Why aren't code regions allowed within method bodies in VB.NET?

Question

Normally I wouldn't "need" or even consider a ridiculous feature such as code regions within method bodies but: I'm refactoring VB.NET code where methods routinely run five hundred lines and the references are so tightly coupled that the code defies simple refactoring such as method extraction.

And that's why I thought I would try regions within a method body. I just wanted to organize the code for the short term. But the IDE didn't let me (resulted in a compiler error.) I'm just curious as to why? Seems like code regions shouldn't impact the compiler, intellisense etc. Am I missing something? (Still using VS 2005 btw.)

Interesting: This seems to be language specific. It's OK in C# (I didn't check that initially) but not in VB.NET.

public module MyModule
    Sub RunSnippet()
        dim a as A = new A (Int32.MaxValue )

        #region 
        Console.WriteLine ("")
        #end region
       ....

that gets a compiler error but the C# version is ok.

Answer 1

I think code regions probably wouldn't be supported in method bodies since they, as you put it, would be a (somewhat) "ridiculous feature" - However, in C#, this does work, at least in VS 2008 and VS 2010 - just not in VB.NET.

That being said, I would avoid it. Putting regions within a method body would just leads to people making larger methods (since that's the only time when it would be worthwhile), which is something that should be avoided, not encouraged.

If your code:

defies simple refactoring such as method extraction

I would focus, instead, on doing "complex" refactoring (or whatever it takes) to try to break up those methods. There is no way your "four or five hundred lines" long methods are at all maintainable in their current state.

Personally, I would leave them causing "pain" - make it obvious that they need work, right front and center, until you can break them up and refactor out portions.

Answer 2

I don't know about VB, but in C# this has been allowed since 1.0 as far as I'm aware.

Indeed, you can even put code regions in odd places which cross scopes. For example:

class Test
{
    static void Main()
    {
        if (DateTime.Now.Hour > 12)
        {
#region Foo
            Console.WriteLine("Afternoon");            
        }
#endregion
    }
}

Here the region starts within the if statement, but ends outside it. Horrible, but the compiler is fine with it.

What do you mean when you said the IDE didn't "let" you put code in regions? Did you get a compiler error?

Answer 3

This was simply a choice the VB team made when adding the regions feature into version 7 of the Visual Basic language. It was seen as a feature which was useful for organizing at a declaration level and not inside a method and hence was allowed only at that level.

The C# team felt differently about this feature and allow it in many other places. I've always found it surprising that C# #region directives can occur in different declaration contexts.

#region Foo
class Bar {
#endregion

}

The equivalent code is not allowed in VB.

Answer 4

Visual Studio 2003 had them for VB.NET, but feature was removed in Visual Studio 2005 and later. Really annoying when refactoring large procedures, yet you can split the code window.

Honestly, I wish C# would restrict region use because they are overly used. I have a macro that strips them out of all code files when inheriting C# projects.

Another feature removed was the list of overridable methods in the Navigation Bar. I check to see if they re-added this feature for every new version of Visual Studio since 2005.