flavorSuperClass

Additional

Language
Java
Version
1.0.0 (Jun 19, 2019)
Created
Jun 13, 2019
Updated
Jun 24, 2019
Owner
Rostyslav Lesovyi (MatrixDev)
Contributor
Rostyslav Lesovyi (MatrixDev)
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Source code

Commercial

flavorSuperClass

Overview

Normally when working with multiple flavors and only one of those needs different implementation, you'd have to copy same implementation to each other flavor. For example if you had 100 flavors and some class had different behavior for one of those, you'd still need 100 copies of that class in each flavor with only one beeing different.

This is caused by gradle's limitation which forbids class files replacement through flavors (yet you still can replace other resources).

There are few possible ways to overcome this limitation:

  • move all affected classes from main to flavor folder - leads to tons of duplicated code
  • use reflections to dynamically load classes from flavors - proguard will see those as unused which requires additional rules
  • use code generation to switch classes at compile time

This library uses code generation to create new super classes based on priorities. It is also can be used for pure Java projects.

It is better to use flavorAlias in pure Kotlin projects as it has less limitations and overheads.

Limitations

There are few limitations that you sould be aware:

  1. base classes must not be final
  2. base classes must have at least one non-private constructor
  3. additional annotations from base classes will not be copied to generated class

Example

Lets assume that we have 3 flavors and MyObject class which we need to have different implementation only for flavor3.

Step 1

Create base MyObject implementation in main flavor:

@GenerateSuperClass("MyObject", priority = 1)
class MyObjectMain {
    final String value;

    MyObjectMain(String value) {
        this.value = value;
    }
}

Actual class name must be unique for each flavor and also must be different from generated class name.

@GenerateSuperClass is the only annotation provided by the library and it takes only two arguments:

  1. name - this will be the name of the generated class
  2. priority - class annotated with the highest available priority wins and will havebe extended

Step 2

Create base MyObject implementation in flavor3 flavor:

@GenerateSuperClass("MyObject", priority = 2)
class MyObjectFlavor3 extends MyObjectMain {
    final String extra = "extra";

    MyObjectFlavor3(String value) {
        super(value);
    }
}

MyObjectFlavor3 extends MyObjectMain just to keep some consistency. There is no actual requirement to do this.

Step 3

Thats it, there is no step 3 :)

At this time library will generate new class with name MyObject that will extend annotated class with highest available priority and can be used everywhere in the code:

MyObject object = new MyObject("abc")
assert object.value == "abc"
assert object.extra == "extra" // <- this will compile only for flavor3

Generated class will be extending MyObjectFlavor3 when building project with flavor3 variant:

class MyObject extends MyObjectFlavor3 {
  MyObject(String value) {
    super(value);
  }
}

And for all other build variants it will extend to MyObjectMain:

class MyObject extends MyObjectMain {
  MyObject(String value) {
    super(value);
  }
}

Project structure should look something like this:

main
  -> MyObjectMain.java
  
flavor3
  -> MyObjectFlavor3.java

generated
  -> MyObject.java

How to add dependencies?

To use this library in your project just add following lines:

Step 1

Add JitPack repository in your root build.gradle file:

allprojects {
    repositories {
        maven { url 'https://jitpack.io' }
    }
}

Step 2

Add actual library and compiler dependencies:

dependencies {
    implementation 'com.github.MatrixDev.flavorSuperClass:flavorSuperClassLib:1.0.0'
    
    kapt 'com.github.MatrixDev.flavorSuperClass:flavorSuperClassCompiler:1.0.0'
}

More info can be found at https://jitpack.io/#MatrixDev/flavorSuperClass

License

MIT License

Copyright (c) 2018 Rostyslav Lesovyi

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.