectNodeContents(e);
  r.deleteContents();
  r.detach();
}

If you need backward compatibility with older browsers, you can check whether the range API is supported and use the old method otherwise:

var removeAllChildren = document.createRange
  ? function(e) {
    var r = document.createRange();
    r.selectNodeContents(e);
    r.deleteContents();
    r.detach();
  } : function(e) {
    while(e.firstChild) {
      e.removeChild(e.firstChild);
    }
  };

Shuffle an array in JavaScript

Thu, 18 Jan 2018 00:00:00 +0000

If you have an array, and you want to randomly shuffle its elements, you can use the Fisher–Yates shuffle algorithm. In JavaScript, it looks like this:

function shuffle(xs) {
  var i = xs.length, x, rnd;
  while(i) {
    rnd = Math.floor(Math.random() * i);
    i -= 1;
    x = xs[i];
    xs[i] = xs[rnd];
    xs[rnd] = x;
  }
}

Update SysInternals Suite via PowerShell

Mon, 05 Sep 2016 00:00:00 +0000

SysInternals Suite is a collection of troubleshooting tools for Windows, developed by Microsoft. You can download the tools as a ZIP-file, that you can extract into a directory, and run the individual applications without having to install them.

When I find out there’s a new version of the SysInternals Suite, I have to click the link to the website, click the download link, save the ZIP-file, open the ZIP-file and select the destination folder to extract to. After having done this for the umpteenth time, I wrote the following PowerShell-script to automate the process:

$url = 'https://download.sysinternals.com/files/SysinternalsSuite.zip'
$zipPath = 'd:\dev\tools\SysinternalsSuite.zip'
$tempFolder = 'd:\dev\tools\temp-sys-internals'
$folder = 'd:\dev\tools\sys-internals'

Write-Host 'Downloading' $url 'to' $zipPath
$web = New-Object System.Net.WebClient
$web.DownloadFile($url, $zipPath)

Write-Host 'Extracting' $zipPath 'to' $tempFolder
Add-Type -assembly 'System.IO.Compression.FileSystem'
[System.IO.Compression.ZipFile]::ExtractToDirectory($zipPath, $tempFolder)

Write-Host 'Copying files from' $tempFolder 'to' $folder
Copy-Item (Join-Path $tempFolder '*') $folder

Write-Host 'Removing temporary files'
Remove-Item $zipPath
Remove-Item $tempFolder -Recurse

The above script installs the SysInternals Suite in the directory d:\dev\tools\sys-internals. Please change the variables for your specific installation, before running the script.

Synchronize KeePass via Amazon S3

Fri, 13 May 2016 00:00:00 +0000

I use KeePass to manage my passwords, but I need to access these passwords from my PC at home, and my PC at work. To keep these databases synchronized, I put a copy on Amazon’s cloud storage service S3. Until recently, I synchronized manually: whenever I add a new password entry on 1 PC, I upload it to S3 (using Cyberduck), and when I’m on the other PC I download it from S3 (unless I forget).

This week, I discovered there are plugins for KeePass that enable you to open/save/synchronize your passwords with cloud storage systems like Dropbox, Google Drive, or Amazon S3. For my system, I use the KeeCloud plugin. Because I don’t want to give the KeeCloud plugin full access to my Amazon S3 account, I figured out how to create an AWS user with the minimal permissions necessary for accessing only my password database. Here’s a description of the full process. This example uses the bucket name passwords and the password database name passwords.kdbx.

Configure Amazon S3

Skip this step if you already have a bucket where you want to store your password database.

Log in to the AWS Management Console
Navigate to S3
Create a bucket for your password database (e.g. passwords)

Create AWS user

To have maximum security, it’s important to create a dedicated AWS user that has limited access to only your password database (and nothing else on AWS).

Navigate to Identity and Access Management
Navigate to the Users-screen
Create a new user, give it a name
Copy the Security Credentials of the user (Access Key ID and Secret Access Key): you will need these later to sign in
Navigate to the created user, to the Permissions-tab
Open the Inline Policies-view, and press Create User Policy
Select Custom Policy, and press Select

Give the policy a name, and enter the following Policy Document:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:DeleteObject",
        "s3:GetObject",
        "s3:PutObject"
      ],
      "Resource": [
        "arn:aws:s3:::passwords/passwords.kdbx",
        "arn:aws:s3:::passwords/passwords.kdbx.tmp"
      ]
    }
  ]
}

Install and configure KeeCloud

Download the latest version of KeeCloud from the Downloads-page (download the PLGX-file)
Put the PLGX-file in the KeePass installation directory:
- 32-bit Windows: C:\Program Files\KeePass Password Safe 2
- 64-bit Windows: C:\Program Files (x86)\KeePass Password Safe 2
Start (or restart) KeePass
Open the database you want to synchronize
Navigate to the menu File > Synchronize > Synchronize with URL…
Enter the following information:

URL s3://passwords/passwords.kdbx

User name The Access Key ID of your AWS user

Password The Secret Access Key of your AWS user

URL	`s3://passwords/passwords.kdbx`
User name	The Access Key ID of your AWS user
Password	The Secret Access Key of your AWS user

Instead of synchronizing a local file with S3, you can also just open the database directly from S3, using the menu File > Open > Open URL…

Spelling out numbers in words (French)

Tue, 15 Sep 2015 00:00:00 +0000

Here’s an algorithm (in pseudo-code) for spelling out numbers in French words (e.g. convert 123 to "cent vingt-trois"):

-- spell out an integer number in words (French)
function numberToWordsFrench(number)
  var result, iteration, iterationText, hundreds, hundredsText

  if number = 0
    return "zero"
  end
  
  result ← ""
  iteration ← 1
  
  -- iterate per 3 digits (starting with last)
  while number > 0
    hundreds ← number modulo 1000 -- e.g. 23456 → 456
    number ← floor(number / 1000) -- e.g. 23456 → 23
    
    if hundreds > 0
      -- 3 digits to text
      hundredsText ← getHundredsText(hundreds)
      if iteration > 1
        -- mille, million, …
        iterationText ← getIterationText(iteration)
        hundredsText ← hundredsText + iterationText
        if hundredsText = "un mille "
          hundredsText ← " mille "
        end
      end
      
      result ← hundredsText + result
    end
    
    iteration ← iteration + 1
  end
  
  return trim(result)
end

function getHundredsText(number)
  var result, hundreds, tens
  
  result ← ""
  
  hundreds ← floor(number / 100) -- e.g. 456 → 4
  if hundreds > 0
    number ← number modulo 100 -- e.g. 456 → 56
    if hundreds > 1
      -- deux cents, trois cents, …
      result ← result + getLessThanTwentyText(hundreds) + " cents"
    else
      result ← result + "cent"
    end
  end
  
  if number > 0
    if hundreds > 0
      -- space after "cent(s)"
      result ← result + " "
    end
    
    if number < 20
      -- < 20 ⇒ look up
      result ← result + getLessThanTwentyText(number)
    else
      tens ← floor(number / 10) -- e.g. 42 → 4
      number ← number modulo 10 -- e.g. 42 → 2
      
      case tens
        when 7
          -- soixante dix, soixante onze, …
          result ← result + "soixante"
          number ← number + 10
        when 8
          if number > 0
            result ← result + "quatre-vingt"
          else
            result ← result + "quatre-vingts"
          end
        when 9
          -- quatre-vingt dix, quatre-vingt onze, …
          result ← result + "quatre-vingt"
          number ← number + 10
        otherwise
          -- vingt, trente, quarante, …
          result ← result + getTensText(tens)
      end
      
      if number > 0
        if number = 1 and tens ≠ 8
          result ← result + " et un"
        else
          result ← result + "-" + getLessThanTwentyText(number)
        end
      end
    end
  end
  
  return result
end

function getLessThanTwentyText(number)
  case number
    when 1 return "un"
    when 2 return "deux"
    when 3 return "trois"
    when 4 return "quatre"
    when 5 return "cinq"
    when 6 return "six"
    when 7 return "sept"
    when 8 return "huit"
    when 9 return "neuf"
    when 10 return "dix"
    when 11 return "onze"
    when 12 return "douze"
    when 13 return "treize"
    when 14 return "quatorze"
    when 15 return "quinze"
    when 16 return "seize"
    when 17 return "dix-sept"
    when 18 return "dix-huit"
    when 19 return "dix-neuf"
    otherwise error
  end
end

function getTensText(tens)
  case tens
    when 2 return "vingt"
    when 3 return "trente"
    when 4 return "quarante"
    when 5 return "cinquante"
    when 6 return "soixante"
    otherwise error
  end
end

function getIterationText(iteration)
  case iteration
    when 1 return ""
    when 2 return " mille "
    when 3 return " million "
    when 4 return " milliard "
    when 5 return " billion "
    when 6 return " billiard "
    when 7 return " trillion "
    when 8 return " trilliard "
    otherwise return " ??? "
  end
end

Spelling out numbers in words (Dutch)

Mon, 14 Sep 2015 00:00:00 +0000

Here’s an algorithm (in pseudo-code) for spelling out numbers in Dutch words (e.g. convert 123 to "honderddrieëntwintig"):

-- spell out an integer number in words (Dutch)
function numberToWordsDutch(number)
  var result, iteration, iterationText, hundreds, hundredsText

  if number = 0
    return "nul"
  end
  
  result ← ""
  iteration ← 1
  
  -- iterate per 3 digits (starting with last)
  while number > 0
    hundreds ← number modulo 1000 -- e.g. 23456 → 456
    number ← floor(number / 1000) -- e.g. 23456 → 23
    
    if hundreds > 0
      -- 3 digits to text
      hundredsText ← getHundredsText(hundreds)
      if iteration > 1
        -- duizend, miljoen, …
        iterationText ← getIterationText(iteration)
        hundredsText ← hundredsText + iterationText
        if hundredsText = "eenduizend "
          hundredsText ← "duizend "
        end
      end
      
      result ← hundredsText + result
    end
    
    iteration ← iteration + 1
  end
  
  return trim(result)
end

function getHundredsText(number)
  var result, hundreds, tens
  
  result ← ""
  
  hundreds ← floor(number / 100) -- e.g. 456 → 4
  if hundreds > 0
    number ← number modulo 100 -- e.g. 456 → 56
    if hundreds > 1
      result ← result + getLessThanTwentyText(hundreds)
    end
    result ← result + "honderd"
  end
  
  if number > 0
    if hundreds > 0 and number ≤ 12
      result ← result + "en"
    end
    
    if number < 20
      -- < 20 ⇒ look up
      result ← result + getLessThanTwentyText(number)
    else
      tens ← floor(number / 10) -- e.g. 42 → 4
      number ← number modulo 10 -- e.g. 42 → 2
      
      if number > 0
        -- een, twee, drie, …
        result ← result + getLessThanTwentyText(number)
        if number = 2 or number = 3
          result ← result + "ën"
        else
          result ← result + "en"
        end
      end
      
