SyntaxError on parse_expr

[Amit Saha]

Hello,

I noticed that passing an invalid mathematical expression causes a
SyntaxError (Python exception). For eg:

>>> parse_expr('2*x*x')

results in:

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python3.3/site-packages/sympy/parsing/sympy_parser.py",
line 164, in parse_expr
expr = eval(code, global_dict, local_dict) # take local objects in
preference
File "<string>", line 1
Integer (2 )*Symbol ('x' )*Symbol ('x' )+Integer (2 )Symbol ('x' )
^
SyntaxError: invalid syntax


I also understand why, since we are basically 'eval' ing:

"Integer (2 )*Symbol ('x' )*Symbol ('x' )+Integer (2 )Symbol ('x' )"

Shouldn't this be raised as a separate exception class from SymPy (on
the lines of class sympy.parsing.sympy_tokenize.TokenError, for
example)?

Best,
Amit.


--
http://echorand.me

[Aaron Meurer]

I'm assuming you pasted the wrong thing. 2*x*x is correct syntax.

That can be debated. Currently, parse_expr is an internal function. We
don't actually have a user-level function for parsing, so it's what
we've pointed people to for the advanced parsing features that have
been implemented, but it does mean that the interface is not as nice
as it could be (it also means that the inteface may change at any
time).

Aaron Meurer

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