C# on Marko Apfel

Entity Framework, Code First: where is the database?

Sat, 20 Oct 2012 17:26:00 +0200

With Entity Framework 5 in Visual Studio 2012 the code first feature could let you come to the question “Where is the automatically created database located?”

I run in the question after changing the model which throws during the next run this error:

LINQ and ArcObjects

Wed, 12 Sep 2012 15:20:00 +0200

Motivation

LINQ (language integrated query) is a component of the Microsoft. NET Framework since version 3.5. It allows a SQL-like query to various data sources such as SQL, XML etc.

Like SQL also LINQ to SQL provides a declarative notation of problem solving – i.e. you don’t need describe in detail how a task could be solved, you describe what to be solved at all. This frees the developer from error-prone iterator constructs.

Strange error “argument type ‘lambda expression’ is not assignable to parameter type ‘string’”

Sun, 01 Jul 2012 11:08:00 +0200

During playing with EF and LINQ I run in this UI-error:

argument type ‘lambda expression’ is not assignable to parameter type ‘string’

The Compiler themselves states:

Cannot convert lambda expression to type ‘string’ because it is not a delegate type.

xUnit runner eats system diagnostic output

Mon, 07 Nov 2011 13:28:00 +0100

Problem

When using xUnit and constructs like Debug.WriteLine the DbgView-tool does not show the written output anymore.

Solution

Add a new Listener – for example:

Debug.Listeners.Add(new DefaultTraceListener());

"Failure has occurred while loading a type."

Fri, 28 Oct 2011 12:08:00 +0200

Motivation

During programming suddenly this error (“Failure has occurred while loading a type”) was thrown by accessing a artifact of a referenced library.

In such cases I take the assembly fusion logger fuslogvw to search for problems of loading assemblies. Sometimes an old version from a not expected folder is binded. But all bindings were correct.

InternalsVisibleTo, PublicKey and PublicKeyToken

Thu, 27 Oct 2011 14:35:00 +0200

Intro

If you want to test the internals of a productive assembly you must mark the assembly with the InternalsVisibleTo-attribute. This attribute has only one constructor which needs the name of the testing assembly.

Break the mechanism, that GAC-assemblies could only bind to other GAC-assemblies

Tue, 31 May 2011 08:30:00 +0200

Till yet I thought, that if you have an assembly in the GAC all referenced assemblies must also be in the GAC. So a break of this GAC-assembly resolving chain is impossible.

Suppressing Add-in-registration task during build process

Mon, 16 May 2011 07:17:00 +0200

If you develop ArcGIS Add-ins with Visual Studio under limited permissions you get during the build process an error, that the stuff could not be registered.

Normally its enough to run one times this build as an admin. Then all needed information are set and also taken for users with limited access.

Castle Windsor: order of configurations and resulting resolvings

Tue, 03 May 2011 05:46:00 +0200

If different implementations for the same interface are specified without named keys, then a resolving is made in order of the configurations. So the first fitting implementation is taken.

Different implementations for the same interface is a typical scenario for patterns like “chain of responsibility” and “decorator”. If you want to describe such a chain you could use the next handler as a constructor- parameter in the actual one.

Differences by pasting formatted text in Word and OneNote

Sun, 02 Jan 2011 08:54:00 +0100

By pasting formatted text in Word and OneNote both applications act a little bit different. Meanwhile Word supports RTF-formatting OneNote does not.

OneNote could only handle HTML-formatting.

In combination with presenting source code for Visual Studio the Add-in CopySourceAsHtml is available.

Wie spricht man den Lambda-Operator aus?

Wed, 05 May 2010 09:27:00 +0200

Da gibt es unterschiedliche Auffassungen.

Im Englischen:

Func f = x => x * 2; ”x goes to x * 2” ”x maps to x * 2” ”x becomes x * 2” ”x induces x * 2”
Func test = c => c.City == “London”; “c for which c.City equals London”

Im Deutschen:

Gefahren des “cleanup code refactoring” im Zusammenhang mit P/Invoke und übergebenen Strukturen

Wed, 28 Apr 2010 09:40:00 +0200

Problemkontext

So schön auch das automatische “cleanup code refactoring” von ReSharper ist, im Zusammenhang mit Strukturdefinitionen, die als Übergabe-Parameter für unmanaged Code Aufrufe benötigt werden, lauert eine große Gefahr.

