Elementwise -//- first release -//- Element-wise (vectorized) function, method and operator support for iterables in python.

[Nathan Rice]

> Have you seen PyLINQ? It has a similar approach to operating on
> collections, returning a PyLINQ object after each call to facilitate
> chaining. https://github.com/kalessin/PyLINQ/blob/master/pylinq/linq.py

I hadn't seen it previously.  I am a VERY heavy user of SQL Alchemy
though, and I am sure chaining generative ClauseElements/Queries/etc,
has burned some patterns into my subconscious at this point.

> This is a personal opinion on the code, but I'd move instantiating the
> new ElementwiseProxy out of each method and into its own decorator:
>
>    # declare this outside of the class
>    def chainable(fn):
>        def _(self, *args, **kwargs):
>            return ElementwiseProxy(fn(self, *args, **kwargs), self)
>        return _
>
> This way, each method that is chainable is a little more obvious
> without inspecting the code, and the method body itself is only doing
> what the method says it does:
>
>    @chainable
>    def __add__(self, other):
>        return (e + other for e in object.__getattribute__(self,
> "iterable"))

This is a reasonable suggestion and I will play with something along
those lines soon.

> Incidentally, displaying an ElementwiseProxy instance doesn't go down
> well with iPython:
>
> In [1]: from elementwise import *
>
> In [2]: e = ElementwiseProxy(['one','two','three'])
>
> In [3]: e
> Out[3]: ERROR: An unexpected error occurred while tokenizing input
> The following traceback may be corrupted or invalid
> The error message is: ('EOF in multi-line statement', (6, 0))

I love IPython, but it has had known problems with iterators for
years.  A long time ago, I agonized over what I thought was a bug in
my code where itertools.count would skip numbers in IPython, but my
unit tests all passed.  Everything should work fine if you tuple() it
first.

Nathan