hpi-swa-teaching / koans

Next-level Koans

Next Level Koans

Next Level Koans is an HPI project to improve teaching of Smalltalk and Squeak to students in the lecture series Software Architecture. Koans consist of testsuites, introducing idioms and basic concepts through coding exercises within a graphical user interface.

How to Install

The Koans are compatible with either Squeak 5.1 or Squeak trunk (check Travis for more information). The easiest way to install the Koans is by getting Metacello and then executing the following snippet:

Metacello new
  baseline: 'Koans';
  repository: 'github://hpi-swa-teaching/Koans/src';
  load.

How to Start

1. In the menu bar click on Apps>>Koans.

   

2. This should open the KoanBrowser. The KoanBrowser shows all the available chapters on the left, a description of the selected chapter in the top richt and the list of Koans inside the selected chapter on the bottom right.
   Note: The chapters are sorted by priority / the order they are meant to be solved.

   

3. To start a specific Koan, first select its chapter on the left and then click the corresponding entry in the list on the right. This opens the KoanEditor. The KoanEditor consists of the statusbar at the top, the code panel in the center and a row of buttons at the bottom.

   

Editing Koans

• You can navigate through the chapter of the currently opened Koan via the 'Previous' and 'Next' buttons. To change the chapter you have to return to the KoanBrowser via the 'Overview'-button.

• The status of the opened Koan is represented by the status bar. It changes color depending on wheter the Koan is solved (green), failing (yellow) or erroring (red). In case the Koan is not successfully run, the bar also shows additional information about what went wrong.

  

• By default the Koan is tested (and the status bar updated) whenever changes to the opened Koan (or the Koan's required classes) are saved. This can be turned off (globally) via the editor's window menu.

  

• If the test on save functionality has been turned off, the only way to test the opened Koan is through the 'Test'-button. It also saves the currently made changes.

• The opened Koan can be returned to its original state through the 'Reset Koan'-button.

• The 'Debug'-button opens a debugger on an execution context of the currently opened Koan.

• Some Koans require the user to edit or look at specific classes. These classes can be easily accessed through a browser opened by the 'Browse Project'-button.

  

Contributors

Over the years, the following people have contributed to the Koans project:

Robin Schreiber, Patrick Rein, Eric Seckler, Daniel Stolpe, Tobias Pape, Jakob Reschke, Willi Müller, Daniel Kurzynski, Wenzel Pünter, Stephan Lutz, J-L-O, Jeilef, Fabio Niephaus, Robert Hirschfeld, Marcel Taeumel

History

You can find previous versions of the Koans project on the previous documentation page.

koans's Issues

Add keyboard shortcuts to navigate the Koans

Making error catching less strict

In case a new line causes an exception it should not be caught. Currently most exceptions are caught (e.g. ZeroDivision). Opening a debugger is a valuable lesson at that point.

Prevent Felix's Problem

If there is an infinite loop in a Koan using the KoanEditor becomes really slow. The major cause for this is the repeated execution of Koans when updating the editor. This can be prevented with less repetitions of Koan executions and a shorter timeout.

On external changes, the Koans should be re-executed

otherwise the list of Koans in the Sensei does not show whether the Koans have been already done.

Squeak 6.0 support

CI should be green

Add example solutions & solution explanations

So students can take a look at that after they solved the Koan (sometimes they get what needs to be done but do not understand they should have seen)

Overwritting should be overriding...

Koans/src/Koans-Chapters.package/KoanAboutInheritance.class/instance/test02methodInheritanceAndOverwrittingExist.st

Line 2 in f48b57d

test02methodInheritanceAndOverwrittingExist

Fix test04methodNamesBecomeSymbols

This Koans includes a do: where a collect: should be

Modulo operator

In KoanAboutCollectionProtocol, test04select includes

self assert: {2 . 4 . 6} equals: ({1 . 2 . 3 . 4 . 5 . 6} select: xx)

This to me looks like [:aNumber | aNumber \\ 2 = 0] or similar. However, \\ as the modulo operator is rather unusual compared to other programming languages the students might already know (most use %, mod or similar). Maybe a hint regarding the operator could be added?

If looking for the operator in Number or SmallInteger as part of the solution finding process is intended, I'm happy to close.

Prevent Christoph's Problem

Christoph created a method which used random. As a result the Koan returned different results on every run. As the different parts of the user interface of the KoanEditor all depend on their own execution of the Koans, the KoanEditor can get into an inconsistent ui state. This should be prevented by:
1.) Less reptitions (see #9)
2.) Setting the random seed to the same value

Redundant tests for symbol identity

In KoanAboutSymbols, test02symbolsCanBeCompared and test03identicalSymbolsAreASingleIdenticalObject are redundant. Symbol identity is already shown in the former, thus the latter shows nothing new.

A potential fix might be changing the former to show equality (=) and inequality (~=) instead, leaving the latter to demonstrate identity (==).

Move Cascades to the back

They are not essential and are confusing at the beginning

Symbols with spaces test ordering

In KoanAboutSymbols, test05symbolsCanBeMadeFromStrings and test06symbolsWithSpacesCanBeMade both show the creation of symbols with spaces (#'Cats and dogs'). The syntax (#'...') is first shown in the latter, leaving the student alone in figuring it out in the former. Also, the two tests are almost redundant.

A potential fix might be showing the creation of symbols without spaces from strings in the former (e. g. #Cats == 'Cats' asSymbol), while keeping the latter as it is. This way, the student doesn't need to figure out new syntax, because #Smalltalk (no space) is shown in the first test, and the symbol-with-spaces syntax is still shown in the latter for completeness.

Improve description and logic of cascade Koan

The Koans about Cascades could use an improved comment and should include more steps to make the introduction less confusing.

Figure out and fix broken Travis Build

So far I could not reproduce it locally but will investigate tomorrow.

Koan on the difference between instance variables and methods

In order to clarify the difference between the two

View & Enhance all Koans