      -- dertig, veertig, …
      result ← result + getTensText(tens)
    end
  end
  
  return result
end

function getLessThanTwentyText(number)
  case number
    when 1 return "een"
    when 2 return "twee"
    when 3 return "drie"
    when 4 return "vier"
    when 5 return "vijf"
    when 6 return "zes"
    when 7 return "zeven"
    when 8 return "acht"
    when 9 return "negen"
    when 10 return "tien"
    when 11 return "elf"
    when 12 return "twaalf"
    when 13 return "dertien"
    when 14 return "veertien"
    when 15 return "vijftien"
    when 16 return "zestien"
    when 17 return "zeventien"
    when 18 return "achttien"
    when 19 return "negentien"
    otherwise error
  end
end

function getTensText(tens)
  case tens
    when 2 return "twintig"
    when 3 return "dertig"
    when 4 return "veertig"
    when 5 return "vijftig"
    when 6 return "zestig"
    when 7 return "zeventig"
    when 8 return "tachtig"
    when 9 return "negentig"
    otherwise error
  end
end

function getIterationText(iteration)
  case iteration
    when 1 return ""
    when 2 return "duizend "
    when 3 return " miljoen "
    when 4 return " miljard "
    when 5 return " biljoen "
    when 6 return " biljard "
    when 7 return " triljoen "
    when 8 return " triljard "
    otherwise return " ??? "
  end
end

Spelling out numbers in words (English)

Fri, 11 Sep 2015 00:00:00 +0000

Here’s an algorithm (in pseudo-code) for spelling out numbers in English words (e.g. convert 123 to "one hundred twenty-three"):

-- spell out an integer number in words (English)
function numberToWordsEnglish(number)
  var result, iteration, iterationText, hundreds, hundredsText

  if number = 0
    return "zero"
  end
  
  result ← ""
  iteration ← 1
  
  -- iterate per 3 digits (starting with last)
  while number > 0
    hundreds ← number modulo 1000 -- e.g. 23456 → 456
    number ← floor(number / 1000) -- e.g. 23456 → 23
    
    if hundreds > 0
      -- 3 digits to text
      hundredsText ← getHundredsText(hundreds)
      if iteration > 1
        -- thousand, million, …
        iterationText ← getIterationText(iteration)
        hundredsText ← hundredsText + iterationText
      end
      
      result ← hundredsText + result
    end
    
    iteration ← iteration + 1
  end
  
  return trim(result)
end

function getHundredsText(number)
  var result, hundreds, tens
  
  result ← ""
  
  hundreds ← floor(number / 100) -- e.g. 456 → 4
  if hundreds > 0
    number ← number modulo 100 -- e.g. 456 → 56
    result ← result + getLessThanTwentyText(hundreds) + " hundred"
  end
  
  if number > 0
    if hundreds > 0
      -- space after "hundred"
      result ← result + " "
    end
    
    if number < 20
      -- < 20 ⇒ look up
      result ← result + getLessThanTwentyText(number)
    else
      tens ← floor(number / 10) -- e.g. 42 → 4
      number ← number modulo 10 -- e.g. 42 → 2
      
      -- thirty, forty, …
      result ← result + getTensText(tens)
      
      if number > 0
        -- one, two, three, …
        result ← result + "-" + getLessThanTwentyText(number)
      end
    end
  end
  
  return result
end

function getLessThanTwentyText(number)
  case number
    when 1 return "one"
    when 2 return "two"
    when 3 return "three"
    when 4 return "four"
    when 5 return "five"
    when 6 return "six"
    when 7 return "seven"
    when 8 return "eight"
    when 9 return "nine"
    when 10 return "ten"
    when 11 return "eleven"
    when 12 return "twelve"
    when 13 return "thirteen"
    when 14 return "fourteen"
    when 15 return "fifteen"
    when 16 return "sixteen"
    when 17 return "seventeen"
    when 18 return "eighteen"
    when 19 return "nineteen"
    otherwise error
  end
end

function getTensText(tens)
  case tens
    when 2 return "twenty"
    when 3 return "thirty"
    when 4 return "forty"
    when 5 return "fifty"
    when 6 return "sixty"
    when 7 return "seventy"
    when 8 return "eighty"
    when 9 return "ninety"
    otherwise error
  end
end

function getIterationText(iteration)
  case iteration
    when 1 return ""
    when 2 return " thousand "
    when 3 return " million "
    when 4 return " billion "
    when 5 return " trillion "
    when 6 return " quadrillion "
    when 7 return " quintillion "
    when 8 return " sextillion "
    otherwise return " ??? "
  end
end

Synchronize Google Calendar & Contacts with iOS 6

Mon, 24 Aug 2015 00:00:00 +0000

I still use a 4th generation iPod Touch. Although I’m stuck with iOS 6, it still works fine for doing the things I use it for: e-mail, contacts, calendar, alarm clock, reading RSS-feeds (Reeder, reading from Feedly), Twitter (using Tweetbot), and Pocket.

For e-mail, I use the GMail application. For contacts and calendar, I use Apple’s native Contacts and Calendars apps, synchronized with my Google account via the Exchange protocol. Until recently, this worked fine. I had offline access to my contacts and calendar events, and it synchronized when I was online.

About a month ago, synchronization stopped working. I don’t get any error message, it just doesn’t synchronize anymore. Today, I solved the problem by removing the Exchange account, and performing the following steps.

