davidafsilva / pretty-string

Kotlin's data class toString pretty cousin

pretty-string

This small Kotlin library provides an alternative to the regular toString implementation that is generated for data classes, which does not support prettifying its output right out-of-the-box.

Table of Contents

• Usage
  • Import
    • Gradle
    • Maven
  • API
    • Example
• Building

Usage

Import

1. Add maven central repository to your configuration
2. Import the library

Gradle

Groovy:

repositories {
    mavenCentral()
}
dependencies {
    implementation("pt.davidafsilva.jvm.kotlin:pretty-string:0.1.0")
    // be sure to include kotlin-reflect as one of your kotlin dependencies, if you don't have it already
    // implementation(kotlin("reflect")) 
}

Maven

<dependencies>
  <dependency>
      <groupId>pt.davidafsilva.jvm.kotlin</groupId>
      <artifactId>pretty-string</artifactId>
      <version>0.1.0</version>
  </dependency>
  <!-- be sure to include kotlin-reflect as one of your kotlin dependencies, if you don't have it already -->
  <!--
  <dependency>
    <groupId>org.jetbrains.kotlin</groupId>
    <artifactId>kotlin-reflect</artifactId>
  </dependency>
  -->
</dependencies>

API

This public API is very small. In fact, it only exposes single toPrettyString() top-level function. It is defined as an extension of Any?, thus you should be able to call it with any receiver.

Example

Let's say you have the following data classes definitions:

data class Person(
    val fullName: String,
    val birthDate: LocalDate,
    val children: List<Person> = emptyList(),
    val socialProfiles: List<SocialProfile> = emptyList(),
)

data class SocialProfile(
    val name: String,
    val url: String
)

And you have the following instance of it:

val person = Person(
    fullName = "John Doe",
    birthDate = LocalDate.of(2000, Month.JANUARY, 31),
    children = listOf(
        Person(fullName = "John Doe Jr.", birthDate = LocalDate.of(2022, Month.MARCH, 13))
    )
)

Calling person.toPrettyString() should return something along the lines of:

Person@3e3abc88(
  fullName = "John Doe",
  birthDate = "2000-01-31",
  children = [
    Person@7857fe2(
      fullName = "John Doe Jr.",
      birthDate = "2022-03-13",
      children = [],
      socialProfiles = [],
    ),
  ],
  socialProfiles = [],
)

Optionally, you can specify the indentation to be applied during the formatting via the indentationWidth parameter. When omitted, it defaults to 2.

Building

At the project root, run the following command:

./gradlew clean build

The above command will run both the tests and verification checks.

Disclaimer

The function has support for what I consider to be the bare minimum to properly prettify most of the data class definitions we (developers) usually create. If there's something missing and you'd like to see it supported, feel free to file an issue or just go ahead an open the PR with its support :)