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Ok, this should be a nobrainer for most of C# developers, me included. Still it happened to me and believe me I was dumbstruck.
I wrote a piece of code like the one below:

namespace TestInheritance
{
public class BaseClass
{
public BaseClass(string parameter) {}
}

public class ChildClass : BaseClass
{
public ChildClass() {}
}
}

Nothing special here but on compile time you get an error: “No overload for method ‘BaseClass’ takes ’0′ arguments“. Doh! how come? We don’t expect this to happen ussually but the little devil here is the inheritance and the non default constructor of the base class. When the constructor of the child class is called, it calls first the constructor of the base class with the same parameters. But if the compiler does detect a non default constructor it will not create the default one. So you get this error.

Cheers!

Once upon a time in Developer Land, a developer was instructed to build a page that will show the great achievements of the ancients. He diligently started to create a model and used all that he could think of in order to make it good and make its employers proud. He added text and used nice fonts and alignment tags. He used lists to enumerate battles and deeds, and images to depict the stories.

The developer was good in his work and always printed his masterpieces at InternetExplorer’s shop because they were good friends and got to know each other well. And so his latest work got printed there also and it was looking marvelous.

Unfortunately this developer never got to read all 100 Commandments passed down to developers and stopped just short of 57 where it said:

“All tags should be finished by /> or </ …>”

But his friend, the apprentice from InternetExplorer shop knew him well, and if he found a tag not looking like it should he tried to make the best out of it and it was always good.

One day the employers hired a new developer and he was good also, but this one had read the commandments and even though he did not remember them all he had a tool that checked those rules and saw that in his colleague work an <img> tag was missing the end tag and he added it. When printing it at InternetExplorer shop it was looking fine. But there was you see something wrong, as this infamous tag was looking at first like this:

<img id=”imgAchievement” >

but after the second developer with his tool had modified it, it looked like this:

<img id=”imgAchievement” alt=”" />

Now the apprentice at InternetExplorer shop saw this but did not know where is the image that he should put in place and he said to himself that the developer erred and he went about his work and everything was good.

But one day a client said “I don’t like the guys at InternetExplorer shop and I want to use FireFox shop to print” and so he did, but there the apprentice of FireFox was a genius and knew all commandments and when looking at the <img> tag, he saw it was not saying where the image was and so he went about and did what he knew was right and showed there a picture of the whole artwork. But this was not good for the customer and so they tried to fix it but the developer could not speak with the apprentice from FireFox shop because they spoke different languages and only knew what the client said and so they struggled for what seemed to be an eternity.

Then the original developer remembered that a long time ago another client used to print this work at FireFox shop and that there was no problem and so he said “Why don’t we give this customer what I gave the customer from a long time ago ?”. And this was good ’cause the print was fine and wonderful and this because of one tiny thing. The old print had the old <img> tag which the apprentice from FireFox shop saw it was wrong and incomplete and ignored the troublemaker.

But our story does not end here because the new developer was a perfectionist and his proofing tool never failed and when he saw that the model was wrong again he modified it unaware of the troubles it would bring. A while later another client went and used the FireFox shop and the problems were there again. But this one was determined to find out why, and so he took the long journey to the city where FireFox Inc. had shop and through endless discussions and sign languages he found what the problem was, and then he was struck. He did not need that <img> tag, it was not doing anything but trouble and so he removed it and that model was still printed for years to come even on the shop of Safari Inc.

Conclusion

You see young developers we all must abide by the commandments, because by them work also the print apprentices ,and while some learn our habbits and move and make shop in other countries calling themselves FireFox 2 or FireFox 3.0.3 or Internet Explorer 6.1 or 7.0 they all know the commandments. And if we make the model by those commandments we can be sure the prints are as we envision them.

Damn, I knew it would come to this … probably gonna take a holiday …

For the nostalgic ones here are some movies from past fallouts:

The intro from Fallout1

This is the famous “War never changes …” story from the intro of Fallout2. It took quite some time to find one that has the sound in good quality.

And finally the intro from Fallout3

Yesterday I cam across an issue while integrating a project in our CruiseControl.Net (CC). We needed a file from a project to be checked out always on the CC server. This is impossible with the current implementation of CC because when it tries to get the latest version from VSS it would crash, because the combination of parameters that CC sends to VSS is such that it cannot ignore locally checked out files.

