CODEWITHSUNDEEP
c#.netgenericsreflection
Raheel Khan
Raheel Khan

Reputation: 14787

Determine if a derived class implements a generic interface with itself as the generic parameter

I have seen answers on SO with similar questions but did not find one addressing all criteria below.

How can I determine whether class B meets the following criteria when B inherits from A:

The following 

object o = new SomeObject();
bool result = (o.GetType().GetInterfaces()[0] == typeof(IKnownInterface<???>));
// ??? should be typeof(o). How to achieve this?

I know I can get the interface name string from the type which is something like "NameSpace.ClassName+IKnownInterface'1[[SomeType, ModuleName, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]" but this does not seem intuitive or safe. Plus the '1 notation is incremental based on the number of generic types used for that interface.

I am either going about this the wrong way or missing something silly here. Please advise.

Upvotes: 2

Views: 620

Answers (2)

Rune FS
Rune FS

Reputation: 21752

This should do the trick

//get the two types in question
var typeB = b.getType()
var typeA = typeB.BaseType;
var interfaces = typeA.GetInterfaces();

//if the length are different B implements one or more interfaces that A does not
if(typeB.GetInterfaces().length != interfaces.length){
   return false;
} 

//If the list is non-empty at least one implemented interface satisfy the conditions
return (from inter in interfaces
        //should be generic
        where inter.IsGeneric
        let typedef = inter.GetGenericTypeDefinition()
        //The generic type of the interface should be a specific generic type
        where typedef == typeof(IKnownInterface<>) &&
        //Check whether or not the type A is one of the type arguments
              inter.GetGenericTypeArguments.Contains(typeA)).Any()

Upvotes: 2

Oleh Nechytailo
Oleh Nechytailo

Reputation: 2205

try:

 o.GetType().GetInterfaces()[0] == 
                   typeof(IKnownInterface<>).MakeGenericType(o.GetType())

http://msdn.microsoft.com/en-us/library/system.type.makegenerictype.aspx

Upvotes: 1

Related Questions