The operator module supplies function equivalents for Python operators, letting a program select an operation as data instead of branching through an if statement. section 6.6 section 6.7
A prefix calculator can split an input such as `+ 2 3`, convert its operands, and dispatch through a dictionary keyed by `+`, `-`, `*`, `/`, `**`, or `%`. section 6.6 section 6.7
Sorting records with itemgetter
`operator.itemgetter('last', 'first')` creates a key function that retrieves both dictionary values, allowing `sorted(people, key=itemgetter('last', 'first'))` without a one-off function or lambda. section 3.12
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
Browse a complete calculator implementation: define one function per operation, map operator strings to functions, unpack the input, convert operands, and invoke the selected function. section 6.7
