A nice series of posts about Covariance and Contravariance in a hypothetical future version of C# by Eric Lippert.

1. Covariance and Contravariance in C#, Part One
2. Covariance and Contravariance in C#, Part Two: Array Covariance
3. Covariance and Contravariance in C#, Part Three: Member Group Conversion Variance
4. Covariance and Contravariance in C#, Part Four: Real Delegate Variance
5. Covariance and Contravariance In C#, Part Five: Higher Order Functions Hurt My Brain
6. Covariance and Contravariance in C#, Part Six: Interface Variance
7. Covariance and Contravariance in C# Part Seven: Why Do We Need A Syntax At All?
8. Covariance and Contravariance in C#, Part Eight: Syntax Options
9. Covariance and Contravariance in C#, Part Nine: Breaking Changes
10. Covariance and Contravariance in C#, Part Ten: Dealing With Ambiguity

Eric added another part:

11. Covariance and Contravariance, Part Eleven: To infinity, but not beyond

I moved the Google chart API wrapper development to CodePlex and published a first Alpha release of the source code. Several more releases should follow in the coming weeks, focusing initially on completing the API and changing some things I'm not really happy about.

After the initial release I plan to work on adding designers to make integrating the charts in your ASP.NET applications easier.

From Rands:

Here is an audacious goal for your resume: to get you to a point in your career where you no longer need a resume. It’s the point that in your chosen industry people know who you are and what you are capable of. And they want you doing it at their companies.

The documentation for the DoesUserHavePermissions method starts hopeful:

"The DoesUserHavePermissions method of the SPPermissionCollection class returns a value that indicates whether the current user has the specified permissions."

But it goes downhill in the "return value" section:

"true if the current user has the specified permissions; otherwise, raises an access denied exception and prompts the user for authentication."

It is not exceptional for a user to not have permissions, so raising an exception in those cases is not something you would expect to happen; especially since the method returns a boolean, which does support the false value.

A general design guideline for .Net development as described in the Framework design guidelines (p183-188) is: "DO NOT use exceptions for the normal flow of control, if possible."

Saw the new (?) chart API  yesterday and so far I am impressed with the amount of options you have when you generate charts. For the moment the only limitation is that you're limited to 50k requests per day, but that should be enough for most uses (esp. when you use some smart caching).

To make using the API just a bit easier I started with a wrapper in C#; for now it only supports the most basic options for the 2D and the 3D piecharts, but the more to come soon.

If anybody is interested in helping complete the wrapper, let me know and I'll host the source on CodePlex.

Nice, you can use any IEnumerable as the source for you LINQ queries.

class Program {
    static void Main(string[] args) {

         var result = from x in GetSequence(12) where (x%2) == 0 select x;

         foreach (var x in result) {
             Console.WriteLine(x);
         }

        Console.ReadLine();

    }

    static IEnumerable<int> GetSequence(int max) {

        for (int i = 0; i < max; i++) yield return i;

    }
}

A nice surprise today when the mailman brought 4 new books:

1. Programming Pearls, 2nd Edition by Jon Bentley
2. The No Asshole Rule by Robert I. Sutton, PhD
3. Mastering Regular Expressions, 3rd edition by Jeffrey E.F. Friedl
4. Code Complete, 2nd Edition by Steve McConnell

1,2 and 4 I consider required reading for any serious developer, allthough I have only read Code Complete myself.

Now the only thing left is to actually read all the books I have collected in the last couple of weeks.

I. M. Wright's Hard Code is a collection of 49 columns Eric Brechner wrote for the Interface magazine at Microsoft from June 2001 till April 2007. The topics of the columns range from software development to career development to being a better manager. And along the way give you great insight in the process of software development at Microsoft.

The best column is "Where's the beef? Why we need quality", which describes the change Microsoft needed to make when the primary users switched from enthusiasts to consumers and enterprises. Customers that want a turnkey solution - you turn it on and it works. The key to making the switch is, according to Eric, raising the quality bar and focus on customer issues. And the three areas to work on are:

• Better design and code
• Better instrumentation and test
• Better supportability and recovery

Highly recommended.

Also read Eric's blog, where he posts a column every month.