Tuple unpacking for shell escape

[wimglenn]

Assigning the output of a !shell_escape command to a variable results in a list of strings. Even when the output is a single line, the result will be a list with one element. Tuple unpacking on this list is inconsistent with the tuple unpacking syntax in python, only a subset of cases are working. In the examples below, the first case works correctly but the 2nd case (one-element unpack) and the 3rd (splat unpacking) are syntax errors.

In [1]: a, b, c = !echo 'a\nb\nc'

In [2]: a, = !echo 'a'
  File "<ipython-input-2-cf81f7d7733e>", line 1
    a, = !echo 'a'
         ^
SyntaxError: invalid syntax


In [3]: a, *bc = !echo 'a\nb\nc'
  File "<ipython-input-3-471e46e39f1a>", line 1
    a, *bc = !echo 'a\nb\nc'
             ^
SyntaxError: invalid syntax

My system info:

wim@wim-zenbook:~$ python3 -c "import IPython; print(IPython.sys_info())"
{'commit_hash': '<not found>',
 'commit_source': '(none found)',
 'default_encoding': 'UTF-8',
 'ipython_path': '/usr/lib/python3/dist-packages/IPython',
 'ipython_version': '0.13.2',
 'os_name': 'posix',
 'platform': 'Linux-3.11.0-18-generic-x86_64-with-Ubuntu-13.10-saucy',
 'sys_executable': '/usr/bin/python3',
 'sys_platform': 'linux',
 'sys_version': '3.3.2+ (default, Feb 28 2014, 00:52:16) \n[GCC 4.8.1]'}

[takluyver]

PR #5321 addresses this.

[wimglenn]

That was quick!

[takluyver]

The actual fix was easy enough, since I'm already familiar with that code - just a regex that was a bit too restrictive.

[wimglenn]

There are also cases I didn't mention like first, *blah, last, will the regex also handle them?

[takluyver]

It should do. That PR has been merged now, so feel free to pull from master and try it out.