Synchronized calendars: add a Google account

Go to “Settings › Mail, Contacts, Calendar › Add Account › GMail”
Enter the following information:

Name your full name

Email your e-mail address

Password your Google account password

Description a description of the account
Select which services you want to synchronize: E-mail, Calendars, Notes (I only synchronize calendars)

Name	your full name
Email	your e-mail address
Password	your Google account password
Description	a description of the account

Synchronized contacts: add a CardDAV account

Go to “Settings › Mail, Contacts, Calendar › Add Account › Other › Add CardDAV Account”
Enter the following information:

Server google.com

User Name your e-mail address

Password your Google account password

Description a description of the account

Server	google.com
User Name	your e-mail address
Password	your Google account password
Description	a description of the account

Messaging protocols

Thu, 19 Mar 2015 00:00:00 +0000

While investigating messaging protocols for communication between devices and systems, I collected a list of articles, documents, presentations and specifications. Because this might be useful for other developers, I decided to share it here. The protocols I investigated are AMQP, MQTT, CoAP, and STOMP.

Update: I received a link to a series of articles about the essentials of MQTT, which I added to the list.

AMQP

MQTT

CoAP

STOMP

Comparisons

ASCII, Unicode and UTF‑8

Mon, 30 Sep 2013 00:00:00 +0000

In the following video, Tom Scott gives an overview of the history of ASCII, Unicode and UTF-8, providing a great explanation how it works.
youtu.be/MijmeoH9LT4 (9:37)

Properly using and implementing the IDisposable pattern

Fri, 16 Nov 2012 00:00:00 +0000

IDisposable is a pattern in .NET that is used to implement deterministic cleanup of unmanaged resources. .NET has a garbage collector, but that is only used to manage memory, not resources like I/O (file handles, sockets, …). While in C++ destructors are called deterministically when an object goes out of scope, finalizers in C# get called by the garbage collector, but we can’t determine when that will happen (indeterministic deallocation). Don’t depend on the garbage collector for unmanaged resources!

Properly disposing resources

The IDisposable-interface has a single method void Dispose(). This method is used to clean up the disposable object and release the unmanaged resources it holds. To make sure that you always call it, even if an exception occurs in the code between creating the object and calling its Dispose-method, you should use the try-finally-construct, like this:

var x = new X(); // X is a class that implements IDisposable
try
{
  // do something with x
}
finally
{
  x.Dispose();
}

Because this pattern is so common, C# has the using-construct that does this more succinctly:

using (var x = new X())
{
  // do something with x
}

The advantage of this construct is that you can easily nest it without writing a lot of code:

using (var stream = new FileStream(fileName, FileMode.Create, FileAccess.Write))
{
  using (var writer = new StreamWriter(stream, Encoding.UTF8))
  {
    foreach (string line in lines)
    {
      writer.WriteLine(line);
    }
  }
}

Or with less indentation and curly braces:

using (var stream = new FileStream(fileName, FileMode.Create, FileAccess.Write))
using (var writer = new StreamWriter(stream, Encoding.UTF8))
{
  foreach (string line in lines)
  {
    writer.WriteLine(line);
  }
}

This is (more or less) equivalent to the following code:

var stream = new FileStream(fileName, FileMode.Create, FileAccess.Write);
try
{
  var writer = new StreamWriter(stream, Encoding.UTF8);
  try
  {
    foreach (string line in lines)
    {
      writer.WriteLine(line);
    }
  }
  finally
  {
    writer.Dispose();
  }
}
finally
{
  stream.Dispose();
}

Properly implementing `IDisposable` in your own classes

Here’s the minimal proper implementation of IDisposable for a regular class that can be inherited (i.e. is not sealed):

public class MyDisposableType : IDisposable
{
  ~MyDisposableType()
  {
    // the finalizer also has to release unmanaged resources,
    // in case the developer forgot to dispose the object.
    Dispose(false);
  }
 
  public void Dispose()
  {
    Dispose(true);
 
    // this tells the garbage collector not to execute the finalizer
    GC.SuppressFinalize(this);
  }
 
  protected virtual void Dispose(bool disposing)
  {
    if (disposing)
    {
      // clean up managed resources:
      // dispose child objects that implement IDisposable
    }
 
    // clean up unmanaged resources
  }
}

In the classes that derive from such a disposable class, you don’t have to implement the entire pattern again: you can just override the Dispose(bool disposing)-method to add extra clean-up code. Just make sure you call the base-method (after the added code, in a finally-block):

public class MyDerivedDisposableType : MyDisposableType
{
  protected override void Dispose(bool disposing)
  {
    try
    {
      if (disposing)
      {
        // clean up managed resources:
        // dispose child objects that implement IDisposable
      }
 
      // clean up unmanaged resources
    }
    finally
    {
      // always call the base-method!
      base.Dispose(disposing);
    }
  }
}

If your class is sealed (so there can be no derived classes), you cannot have virtual methods. To properly implement the IDisposable-pattern, you could make the Dispose(bool disposing)-method private and not virtual:

public sealed class MySealedDisposableType : IDisposable
{
  ~MySealedDisposableType()
  {
    // the finalizer also has to release unmanaged resources,
    // in case the developer forgot to dispose the object.
    Dispose(false);
  }
 
  public void Dispose()
  {
    Dispose(true);
 
    // this tells the garbage collector not to execute the finalizer
    GC.SuppressFinalize(this);
  }
 
  private void Dispose(bool disposing)
  {
    if (disposing)
    {
      // clean up managed resources:
      // dispose child objects that implement IDisposable
    }
 
    // clean up unmanaged resources
  }
}

GitHub & Gist

Thu, 22 Mar 2012 00:00:00 +0000

I decided to create a GitHub-account, specifically to manage the code snippets I occasionally publish on this blog via Gist. Now you get nice syntax-coloring, and it’s easier for me to manage and update the snippets.

