Guide for manager during performance review
Introduction
Posts by Year
2024
The 7 success factors in building 5 millions downloaded app
Why I write it
Notes from Clockwork
About this book
Ruby on Rails (part 3)
Controllers and CRUD
Ruby on Rails (part 2)
Models and ActiveRecord
Ruby on Rails (part 1)
What is Ruby on Rails
Learning from Crucial Conversation
About this book
What I learnt from Team of Teams
About this book
2023
Coroutine Launch vs Async
If you are new to coroutine or looking for the continuation, you could start from the previous article.
Coroutine Builders
Coroutine Builders
Quick peek into KMM (Kotlin Multiplatform Mobile)
Introduction
2022
Image compression (Part 3) - Vector Graphic like SVG
Introduction
Image compression (Part 2) - Choosing image format
Introduction
Image compression (Part 1) - Image Quality
Introduction
Discover what people want
I am quitting
How to compare with others
Why wasn’t I the one who get promoted?
Late initialization
Sometimes, we want to initialize the properties of the class after it is created, but in a separate member function instead of using lazy
Lazy initialization
So far, we have two ways to initialize properties:
Property Delegation Tools
The standard library contains special property delegation properties. Map is one of the few types in Kotlin library. Each property identifier becomes a Strin...
Property Delegation
In Kotlin, we could connect a property to a delegate with the by keyword:
Operator Overloading
Back in the school while I was learning C++, operator overloading was one of the topics in academic. But in practice, I rarely overload operators. However, i...
Generics in Kotlin
I love template in C++ in the olden day. In many good languages that I had chance to come across, such as TypeScript, Java (it was added later) and Kotlin, t...
Scope function
When I started doing Kotlin, the one that confused me the most was scope functions. However, once I understand what it is, it becomes my most favorite Kotlin...
Extension lambdas
Any fool can write code that a computer can understand. Good programmers write code that humans can understand.
Resource Cleanup
Using try, catch and finally blocks for resource cleanup is tedious and error-prone. In fact, Kotlin has a library functions that could help us to manage cle...
Nothing
What is Nothing in Kotlin? Does it even exist? A Nothing return type indicates a function that never returns. This is usually a function that always throws a...
Check Instructions
Check Instructions are like assert - they act like a constraints that must be met before it could proceed. Usually, they are used to validate function argume...
Kotlin Exception Handling
Failure is always a possibility
Companion Object
Companion Object
Inner class
Inner class
Object Object Object
What is object
Nested class
Nested Class
Sealed class in Kotlin
To constrain a class hierarchy, we have to declare the superclass sealed. Without the constraint, our code will look like this:
Downcasting
Downcasting is to discover the specific type of a previously upcast object. Upcast is always safe because the base class cannot have a bigger interface than ...
Another choice for middle ground (Composition Vs Inheritance)
Both composition and inheritance place sub objects inside the new class. With composition, the sub object is explicit whereas the sub object with inheritance...
Composition
One of most compelling arguments for object oriented programming is code reuse.
Another look in Inheritance
We touched a bit on Inheritance concept. Inheritance is sometimes used to add functions to a class as a way of reuse for a new purpose.
2021
Polymorphism
One of the Object Oriented Programming concept is the ability of polymorphism. The word, polymorphism is an ancient Greek term. It means many forms. In progr...
Upcasting class
What is upcasting?
Abstract or Interface
An abstract class is like an ordinary class except one or more functions or properties is incomplete - ie. a function without implementation or a property wi...
Primary Constructor vs Secondary Constructor
A constructor is a special function that creates a new object. Using var or val in the parameter list makes them accessible from outside the object.
Ask for inheritance
Inheritance is a mechanism for creating a new class by reusing and modifying an existing class.
Making recursion more efficient with tailrec
What is recursion?
Folding and Reducing List
fold() combines all elements of a list, in order to generate a single result. Here is how we can use fold() to calculate the sum -
Elegant Local Function
What exactly is local function? It was new to me in Kotlin and thought it is interesting to dig deeper. In a normal class, we have many functions within a cl...
Sequence: lazy evaluation
What is Sequence? A Kotlin Sequence is like a List, but you can only iterate. You cannot index into Sequence. And this restriction produces very efficient ch...
Zipping and Flattening List
List Manipulation
Higher-Order Function
What is it? If you are coming from JavaScript, this concept may sound familiar to you. Otherwise, here is what it means.
Is Kotlin truly functional
Background
Things that you might not know about Collections
Most functional programming has a great support for working with collections and so is Kotlin. If you are coding with Kotlin for sometimes, you might notice ...
Why Lambda
To some people, lambda may seem like syntax sugar, but it is more than that. If you have to repeat some codes with minor modification, you can leverage on th...
Kotlin Lambda
The unavoidable price of reliability is simplicity – C.A.R Hoare
Kotlin break & continue
Jump history
Sprint Ceremonies in LeSS
Sprint Planning 1
Backlog Refinement Mentality
It is the ongoing effort by the whole team needed within each sprint to refine items in the backlog to be ready to ready for future sprints. There are a numb...
Product Owner
Product Owner Role
Management in Agile
Why Agile
Kotlin generic
Generics Intro
Kotlin Extension Properties
Extension Properties
Elvis operator in Kotlin
This operator is a question mark followed by a colon (?:) with no space in between. It is named for an emoticon (short form of “emotion icon”) of the musicia...
Team
Forming a team
LeSS Agile?
Purpose of Software Development
Destructuring
Many times, you may encounter use cases where you need to return more than one item from a function. One way that people usually do is to create a custom obj...
Definition of Done in LeSS
Definition of Done
When expression
A large part of computer programming is performing an action when a pattern matches.
Kotlin overloading
Overload
Data class
One of main motivation of Kotlin is to reduce repetitive coding. One that many of us have spent a significant amount of time and effort is the class mechanis...
Named and Default Arguments
Some background
Extension function is a magic
This is one of my most favorite features of Kotlin - Extension Function. Imagine this. You are using a 3rd party library - String that have all the things th...
Property Accessor
If you are new to Kotlin, there is something in property accessor that you might find it interesting. There are two methods - get() for getter and set() for ...
Map in Kotlin
So we have seen the wonderful Set. Next, we are going to look at Map.
Why package
A fundamental principle in programming is the acronym DRY: Don't Repeat Yourself.
Set
In computer science, Set is an interesting abstract data type that stores unique values. It is a collection that allows only one element of each value.
Infix notation in function
Another Kotlin treasure that I have not known is the ability to write infix notation in function. We use infix notation in most arithmetic operation such as ...
Variable Argument Lists
Do you know what vararg keyword is? Using this vararg, you can define a function that takes any number of argument.
Kotlin: Is Read-Only List immutable?
A List is a container, which is an object that holds other objects. Containers are also called collections.
Kotlin testing framework
Alright. Who here think that testing is optional? Even though some doesn’t write tests, I believe no one will openly say so. Oops. it hurts.
Some interesting things from Kotlin Objects
Objects are the foundation for many modern languages, including Kotlin.
If expression in String templates
You can insert a value within a String using String templates. Remember to use a $ before the identifier name:
If expression
One of basic things that gives me a spark in the eye is when I realise in Kotlin that:
2 Most Celebrated Kotlin Features
While there are many great features in Kotlin language, there are two features which are very impactful and outstanding.
Why Kotlin
Why Kotlin? I mean why we need Kotlin in this world. Don’t we have enough of programming language already? This was exactly the question that I have when Kot...