In a previous set of posts I talked about how the difference between an average developer and a great developer is enormous, how bad developers can effectively cancel-out your good developers, and why you therefor need to hire just the very best.
Great Developer Key Indicators
The following is a list I’ve accumulated over time. It’s never complete, and certainly up for discussion, but in my experience is a pretty good set of indicators for whether a developer is an ‘A’ player or not.
- Can deal with many levels of abstraction simultaneously.
- Are masters at managing complexity.
- Know space and time trade-offs of the major data structures.
- Understands multi-threading, resource locking, and how it’s implemented.
- Understands that simple is better than complicated, every time.
- Has used a DVCS (git, mercurial, etc).
- Are masters at managing expectations.
- Plays with new technologies and languages and stays aware of upcoming developments.
- Understands what TDD is and why it’s a valuable practice.
- Is likely to develop iteratively and incrementally, adding value with each release.
- Understands how to accomplish loose-coupling and encapsulation, especially in things that are likely to change.
- Is not a lone-coder who goes dark for long periods of time.
- Knows how to communicate well, not just with developers, but all levels of management and stakeholders, and can adjust communication vocabulary/style per context.
- Knows SOLID principles and practices them effectively.
- Recognizes that code reviews are excellent ways to improve yourself, both as an author or reviewer.
- Can grasp the bigger picture.
- Doesn’t just accept work items and marching orders, but also proposes alternatives and improvements.
- Knows 1 procedural language, 1 object-oriented language, 1 functional language, 1 scripting language, 1 statically typed language, and 1 dynamically typed language. (There is much overlap between these categorizations)
- Fluent in major design patterns and how/when to implement them.
- Knows most of these books: Code Complete, Pragmatic Programmer, Clean Code, Mythical Man Month, Design Patterns by the Gang of Four, Programming Perls, Code: The Hidden Language of Computer Hardware and Software, C by K&R.
- Keeps up with development blogs/twitter/podcasts.
- Is highly passionate about software development.
Bad Developer Red Flags
There are some simple things you can do to immediately weed out the really bad developers in an interview scenario.
- Have them write FizzBuzz; believe it or not most developers do poorly on this, and it’s a great way to identify them early on in the process.
- Ask them what the last new language or development environment they learned was. If it’s been a long time since they’ve learned a new one, that’s a red flag.
- Ask them what they think a great developer’s best attributes are. If the answer isn’t in the list above, it’s probably a red flag.
- Have them explain dependency injection to you, and a simple example. If you get a deer-in-headlights response, it’s a red flag.
- Ask them to solve problems that involve in-place manipulation of a linked list or string. If they don’t understand pointers or space/time complexities of a problem, that’s a concern. ‘Reverse a linked list’ is a good one to ask.
- Find out if they have a GitHub/BitBucket/Codeplex/SourceForge. Look for evidence of development both inside and outside of work.
What NOT To Do
- Don’t ask questions that are just quick facts. A programmer that knows what port IMAP runs on isn’t going to be a better programmer than one who doesn’t. Knowing little C compiler optimizations doesn’t make you a better programmer.
- Don’t just ask questions with verbal answers, or open-ended answers. Actually have them write code on the whiteboard. A lot.
- Don’t use questions that are common enough to where they could be googled before hand or memorized.
- Don’t just be satisfied that someone answered something correctly. Talk to them about their solution. Ask them to modify it. Ask them to test it. Challenge their thinking.
This is an organic post, and I suspect I’ll add many suggestions from readers.