My GitHub account-name is tommy-carlier, and you can find my code snippets here.

Removing diacritics from a string

Thu, 17 Nov 2011 00:00:00 +0000

Recently I had to write a function that removes all diacritics from a string (e.g.: turning José into Jose). Searching the web, I quickly found the blog post “Stripping is an interesting job” by Michael Kaplan. His code is simple and good, but I saw some opportunities for optimizations (obvious stuff): because we know the approximate length (actually the maximum length) of the resulting string, we could give the StringBuilder-instance an initial capacity equal to the length of the original string. In some simple cases I actually like using a char-array instead of a StringBuilder, because it has even less overhead. Another obvious optimization is to check whether the original string is not empty. Here’s my optimized version:

using System;
using System.Globalization;
using System.Text;
 
namespace TC
{
  // Removes diacritics from a string
  //
  // Original version by Michael Kaplan: 
  // → http://blogs.msdn.com/b/michkap/archive/2007/05/14/2629747.aspx
  //
  // Optimized version by Tommy Carlier:
  // → http://www.tcx.be/blog/2011/remove-diacritics/
  public static class DiacriticsRemover
  {
    public static string RemoveDiacritics(this string text)
    {
      if (text == null) throw new ArgumentNullException("text");
 
      if (text.Length > 0)
      {
        char[] chars = new char[text.Length];
        int charIndex = 0;
 
        text = text.Normalize(NormalizationForm.FormD);
        for (int i = 0; i < text.Length; i++)
        {
          char c = text[i];
          if (CharUnicodeInfo.GetUnicodeCategory(c) != UnicodeCategory.NonSpacingMark)
          {
            chars[charIndex++] = c;
          }
        }
 
        return new string(chars, 0, charIndex).Normalize(NormalizationForm.FormC);
      }
 
      return text;
    }
  }
}

Google Analytics in ASP.NET

Thu, 04 Mar 2010 00:00:00 +0000

Here’s a little C# function I occasionally use to insert a Google Analytics-snippet in an ASP.NET website. It takes a Google Analytics-ID as an argument, which you can leave blank in debug-mode (to not render the snippet). It uses the recently introduced asynchronous loading method (which doesn’t block the rendering of your website). It’s not literally the same snippet you can find on the Google Analytics site, but it does the same thing (only with a slightly smaller dynamically built JavaScript-snippet).

using System;
using System.Web;
 
namespace TC
{
  public static class GoogleAnalytics
  {
    public static string RenderScript(string googleAnalyticsID)
    {
      return string.IsNullOrEmpty(googleAnalyticsID)
        ? ""
        : "<script>"
        + "var _gaq=_gaq||[];"
        + "_gaq.push(['_setAccount','" + googleAnalyticsID + "']);"
        + "_gaq.push(['_trackPageview']);"
        + "(function(d,s){"
        + "var e=d.getElementsByTagName(s)[0],"
        + "x=d.createElement(s);"
        + "x.async=1;"
        + "x.src='"
        + (HttpContext.Current.Request.IsSecureConnection
            ? "https://ssl" : "http://www")
        + ".google-analytics.com/ga.js';"
        + "e.parentNode.insertBefore(x,e)}(document,'script'))</script>";
    }
  }
}

I usually keep the Google Analytics-ID in my application settings (web.config), which allows me to use a different one for different deployments (or an empty one for debugging). So I have a second function (in a SiteUtilities-class) that doesn’t take an argument, but takes the Google Analytics-ID from the settings:

public static string RenderGoogleAnalyticsScript()
{
  return TC.GoogleAnalytics.RenderScript(Settings.Default.GoogleAnalyticsID);
}

In my master-page, I then use the following snippet to insert it into the body of the page (note that you have to use the fully qualified type name, including namespace):

<%= MyNamespace.SiteUtilities.RenderGoogleAnalyticsScript() %>

if-read-do-while-read – part 2

Fri, 08 Jan 2010 00:00:00 +0000

I just received a comment on my previous post about the if-read-do-while-read construction. Tanton suggests that I could create a method that encapsulates this construction, using delegates for the before, during and after steps. Here’s a quick version of an extension method on IDataReader that does this:

public static class DataReaderExtensions
{
  public static void ReadAll(
    this IDataReader reader,
    Action before,
    Action<IDataRecord> during,
    Action after)
  {
    if (reader == null) throw new ArgumentNullException("reader");

    if (reader.Read())
    {
      if (before != null)
      {
        before();
      }
      
      do
      {
        if (during != null)
        {
          during(reader);
        }
      }
      while (reader.Read());
      
      if (after != null)
      {
        after();
      }
    }
  }
}

And here’s a rewrite of the HTML-example, using this extension method:

StringBuilder html = new StringBuilder();
using (IDataReader reader = command.ExecuteReader())
{
  reader.ReadAll(
    () => html.Append("<ul>"),
    record => html.AppendFormat("<li>{0}", record.GetValue(0)),
    () => html.Append("</ul>"));
}

It’s surely shorter, but I’m not entirely convinced it’s cleaner.

if-read-do-while-read

Tue, 29 Dec 2009 00:00:00 +0000

Here’s a construction I occasionally need when reading items from a IDataReader: to execute some code before and after reading through the IDataReader, but only if there are rows in the IDataReader.

