Question

I work in a python shell and some weeks ago I have defined a variable which refers to a very important list. The shell stays always open, but I have forgotten this name. How to get a list of all global names I have ever defined?

Answer 1

All of the globals or just the user-defined ones?

>>> globals()
{'__builtins__': <module '__builtin__' (built-in)>, '__name__': '__main__', '__doc__': None, '__package__': None}
>>> x=2
>>> globals()
{'__builtins__': <module '__builtin__' (built-in)>, '__name__': '__main__', 'x': 2, '__doc__': None, '__package__': None}

To get the things you have defined yourself, it appears that you can filter out from this list all key-value pairs whose keys do not match the regex "__.*?__$".

UPDATE

Here is a better answer:

$ python
Python 2.7.1 (r271:86832, Jun  5 2011, 15:52:25) 
[GCC 4.2.1 (Apple Inc. build 5659)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> x = 3
>>> import re
>>> [name for name in dir() if not re.match(r'__.*?__$', name)]
['re', 'x']

Here I’ve excluded the special names beginning and ending with two underscores, so if you used them yourself they will not show. The $ at the end of the regex to prevent accepting __abc__1. Also I switched to dir() which gets symbols in the current scope, not necessarily the global one, but it seems cleaner. It doesn’t add the leading list comprehension variable like globals() does.