mrocklin/multipledispatch — pull request #39 by mrocklin (2014-08-31 15:35:57+00:00)
Title: first draft for MDNotImplementedError

Here is a trivial implementation of a special NotImplementedError for multiple dispatch that allows for increasingly more general functions to be used. It's pretty janky as is but I thought I'd ask for input sooner rather than later. Here is a basic test

```Python
f = Dispatcher('f')

@f.register(object)
def _(x):
return 'default'

@f.register(int)
def _(x):
if x % 2 == 0:
return 'even'
else:
raise MDNotImplementedError()

assert f('hello') == 'default' # default behavior
assert f(2) == 'even' # specialized behavior
assert f(3) == 'default' # fall bac to default behavior
```

Some particular questions

* Better name than `MDNotImplementedError`?
* Intuitive example to put in the docs?
* How do we feel about copying the code for `dispatch` into `dispatch_iter`? We definitely want to keep the old interface.

cc @eriknw @encukou @quasiben