Source code for

''' Provide the ``Override`` class, for overriding base class property

.. note::
    This class should normally be imported from ````
    instead of directly from this module.


[docs]class Override(object): ''' Override attributes of Bokeh property in derived Models. When subclassing a Bokeh Model, it may be desirable to change some of the attributes of the property itself, from those on the base class. This is accomplished using the ``Override`` class. Currently, ``Override`` can only be use to override the ``default`` value for the property. Keyword Args: default (obj) : a default value for this property on a subclass Example: Consider the following class definitions: .. code-block:: python from bokeh.model import Model from import Int, Override class Parent(Model): foo = Int(default=10) class Child(Parent): foo = Override(default=20) The parent class has an integer property ``foo`` with default value 10. The child class uses the following code: .. code-block:: python foo = Override(default=20) to specify that the default value for the ``foo`` property should be 20 on instances of the child class: .. code-block:: python >>> p = Parent() >>> 10 >>> c = Child() >>> 20 ''' def __init__(self, **kwargs): if len(kwargs) == 0: raise ValueError("Override() doesn't override anything, needs keyword args") self.default_overridden = 'default' in kwargs if self.default_overridden: self.default = kwargs.pop('default') if len(kwargs) > 0: raise ValueError("Unknown keyword args to Override: %r" % (kwargs))