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iOS

Posted by Nathan Bills
Nathan Bills
5,449 Points

What is the technical term for less-than/greater-than symbols when used in a function definition?

I have seen the use of less-than/greater-than symbols when defining a function in the WWDC 2015 video "Protocol-oriented Programming in Swift" and in many other places. Here is an example of what I am talking about:

func swap<T>(inout a: T, inout with b: T) { (a, b) = (b, a) }

I've looked in the Swift Programming Guide on Apple's website and can't find any examples so far. Can anyone point me to where it's described in the documentation and/or tell me what the use of less-than/greater-than is called?

Hope that made sense :)

2 Answers

Jhoan Arango
Jhoan Arango
14,575 Points

Hello:

The example you are showing is a function using in-out parameters, which swap parameter values.

The value in the parameter a is swapped to parameter b. The symbol your are looking at = is the assign operator. You can read all about it Here.

You can also find information about the "Comparison Operators" Here

Comparison Operators

/*
- **Equal to (a == b)**
- **Not equal to (a != b)**
- **Greater than (a > b)**
- **Less than (a < b)**
- **Greater than or equal to (a >= b)**
- **Less than or equal to (a <= b)**
*/

Hope you find this information useful

Good luck.

Nathan Bills
Nathan Bills
5,449 Points
Nathan Bills
Nathan Bills
5,449 Points

Thanks, Jhoan! I just noticed a problem with my original question. My greater-than/less-than's were stripped out of my question because I didn't wrap my code in pre tags. I actually just now found the answer as well. They're called type parameters in generics. Here is the function I meant to post: <pre> func swap<T>(inout a:T, inout with b:T) { (a, b) = (b, a) } </pre>

Thanks again for your reply!!!

https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Generics.html