Abstract Classes¶
Utilities to deal with abstract base classes and virtual subclasses.
New in version 0.2.
- class brownie.abstract.ABCMeta[source]¶
On Python 2.6 this class is actually abc.ABCMeta, on versions lower than that it’s simply a dummy. Which makes implementing abstract classes easier if you want to support Python versions which don’t support class.__subclasscheck__() and class.__instancecheck__().
- class brownie.abstract.VirtualSubclassMeta(name, bases, attributes)[source]¶
A metaclass which allows you to easily define abstract super classes, simply inherit from this metaclass and set the virtual_superclasses attribute to an iterable:
>>> from brownie.abstract import ABCMeta, VirtualSubclassMeta >>> >>> class VirtualBaseClass(object): ... __metaclass__ = ABCMeta >>> >>> class VirtualSubclass(object): ... __metaclass__ = VirtualSubclassMeta ... ... virtual_superclasses = (VirtualBaseClass, ) >>> >>> issubclass(VirtualSubclass, VirtualBaseClass) True
- class brownie.abstract.AbstractClassMeta(name, bases, attributes)[source]¶
A metaclass for abstract base classes which are also virtual subclasses.
Simply set virtual_subclasses to an iterable of classes your class is supposed to virtually inherit from:
>>> from brownie.abstract import ABCMeta, AbstractClassMeta, \ ... VirtualSubclassMeta >>> class Foo(object): ... __metaclass__ = ABCMeta >>> >>> class Bar(object): ... __metaclass__ = AbstractClassMeta ... ... virtual_superclasses = (Foo, ) >>> >>> class Baz(object): ... __metaclass__ = VirtualSubclassMeta ... ... virtual_superclasses = (Bar, ) >>> >>> issubclass(Baz, Foo) True >>> issubclass(Baz, Bar) True
Note
All classes could use AbstractClassMeta as __metaclass__ and the result would be the same, the usage here is just to demonstrate the specific problem which is solved.