Sunday, November 23, 2008

C# 4.0 - Overcomplicated?

I've seen C# 4.0 draft and something came into my mind: is this language as simple as Microsoft used to advertise it? Let me show a few C# 4.0 features.

New C# 4.0 features

Dynamic types

  1: dynamic d = GetDynamicObject(…);
  2: d.M(7); // calling methods
  3: d.f = d.P; // getting and settings fields and properties
  4: d[“one”] = d[“two”]; // getting and setting thorugh indexers
  5: int i = d + 3; // calling operators
  6: string s = d(5,7); // invoking as a delegate

C# used to be a static language. Now you can create dynamic types as well.

Optional parameters

  1: public void M(int x, int y = 5, int z = 7){...};

x is mandatory. y and z are optional parameters.

Named parameters

  1: M(z: 3, x: 1);

COM interop

You have to set a cell in Excel now as follows:

  1: ((Excel.Range)excel.Cells[1, 1]).Value2 = "Hello";

In C# 4.0 you can do this thanks to dynamic types:

  1: excel.Cells[1, 1].Value = "Hello";

The need for language improvements

If you look at C# improvements like generics, var, anonymous methods, dynamics etc., we can see big needs behind them. The main reasons are LINQ and COM interoperability improvements. If you know these 'extensions', you can imagine the complexity of LINQ without e.g. var.


Can you remember Perl? It used to be a very promising (scripting) language. You can code/talk Perl on very different levels (I love Perl for this :)). If you don't know that specific level (expressions), you can hardly read/write that code. An example:

  1: print "Hello, world!\n";


  1: say 'Hello, world!'

Does C# walks the same path? Introducing dynamic types to a basically static language, introducing optional and named parameters to a C(++)-like language. I love changes, but these can generate problems.

You can't use e.g. generics at certain companies because some programmers don't understand them (maybe it's not the best example but I hope you can get my idea).

Can you or do you read/write all the following C# 3.5 features?

  • implicitly typed local variables
    var myInt = 0;
  • automatic properties
    class Car
       public string PetName { get; set; }
  • extension methods
    static class MyExtensions
      public static void DisplayDefiningAssembly(this object obj)
      Console.WriteLine("{0} lives here:\n\t->{1}\n", obj.GetType().Name, Assembly.GetAssembly(obj.GetType()));
  • lambda expressions
    Increase lambdaDelegate = value => value * 2;
    Console.WriteLine(string.Format("Lambda expression: {0}", lambdaDelegate(5)));

I think you don't have to use all of them or even read all of them. Unfortunately I'm sure that a lot of developers can't even read many of them.

Wednesday, November 19, 2008

DB optimization

Someone asked me to help him optimize a SQL operation. He said he is using SQLite database but his query is very slow. He tried indices as well, but it takes 1 hour to insert 20 users into his database. It's just 1 minute to insert 7 users without indices. Finally he sent me a query that runs awfully slow (for hours):

SELECT SUM(size) AS s FROM (SELECT DISTINCT hash, size FROM files);


If you define an index on a column, it takes time to maintain it. In this case it took a lot of time to insert new data into the index structure (usually something like a B* tree). He had to insert hundreds of users in one batch. It can worth disabling or deleting indexes before inserting such an amount of new records once. You can recreate or regenerate the indices after running the whole batch.


The SQL query above ran very slow because of the DISTINCT keyword. I advised to try it without DISTINCT and the query ran very fast.


Keep in mind that indices can make insert operations very slow and projections and joins can make a select very slow. It worths to measure performance and use real usage statistics to tune your database and queries.

Tuesday, November 18, 2008

Silverlight 2 Designer crash

Visual Studio 2008 crashed every time I opened a XAML file. No crash dump, no messages, VS just disappeared. I used Silverlight designer before and worked fine. One day it just started crashing.

I've removed everyting from my computer containing Silverlight in it's name. I ran Microsoft Silverlight Tools Beta 2 for Visual Studio 2008 after that. Silverlight 2 content appeared in my browser, but Visual Studio 2008 keeped crashing. I reran Visual Studio 2008 SP1 setup. It didn't help.

Finally I tried Microsoft® Silverlight™ Tools for Visual Studio 2008 SP1. It works. XAML designer works, Visual Studio 2008 doesn't crash!!! It seems Silverlight chainer doesn't contain SP1 tools. So don't forget to install it manually if you have similar problems.