Coding-Design on dlow's blog

Objects and Data Structure/Container

Wed, 14 Oct 2020 06:34:42 +0100

The differences and how it affects code maintenance.

Anti pattern: turning struct into interface

Sun, 24 May 2020 12:44:55 +0100

Previously I wrote about using struct embedding to achieve pseudo inheritance for code reuse. In this post, I want to explore an example of what I think is an anti pattern as a result of the lack of inheritance and how I think it could be better.

In the absence of inheritance in golang, it is very tempting to turn fields into functions of an interface.

As an motivating example, consider the following:

Struct embedding as implicit composition

Fri, 22 May 2020 11:26:33 +0100

In programming, the principle “don’t repeat yourself”, DRY for short, recommends that we try to reuse the same implementation where possible. In this post, I will cover what it’s like to do it in golang through struct embedding and my personal thoughts on that pattern.

Golang struct embedding

One common way of code reuse is inheritance. In Java, we can do this by implementing a method on the parent class, then subclasses will inherit this implementation.

Monadic Boolean 2

Thu, 04 Jul 2019 23:04:54 +0100

Previously, I concluded that using Either[String, Unit] is quite a nice way to compose predicates. Since then I have noticed some other patterns in my code that I would argue is an improvement.

We will still keep the “for-comprehension” style as I find that it makes the code more readable due to the shorter indentation compared to nested if else blocks.

The main difference is rather than defining functions that take the input and produce the monad, we use implicits to turn a boolean (or any other types as we shall see) into the monad we want for composition.

Monadic Boolean

Mon, 25 Mar 2019 21:42:51 +0000

The following task is quite common: do something if all given predicates are satisfied and if some predicate fails, make it obvious which failed.

Consider the contrived scenario where we are asked to save a number to the database if it satisfy all our conditions:

def isGood(x: Int): Boolean = isConditionA(x) && isConditionB(x) ...

def usage(x: Int): Unit = if (isGood(x)) saveNumber(x) else doNothing()

Some time later, we notice that some numbers are being rejected, and we have no idea why, so we decide to add logging when a number is rejected. How should we go about it?