Extension Methods (part 2)

re: Extension Methods (part 2)

Keith Matzen — Fri, 12 Jan 2007 21:36:10 GMT

Will we have the ability to add an Interface to a type?

Would we be able to add a virtual Interface to a type for use with Generics?

One of the problems with Generics is that existing Interfaces don't tell you enough about the types capabilities. For example, it would be nice to be able to distinguish between Numeric and Non-numeric or Integer and Floating Point types.

re: Extension Methods (part 2)

VBTeam — Sat, 13 Jan 2007 06:01:56 GMT

Hi Keith,

No, you will not be able to add an Interface to a type without directly modifying its definition. We did have some plans to implement "Dynamic Interfaces" in order to enable type safe duck typing, which would enable the scenarios you descrube. but this feature was cut from Orcas because of scheduling constraints. However, I will forward your request over to the language design team and let them know that you are interested in this feature so that they can consider it for inclusion in a later version of the product.

-Scott

re: Extension Methods (part 2)

Anthony D. Green, MCPD — Sat, 13 Jan 2007 09:42:35 GMT

Those scheduling constraints that seem to continually screw over the language until the next version are starting to become bothersome.

If the CLR isn't changing then VB could theoretically have shorter development cycles with smaller features sets all emitting backwards compatable IL. At least then "until a future version" wouldn't feel like "We're going to leave you disappointed and bitter for another two years". VB 2003 to 2005 and now 2005 to 2007.

That all said this looks good and I'm happy to see the flexibility you have with this as far as ByVal and ByRef, etc. Thanks for saving the occassional useful feature for this version.

I disagree with the Modules only rule for one reason only - that I disagree with the auto-hoisting requirement on Modules. I love the auto-shared quality of modules and don't mind that I can't nest them, though often I'd like to. What I would like though is to turn off the auto-static import of a module (with an attribute or something) otherwise I have to make all my utility classes non-module classes so that their members don't clutter my intellisense. I'm sure you might get to this issue 4 versions from now but I thought I'd throw my name into the feature hat now.

Still, great job- - I look forward to this next version daily (though I'll miss Dynamic Interfaces soo much).

-Anthony D. Green, MCPD

P.S. "One big problem was the fact that it was different than C#" is the worst possible way to start out a justification for a VB language design decision. I can infer that you meant it different but still it stings a little to hear it.

Articles about Extension Methods

The Visual Basic Team — Wed, 24 Jan 2007 22:11:31 GMT

Here is a list of links to posts on this blog that talk about extension methods: Extension Methods Part

Extension Methods Best Practices (Extension Methods Part 6)

The Visual Basic Team — Sun, 11 Mar 2007 02:40:09 GMT

This is the sixth installment in my series of posts about extension methods. You can find links to the

Extension methods missing from System.String in the .NET Framework 3.5 (Beta 1)

Paulo Morgado — Sun, 13 May 2007 21:41:21 GMT

Extension methods are a feature of the new C# language specification (also available in Visual Basic

Extension methods missing from System.Array in the .NET Framework 3.5 (Beta 1)

Paulo Morgado — Sun, 13 May 2007 21:51:58 GMT

Extension methods are a feature of the new C# language specification (also available in Visual Basic

Métdos de extensão em falta na classe System.String da plataforma .NET 3.5 (Beta 1)

Paulo Morgado — Sun, 13 May 2007 21:58:48 GMT

Métodos de extensão são uma nova funcionalidade da especificação da linguagem C# (também disponível no

Métdos de extensão em falta na classe System.Array da plataforma .NET 3.5 (Beta 1)

Paulo Morgado — Sun, 13 May 2007 22:04:53 GMT

Métodos de extensão são uma nova funcionalidade da especificação da linguagem C# (também disponível no

re: Extension Methods (part 2)

mekuto s — Thu, 08 Oct 2009 10:02:52 GMT

can you write this extension methods in a report form