Equatable Protocol on Daniel Lyons

Introducing SelectiveEquatable

Thu, 12 Dec 2024 00:00:00 +0000

A few weeks ago, I released a blog post named “Selective Equality Checking in Swift”. In that post, I designed and implemented an API to check for equality on specific properties of a type. Today, I am excited to announce a new Swift protocol named SelectiveEquatable, that makes all of this even easier. Let’s see it in action.

Using SelectiveEquatable

To use the SelectiveEquatable protocol, all you need to do is add a conformance to it like this:

Selective Equality Checking in Swift

Tue, 05 Nov 2024 00:00:00 +0000

The humble Equatable protocols is one of the most fundamental tools in Swift, but sometimes it is not always the best tool for the job. Last week we learned how to check equality for collections while ignoring order. Today we will learn how to pick and choose exactly what properties we would like to check equality on. But first let’s talk about the problem:

Why Not Just Use Equatable

For the majority of use cases the best option is to just use the plain old == operator. We get this operator automatically when a type conforms to Equatable. However it’s not always easy conform to Equatable. Here are some situations when it might not be feasible or even possible to conform to Equatable.

Unordered Equality Checking in Swift

Tue, 29 Oct 2024 00:00:00 +0000

Have you ever needed to compare two arrays in Swift, but the order of elements doesn’t matter? I find this often happens to me when convert between an ordered type such as Array and an unordered type such as Set or Dictionary. Today, we’ll explore how to implement unordered equality checking in Swift, starting with the basics and working our way up to a flexible, protocol-based solution.

What is Deep Equality?

Before diving into unordered equality, let’s briefly discuss deep equality. Many programming languages struggle with deep equality comparisons. Take JavaScript, for example: