Interface as parameter

Question

Hi I am trying to create a method that needs to take an interface as a reference type. Firstly is this even possible? Basically my method needs to be called twice and the first param will be different types but both implement the interface so I have something like this private void validate( ref CMS.TreeEngine. TreeNode sku DocTypeDefinition col string productData) { NewMethod(ref sku col productData); } private void validate( ref SKUInfo sku DocTypeDefinition col string productData) { NewMethod(ref sku col productData); } private static void NewMethod( ISimpleDataContainer sku DocTypeDefinition col string productData) { switch (col.ColumnType) { case integer : sku.SetValue(col.ColumnID ValidationHelper .GetInteger(productData 0)); break ; } } So you can see that the first param in validate is of different types but both methods call the new method whose first param is an interface. This approach does not work it throws a complier error. Can anyone point me in the right direction please? Thanks

Mike Gold · Answer

You don't need the ref keyword with an Interface. An interface is already a reference type. ref is only necessary when you have a value type and you want to pass it as a parameter that can be modified and returned to the calling function. Also if CMS.TreeEngine. TreeNode is a class and SkuInfo is a class they are already reference types so you don't need ref. the exception is if either TreeNode or SkuInfo are structs. But in general you do not want to put interfaces on structs if you don't have to. You are better off making your struct a class. Below is a good thread to read on the reason: http://stackoverflow.com/questions/63671/is-it-safe-for-structs-to-implement-interfaces

Amit Choudhary · Answer

Hi friend Yes you are right it will give you the compilation error.. cause you cannot use ref and out with Interface reference.. try without using ref and out. also you have used it like: which is also not possible until you assign a reference of its inherited class. Thanks.