We have recently been receiving lots of applicants for our open developer positions from people who I like to refer to as "legacy" programmers. I don't like the term "old" because it seems a little prejudiced (especially to HR!) and it doesn't accurately reflect what I mean.

We are a company that does primarily .NET development using TDD in an Agile environment, we use Git as a source control system, we make heavy use of OSS tools and projects and we contribute to them as well, we have a strong bias towards adhering to strong Object-Oriented principles, SOLID, etc, etc, etc...

Now, the normal list of questions that we ask doesn't really seem to apply to applicants that are fresh out of school, nor does it seem to apply to these "legacy" programmers. Here is how I (loosely) define a "legacy" programmer.

• Spent a significant amount of their career working almost exclusively with Assembly/Machine Languages.
• Primary accomplishments include work done with TANDEM systems.
• Has extensive experience with technologies like FoxPro and ColdFusion

It's not that we somehow think that what we do is "better" than what they do, on the contrary, we respect these types of applicants and we are scared that we may be missing a good candidate. It is just very difficult to get a good read on someone who is essentially speaking a different language than you. To someone like this, it seems a little strange to ask a question like:

What is the difference between an abstract class and an interface?

Because, I would think that they would almost never know the answer or even what I'm talking about. However, I don't want to eliminate someone who could be a very good candidate in their own right and could be able to eventually learn the stuff that we do. But, I also don't want to just ask a bunch of behavioral questions, because I want to know about their technical background as well.

Am I being too naive? Should "legacy" programmers like this already know about things like TDD, source control strategies, and best practices for object-oriented programming?

If not, what questions should we ask to get a good representation about whether or not they are still able to learn them and be able to keep up in our fast-paced environment?

EDIT: I'm not concerned with whether or not applicants that meet these criteria are in general capable or incapable, as I have already stated that I believe that they can be 100% capable. I am more interested in figuring out how to evaluate their talents, as I am having a hard time figuring out how to determine if they are an A+ "legacy" programmer or if they are a D- "legacy" programmer. I've worked with both.