When input selects an operation, map each identifier to a function instead of expanding an if/elif chain. Look up the function, then call it with the required arguments. section 7.7
A calculator can split an expression into an operator and operands, convert the operands, and invoke operations[op](first, second). A dictionary stores functions as values, while **kwargs can build a similar table dynamically for menu options. section 7.7 section 9.7
def add(a,b):
return a + b
def sub(a,b):
return a - b
def mul(a,b):
return a * b
def div(a,b):
return a / b
def pow(a,b):
return a ** b
def mod(a,b):
return a % b
def calc(to_solve):
operations = {'+' : add, #1
'-' : sub,
'*' : mul,
'/' : div,
'**' : pow,
'%' : mod}
op, first_s, second_s = to_solve.split() #2
first = int(first_s) #3
second = int(second_s)
return operations[op](first, second) #4
Use the executable calculator pattern to inspect function registration, input unpacking, conversion, and final lookup-and-call behavior. section 7.7
Practice the pattern by varying the selection and input path:
- Use split(maxsplit=3) when the final field may contain spaces instead of assuming an exact number of results. section 7.7
- Display valid menu keys by joining sorted dictionary keys before requesting input. section 9.7
