This is How Easy it is to Make Changes to DrRacket

DrRacket is open-source (LGPL) editor for Racket. Sometimes you want to make changes to it. For example today I wanted to enable online compilation on single-core machines. Here is how easy it is to do it:

1. Assuming that DrRacket is already installed. This is a normal installation using the installer; you do not typically have to check out the Git repo to make changes.
2. Asked Robby how to make the change. Robby is super everybody knows that, he explained the fix. The check for enabling the feature is in module-language.rkt. Here are the steps

3. cd /opt/racket/5.3.1/collects/drracket/private/
   sudo cp module-language.rkt module-language.rkt-ORG
   # Made the change
   # View it
   diff module-language.rkt module-language.rkt-ORG
   1329,1330c1329
   <                    ;;(> (processor-count) 1))
   <                    (> (processor-count) 0))
   ---
   >                    (> (processor-count) 1))
   1348,1349c1347
   <                    ;;(> (processor-count) 1))
   <                    (> (processor-count) 0))
   ---
   >                    (> (processor-count) 1))
   # Tell Racket to recompile that collection (aka library)
   sudo raco setup -l drracket
   # Restart DrRacket
   

4. Now the online compilation indicator shows up and errors are automatically flagged.
5. It works fine on a 1.6GHz Pentium with 2GB of RAM.

Hope this gave you a taste of how easily and quickly you can try new stuff out in DrRacket itself.
Here is how it looks with it turned on: