In line with the approach taken in the Changes & Versions Tool, a user can make changes and commit a series of transactions, and when ready to version, can press the Save Version button in the Changes & Versions Tool. The VCS integration puts the current state into the VCS working directory, and makes a VCS version from there.

The VCS working directory is kept separate from the MetaEdit+ directory, because VCSs cannot work sensibly with a live set of database files. MetaEdit+ copies the repository into the VCS working directory (using its backup functionality to allow the user to remain logged in). It also writes the current textual snapshots of each graph, and the metamodel as a textual snapshot, including generators as separate .rep files. These textual files add about 10% to the initial size, but as only small parts change in subsequent versions, the improvement in the ability to compare versions within the VCS itself is well worth it. The VCS working directory contains the textual snapshots of the graphs, a metamodel subdirectory containing each Graph type’s generators and textual snapshot, and a versionedDB subdirectory containing the MetaEdit+ repository files.

The standard way of using command-line VCSs – manually change a file, and in a separate command manually tell the VCS that the file has changed – is not necessary in a situation where a tool can guarantee that what is in the working directory is the exact state of the next version. Only a few VCS commands are thus needed, and MetaEdit+ will handle calling them. The commands are specified in a few MERL generators called by the various phases of the Save Version action. Having the commands in MERL generators allows users to tweak the integration if necessary, and also to add integration for new VCSs. The generators are saved in Graph, as _vcs*, with a suffix for the VCS name when necessary – e.g. _vcsCheckIn_git() checks in the current working directory contents, adding and committing them locally, and syncing and pushing them to a remote Git repository if one is defined.