[IPython-dev] Cell magic for closures

[MinRK]

Here's an example<https://github.com/minrk/ipython_extensions/blob/master/closure.py>of
what two approaches might look like.



On Fri, May 17, 2013 at 5:23 AM, Jeffrey Tratner <jtratner at gmail.com> wrote:

> That's a good point about unbound locals. Thanks for the link to the
> extensions page.
> On May 17, 2013 8:15 AM, "Thomas Kluyver" <takowl at gmail.com> wrote:
>
>> Hmm, that's an interesting idea. Running it under a def might cause some
>> other problems, like UnboundLocalErrors when you try to modify variables.
>> Another approach might be a cell magic that remembered what globals were
>> defined at the start of the cell, and removed any new ones after running
>> the cell.
>>
>> Perhaps it would be best to collect some examples of cases where this
>> would be useful, to see what's the best way to do it. You can of course
>> write an extension for it:
>> http://ipython.org/ipython-doc/stable/config/extensions/index.html
>>
>> Best wishes,
>> Thomas
>>
>>
>> On 17 May 2013 04:55, Jeffrey Tratner <jtratner at gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> I've been using ipython notebook for a project at work and I really
>>> enjoy it. The only issue that I have is that sometimes using the code in
>>> cells and editing code on the fly means that you unintentionally define
>>> globals without meaning to. Clearly you can define a new function, but that
>>> also pollutes the name space and just feels weird.
>>>
>>> Javascript has a convention of wrapping code in an immediately executed
>>> function and I know that someone has proposed adding something like a given
>>> keyword to python to accomplish something similar, but it'd be nice to be
>>> able to do it without adding an extra level of indentation and to be able
>>> to do it in 2.7.
>>>
>>> I'm imagining a syntax like %%closure that consumes a cell and executes
>>> it as if it were underneath a def statement. This has the benefit of
>>> reducing the level of indentation as well as doing things like this:
>>>
>>> within_cell_variable = xyz
>>>
>>> # do something
>>>
>>> del within_cell_variable
>>>
>>> ---
>>>
>>> or if you need to iterate over something, suddenly you've polluted the
>>> namespace with a random off variable.
>>>
>>> I'd love to have this, I think it would be useful in the context of a
>>> notebook and reduce the amount of def statements used only to encapsulate
>>> variables. It's also kinda magical I guess.
>>>
>>> Best,
>>>
>>> Jeff
>>>
>>> _______________________________________________
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>>>
>>>
>>
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