This document covers the steps needed to install DUCK and start using the compiler for the Serpentine language. If you are reading this document online, you will need to download the respository containing it to your workstation. This is covered in the Installation section below.
Since DUCK is a set of modules and tools written in the Python language, you will need to install a Python interpreter. Specifically, you will need to install the latest release of Python 2.7 or Python 3. You will also need to install the corresponding PyCrypto package for the version of Python you have installed and the Python Imaging Library (or the Pillow fork of PIL).
If you have not yet downloaded the DUCK repository, you will need to install Git since that is what we will use to obtain the repository.
You need to install ImageMagick and librsvg2 - these are used to generate icons for applications from SVG files. If ImageMagick is provided as a set of packages for your system you will also need the extras package that includes the SVG plugin.
The documentation generator relies on Markdown and Pygments.
You will also need to install OpenSSL because the
openssl tool is used to create and manage keys and certificates used for
signing packages.
Additionally, if you want to be able to install packages via a USB cable to an
attached device, you need to install the adb tool.
If you are using Debian GNU/Linux you can install these dependencies with one the following commands depending on which version of Python you are using.
For Python 2:
sudo apt-get install git python python-crypto imagemagick \
libmagickcore-extra openssl android-tools-adb \
python-markdown python-pygments
For Python 3:
sudo apt-get install git python3 python3-crypto imagemagick \
libmagickcore-extra openssl android-tools-adb \
python3-markdown python3-pygments
Other GNU/Linux distributions and Unix-like systems should have packages that correspond to these.
If you haven't already done so, you need to download the repository containing this document. First, open a console and change into a directory where the repository will be placed, then use Git to clone the repository using the following command if you are using Python 2:
git clone https://gitlab.com/dboddie/DUCK
Use this command if you are using Python 3:
git clone -b python3 https://gitlab.com/dboddie/DUCK
There should now be a directory called DUCK in the current directory.
Currently, there is no way of installing the modules and tools to a system-wide
location. To allow Python scripts to access the modules, and to run the
compiler for Serpentine, you need to add the directory to the PYTHONPATH
environment variable. On GNU/Linux and other Unix-like systems, you can do this
by typing the following in the console (running a bash shell):
export PYTHONPATH=$PWD/DUCK:$PYTHONPATH
To test the installation, run Python from the console in the following way:
python -c 'import Dalvik'
This should run without error messages.
The following information is given in the Creating Keys and Certificates document. You can create a key to use for signing packages and a corresponding certificate using OpenSSL with the following commands:
openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3
openssl req -new -x509 -days 365 -sha1 -key key.pem -out cert.pem
The key.pem and cert.pem files are used to sign packages. The Android
documentation contains the Implementing Security
document which gives advice about handling signing keys.
The DUCK repository contains some simple application examples and some regression tests. These are described in the Examples README.html and Tests README.html files respectively.
To quickly check that package building works, type the following command in the
console, remembering to set the PYTHONPATH as described above:
DUCK/Examples/Serpentine/Hello/build.py key.pem cert.pem Hello.apk
This should run without errors. If the Hello.apk package is created in the
current directory, you can install it with the following command:
adb install Hello.apk
If successful, some information about the installation process and the word
Success should be printed to the console. Otherwise, you may find it useful
to inspect the debug log for the device by running the following command:
adb logcat
You will need to terminate this process with Ctrl-C when you have finished examining the debugging output.
Applications are written in the Serpentine language, which has a syntax based
on that of the Python language. Although source code written in this language
is compiled, there isn't a front-end for the compiler. Instead, it is invoked
using a build script written in Python. The examples in the
Examples/Serpentine directory are stored in
self-contained directories, each with their own build.py script.
The Introduction to Serpentine document gives an overview of the language, providing code examples, and discusses aspects of it where its semantics differ from those of the Python language.