Example about @autoclosure in Swift

autoclosure.swift

/*
An autoclosure is a closure that is automatically created to wrap an expression that’s being passed as an argument to a function. 

It doesn’t take any arguments, and when it’s called, it returns the value of the expression that’s wrapped inside of it
*/

let greeting: () -> (String) = { 
	print("You can do other things here...")
	
	return "Hi everyone!" 
}


/// With autoclosure feature...
func autoclosureFunction(message: @autoclosure () -> (String)) -> Void
{
	print(message())
}

/// Without autoclosure
func nonAutoclosureFunction(message: () -> (String)) -> Void
{
	print(message())
}



// Autoclosure calling...

autoclosureFunction(message: greeting())
// OK. @autoclosure create a wrap around parameter
autoclosureFunction(message: "Hi everyone from a common parameter.")

// Non autoclosure calling...

nonAutoclosureFunction(message: { return "Hi everyone without a wrap !" })
// Line below terminate with ERROR
nonAutoclosureFunction(message: "Hi everyone without a wrap and from a common parameter!")