Suggestion: on Duck Typing and C#/.NET

My comment at:

http://visualstudio.uservoice.com/forums/121579-visual-studio-2015/suggestions/4272089-support-implicit-interfaces-for-code-reuse

It would be nice indeed if one could define at the client object’s side a static interface that is a subset of the methods of a server (or serving if you prefer) object (it is only the view of the server that the client has gained knowledge of) that has been passed on to the client

Then there could be a service (a facility I mean) that accepts the server object instance and the interface the client has defined (the duck type) and case the server object to that interface by CHECKING that the duck interface is indeed a subset of the methods the server object implements

the check if our duck interface is indeed covered by what the object to be duck-typed offers can be implemented via reflection already

the implementation could be hacked by spitting out a new object (bytecode generation) that wraps each property/method of the object to be duck-typed and calls into the original object, but it would be much better if there was support in the compiler for that (viewing an object via an interface that is compatible to it in functionality, not in strong typing concept)

…when I say support in the compiler, I mean to avoid the proxying layer (of course security should also be considered carefully when implementing such a thing, in case there are pitfalls)

 

A very interesting article on the subject showing how to do DuckTyping in .NET is:

http://www.codeproject.com/Articles/122827/DynamicObjects-Duck-Typing-in-NET

 

Not sure if in the time that has passed (5 years) there have been any DuckTyping-specific additions at C#/.NET

Suggestion: Add support for constants in C# (and VB.net etc.) interfaces

It is rather unfortunate that C# doesn’t support constants in interfaces, whereas Java does.

If IL (intermediate language) that C# usually compiles to (when not using AOT that is like in .NET Native or Xamarin iOS) doesn’t support this, then the compiler could create a special sealed class to carry the constants.

Then, wherever they’re used via the interface it could get them via that class. This would happen internally without the programmer noticing. The programmer should be able to access the constants using:

ISomeInterface.SomeConstant

SomeClass.SomeConstant, where SomeClass implements ISomeInterface

just SomeConstant when the code is inside the body of SomeClass that implements the ISomeInterface

just SomeConstant when there is a “using static” statement (that newer C# has introduced) like “using static ISomeInteface” or “using static ISomeClass”

You can vote up this suggestion at:
http://visualstudio.uservoice.com/forums/121579-visual-studio-2015/suggestions/10724265-add-support-for-constants-in-c-and-vb-net-etc