What C++ open-source projects have good and clean code to learn from?

Question

What C++ open-source projects have good and clean code? I would like to go through it and learn the design and implementation tricks used there.

There was a similar question about C code here, but I would be specifically interested in C++ projects, especially in ones that use modern programming approaches and have modular but not bloated overall structure and object-oriented design.

I know I could look at code in Project Euler or Topcoder, but I'd like to see the architecture and design of a whole nicely-sized, but not too large project (say, up to 50 or so classes).

There was also this question, but no one mentioned C++ projects.

And one more thing: I know the best way to learn is actually writing code yourself. But I'm already doing that. A lot.

Answer 1

The Boost C++ libraries are very good examples of good modern C++ design.

Answer 2

Trolltech's Qt library has a great design.

Another good way is to learn good design is to read a book on design patterns, such as this one.

Answer 3

IMHO, DC++ (a client for the Direct Connect protocol) is quite well done, makes use of C++'s features in all the right ways and has a manageable size. I always liked poking around in its source.

Answer 4

I've learned from the code of Binutils Gold and i liked the clean style of the LLVM source-code.

You can also have a look into the boost code. It's probably not easy to understand because their writers know a lot of C++ and assume its readers know too. But of course its code is the lingua franca of C++.

Answer 5

I would like to read some good C++ books instead of study these codes. I think for every project, they have different background, design and implementation, most of them didn't provide a good document.

Answer 6

I've always admired the OpenSceneGraph for a really clean, modern approach to C++. It's a larger code base but very modular, so you don't need to chew off too much at a time :)

Not a lot of comments though, so be prepared to actually read some code.

Answer 7

I recommend looking at ACE for examples of good C++ code and design principles.

Answer 8

A great example of a large system in C++ is Chrome. The C++ is fairly nice, and it's interesting to see how they tackled the challenge of organizing such a large system.