A central company-wide repository and modular code are not mutually exclusive. It's not that people at facebook or google are having all the code in one messy u

A central company-wide repository and modular code are not mutually exclusive. It's not that people at facebook or google are having all the code in one messy unmanageable soup. The build systems offers fine grained dependency management and the repository is organized so that different teams have responsibility over their components, just as if they were different repositories for all practical purposes. The advantage of having them in a single repository are: * atomic operations, i.e. you can refactor components and avoid code rot, or apply and API upgrade to all the clients, thus reducing the amount of time you have to maintain backward compatible APIs * having a single, monotonically increasing, number that describes exactly which bugs or bug fixes your codes has. This simplifies greatly the management of rollouts in case of complex component dependencies.