Developer's Guide

The BLOG project is hosted on Github. Contributions in the form of GitHub pull requests. In the following part of this guide, for anything concerns the sbt file, we will only write it as sbt/sbt. For Windows users, please use sbt\sbt instead.

General guideline

Code style

Use google java style * 2 spaces for indent * no long lines * Please use \n for line terminator!

Build Tool

BLOG uses sbt for building and releasing packages. The minimal requirement is sbt version 0.13.


To set up Eclipse for BLOG development:

  1. Download the Scala IDE. This is just Eclipse bundled together with the Scala plugins.
  2. Generate the Eclipse project file using sbt/sbt eclipse.
  3. Import the project into Eclipse

Code style:

Eclipse config file is provided. Please use the version already in git master branch.

To run a BLOG model from within Eclipse:

  1. Enter Run Configurations, create a new configuration
  2. Set project to blog
  3. Set Main class to blog.Main
  4. In the Arguments tab, pass in the path to the BLOG model, and any parameters


Some things to try if you run into trouble:

  1. In the Eclipse menu, click Project > Clean
  2. Right click on the project, click Scala > Add Scala Library to Build Path

Generating Lexer and Parser

You only need to do this if you modified BLOGLexer.flex or BLOGParser.cup

  sbt/sbt lexer
  sbt/sbt parser

Compiling source

  sbt/sbt compile
  sbt/sbt stage

The second command is to ensure you can run blog and iblog in development environment.

Unit Test

  sbt/sbt test


To make a release

  sbt/sbt compile
  sbt/sbt html
  sbt/sbt universal:package-bin

Generate Debian installation package

  sbt/sbt debian:package-bin

Generate Windows Installation package

You must have WIX installed. Obtain it from

  sbt/sbt windows:package-bin

Git Basics

You may also be interested in some Git basics:

Pull Request

The basic unit of code review is a pull request. Here is how you make one. Note you can PR off branches, so there is no need to fork the repo. This is what's referred to as "Shared Repository Model" in the doc below.

How to use Pull Requests

You should create a feature branch whenever you start to work on something. This is the branch you will work off for the entire development cycle. When you finish development on the feature, you will merge this branch back into master. This way, we can ensure that our master branch is always in a good state, and never has anything that is only partially complete.

$ git checkout -b feature_name 

As early as you can (you can even do this before you start any work) start a pull request on Github. You should use the PR for discussion about this particular feature as well. Periodically push your code to this branch, which will update the PR. It's recommended that you get your code reviewed at regular intervals rather than all at once.

Managing Feature Branches & Pull Requests

Squashing Commits

The git motto is that you should commit often. Some people go as far as committing every 5-10 minutes. This is perfectly fine, and recommended for your local history while you work. It allows you to revert easily fi you make a mistake.

However, all these granular commits may not be the easiest thing for a reviewer to address (b/c each commit shows up as a separate page you have to click on and comment). Therefore, you should commit often but squash your commits before you push to the PR.

Updating Your Branch

For long features, your feature branch may fall behind of master a lot. This is bad, since it will introduce difficult merge issues later on (the more you fall behind of master, the harder it is for you to merge your changes back into it). Therefore, you will want to regularly update your feature branch with commits that happened on the master branch.

The desired operation here is a rebase rather than a merge. A rebase will take the history seen on master, and replay it as if they happened on your branch. This has the effect of keeping the history clean, as the only "merge" entries we will see are when we merge feature branches back into master.

The commands you should run to rebase are

git fetch --all
git rebase origin/master

When you do push your code after a rebase, you will have to do so with

git push --force

The --force option is required since a rebase re-writes revision history, so your local history and the upstream history will disagree. --force tells git you want to override the upstream history with the rebased history.

Closing a Pull Request

When you get an LTGM, just click the merge button on github to merge your changes into master.