Ob

class discopy.cat.Ob(name)

Bases: object

Defines an object in a free category, only distinguished by its name.

Parameters:

name (any) – Name of the object.

Note

When printing an object, we only print its name.

>>> x = Ob('x')
>>> print(x)
x

Objects are equal only to objects with equal names.

>>> x = Ob('x')
>>> assert x == Ob('x') and x != 'x' and x != Ob('y')

Objects are hashable whenever their name is.

>>> d = {Ob(['x', 'y']): 42}
Traceback (most recent call last):
...
TypeError: unhashable type: 'list'

property name

The name of an object is immutable, it cannot be empty.

>>> x = Ob('x')
>>> x.name
'x'
>>> x.name = 'y'
Traceback (most recent call last):
...
AttributeError: can't set attribute...