VSS is actually called using the executable “ss.exe”. This accepts an option for the get command called “-GWS”. The problem is that the configuration section of CC does not support this parameter so we don’t have any way to tell VSS about skipping checked out files.

The solution looks simple although it caused me some headaches. You just have to  create a batch file that calls “ss.exe” with the right parameters. Below is the file:

@echo off

IF %1==history GOTO lhistory
IF NOT %1==history GOTO lget

:lhistory
“c:\Program Files\Microsoft Visual SourceSafe\ss.exe” %*
GOTO lend

:lget
“c:\Program Files\Microsoft Visual SourceSafe\ss.exe” %* -GWS
GOTO lend

:lend

@echo on

So what does this? It looks at the first parameter of the command sent by the CC and if it is “history” then it would just call the “ss.exe” with the parameters received from CC otherwise it would add another parameter “-GWS”. Why the branch? because the history command does not support the option GWS and you’d get errors.

To use this just replace the name of the executable of VSS in your ccnet.config file to use the batch file and not “ss.exe”. Like this:

<executable>c:\Program Files\Microsoft Visual SourceSafe\SS.bat</executable>

Of course this can be further improved and the idea used for other purposes.

Happy integration!

This week I did alot of work with FormView and of course databinding when I encountered strange cases of data not being posted back to the business objects that it was bound to. It did give me a hard time but in the end the answer was simple. Take a look below:

<asp:formview ID=”frmAddress” runat=”server” DataSourceID=”odsAddress”>

     <ItemTemplate>

        <table cellspacing=”10″>

            <tr runat=”server” id=”trMainAddress”>

                <td style=”width:200px;” valign=”top”>

                    <b style=”font-size:large”>Main address:</b>

                </td>

                <td valign=”top”>

                    <asp:Textbox ID=”txtAddress” runat=”server”

                         Text=’<%# Eval(“AddressAsString”) %>‘>

                   </asp:Textbox >

                </td>

            </tr>

        </table>

    </ItemTemplate>

</asp:formview>

The reason was the striked out code at line 4. Because the table row has a runat attribute and an ID,  it is regarded as a server control.

An example on what happens can be easily understood by the syntax change for getting a refference to the textbox txtAddress:

// table row does not have runat and id

TextBox txt = (TextBox)frmLabelOnly.FindControl(“txtAddress”);

// table row has runat and id set

TextBox txt =

   (TextBox)(frmLabelOnly.FindControl(“trMainAddress”).FindControl(“txtAddress”));

In the case of the row having an id and runat attribute, the formview simply does not see the textbox because it’s on a level below the controls list. and cannot thus gather the information entered by the user and cannot send this data to the dataobject that it was bound to. And of course it can give you a massive headache

Cheers.

Hilarious …

Check this out : http://www.thewebsiteisdown.com/salesguy.html

I have a side project on reflection where I try to reproduce Lutz Roeder’s Reflector in such a way as to allow me to inspect several issues within my projects. This has led me to research into all kinds of issues from MSIL to C# code model and Reflection, the latest one becoming one of my favorite topics from .NET technologies.

My lattest hurdle was to overcome the devious “FileNotFoundException” when trying to resolve a type which is not in the main loaded assembly for reflection.

What happens? Let’s suppose you load an assembly which you want to inspect using reflection. You would use something like:

Assembly assembly = Assembly.LoadFile(path);
Type[] types = assembly.GetTypes();
MethodInfo[] methods = types[0].GetMethods();
ParameterInfo[] parameters = methods[0].GetParameters();

Then you start the usual work of gettting the types and then get the methods of one of the types and then of course try to see something like the parameters of one of the methods. Ain’t reflection great?

NO. Not if you don’t know how to use it. Because when you hit the line where you want to load the parameters of a method, the application will crash with a “FileNotFoundException” when the dll inspected is not in the same directory as the executable that is loading that assembly. Why the hell is that happening. Well I scoured the net for an answer and all where giving partial responses but none were actually giving me a sollution.

