model.py

class Model:
	def __init__(self):
		self.sol = 0.0
	
	def validateNumber(self, num): #Checks for valid number input
		if num == "ans":
			return True
		else:
			try:
				returnNum = float(num)
				return True
			except ValueError: #Input was not a number or 'ans' so requests the number again
				return False
	
	def validateOperator(self, op): #Checks for valid operator input (+,-,*,/,^)
		if op == "+" or op == "-" or op == "*" or op == "/" or op == "^":
			return True
		else:
			return False
	
	def returnTrueValue(self, num): #If number is 'ans' then convert to that number
		if num == "ans":
			return str(self.sol)
		else:
			return num
	
	def divByZero(self, num2, op): #Checks for divide by zero
		if float(num2) == 0.0 and op == "/":
			return True
		else:
			return False
	
	def performOperation(self, num1, num2, op): #Returns solution to operation
		if op == "+":
			self.sol = float(num1) + float(num2)
		elif op == "-":
			self.sol = float(num1) - float(num2)
		elif op == "*":
			self.sol = float(num1) * float(num2)
		elif op == "/":
			self.sol = float(num1) / float(num2)
		else: # ^
			self.sol = float(num1) ** float(num2)
		return [num1, num2, op, self.sol]