8.5. Partial Source Trees

On really large projects, just checking out and maintaining the source can be a burden on developers. If a system consists of many modules and a particular developer is modifying only a localized part of it, checking out and compiling the entire project can be a large time sink. Instead, a centrally managed build, performed nightly, can be used to fill in the holes in a developer's source and binary trees.

Doing so requires two types of search. First, when a missing header file is required by the compiler, it must be instructed to search in the reference source tree. Second, when the makefile requires a missing library, it must be told to search in the reference binary tree. To help the compiler find source, we can simply add additional -I options after the -I options specifying local directories. To help make find libraries, we can add additional directories to the vpath.