MergingInsideSqueak

Group 18

What is it?

MergingInsideSqueak (MIS) is a project that aims at providing a starting point for Squeak native merging tool that aids the user when merging and is independent from the underlying version control system (Git, Monticello).

What can it do?

Compared to previous legacy solutions, we added

• A nicer user interface that allows the user to merge versions interactively by selecting which variant to use for each conflicting line in a change instead of only being able to include or exclude the entire change
• Can merge both Monticello and GitBrowser
• Is an independent tool that can be adapted to work with many more version control systems
• diffing, which is basically the implementation of the Legacy system (- we also added line based diffing which almost works sufficient but would need a little more love before being production ready)

How to use it?

If you want to experiment and get a feel of how the tool works, you can open the tool with

MISMergeUiView openWithMockData

in your workspace.

However, if you install the included .sar archive or clone from this repository, the tool is configured to merge both when using Monticello or the GitBrowser. Open one of the tools, open a repository, choose a new change and click Merge.

How does it work?

The tool consists of the independent merging tool core inside the package MergingInsideSqueak-Core, which holds the MVC User Interface and the required data models. The core diffing functionality is contained in the MergingInsideSqueak-Diff2 package.

The GitBrowser adapter overwrites the SquotWorkingCopy>>mergeVersionInteractively:ifCanceled: method in the Squot-Core package and performs the merge by bridging to our tool.

Similarily, the Monticello adapter overwrites the MCVersion>>merge method in the Monticello-Versioning package and performs the merge using the MISMCVersionMerger by bridging to our tool.

Other included packages are dependencies or have been slightly altered to provide convenience conversion interfaces. The tool passes legacy tests, but additional tests tailored to the independent tool can be found in the MergingInsideSqueak-Tests package.

Limitations and future work

We focused most on the compatibility with the existing Squeak legacy systems, the user interface and the diffing.

A major drawback that is shared with the existing legacy solutions is the lack of freetype merging. While we provide the advantage of being able to select either version for each confliting line instead of the entire method, there is no support to edit the merged version freely while keeping the comfort of selecting versions with a button.

Currently, some possible changes like class comments or timestamps are not taken into consideration and figuring out nice ways to display those changes (e.g. an additional layer in the PluggableTreeViewMorph).

There is also no support for automatic merging or more complex 3-way merges, but these were out of our scope and it is left to evaluate the relevance of such features. Nevertheless, those ideas could be a staring point for future improvement.