[IPython-dev] Cell magic for closures

[Jeffrey Tratner]

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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