Neko is a toolkit designed to make Android development using Clojure easier and more fun. It accomplishes this by making adding Clojure support to your Android project easy and providing functional wrappers and alternatives to Android’s Java API.
Warning
|
Note that the libraries are under heavy development. APIs are subject
to change. In particular, neko.threading will be changed.
|
The toolkit comes as two components:
-
Simplified build support for Clojure using Android’s Ant-based build system, and
-
The following Clojure libraries:
-
neko.compilation
helps set up dynamic compilation. -
neko.context
helps retrieve resources from the application’s context. -
neko.listeners
contains namespaces that take the tedium to adding callback code to various widgets. -
neko.log
interns functions that make logging from your code clean and simple. -
neko.threading
will contain utilities to manage asynchronous tasks and working with UI threads.
-
Using Neko requires the following:
- Clojure 1.2 or newer
-
Clojure 1.2 works on Android 2.2 and newer. Clojure 1.3 and newer work on Android 2.3 and newer.
If you would like to use dynamic compilation with Android 2.3 and newer, use the Clojure available from the
android
branch from this repository on GitHub. This branch is based off the latest Clojure development version.If you would like to use dynamic compilation, but must support Android 2.1, you will need to use the version from branch
android-1.2.x
, available here. This is based off of Clojure 1.2.1. - Android SDK Tools
-
Neko has been developed with the latest revision of the Android SDK tools, and is compatible with r17 and up of the Android SDK.
WarningRevisions 14 and 17 of the Android SDK introduced changes in the Ant build system. Neko has been updated to use the build system in r17. You will probably need to change your project if you have been using an older version of Neko/SDK. For more detailed information, check the Android Tools Project site for information about the breaking changes in r14 and r17. - Android Platform SDK 7 (2.1/Eclair) or newer
-
In order to maintain backwards-compatibility, Neko does not support any APIs for newer versions of the platform.
The following instructions should help you to add Clojure support to your project’s build and allow you to use the libraries within your application.
You can get this from directly from Google. You will need to be sure to also install a platform for development. The CyanogenMod wiki has some more detailed instructions.
Just clone the repository to your computer:
% git clone https://github.com/clojure-android/neko.git
If all went well, Neko should now be in a directory called neko
.
Now, go into the neko
directory and created a directory called libs
. Copy
clojure.jar
into that directory. If you don’t already have Clojure
installed, you can download it from the project’s
page.
Next, you will need to create a new Android project using the android
command
from the Android SDK, as follows:
% android create project -p <directory> -t <target> -k <package> -a <activity>
The arguments to this command are:
<directory>
-
The name of the directory for your new project.
<target>
-
The target API version you will use for development. For example, you could use
android-15
to target the Android 4.0.3 platform. You can see a list of targets available by runningandroid list targets
. <package>
-
This unique string will be used to identify your application. You should follow the package naming conventions. An example may be
com.example.cool_clojure_app
. <activity>
-
This is the name of a class that will be the entry point of your application.
Once you run this, you will see a bunch of output as the SDK generates your project, for example:
% android create project -p hello -k com.example.hello_clojure -a HelloActivity -t android-15 Created project directory: hello Created directory /home/dan/devel/android/hello/src/com/example/hello_clojure Added file hello/src/com/example/hello_clojure/HelloActivity.java Created directory /home/dan/devel/android/hello/res Created directory /home/dan/devel/android/hello/bin Created directory /home/dan/devel/android/hello/libs Created directory /home/dan/devel/android/hello/res/values Added file hello/res/values/strings.xml Created directory /home/dan/devel/android/hello/res/layout Added file hello/res/layout/main.xml Created directory /home/dan/devel/android/hello/res/drawable-hdpi Created directory /home/dan/devel/android/hello/res/drawable-mdpi Created directory /home/dan/devel/android/hello/res/drawable-ldpi Added file hello/AndroidManifest.xml Added file hello/build.xml Added file hello/proguard-project.txt
Change into the new directory for your project and calculate the relative path to the directory where you cloned Neko. Now, run the following command:
% android update project -p . -l <../relative/path/to/neko>
For example:
% cd hello % android update project -p . -l ../neko Resolved location of library project to: /home/user/work/neko Updated project.properties Updated local.properties Updated file ./proguard-project.txt
To enable Neko’s build support for Clojure, you will need to make two
modifications to the build.xml
file in your project directory.
-
You must add a line to similar to the following before the line with
<import file="${sdk.dir}/tools/ant/build.xml" />
.<import file="/path/to/neko/build-support/clojure.xml"/>
The important thing is that the value of the
file
attribute should resolve to theclojure.xml
in thebuild-support
directory of this repository. It may be either a relative or absolute path. -
You must find the line that reads
<!-- version-tag: 1 -->
and change the1
tocustom
. If you do not do this, Android may overwrite your changes.
You may have noticed that when you created the project file, Android generated a Java file corresponding to the package and activity name. Delete it. For example:
% rm -r src/com
By default, Neko looks in src/clojure
.
% mkdir src/clojure
For replicate the default activity that the SDK created in Clojure, you will
need to create a source file with the same namespace as the original file.
For example, given the package com.example.hello_clojure
and the activity
HelloActivity
, you would create the file
src/clojure/com/example/hello_clojure/HelloActivity.clj
as follows:
(ns com.example.hello_clojure.HelloActivity
(:gen-class :main false
:extends android.app.Activity
:exposes-methods {onCreate superOnCreate})
(:import [com.example.hello_clojure R$layout]))
(defn -onCreate
[this bundle]
(doto this
(.superOnCreate bundle)
(.setContentView R$layout/main)))
As a gist: https://gist.github.com/2361385
You can now run and install the application to a running emulator or a connected device using:
% ant debug install
If all went well, you should be able to find your application in the launcher. When you run it, after several seconds, you should see a simple ‘Hello World’ appear.
Here are some more things you can do with Neko:
You can place a clojure.properties
file in the build-support
directory from
Neko (where clojure.xml
lives). This file will be sourced and used in any
project in which you have enabled Clojure build support.
To enable reflection warnings during compilation, simply set the
clojure.warn.reflection
property to true
. This is something that might be
good to put in that clojure.properties
file.
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