When is a .NET namespace implemented by a .NET Framework component?

Question

(Yet another question from my "Clearly I'm the only idiot out here" series.)

When I need to use a class from the .NET Framework, I dutifully look up the documentation to determine the corresponding namespace and then add a "using" directive to my source code:

using System.Text.RegularExpressions;

Usually I'm good to go at this point, but sometimes Intellisense doesn't recognize the new class and the project won't build. A quick check in the Object Browser confirms that I have the right namespace. Frustration ensues.

Using HttpUtility.UrlEncode() involved adding the appropriate directive:

using System.Web;

But it also required adding a reference to .NET Framework Component for System.Web, i.e. right-click the project in Solution Explorer, select Add Reference and add System.Web from the .NET tab.

How might I discern from the documentation whether a .NET namespace is implemented by a .NET Framework Component that must be referenced? I'd rather not hunt through the available components every time I use a namespace on the off chance that a reference is needed.

(For those who like to stay after class and clean the erasers: Will Organize Usings > Remove and Sort also remove references to componenents that are not used elsewhere in the project? How do you clean up unnecessary references?)

Answer 1

You'll note that the documentation (e.g. http://msdn.microsoft.com/en-us/library/system.web.httputility.aspx) tells you the name of the assembly/DLL that the class should be found in, along with the class's namespace.

Namespace: System.Web
Assembly: System.Web (in System.Web.dll)

On a side note, I know it can be a little dear, but Resharper makes things like this so much easier. If you're a serious developer, you may want to consider investing in a license. For the eraser-cleaners, Resharper adds a handy little "Find Code Dependent on Module" item to the right-click menu on references in the Solution Explorer. It's not quite an automatic cleanup, but it makes it a lot easier to see whether something's still being used by your project.

Answer 2

Check out this link for UrlEncode:

Namespace: System.Web

Assembly: System.Web (in System.Web.dll)

The Assembly line tells you which dll to reference.