Lively ChangeSets

This modules implements ChangeSets for Lively.

The exported gitInterface can be used anywhere a localInterface is used but in addition to reading and writing resources to the file system, it also supports reading and writing to a current ChangeSet.

Example use:

import { gitInterface, createChangeSet } from "lively.changesets";
 
const origSrc = await gitInterface.moduleRead("lively.modules/index.js");
 
const cs = await createChangeSet("test");
cs.setCurrent();
await gitInterface.moduleWrite("lively.modules/index.js", "export const x=1");
const newSrc = await gitInterface.moduleRead("lively.modules/index.js");
// newSrc == "export const x=1";
 
cs.delete();
const restoredSrc = await gitInterface.moduleRead("lively.modules/index.js");
// restoredSrc == origSrc;

Implementation

The ChangeSet implementation requires a Lively system with packages that are managed by lively.modules and have a package address (typically a URL as string).

ChangeSets

When a package is changed with an changeset, the change will be stored as a branch for the git repository of the package.

Besides the name, a ChangeSet is simply a set of these branches.

Branches

A branch always belongs to a ChangeSet and a package and holds changes in the git format for branches. Therefore, the branch references blobs, trees and previous commits by their hash values. By default, missing blobs, trees and commits are automatically fetched from GitHub if the package has a configured repository URL in its package.json file.

The actual git objects and refs are stored in the IndexedDB of the browser. The reference of the branch itself is named after the package address and the name for the ChangeSet:

${packageAddress}/heads/${changeSetName}

By keeping changes as git objects, it is easy to push ChangeSets as new pull requests to GitHub, thereby integrating with the normal Lively development process.

All changesets in the current browser session are found by searching the IndexedDB of the browser for refs in the format above for each registered pacakge.

Notifications

There are four different types of system-wide notifications:

1. {type: "lively.changesets/added", changeset}
2. {type: "lively.changesets/changed", changeset, path}
3. {type: "lively.changesets/switchedcurrent", changeset, before}
4. {type: "lively.changesets/deleted", changeset}

These notifications are all emitted with lively.notifications.

Tools

TODO: ChangeSorter