Compilation strategy

Unlike other compilers, rock takes care of building whole projects at a time, not just single modules. However, how much you want to let up to rock is your choice, thanks to different drivers, or compilation strategies.

Sequence driver

This is the default driver. It’ll parse all relevant .ooc files, generate C files, and call the C compiler to produce object files, then link the result.

It can be customized using the following options:

Parsing only

If you only want rock to make sure there are no syntax errors, using the --onlyparse option will work.

Checking only

If you want rock to parse and make sure that the code is correct ooc (e.g. types correspond, all functions calls have corresponding definitions, etc.), the --onlycheck option will do that.

Generation only

If you just want rock to generate C files to look at what is being done under the hood, the --onlygen option can be used. They will be output in the rock_tmp (for .c files) and .libs (for header files) folders by default.

If the goal is to tinker with the


By default, rock will attempt to max out your processors by launching C compiler jobs in parallel. One can adjust the level of parallelism by specifying -jN to rock, where N is an int. To completely disable parallelism (ie. behave in a purely sequential way), pass -j0.


Lib-caching is very convenient, yet at the same time it can cause unforeseen issues. The basic idea is that, between two compilations, only a portion of generated C code is affected by the changes, there is no reason to recompile what hasn’t changed.

It is active by default, which means that even though the first compilation might take some time, subsequent compilations will be shorter. If a compilation seems to fail because of the remainder of previous compilations, running rock -x should fix it up.

To temporarily disable lib-caching, one can use the --nolibcache compiler option.

Make driver

The make driver is particularly useful when an ooc project is to be compiled on another platform lacking the ooc toolchain (for example, when bootstrapping rock), or when one wants to modify the C output of rock and recompile afterwards.

By using --driver=make, the compile process looks something like this:

# In project directory
rock --driver=make
cd build/

The build directory which is generated and populated with C files and a stand-alone Makefile, can be packaged and distributed on other platforms.

Note that the $GC_PATH environment variable might need to be adjusted for the exported sources to build somewhere else. It could be as simple as installing the Boehm GC in /usr and setting GC_PATH to -lgc.

One can use make clean to clean the produced objects and binaries. Modifying sources and partial recompilation is possible. Make accepts parallelism options similar to rock, e.g. with 8 cores, one might want to use make -j7.

CMake driver

The CMake driver is similar to the make driver but generates a CMakeLists.txt file instead. The process looks like:

# In project directory
rock --driver=cmake
cd build/
cmake .

Note that CMake is itself a build file generator. In the example above we’re using the default Makefile output of CMake, but it could be used to generate Visual Studio project files, XCode project files, etc.

Android driver

In spirit, the Android driver (invoked with --driver=android) is similar to the make driver, excepts that instead of generating Makefiles, it will generate files, suitable for usage with the ndk-build utility from the Android NDK toolchain.