On Sat, Feb 11, 2017 at 7:08 PM, Steven D'Aprano <st...@pearwood.info> wrote: > On Sat, Feb 11, 2017 at 02:28:42PM -0600, boB Stepp wrote: > >> Back in the main Python list thread, Marko Rauhamaa suggested >> (https://mail.python.org/pipermail/python-list/2017-February/719322.html): >> >> " >> ... >> Haven't been following the discussion, but this should be simply: >> >> ast.literal_eval("...") >> ... >> " >> >> This looks like it may do the trick quite concisely: > > Nope. Not even close. The problem is that you have to accept ints and > floats, but reject anything else, and literal_eval does not do that. > > py> import ast > py> ast.literal_eval('[1, {}, None, "s", 2.4j, ()]') > [1, {}, None, 's', 2.4j, ()]
My intent was to follow up with type(ast.literal_eval(string_input_from_user)) and if that does not come out 'int' or 'float', then it can be rejected as invalid input from the user. In your example type() would return a list, which would be invalid input for the OP's case. Of course this seems like swatting a gnat with a sledge hammer, but it still seems that the combination of checking the return of type(ast.literal_eval(user_input)) does the job since everything that is not float or int can be rejected as invalid input, and the float case can get its special error message. Or am I missing something? boB _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
