Question about interfaces

[mortb]

Why can't you place static methods in an interface?
For example, if I want an uniform manner to create instances of classes that
implement my interface I'd like to put a static factory mehtod in the
interface. However, this is not possible as the interface does not allow
static memebers.

Is there a good reason for this design?

/mortb

 

[Greg Young]

Actually you can (in IL).

I would imagine it was done this way in most of the .net langauges as it is
a bit of a confusing concept ... I can understand the logic of treating an
interface as a special type which can only represent a contract.

Cheers,

Greg Young
MVP - C#

 

[Guest]

Interface only provides you template and it is independed of scope and access
modifiers and implementation details. Specifiying something is Implementation
Detail. For this purpose you can use Abstract Classes.

 

[Peter Morris [Droopy eyes software]]

For example, if I want an uniform manner to create instances of classes

that implement my interface

For this you should use the factory pattern.

 

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

An Interface is intented to be used only as a contract, with no
implementation at all. If you can define a static member you must provide an
implementation for it, thus breaking the no-code feature. Even more you
could need a static constructor (as a method that is called only once ,
before any other static member) so you ends with a class , or a class-like
entity

If you want to provide a Factory , simply use a factory class.