The Object Teams Blog

Adding team spirit to your objects.

Using git for an interactive video – Replay the JDT tutorial

with 2 comments

When preparing the tutorial How to train the JDT dragon, Ayushman and me packed way more material than we could possible teach in 3 hours time.

Luckily, Ayush came up with an idea that enables all of you to go through the exercise all on your own: instead of creating zip files with various stages of the example projects, we pushed everything to github. I apologize to those who were overwhelmed by how we pushed git onto the tutorial participants in Reston.

Now, as EclipseCon is over, here’s what you can do:

  • Fetch the slides: PDF or slideshare
  • Clone the material for the plain JDT part (git: URL), containing two projects for the first two exercises.
    • org.eclipsecon2012.jdt.tutorial1: traverse the Java Model starting from the element selected in the UI
    • org.eclipsecon2012.jdt.quickFix1: implement a quickfix for adding a missing null check
  • Clone the misc repo (git: URL), containing
    • handouts: instructions for the exercises
    • org.eclipsecon2012.jdt.populator: plug-in that was used in the tutorial to create sample content in the runtime workbench; show cases how to programmatically create Java files from String content
  • Clone the OT repo (git: URL), containing
    • AntiDemo: the OT/Equinox hello-world: prohibition of class names starting with “Foo”.
    • Reachability: a full blown reachability analysis in < 300 LOC.

The last exercise, “Reachability”, we couldn’t even show in Reston, but luckily this is the most detailed repo: in 13+1 commits I recorded the individual steps of adding inter-procedural reachability analysis piggy-back on top of the JDT compiler. If you replay these commits from the git repo you can watch me creating this little plug-in from scratch. Starting from step 5 you’ll be able to see the results when you fire up a runtime workbench: the analysis will print to stdout what methods it found during each full build.

Look at the commit comments which summarize what I would have explained in demo mode. Still the material is pretty dense as it explains three technologies at the same time:

  1. How does this analysis work?
  2. What points in the JDT do we hook onto?
  3. How is the integration achieved using Object Teams.

Speaking of integration: using the “Binding Editor” you can see all bindings in a tabular view:

Bindings of the Reachability plug-in

The right hand side of the table give the full list of JDT elements we connect to:

  • classes that are extended using a role_obj role
  • methods/fields that are accessed externally via a callout binding callout binding
  • methods that are intercepted using a callin binding (after) callin binding.

As a special bonus, step 14 in the git repo shows how to add problem markers for each unreachable method, so that the JDT will actually offer its existing quickfix for removing:
Unreachable methods
(Yep, both methods are detected as unreachable: calling each other without being called from another reachable method doesn’t help).

I hope you enjoy playing with the examples. For questions please use one of the forums:

Advertisements

Written by Stephan Herrmann

April 7, 2012 at 15:20

2 Responses

Subscribe to comments with RSS.

  1. Thanks guys for the great work!

    Is it possible to see the video of the presentation?

    Sergey X

    June 10, 2016 at 07:18

    • The slides are available (see links in the post), but I don’t recall any video recording. Given the interactive nature of tutorials, such a video may actually not be very helpful, I’d say.

      Stephan Herrmann

      June 11, 2016 at 13:17


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: