dimanche 15 février 2009

One possible path

VLAM will soon hire an intern. This brings a host of questions about cv selection, which school to choose, the interview process, etc. What interests me the most at this point is how to educate a junior programmer up to the point where we will be able to trust his code.

One possible path I think can work is the one displayed on the left.


VLAM is a real-world software production environment and we need our programmers productive right-away. I find that even if functional programming has a definite mathematical beauty and simplicity, juniors don't get it right away. They do get that variables can refer to different values as the program is executed.

On a very practical note, we use 3rd party software that have very procedural interfaces. Procedural programming is the basis, the starting point and the common denominator. I hope I won't actually have to teach basic structs, unions, file handling, printf and C function pointers ; but if I have to, I'll try to get it out of the way right from the start.


Inheritance, overloading, overriding, constructors, destructors - a junior coder has to master all of that before he can tackle exceptions (with of course exception-safe software design) and functional programming. Object-oriented programming is not a goal, but it is full of very usefull tools. Please, for the love of gods, don't stop here. Don't end up with "object-oriented programmers". Teach juniors patterns, so they can detect and factor them out in the future.

Key concepts :
  • The construction, allocation, destruction and deallocation of objects
  • Overloading, overriding
  • Multiple inheritance (and the diamond of death)
  • Patterns
Books to read :
  • The effective C++ series
  • Agile Software Development, Principles, Patterns, and Practices

Contracts, error handling and exceptions

I won't go on here about why you should use exceptions - that can be the subject of another post. Needless to say, proper error handling, asserts and exception safety is very important. Unfortunatly very few programmers in the real world are able to write code that won't leak or fail miserably when not everything goes as expected.

Key concepts :
  • RAII
  • asserts & contracts
  • try/catch
Books to read :
  • The exceptional C++ books

By this point, it should be clear to the new programmer that it's easier to write correct, extensible code when it's stateless. If C++ is your main tool, now is the time to fully understand how to use boost::function and boost::bind.

Key concepts :
  • Closures
  • Declarative-style programming
Books to read :
  • Structure and Interpretation of Computer Programs

This is a big one. Templates in C++, generics in Java and C#. They can be as painful as they can be useful. You absolutely need to cover object-oriented programming before, because you will need all the tools of classes to actually implement to opposite idea : the separation of algorithms from data structures.

Key concepts:
  • Runtime vs compile-time
  • Code generation
Books to read:
  • C++ Templates - The Complete Guide
  • On Lisp
  • Modern C++ Design

Many would start with scripting, and yet I put it at the end. I don't mean that a junior programmer should wait to learn python or ruby until he masters C++ templates - quite the opposite. I think juniors should already know a scripting language before you hire them in the first place. I'm talking about the integration of scripting in applications.

After a programmer has suffered through C++ templates, once he understands what it take to write statically-typed reusable code, he is ready to bridge the gap between static and dynamic languages. Swig is no easy piece of cake, but if it allows you to write most of the code in a sane language, it's a small price to pay!

Key concepts:
  • Embedding
  • Foreign interfaces
  • Domain-specific languages
Any book suggestions?

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