DEVEL.md

Bootstrap

To bootstrap b0, we need to find the paths to the cmdliner and unix library directories. These are discovered using a few heuristics which can be by-passed by explicitly setting:

export B0_BOOT_CMDLINER_LIBDIR=/path/to/cmdliner/dir
export B0_BOOT_UNIX_LIBDIR=/path/to/unix/dir

Now the following OCaml scripts can be invoked (see below for more explanations):

ocaml boot/strap            # build boot/run and run it
ocaml boot/strap --no-exec  # only build boot/run
./boot/run                  # run the bootstrap build
ocaml boot/strap --clean    # clean the bootstrap build

The boot/strap invocation produces the boot/run executable which has B0's own B0 file linked with the b0 tool driver. Running boot/run it is equivalent to run b0 on the root B0.ml file. After this usable b0 executables and libraries are in the _b0 directory. These can be used by having the B0_BOOTSTRAP and B0_DRIVER_BOOTSTRAP point to the library directories (see boot/env).

There are a few ways to use the bootstrap built which we describe next.

By locking the b0 root

The recommended way to use the bootstrap build is by executing the b0 build unit via b0 -- b0. If you want to use it outside the b0 repository to test on other project the best way is to lock b0 on the b0 repository as the environment of the unit execution of b0 unlocks it:

eval $(b0 lock)      # lock b0 on the b0 repo 
cd ~/project && b0 -- b0  # Run b0 via b0
eval $(b0 unlock)

This makes sure you are always running an up-to-date b0.

By using the bowl action

Another way is to symlink a b0 repo to bowl in the source directory

mkdir -p /tmp/bowl
b0 -- b0 gather /path/to/repos/* > /tmp/bowl/B0.ml
ln -s /tmp/bowl bowl
b0 -- bowl …

By changing the shell environmen

Another way is to setup your shell environment (for example if you need to test scripts that run b0. This can be done as follows:

./boot/env.bat   # let `b0` invocations be the bootstrap build on Windows
source boot/env  # let `b0` invocations be the bootstrap build on Unix
cd ~/project && b0 
unset -f b0      # stop using bootstrap b0 on Unix

The disavantage of this approach is that you may run an outdated b0 if you made changes and did not rebuild.

Source map

• src/std has the b0.std library. This has a few things that should be in the stdlib and a few others that shouldn't but are useful for b0 based programs.

• src/memo is the core b0.memo build library.

• src/file has the b0.file library which for describing software construction and deployments and provides programmatic access to the definitions of B0.ml files.

• src/kit is the b0.kit library, it contains build domain specific logics.

• src/tool is the b0 tool driver. This implements the b0 tool.

• src/lowtools has a few b0 low-level tools: b0-cache, b0-log, b0-hash, show-uri.