How can I pass in a func with a generic type parameter?
I like to send a generic type converter function to a method but I can't figure out how to do it.
Here's invalid syntax that explains what I like to achieve, the problem is I don't know how to specify the generic type together with my func:
public void SomeUtility(Func<T><object,T> converter)
{
var myType = converter<MyType>("foo");
}
Edit (see also my discussion in the comments with Lawrence) : By "generic type converter" I meant I would like to pass in a converter that can convert to any strong type <T> (not object), so the next line in my method could be:
var myOtherType = converter<MyOtherType>("foo");
The delegate I like to pass as a parameter would look something like this:
private delegate TOutput myConverterDelegate<TOutput>(object objectToConvert);
This is more a syntax / C# exploration now, to get things done I will probably use an interface instead, but I do hope this is possible to accomplish with a func/delegate.
Solution 1:
You cannot have instances of generic functions or actions - all type parameters are defined upfront and cannot be redefined by the caller.
An easy way would be to avoid polymorphism altogether by relying on down-casting:
public void SomeUtility(Func<Type, object, object> converter)
{
var myType = (MyType)converter(typeof(MyType), "foo");
}
If you want type safety, you need to defer the definition of the type parameters to the caller. You can do this by composing a generic method within an interface:
public void SomeUtility(IConverter converter)
{
var myType = converter.Convert<MyType>("foo");
}
interface IConverter
{
T Convert<T>(object obj);
}
Edit:
If the 'converter type' is known at the call-site, and only this type will be used inside the utility method, then you can define a generic type on the method and use that, just like other posters have suggested.
Solution 2:
public void SomeUtility<T>(Func<object, T> converter)
{
var myType = converter("foo");
}
and then:
SomeUtility(arg => new MyType());
The generic type inference will work in this case.