5. Extending and developing Bakefile

5.1. Writing Bakefile plugins

As mentioned in Loading plugins, it is possible to use plugins written in Python to extend Bakefile functionality. The most common types of plugins are those defining custom tool sets, i.e. new output formats, or custom build steps, allowing to perform more or less arbitrary actions.

But the simplest possible custom step plugin may actually not do anything at all, but just define some properties that can be used in bakefiles. For example, here is a complete example of a plugin:

from bkl.api import CustomStep, Property
from bkl.vartypes import StringType

from datetime import date

class MyVersion(CustomStep):
    Simple bakefile plugin defining MY_VERSION property.

    The value of the version is just the current date.
    name = "my_version"

    properties_project = [

This plugin can then be used in the following way:

plugin bkl.plugins.my_version.py;

program my_program {
    basename = my_program-$(MY_VERSION);

Of course, a more realistic example would use something other than just the date of the last Bakefile execution as version. As plugin is just a normal Python script, there are a lot of possibilities, for example it could extract the version from the VCS used by the program or read it from some file inside the source tree.