trac源代码阅读 - 4 ("|" or operator)

__or__ == |

Error:

>>> a={'a':1, }

>>> b = lambda x: x*2

>>> a | b

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

TypeError: unsupported operand type(s) for |: 'dict' and 'function'

the first object must has "__or__" method

Right:

>>> class a(object):

...     def __or__(self, t):

...             return id(t)

...

>>> c = a()

>>> d = a()

>>> c|d

13041232

>>> id(c)

13041264

>>> id(d)

13041232

>>> c|""

12492856

Example: (Transformer)

http://trac.edgewall.org/browser/trunk/sample-plugins/ticket_clone.py