equatable 0.1.6

  • README.md
  • CHANGELOG.md
  • Example
  • Installing
  • Versions
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Simplify Equality Comparisons

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Overview

Being able to compare objects in Dart often involves having to override the == operator as well as hashCode.

Not only is it verbose and tedious, but failure to do so can lead to inefficient code which does not behave as we expect.

By default, == returns true if two objects are the same instance.

Let's say we have the following class:

class Person {
  final String name;

  const Person(this.name);
}

We can create create instances of Person like so:

void main() {
  final Person bob = Person("Bob");
}

Later if we try to compare two instances of Person either in our production code or in our tests we will run into a problem.

print(bob == Person("Bob")); // false

For more information about this, you can check out the official Dart Documentation.

In order to be able to compare two instances of Person we need to change our class to override == and hashCode like so:

class Person {
  final String name;

  const Person(this.name);

  @override
  bool operator ==(Object other) =>
    identical(this, other) ||
    other is Person &&
    runtimeType == other.runtimeType &&
    name == other.name;

  @override
  int get hashCode => name.hashCode;
}

Now if we run the following code again:

print(bob == Person("Bob")); // true

it will be able to compare different instances of Person.

You can see how this can quickly become a hassle when dealing with complex classes. This is where Equatable comes in!

What does Equatable do?

Equatable overrides == and hashCode for you so you don't have to waste your time writing lots of boilerplate code.

There are other packages that will actually generate the boilerplate for you; however, you still have to run the code generation step which is not ideal.

With Equatable there is no code generation needed and we can focus more on writing amazing applications and less on mundane tasks.

Usage

First, we need to do add equatable to the dependencies of the pubspec.yaml

dependencies:
  equatable: ^0.1.6

Next, we need to install it:

# Dart
pub get

# Flutter
flutter packages get

Lastly, we need to extend Equatable

import 'package:equatable/equatable.dart';

class Person extends Equatable {
  final String name;

  Person(this.name) : super([name]);
}

We can now compare instances of Person just like before without the pain of having to write all of that boilerplate.

Recap

Without Equatable

class Person {
  final String name;

  const Person(this.name);

  @override
  bool operator ==(Object other) =>
    identical(this, other) ||
    other is Person &&
    runtimeType == other.runtimeType &&
    name == other.name;

  @override
  int get hashCode => name.hashCode;
}

With Equatable

import 'package:equatable/equatable.dart';

class Person extends Equatable {
  final String name;

  Person(this.name) : super([name]);
}

Performance

You might be wondering what the performance impact will be if you use Equatable.

Performance Tests have been written to test how Equatable stacks up to manually overriding == and hashCode in terms of class instantiation as well as equality comparison.

Results (average over 10 runs)

Equality Comparison A == A

ClassRuntime (microseconds)
RAW0.143
Empty Equatable0.124
Hydrated Equatable0.126

Instantiation A()

ClassRuntime (microseconds)
RAW0.099
Empty Equatable0.121
Hydrated Equatable0.251

0.1.0

Initial Version of the library.

  • Includes the ability to extend Equatable and not have to override == and hashCode.

0.1.1

Minor Updates to Documentation.

0.1.2

Additional Updates to Documentation.

  • Logo Added

0.1.3

Bug Fixes

0.1.4

Performance Optimizations

0.1.5

Additional Performance Optimizations & Documentation Updates

0.1.6

Documentation Updates

  • Performance Tests

example/main.dart

import 'package:equatable/equatable.dart';

class Credentials extends Equatable {
  final String username;
  final String password;

  Credentials({this.username, this.password}) : super([username, password]);
}

void main() {
  final credentialsA = Credentials(username: 'Joe', password: 'password123');
  final credentialsB = Credentials(username: 'Bob', password: 'password!');
  final credentialsC = Credentials(username: 'Bob', password: 'password!');

  print(credentialsA == credentialsA); // true
  print(credentialsB == credentialsB); // true
  print(credentialsA == credentialsB); // false
  print(credentialsB == credentialsC); // true
}

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:


dependencies:
  equatable: ^0.1.6

2. Install it

You can install packages from the command line:

with pub:


$ pub get

with Flutter:


$ flutter packages get

Alternatively, your editor might support pub get or flutter packages get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:


import 'package:equatable/equatable.dart';
  
Version Uploaded Documentation Archive
0.1.6 Jan 10, 2019 Go to the documentation of equatable 0.1.6 Download equatable 0.1.6 archive
0.1.5 Jan 7, 2019 Go to the documentation of equatable 0.1.5 Download equatable 0.1.5 archive
0.1.4 Jan 7, 2019 Go to the documentation of equatable 0.1.4 Download equatable 0.1.4 archive
0.1.3 Jan 7, 2019 Go to the documentation of equatable 0.1.3 Download equatable 0.1.3 archive
0.1.2 Jan 7, 2019 Go to the documentation of equatable 0.1.2 Download equatable 0.1.2 archive
0.1.1 Jan 6, 2019 Go to the documentation of equatable 0.1.1 Download equatable 0.1.1 archive
0.1.0 Jan 6, 2019 Go to the documentation of equatable 0.1.0 Download equatable 0.1.0 archive
Popularity:
Describes how popular the package is relative to other packages. [more]
83
Health:
Code health derived from static analysis. [more]
100
Maintenance:
Reflects how tidy and up-to-date the package is. [more]
100
Overall:
Weighted score of the above. [more]
91
Learn more about scoring.

We analyzed this package on Jan 15, 2019, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.1.0
  • pana: 0.12.10

Platforms

Detected platforms: Flutter, web, other

No platform restriction found in primary library package:equatable/equatable.dart.

Dependencies

Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.0.0-dev.28.0 <3.0.0
collection ^1.14.11 1.14.11
Dev dependencies
test >=1.3.0 <2.0.0
test_coverage ^0.2.0