One option is to use a boolean variable that determines whether the collection has items, like this:

using (IDataReader reader = command.ExecuteReader())
{
  bool hasRows = false;
  while (reader.Read())
  {
    if (!hasRows)
    {
      hasRows = true;
      Before();
    }

    During();
  }

  if (hasRows)
  {
    After();
  }
}

But the following construction (which I call the if-read-do-while-read construction) does not need the boolean variable and is cleaner:

using (IDataReader reader = command.ExecuteReader())
{
  if (reader.Read())
  {
    Before();

    do
    {
      During();
    }
    while (reader.Read());

    After();
  }
}

Here’s a practical example: creating HTML-code with a UL-list for the data, but only if there are items:

StringBuilder html = new StringBuilder();
using (IDataReader reader = command.ExecuteReader())
{
  if (reader.Read())
  {
    html.Append("<ul>");

    do
    {
      html.AppendFormat(
        "<li>{0}",
        reader.GetValue(0));
    }
    while (reader.Read());

    html.Append("</ul>");
  }
}

You could use the same technique on an IEnumerable<T>, but you wouldn’t be able to use foreach anymore:

using (var enumerator = collection.GetEnumerator())
{
  if (enumerator.MoveNext())
  {
    Before();

    do
    {
      var item = enumerator.Current;
      During();
    }
    while (enumerator.MoveNext());

    After();
  }
}

NDepend

Thu, 12 Nov 2009 00:00:00 +0000

A while ago, I received an e-mail from Patrick Smacchia, offering me a license for NDepend and asking me whether I could try it out, give some feedback and if I liked it, maybe I could blog about my experience with NDepend. Because I was already subscribed to the RSS-feed of Patrick’s blog, I knew about NDepend and how it could help developers write better code. I like trying out stuff like this, but somehow I hadn’t found time to install and properly test it. I was already using Visual Studio’s Code Analysis (FxCop) and StyleCop to analyze my code and improve its quality, so I never had the right incentives to use additional tools. But it would be rude to just say no to Patrick, so I decided to give it a try.

After installing it (which just means downloading: NDepend is a portable application that doesn’t really have to be “installed”), I started Visual NDepend (the GUI version of NDepend) and was greeted with a start page that looks like the Visual Studio start page. I decided not to just jump in and try stuff, but to first watch some of the screen casts and tutorials on the NDepend website. And I’m glad I did. After trying to analyze some of my projects, I discovered that NDepend produces a lot of data, reports and graphs that only make sense after you have learnt what it all means. This is a tool that you have to learn how to use and how to interpret its results. The user interface is very flexible, but also a bit overwhelming. But because I don’t really have an idea how I would design a UI for an application like this, I can’t really criticize it.

Comparing it to FxCop and StyleCop is not really fair. There is some overlapping functionality between the 3 tools, but NDepend offers a lot more. First of all, FxCop and StyleCop just analyze your code according to fixed rules and the result is a bunch of errors and warnings. NDepend can also be used like this, but the rules are not fixed and are defined in CQL, a query language that looks and feels like SQL, but allows you to query code constructs. The advantage of this approach is that you can write ad-hoc queries to gain insight in your code (or someone else’s assemblies). Here’s an example of a CQL query:

WARN IF Count > 0 IN SELECT TOP 10 TYPES WHERE NbMethods > 20 ORDER BY NbMethods DESC

This query will generate a warning if your code has classes (and structs) with more than 20 methods. All the built-in rules are written as CQL queries, which you can just modify (or you could just create additional rules).

Another area of analysis that NDepend offers that FxCop and StyleCop do not have is the visual views of your projects. There’s a metrics treemap that shows the proportions of different metrics of your project (methods, types, fields, …) and there are 2 ways to show dependencies: a dependency graph and a dependency matrix. While the dependency graph looks familiar and very graphical, it fails when there are too many elements and dependencies. This is not a failure of NDepend, but just a limitation of dependency graphs in general. Dependency matrices on the other hand are great to understand dependencies, even when there are a lot of elements, but they are less intuitive and you have to learn how to use them and interpret what you see.

My conclusion is that NDepend is a great tool to analyze your code and improve its quality, but it takes getting used to. You have to learn how to use it and how to interpret the results you get. I feel like I have just seen the tip of the iceberg. NDepend also contains a console-application, and can be automated and integrated in your build process (MSBuild, NAnt, …). It has add-ins for Visual Studio and Reflector, and can be used to compare different versions of a code base (for example: to see if compatibility is broken).

If you want to try it yourself, I suggest you first watch the screen casts, download NDepend and start analyzing some of your projects. Another suggestion I have is to start reading Patrick Smacchia’s blog, because he has written about some cool things you can do with NDepend. He also explains how he has analyzed some existing .NET applications (Paint.NET, NHibernate, SharpDevelop, …) and even how he uses NDepend to find what has changed between different versions of the .NET Framework BCL.

Awesome videos on Channel 9 this week

Fri, 02 Oct 2009 00:00:00 +0000

Channel 9 has always produced nice videos with interviews, or weekly shows (This Week on Channel 9, Ping), but this week they have exceeded themselves in quality and awesomeness. I especially liked the following videos:

Reactive Framework (Rx) Under the Hood: part 1, part 2
The Visual Studio Documentary: part 1, part 2
C9 Lectures: Dr. Erik Meijer – Functional Programming Fundamentals, Chapter 1 of 13

Besides being a fan of This Week on Channel 9 and Ping, I also loved the series “The History of Microsoft” (25 episodes) a while ago. I think Channel 9 is still revolutionary (related to the videos), despite the buggy forum.

Calctor 2.1.2

Tue, 28 Jul 2009 00:00:00 +0000

I’ve just made a small update to Calctor. I added the option to use comma as a decimal separator.