Let’s consider the following.

namespace A
{
   public class C1
   {
   }
}
 
namespace B
{
   public class C2
   {
      public void MyMethod(A.C1 param1)
      {
      }
   }
}

And let’s consider that the namespaces A and B are declared in separate projects and thus result in two different dlls and the project that defines namespace B references the project that defines namespace A.

Now you want to load the “B.dll” to inspect the parameters from method “MyMethod” and you use the code I described above. Here the runtime will fail because he does not have a definition of the class C1, only of the class C2 which he already loaded and he will try to load the dll from the current directory (the directory of the running assembly – not A or B, but you program which inspects B). If the “A.dll” is not located there he will try in GAC and if that fails he will throw an exception. How do you fix this? Well you have the choice to copy the “A.dll” in your running directory or registed in GAC but hell, it is not nice and sometimes not possible.

What you can do is to instruct the application domain to call a custom method defined by you when he needs to load an assembly.

AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(CurrentDomain_AssemblyResolve);

static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
{
Assembly ass =
    Assembly.LoadFile(AppDomain.CurrentDomain.RelativeSearchPath + args.Name.Substring(0, args.Name.IndexOf(“,”)) + “.dll”);
return ass;
}
 

What I told the domain here is to call tyeh CurrentDomain_AssemblyResolve method and there I made an assumption. When you compile the namespace B, in it’s debug directory the dll of namespace A is also copied. So if you load the assembly of namespace b from it’s debug directory, in the same directory we will have also the assembly of A. So we will load the assembly from there

Simple and effective. This approach solves also the error “Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.”

Cheers

Today I want to talk about a strange issue and my workaround.

Scenario: you have an UpdatePanel and a button outside it. You want upon an asyncronous postback to execute some custom javascript on the button outside the UpdatePanel. Normally this would be done by inserting a javascript from codebehind, either by using ClientScriptManager.RegisterScript or by adding a literal control which is actually a simple script. Well, this does not work during asyncronous postbacks, or at least not as it normally should.

The document.GetElementById is returning always null when calling from an updatepanel with an ID of an element outside the updatepanel. So how to run that javascript?

Subscribe a javascript function to the EndRequest event of the PageRequestManager:

<script language=”javascript” type=”text/javascript”>
   function EndRequestHandler()
   {
      document.getElementById(‘myButton’).style.visibility = “visible”;
   }
   Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
</script>

What this does is to define a function and then set it to be executed after successfully asyncronous postback.

Cheers!

I never thought to live this day. I have Vista for over an year now and I have never seen the dreaded blue screen on it. I thought it was a thing of the past, an pre-Vista feature . Still it happened. I tried running the Windows version of the TCPDump and the moment packets started flying through the network pipeline I was presented with the blue screen. Still this happened once in 1.3 years so I can say it’s a pretty good record so far.

Vista is the most stable Windows version I worked with and even though it’s a resource hog, on a high end machine it moves like it should.

Cheers.

Since the Microsoft Ajax was released, a lot of ASP.Net developers began using UpdatePanel for streamlining their applications and indeed the WWW starts to seem a little bit more fluent nowadays.

Unfortunately UpdatePanel is not used always in the right places or in the right way, some applications begin to feel clumsy and slow and you’re thinking WHY?! Below I compiled a small list of tips and tricks on how and where to use an UpdatePanel.

• In web.config use this:

<system.web.extensions>
    <scripting>
        <scriptResourceHandler enableCompression=“true” enableCaching=“true”/>
    </scripting>
</system.web.extensions>
This will improve script handling by adding compression and caching

• When deploying to a live server use: <compilation debug=“false”> 
• Don’t use AJAX to update the complete page by putting everything in a UpdatePanel. You want to save time and raffic when running the web page. Never update parts of the web site that can be changed using JavaScript and DHTML (DOM).
• Have in mind that there are a couple of visitors that have JavaScript disabled or using a web browser with an older or less JavaScript implementation like the most mobile devices have. What does your visitor see if everything is disabled? I don’t recommend to have the full web site available as a JavaScript disabled version!
• Cache the same requests on client-side web browser or implement any caching on the web server.
• Remember that the page lifecycle is the same also during an asyncronous postback. That means that the Page_Load for example is executed also during an asyncronous postback. The IsPostback will be true in an asyncronous postback also.
• Set the UpdateMode to “conditional” in the update panel

There are more,  feel free to add your own