string to list when the contents is a list

[Tim Chase]

Wes James wrote:
> I have been trying to create a list form a string.  The string will be
> a list (this is the contents will look like a list).  i.e. "[]" or
> "['a','b']"
> 
> The "[]" is simple since I can just check if value == "[]" then return []
> 
> But with "['a','b']" I have tried and get:
> 
> a="['a','b']"
> 
> b=a[1:-1].split(',')
> 
> returns
> 
> [ " 'a' "," 'b' " ]
> 
> when I want it to return ['a','b'].

Just to add to the list of solutions I've seen, letting the 
built-in csv module do the heavy lifting:

   >>> s = "['a','b']"
   >>> import csv
   >>> no_brackets = s[1:-1] # s.strip(' \t[]')
   >>> c = csv.reader([no_brackets], quotechar="'")
   >>> c.next()
   ['a', 'b']

This also gives you a bit of control regarding how escaping is 
done, and other knobs & dials to twiddle if you need. 
Additionally, if you have more than one string to process coming 
from an iterable source (such as a file), you can just pass that 
iterator to csv.reader() instead of concocting a one-element list.

-tkc