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Eliot Murton
7,315 PointsXcode Swift issue with initializing.
I am creating the model for a calculator and Xcode keeps telling me that for the init method that I cannot invoke BinaryOperation/UnaryOperation with the relevant Enum cases. Why is this. It is really confusing me.
class CalculatorBrain {
enum Op {
case Operand(Double)
case UnaryOperation(String, Double -> Double)
case BinaryOperation(String, (Double -> Double) -> Double)
}
var opStack = [Op]()
var knownOps = [String:Op]()
init() {
knownOps["×"] = Op.BinaryOperation("×") { $0 * $1 }
knownOps["÷"] = Op.BinaryOperation("÷") { $1 / $0 }
knownOps["+"] = Op.BinaryOperation("+") { $0 + $1 }
knownOps["−"] = Op.BinaryOperation("−") { $1 - $0 }
knownOps["√"] = Op.UnaryOperation("√") { sqrt($0) }
}
func pushOperand(operand: Double) {
opStack.append(Op.Operand(operand))
}
func performOperation(symbol: String) {
}
}
2 Answers
Jhoan Arango
14,575 PointsThis will resolve your issue, but not sure if it will make your code work as you intend to.
class CalculatorBrain {
enum Op {
case Operand(Double)
case UnaryOperation(String, Double -> Double)
case BinaryOperation(String, (Double, Double) -> Double)
}
var opStack = [Op]()
var knownOps = [String:Op]()
init() {
knownOps["×"] = Op.BinaryOperation("×") {$0 * $1}
knownOps["÷"] = Op.BinaryOperation("÷") {$1 / $0}
knownOps["+"] = Op.BinaryOperation("+") {$0 + $1}
knownOps["−"] = Op.BinaryOperation("−") {$1 - $0}
knownOps["√"] = Op.UnaryOperation("√") {sqrt($0)}
}
func pushOperand(operand: Double) {
opStack.append(Op.Operand(operand))
}
func performOperation(symbol: String) {
}
}
Eliot Murton
7,315 PointsIm sorry. I think I am being slow and missing something obvious. What is it you changed? I copy and pasted it in and it works but I am stumped at what you did.
Jhoan Arango
14,575 PointsThis is one of those things that will drive anyone crazy trying to figure out what went wrong with your code.
Look at the tuple in your enum.
case BinaryOperation(String, (Double ->Double) -> Double)
case BinaryOperation(String, (Double, Double) -> Double) // here is the change.