RxComprehensions

Additional

Language
Java
Version
1.3.0 (Feb 24, 2017)
Created
Aug 30, 2016
Updated
Feb 24, 2017 (Retired)
Owner
Paco (pakoito)
Contributor
Paco (pakoito)
1
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RxComprehensions

RxComprehensions is a library to reduce boilerplate and simplify your Observable chains.

Rationale

As your code starts getting more and more functional, you find that you have to chain multiple Observable by means of flatMap(), concatMap(), or switchMap(). This causes indentation levels to go quite high, and would often require that you split the code in several methods just to keep it readable.

Observable<String> getUserFriends =
    profileClicks()
            .flatMap { position ->
                getUserFromProfile(position)
                        .flatMap { user ->
                            requestFriendListForUser(position, user.id)
                                    .flatMap { friends ->
                                        storeUserAndFriends(user, friends)
                                                .flatMap { result ->
                                                    toUserDisplayString(position, user, friends, result)
                                                }
                                    }
                        }
            }

Comprehensions are a language feature that allow you to define such a chain in a way where every observable is a function at topmost indentation, yet still contains all the parameters received in the previous functions.

Usage

Map comprehensions

RxComprehensions contains static methods doFlatMap() for flatMap(), doConcatMap() for concatMap(), doSwitchMap() for switchMap(). Each takes from 1 to 9 FuncN each with an increasing number of parameters, and returns an Observable of the type of the return of the last function.

Observable<String> getUserFriends =
    // chained with flatMap()
    RxComprehensions.doFlatMap(
        () -> profileClicks(),
        position -> getUserFromProfile(position),
        position, user -> requestFriendListForUser(position, user.id),
        position, user, friends -> storeUserAndFriends(user, friends),
        position, user, friends, result -> toUserDisplayString(position, user, friends, result)
    );

Compose comprehensions

RxComprehensions contains static methods doCompose() for compose(). Each takes from 1 to 9 Transformer<T, U> (RxJava 1.X) or ObservableTransformer<T, U> (RxJava 2.X), and returns an Observable of the type of the return of the last one.

Observable<List<Siblings>> getRelatives =
    // chained with compose()
    RxComprehensions.doCompose(
        () -> requestRelative("12345"),
        validate(),
        assureThreads(Schedulers.io(), AndroidSchedulers.main()),
        respectLifecycle(activity),
        toUILayerModel(),
        groupSiblings()
    );

Observable<RelativeDto> requestRelative(String id) { /* ... */ }

ObservableTransformer<RelativeDto, RelativeDto> validate() { /* ... */ }

ObservableTransformer<RelativeDto, RelativeDto> assureThreads(Scheduler in, Scheduler out) { /* ... */ }

ObservableTransformer<RelativeDto, RelativeDto> respectLifecycle(Activity activity) { /* ... */ }

ObservableTransformer<RelativeDto, Relative> toUILayerModel() { /* ... */ }

ObservableTransformer<Relative, List<Siblings>> groupSiblings() { /* ... */ }

Distribution

RxJava 1.X

Add as a dependency to your build.gradle

repositories {
    ...
    maven { url "https://jitpack.io" }
    ...
}
    
dependencies {
    ...
    compile 'com.github.pakoito.RxComprehensions:rxcomprehensions:1.3.0'
    ...
}

or to your pom.xml

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependency>
    <groupId>com.github.pakoito.RxComprehensions</groupId>
    <artifactId>rxcomprehensions</artifactId>
    <version>1.3.0</version>
</dependency>

RxJava 2.X

Add as a dependency to your build.gradle

repositories {
    ...
    maven { url "https://jitpack.io" }
    ...
}
    
dependencies {
    ...
    compile 'com.github.pakoito.RxComprehensions:rxcomprehensions2:1.3.0'
    ...
}

or to your pom.xml

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependency>
    <groupId>com.github.pakoito.RxComprehensions</groupId>
    <artifactId>rxcomprehensions2</artifactId>
    <version>1.3.0</version>
</dependency>

License

Copyright (c) pakoito 2016

The Apache Software License, Version 2.0

See LICENSE.md