Access operator functions by symbol

Question

I need a function which takes one of python\'s operator symbols or keywords as a string, along with its operands, evaluates it, and returns the result. Like

Answer 1

If you're going to use such a map, why not map directly to functions instead of having a layer of indirection by name? For example:

symbol_func_map = {
    '<': (lambda x, y: x < y),
    '<=': (lambda x, y: x <= y),
    '==': (lambda x, y: x == y),
    #...
}

While this wouldn't be any more concise than your current implementation, it should get the correct behaviour in the majority of cases. The remaining problems are where a unary and a binary operator conflict, and those could be addressed by adding arity to the dictionary keys:

symbol_func_map = {
    ('<', 2): (lambda x, y: x < y),
    ('<=', 2): (lambda x, y: x <= y),
    ('==', 2): (lambda x, y: x == y),
    ('-', 2): (lambda x, y: x - y),
    ('-', 1): (lambda x: -x),
    #...
}