String to Dictionary conversion in python

[Piet van Oostrum]

Rustom Mody <rustompmody at gmail.com> writes:

> On Saturday, September 16, 2017 at 2:04:39 AM UTC+5:30, jlad... at itu.edu wrote:

> Yeah… I used to think thus
> But literal_eval has excessive crud in its error messages:
>
>>>> from ast import literal_eval
>
>>>> literal_eval("{'x':1}")
> {'x': 1}
>
> Ok…
>
>>>> literal_eval("{x:1}")
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "/usr/lib/python2.7/ast.py", line 80, in literal_eval
>     return _convert(node_or_string)
>   File "/usr/lib/python2.7/ast.py", line 63, in _convert
>     in zip(node.keys, node.values))
>   File "/usr/lib/python2.7/ast.py", line 62, in <genexpr>
>     return dict((_convert(k), _convert(v)) for k, v
>   File "/usr/lib/python2.7/ast.py", line 79, in _convert
>     raise ValueError('malformed string')
> ValueError: malformed string
>

You can catch the exception and print a nice error message:

from ast import literal_eval
def literal(s):
   try:
       return literal_eval('{'+s+'}')
   except Exception as e:
       print "%s: %s" % (type(e).__name__, ', '.join(e.args))

>>> literal("'x':1")
{'x': 1}
>>> literal("x:1")
ValueError: malformed string

But in non-interactive use you probably want to propagate the exception.

-- 
Piet van Oostrum <piet-l at vanoostrum.org>
WWW: http://piet.vanoostrum.org/
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