[IPython-dev] Cell magic for closures

[Jeffrey Tratner]

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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