4) A Cook's tour of QEF

4. The RootPath and QEF Trees

This page discusses the RootPath, the trees of the QEF approach, and introduces the software process that they supports.

In the previous page's description of the qdsrv records, the eighth field is called the "RootPath" and the RootPath in record #46 contained three directories:

	/g/dt/cook/obj /g/dt/cook/work /p/cook/s3.4

These are the root directories of the object tree, working tree, and the baseline (i.e., source) tree. The QEF approach normally uses five types of trees. The Process

*VS: the version system file sytem (e.g., CVS, SCCS, RCS) -- from which is extracted the baselines.
Baseline: the baseline source for the release -- holds the clear text form of the source used to build the product. Changes should be carefully controlled and monitored.
Working: (a.k.a. the sandbox) trees used by developers to hold changed or new source files which override or hide the baseline copy.
Objects: trees in which builds are done holds intermediate files (e.g., *.o files) and created product binaries.
Products: file system that holds constructed product installed from the object trees.
RootPath: list of root directories of the relevant tree such as the roots of the object, working, and baseline trees.

Supplementary notes regarding trees

To change source, the developer fetches a copy of the file or files to be changed from the *VS system and stores writable copies in the working tree. The QEF's SrcPathing mechanism ensures that the developer's source file will take precedence over the baseline version.

Note that a working tree does not have to have all the directories of the baseline. Only those directories required to hold changed source are necessary.

Similarly, a developer's object tree need not duplicate the full directory structure of the baseline. QEF's multi-directory management mechanism will compensate for missing directories.

The developer's product as built from a partial object tree will also be partial. The product built by production will be searched for any files (e.g., headers, libraries, tools) that are not built by the developer.

cook14.qh - 1.16 - 05/09/23