[Tutor] question about listing variables defined since session started

[Prasad, Ramit]

Steven D'Aprano wrote:
> Prasad, Ramit wrote:
> >> Steven D'Aprano wrote:
> >> Robert Sjoblom wrote:
> >>> On 30 April 2012 23:25, Comer Duncan <comer.duncan at gmail.com> wrote:
> >>>> Hi,
> >>>>
> >>>> I have a newbie type question.  Say I have started a python (or
> >>>> ipython) session and have done some imports and have also defined
> some
> >>>> new variables since the session started.  So, I have in my current
> >>>> namespace a bunch of things. Suppose I  want to list just those
> >>>> variable  names which have been defined since the session started but
> >>>> not include the names of the objects that who and whos will return.
> >>>> How to do that?
> >>> Not entirely sure, but something like this might work (untested):
> >>> for name in dir():
> >>>     myvalue = eval(name)
> >>>     print name, "is", type(name), "and is equal to ", myvalue
> >> Please do not use eval unless you know what you are doing, and
> certainly
> >> don't
> >> encourage newbies to use it without a word about the risks.
> >>
> >
> > ast.literal_eval(name) is probably safer.
> 
> Safer, but doesn't work:
> 
> 
> py> import ast
> py> name = 25
> py> ast.literal_eval('name')
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
>    File "ast.py", line 87, in literal_eval
>      return _convert(node_or_string)
>    File "ast.py", line 86, in _convert
>      raise ValueError('malformed node or string: ' + repr(node))
> ValueError: malformed node or string: <_ast.Name object at 0xb7a9560c>
> 
> 
> literal_eval is for evaluating literals, not names.
> 
> py> ast.literal_eval('[123, "ABC", None, {}]')
> [123, 'ABC', None, {}]
> 
> 
> It apparently can also do simply arithmetic, but that's *possibly* an
> implementation detail due to the keyhole optimizer in CPython's compiler.
>

What about just using dir / globals / locals?

global_variables = globals()
for name in dir():
   value = globals_variables[ name ] if name in global_variables else locals[ name ]
   print '{0} is {1} and is equal to {2}'.format( name, type(value), value )   

Ramit


Ramit Prasad | JPMorgan Chase Investment Bank | Currencies Technology
712 Main Street | Houston, TX 77002
work phone: 713 - 216 - 5423

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