Setting up an Integrated Development Environment
The integrated Python editor in openLCA is nice if you want to quickly write and execute small scripts directly in openLCA. However, if you want to do something more complicated it is better to use an editor with advanced features like code formatting, auto-completion, etc. This chapter explains how you can setup the integrated development environment (IDE) PyDev to use it with the openLCA API.
Installing Java and Jython
As described in the previous chapters, openLCA is a standard Java desktop application. To access the openLCA API we use Jython which is a Python implementation that runs on the Java Virtual Machine (JVM) and is directly integrated in openLCA. Thus, if we want to access the openLCA API outside of openLCA we need to first install a Java Runtime Environment (JRE) >= 8 and Jython.
To install the JRE, just go to the Oracle download site, accept the license, and download the respective installation package for your platform (take the x64 package if you have a 64 bit computer and the x86 package if you have a 32 bit computer):
To test if Java is correctly installed, just open a command line and execute the following command:
java -version
This should return something like this:
java version "1.8.0_101"
Java(TM) SE Runtime Environment ...
After this, we can download and run the Jython installer
which is also a Java application. In the installation wizard, we select
the standard installation type and an arbitrary folder, e.g.
~/openlca/jython_ide/jython_2.7:
To test the installation, you can run the jython executable in the
jython_2.7/bin folder which will open a standard
Python REPL.
Installing PyDev
PyDev is a Python IDE for Eclipse with Jython support.
To use it with Jython, we need Eclipse with Java development tools and the
easiest way to get this is to start with an Eclipse installation. Thus, download
the Eclipse IDE for Java Developers
and extract it to a folder (e.g. ~/openlca/jython_ide/eclipse):
Start the Eclipse executable and create a workspace, e.g. under
~/openlca/jython_ide/workspace (this is just a folder where your projects are
stored). Now we can install PyDev via the menu Help > Install New Software....
In the installation dialog click on Add... to register the PyDev update site
http://www.pydev.org/updates:
Then select the PyDev package, accept the license, install it, and restart Eclipse:
After the restart, you can configure the Jython interpreter under
Window > Preferences and select the jython.jar from your Jython installation
(e.g. ~/openlca/jython_ide/jython_2.7/jython.jar):
Using the openLCA API
Now you can create a new PyDev project under File > New > Project... > PyDev Project.
You just need to give it a name and select Jython as interpreter:
When you now create a script, you should be able to run it directly with the Jython interpreter:
When you print somthing on the console, you may get the following error:
console: Failed to install '': java.nio.charset.UnsupportedCharsetException: cp0.
This is related to this Jython issue which
you could just ignore. To fix this, you can set the following parameter under
Run -> Run Configurations -> Arguments -> VM Arguments:
-Dpython.console.encoding=UTF-8
To use the openLCA API in the project, right click on the project and open
the project Properties. Click on the PyDev PYTHONPATH and in the
External Libraries tab on the button Add zip/jar/egg button. Then select
all jar files in the openlca/plugins/olca-app_<version>/libs folder of
an openLCA installation you want to use:
Now you should be able to use all the IDE features of PyDev like auto-completion etc.:
Logging
openLCA uses SLF4J over Log4j for logging.
log4j.rootLogger=INFO, A1
log4j.logger.org.openlca=INFO
log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n