You can download it from Box.

for-i-repeat 1.1

Sun, 31 May 2009 00:00:00 +0000

I just uploaded a new version of for-i-repeat. The only major changes are:

The location and size of the window are now remembered (stored in a settings-file)
The visual style has been improved (uses more recent version of the TC Libraries)

You can download it from Box.

Twitter

Thu, 02 Apr 2009 00:00:00 +0000

I’ve been trying out Twitter for about a week now. I’m still a bit skeptical about it, but I can see at least 1 advantage: there’s a very close contact between followers and followees. It’s a lot easier to write a quick tweet to someone than it is to comment on their blog. There’s a very convenient bi-directional communication. The 140 character limit is something to get used to, but it also makes you think about what you write. I do like the conventions of replying to someone or mentioning someone via @, or referencing an event via #.

My twitter address: @tommycarlier.

for-i-repeat

Sun, 15 Feb 2009 00:00:00 +0000

I just finished developing a small tool called for-i-repeat that can duplicate a text-fragment a number of times using a counter. The reason I needed this is for the following scenario: at work we have a machine that has 50 databases that all have the same schema, but different data. If I want to modify the schema of all 50 databases, I create a SQL script that applies the modifications to 1 database, put USE Database01 in front of it, and run it 50 times, each time modifying the USE-statement with the next database number. for-i-repeat allows me to convert this input:

USE Database{0:00}
ALTER TABLE …

into this output:

USE Database01
ALTER TABLE …
USE Database02
ALTER TABLE …
USE Database03
ALTER TABLE …
…
USE Database50
ALTER TABLE …

A real time-saver! To format the counter {0}, you can use the full range of .NET numeric formatting options, including hexadecimal formatting ({0:X}).

You can download it from Box.

Visual Dooby 0.1

Sun, 11 Jan 2009 00:00:00 +0000

I just uploaded an initial version of Visual Dooby, a portable lightweight database client.

This initial release is quite limited. You can currently only connect to a SQL Server database, the database browser only displays tables, views and columns, and you can save the results of a query to an XML-file.

Some nice features are the advanced customizations when saving to XML, the visualization of data types in the result grid and the grid row numbering.

You can download it from Box.

.NET BCL proposal: read‑only collection interfaces

Tue, 09 Dec 2008 00:00:00 +0000

As a result of this thread on Channel 9, here’s a proposition for a simple enhancement of the .NET BCL, related to collections.

If a class wants to expose a collection of items, the best thing to do is expose the collection as an abstract interface, so the internal class that is used can be changed without changing the API. If you want to expose a read-only collection, the options you have are IEnumerable<T>, ICollection<T> or IList<T>. IEnumerable<T> represents a read-only collection that can be enumerated, but you can’t ask it how much elements it has. ICollection<T> and IList<T> represent collections that could be read-only, but this can only be checked at runtime and not defined at compile-time.

My proposal is to add 2 additional interfaces IReadableCollection<T> and IReadableList<T> that contain a subset of the members of ICollection<T> and IList<T> that can be performed on read-only collections. ICollection<T> could then implement IReadableCollection<T> and IList<T> could implement IReadableList<T> (and also ICollection<T>, like it does now). Adding these interfaces would not break existing code, they would be fully backward compatible and would not even require changes to the classes that implement ICollection<T> and IList<T>: they would automatically also implement the new interfaces (because ICollection<T> and IList<T> implement IReadableCollection<T> and IReadableList<T>).

Here’s what the interface hierarchy would look like:

public interface IEnumerable<T> : IEnumerable
{
  IEnumerator<T> GetEnumerator();
}

public interface IReadableCollection<T> : IEnumerable<T>
{
  int Count { get; }
  bool Contains(T item);
  void CopyTo(T[] array, int arrayIndex);
}

public interface IReadableList<T> : IReadableCollection<T>
{
  T this[int index] { get; }
  int IndexOf(T item);
}

public interface ICollection<T> : IReadableCollection<T>
{
  void Clear();
  void Add(T item);
  bool Remove(T item);
  bool IsReadOnly { get; }
}

public interface IList<T> : ICollection<T>, IReadableList<T>
{
  T this[int index] { get; set; }
  void Insert(int index, T item);
  void RemoveAt(int index);
}

Google Chrome

Sun, 07 Sep 2008 00:00:00 +0000

This week the tech news was primarily dominated by the launch of Google Chrome. I was going to write about it earlier, but because EVERYBODY was blogging about it, I didn’t think I could add anything useful (I’m not a “me too”-blogger). But now that the hype is starting to fade a bit, I want to express my opinion about it.

My first impression: I was pleasantly surprised about the smooth installation, the fast startup and the general performance. But the thing I loved the most, was the subtle and minimalist UI. It has very little features, but I think most normal people (= non-tech) don’t need many features.

Of course, the main criticism you hear about Chrome is the fact that it’s a Google product. And Google has created it for data mining purposes, to track your every move. I don’t believe this. I think they created it because they NEED a healthy web. They NEED browsers that are powerful enough to run Google’s web applications (GMail, Google Docs, Google Maps, …). And I'm not naïve: I know that Chrome is also a new channel to strengthen Google’s position on the web.

To counter the paranoia, I’ll refer to Matt Cutts’ blog post “Preventing paranoia: when does Google Chrome talk to Google.com?”. The only thing I’m a bit worried about is the auto-suggest function that sends whatever you type in the omnibar to Google. Luckily, you can turn it off (see Matt’s post). Matt goes into great detail about what gets sent to Google and what gets downloaded from Google. His conclusion should silence the paranoids: You can double-check me because the browser is open-source.

