Jimmy Bogard wrote a blog quite recently about how to inject generic components without using the generic part. As I have struggled with this in the past, I thought I’d create a little implementation to check out how his article solves the problem.

So I created a GitHub repository named Crossing The Generics Divide. I did put it in a namespace KenBonny, not (only) because I did the copy pasting from Jimmy’s blog, but to show that this is not made by Jimmy. It’s just a tribute. I did do one thing different: Jimmy uses “validators”, I replaced that by “processor” as I wanted to return a result (which is just a bit of text to differentiate between the processors).

The most important lesson that I learned is that the composition has my preference, but that I cannot inject the general IPolicyProcessor (Jimmy’s IPolicyValidator) directly. I need to ask for the specific PolicyProcessor<> as I cannot pass the type of Policy to the factory method with basic dependency injection.

There is an example with the IPolicyProcessor that comes from a factory, but this required a bit of extra work in a console application. The IServiceProvider does not automatically get registered if I did it manually. To get this working, I had to set up a hosting environment (as described by the Microsoft docs). So if the normal execution is an asp.net project, this should work out of the box.