Standardmäßig ist im Profil “Full Cleanup” die Option “Reorder type members” auf “Yes” gestellt.

Remote Debugging mit Visual Studio

Tue, 27 Apr 2010 09:38:00 +0200

Das Debuggen einer Applikation auf einem Rechner ohne installiertes Visual Studio gestaltet sich mit dem Remote Debugging Monitor relativ einfach.

Derartige Konstellationen ergeben sich insbesondere dann, wenn ein Debugging von Anwendungen in Produktiv-Umgebungen notwendig wird.

MSB3105: Duplicate ressource parameter

Mon, 25 Jan 2010 05:17:00 +0100

error MSB3105: The item “BALoginForm.resources” was specified more than once in the “Resources” parameter. Duplicate items are not supported by the “Resources” parameter.

Reason

We use two custom cultures to divide between UIs for two customers. At the machine with this error only one custom culture was installed.

Nachtrag: Casting Anti-Pattern

Thu, 29 Oct 2009 12:40:00 +0100

Wie so oft im Leben sind manche Dinge auf den zweiten Blick komplexer als sie auf dem Ersten den Anschein haben.

Es kam die Anfrage, ob es nicht doch einen Unterschied zwischen “as” und “is” gibt & dann wurden noch ein paar Inputs gefunden, dass im Falle des “Überladens von Cast-Operatoren” mögliche Fallen lauern.

Casting Anti-Pattern

Thu, 29 Oct 2009 12:35:00 +0100

in unten stehendem Code ist ein Anti-Pattern, welches immer wieder im ArcObjects-Kontext zu beobachten ist.

if (element is IMapSurroundFrame)

 IMapSurround mapSurround = ((IMapSurroundFrame)element).MapSurround;

..

Es wird eine is-Abfrage gemacht (element is IMapSurroundFrame) und dann ein Stück später der tatsächliche Cast ((IMapSurroundFrame)element).

Visual Studio 2005 and 2008 compatibility with ReSharper

Wed, 21 Oct 2009 08:57:00 +0200

In our team we have developers with Visual Studio 2005 and 2008. Often we have projects which must be coded by a mixed team.

Visual Studio 2005 and 2008 compatibility for project-files

Normally this is no problem because adding projects in Visual Studio 2005 and manually introducing the ToolsVersion=“2.0” attribut in the new csproj-file allows an coexisting working when using two sln-files for Visual Studio 2005 and 2008.

Using images and cursors in resources

Sat, 01 Nov 2008 12:30:00 +0100

Often i see code-constructs like

 1: try

 2: {

 3: string bitmapResourceName = GetType().Name + ".bmp";

 4: Bitmap bitmap = new Bitmap(GetType(), bitmapResourceName);

 5: }

 6: catch (Exception ex)

 7: {

 8: System.Diagnostics.Trace.WriteLine("Invalid bitmap.");

 9: }

The corresponding codetree has the structure:

Hierarchy of log4net-loggers (namespace vs class)

Thu, 20 Mar 2008 10:02:00 +0100

If you want specify log-parameters for loggers of a whole namespace normally you use a scheme like

<logger name=“GrandNS.ParentNS.ChildNS.*” ..

this is the same like

<logger name=“GrandNS.ParentNS.ChildNS” ..

There is no ambiguous name possible, because it is not allowed to define a class with the name of a namespace at the same namespace-level.

Konfigurationfile für eine Library lesen

Thu, 10 May 2007 16:20:00 +0200

Beim Verwenden des Standard-Mechanismus zum Lesen von Konfigurationsdaten wird immer die config-Datei der EXE gelesen.

Soll eine DLL über eine eigene Konfigurationsdatei verfügen, verwendet man die Klasse ExeConfigurationFileMap.

Beispiel:

 1: ExeConfigurationFileMap ecfm = new ExeConfigurationFileMap();

 2: ecfm.ExeConfigFilename = "MyLibrary.dll.config";

 3: Configuration cfg = ConfigurationManager.OpenMappedExeConfiguration(ecfm, ConfigurationUserLevel.None);

 4: AppSettingsSection ass = (AppSettingsSection) cfg.GetSection("appSettings");

 5: string configValue = String.Empty;

 6: if (aSect != null)

 7: {

 8: configValue = ss.Settings["blabla"].Value;

 9: }