Input parsing issue with %prun

[wesm]

In [5]: %prun grouped.agg({'value1' : 'mean', 'value2' : 'var', 'value3' : 'sum'})
  File "<string>", line 1
    'value1' : 'mean', 'value2' : 'var', 'value3' : 'sum'
             ^
SyntaxError: invalid syntax

[minrk]

git bisect reveals f5687fc as the offender.

The issue is the new var_expand, which uses a DollarFormatter, rather than ItplNS. Formerly, $ was the only expansion, but since we now use string formatting, the {name} syntax is acceptable, and the magic is trying to format the string. This wasn't an issue, because variables wer unambiguous, as they were not Python syntax, but they are now.

The magic argument transform is proving itself to be in irredeemable mess, and needs to be reconsidered in a much cleaner way. For instance, this var_expand call should never be made on magics that aren't shell-ish.

Temporary workaround to just disable variable expansion, if you need it:

get_ipython().var_expand = lambda s, *args, **kwargs: s