On Fri, 04 Jan 2013 13:33:41 +0000, Steven D'Aprano wrote: > On Fri, 04 Jan 2013 07:24:04 -0500, Terry Reedy wrote: > >> On 1/3/2013 6:25 PM, Grant Edwards wrote: >>> >>> I've written a small assembler in Python 2.[67], and it needs to >>> evaluate integer-valued arithmetic expressions in the context of a >>> symbol table that defines integer values for a set of names. The >>> "right" thing is probably an expression parser/evaluator using ast, >>> but it looked like that would take more code that the rest of the >>> assembler combined, and I've got other higher-priority tasks to get >>> back to. >> >> Will ast.literal_eval do what you want? > > No. Grant needs to support variables, not just literal constants, hence > the symbol table.
as a thought why not processes the input string by exploding the literal constants into their numerical values as stage 1 this should result in a string that only contains numbers & mathematical symbols then reject any resultant string that contains any alpha characters. I have to agree that it is still a risky process. -- Loneliness is a terrible price to pay for independence. -- http://mail.python.org/mailman/listinfo/python-list
