Math Expression Evaluation

Question

What is the best way to implement a python program that will take a string and will output its result according to operator precedence (for example: \"4+3*5\" will output 19

Answer 1

I'm not terribly familiar with Python and any extremely Pythonic methods, but you could look at the Interpreter pattern, which is defined in the Gang of Four book. It's designed for processing a "language", and mathematical expressions do follow a particular language with rules. In fact, the example on Wikipedia is actually a Java implementation of a RPN calculator.