Microsoft releases Photosynth

Thu, 21 Aug 2008 00:00:00 +0000

Yesterday, Microsoft released the highly anticipated Photosynth to the public. Now everyone can start synthing (ooh, new verb).

Awesome technology!

Making password TextBox more secure

Mon, 21 Apr 2008 00:00:00 +0000

If you use a Windows Forms TextBox to let your users enter a password, you should know it’s not very secure: external applications can get the password from the TextBox by sending it the WM_GETTEXT message. There are even applications written specifically to do this. If you want to prevent this, you can use the following control that is derived from System.Windows.Forms.TextBox and that prevents external applications from getting the password via WM_GETTEXT. Just use it instead of the regular TextBox for password fields.

using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;
 
namespace TC.WinForms
{
  /// <summary>Represents a text box control for entering passwords.</summary>
  [ToolboxItem(true), ToolboxBitmap(typeof(TextBox))]
  public class PasswordTextBox : TextBox
  {
    private const int
      WM_GETTEXT = 0x000D,
      WM_GETTEXTLENGTH = 0x000E,
      EM_SETPASSWORDCHAR = 0x00CC;
    
    private bool _isAccessingText;
    
    /// <summary>Initializes a new instance of the <see cref="T:PasswordTextBox" /> class.</summary>
    public PasswordTextBox()
    {
      UseSystemPasswordChar = true;
    }
 
    /// <summary>Gets or sets the current text in the <see cref="T:TextBox"/>.</summary>
    /// <returns>The text displayed in the control.</returns>
    public override string Text
    {
      get
      {
        _isAccessingText = true;
        try { return base.Text; }
        finally { _isAccessingText = false; }
      }
      set
      {
        _isAccessingText = true;
        try { base.Text = value; }
        finally { _isAccessingText = false; }
      }
    }
 
    /// <summary>Gets the length of text in the control.</summary>
    /// <returns>The number of characters contained in the text of the control.</returns>
    public override int TextLength
    {
      get
      {
        _isAccessingText = true;
        try { return base.TextLength; }
        finally { _isAccessingText = false; }
      }
    }
 
    /// <summary>Processes Windows message.</summary>
    /// <param name="m">The Windows <see cref="T:Message" /> to process.</param>
    protected override void WndProc(ref Message m)
    {
      switch (m.Msg)
      {
        case WM_GETTEXT:
        case WM_GETTEXTLENGTH:
          if (!_isAccessingText)
          {
            m.Result = IntPtr.Zero;
            return;
          }
          break;
        
        case EM_SETPASSWORDCHAR:
          return;
      }
 
      base.WndProc(ref m);
    }
  }
}

EDIT: I added code to also ignore EM_SETPASSWORDCHAR which can also be used to make the password visible.
EDIT 2 (2008-04-22): I fixed the documentation tags in the code.
EDIT 3 (2008-04-22): I fixed some bugs that denied access to the password from within your program.

PowerShell + Speech API

Fri, 01 Feb 2008 00:00:00 +0000

I just read a blog post about using the Speech API in command-line scripts. So I had to try it but instead of using JScript, I wrote it in PowerShell. It’s so easy and fun:

$v = New-Object -ComObject SAPI.SpVoice
$v.Speak("Who let the dogs out?")

TC Animation Library

Thu, 01 Nov 2007 00:00:00 +0000

I just released the source code of a Windows Forms animation library I wrote last weekend. I first didn’t want to release the source code because the animations looked terrible.

I knew the code I wrote was good and should work, but it ran horribly. The UI would just freeze when 1 animation ran; running multiple animations simultaneously was impossible. This morning I woke up and had a mad idea: to slow down the animation. The reason the UI would freeze was because all the animation steps were performed on the UI-thread and apparently the animation system flooded the UI-thread with work to do, so the normal UI-activities (painting controls, handling input, …) were severely delayed. By adding 1 line of code (Thread.Sleep(5);) to the animation loop, I managed to make the animations run fluently while keeping the UI responsive.

You can find the source code in the Channel 9 Sandbox, here.

Calctor 2.1.1

Sun, 01 Jul 2007 00:00:00 +0000

I’ve just made a small update to Calctor. No additional functionality has been added. I just made some modifications so you can install it on Windows Vista.

You can download it from Box.

Tommy’s stuff: Blog

Remove all children of an element in JavaScript

Shuffle an array in JavaScript

Update SysInternals Suite via PowerShell

Synchronize KeePass via Amazon S3

Configure Amazon S3

Create AWS user

Install and configure KeeCloud

Spelling out numbers in words (French)

Spelling out numbers in words (Dutch)

Spelling out numbers in words (English)

Synchronize Google Calendar & Contacts with iOS 6

Synchronized calendars: add a Google account

Synchronized contacts: add a CardDAV account

Messaging protocols

AMQP

MQTT

CoAP

STOMP

Comparisons

ASCII, Unicode and UTF‑8

Properly using and implementing the IDisposable pattern

Properly disposing resources

Properly implementing IDisposable in your own classes

GitHub & Gist

Removing diacritics from a string

Google Analytics in ASP.NET

if-read-do-while-read – part 2

if-read-do-while-read

NDepend

Awesome videos on Channel 9 this week

Calctor 2.1.2

for-i-repeat 1.1

Twitter

for-i-repeat

Visual Dooby 0.1

.NET BCL proposal: read‑only collection interfaces

Google Chrome

Microsoft releases Photosynth

Making password TextBox more secure

PowerShell + Speech API

TC Animation Library

Calctor 2.1.1

Properly implementing `IDisposable` in your own classes