Add "entry_point" to bead meta

[korenmiklos]

so that other tools can automatically run the computation in the bead after bead develop and bead input load. Like

"entry_point": "stata -b do main.do"

[korenmiklos]

bead command stata -b do main.do
bead save
bead develop NAME
bead input update
bead update

or

bead run

[e3krisztian]

I think entry_point is not a good name, what about build_command instead?

I was also thinking about the command line interface and implementation for using it (rebuilding beads):

bead build [--show] [BUILD COMMAND WITH ARGUMENTS]

Records or executes build commands

• bead build make output records make output as the command used for building the output
• bead build runs the previously recorded build command
• bead build --show shows the previously recorded build command

bead build --recursive [--dir BUILD-DIR]

Rebuilds the workspace, the inputs are updated, and loaded.

Something like

# rebuild inputs
for INPUT in workspace.inputs:
    bead build --recursive --dir BUILD-DIR INPUT.bead_name
    bead input update INPUT.name
# rebuild workspace
bead build

bead build [--recursive] [--dir BUILD-DIR] --package PACKAGE

Rebuilds PACKAGE and if required, all of its dependencies recursively.

a recursive build would work like this:

cd BUILD-DIR
if file PACKAGE exists:
    # this package was already built
    return
bead develop PACKAGE
cd PACKAGE
if recursive:
    bead build --recursive --dir BUILD-DIR
else:
    bead input update
    bead build
bead save
cd ..
bead zap PACKAGE
# leave a sentinel behind to prevent repeated builds
touch PACKAGE

---

Notes:

• existing BUILD-DIR/PACKAGE will prevent building PACKAGE
• BUILD-DIR defaults to abspath('temp/build')
• all bead build-s and bead save-s should be conditional for package builds (i.e. not a workspace initiated build): only if one of its dependencies have been updated

---

Open problem[s]:

• What to do with existing beads? Smart default (make) or fail?
• What should happen when there is a failure rebuilding one of the dependencies (e.g. no build command recorded, or command exiting with error)?