Setting and UnsettingΒΆ

Using options, objects often become “entry points” that represent both a set of capabilities and a set of configurations for how that functionality will be used. As a result, you may want to be able to set the object’s values directly, without referencing their underlying options. It’s convenient to add a set() method, then use it, as follows:

def set(self, **kwargs):
    self.options.set(**kwargs)

one.set(width='*10', color='orange')
one.draw()

yields:

color='orange', width=100, name='one', height=10

one.set() is now the equivalent of one.options.set(). Or continue using the options attribute explicitly, if you prefer that.

Values can also be unset.:

from options import Unset

one.set(color=Unset)
one.draw()

yields:

color='blue', width=100, name='one', height=10

Because 'blue' was the color to which Shape had be most recently set. With the color of the instance unset, the color of the class shines through.

Note

While options are ideally accessed with an attribute notion, the preferred of setting options is through method calls: set() if accessing directly, or push() if stacking values as part of a method call. These perform the interpretation and unsetting magic; straight assignment does not. In the future, options may provide an equivalent __setattr__() method to allow assignment–but not yet.