Interdependencies

The outputs of one phase can serve as the inputs for another. Under the hood, Ninja will know how to create the outputs in the most efficient order, using multiple CPU cores when available. You can specify the relationship easily in Rōnin:

Phase(project=project,
      name='compile',
      executor=GccCompile(),
      inputs=glob('src/*.c'))

Phase(project=project,
      name='link',
      executor=GccLink(),
      inputs_from=[compile],
      output='myprogram')

Note that inputs_from is a list: you can gather inputs from more than one phase. Also, each element of inputs_from can be a string instead of a Phase instance, which will be interpreted as the name of another phase on the same project. (You cannot relate to a phase on another project because it's in a separate Ninja file.)

Sometimes you may want to force a phase to run only if another is complete, but you don't actually want to treat one's outputs as the other's inputs. Use build_if_from:

Phase(project=project,
      name='archive',
      executor=Archive(),
      build_if_from=[compile1, compile2],
      output='myarchive')

In Ninja, this is implemented as "order-only dependencies" (single bar). You can also specify individual files using build_if. You can similarly use rebuild_on and rebuild_on_from to specify Ninja "implicit dependencies" (double bar).