# List of notable changes made between 2.x and 3.0

All breaking changes must be described here. When adding a new entry,
always describe the impact on users and instructions for upgrading
applications from 2.x to 3.0.

## boot.compile is now async and returns context with instructions

Users that uses `boot.compile()` in the following syntax would need to update
their implementation, it now calls callback function with `instructions` in
`context` object rather than synchronously returning instructions.

Before:

```js
var APP_PATH = path.resolve('../sandbox');
var instructions = boot.compile(APP_PATH);
```

New signature:

```js
var APP_PATH = path.resolve('../sandbox');
var instructions;
boot.compile(APP_PATH, function(err, context) {
  instructions = context.instructions;
});
```

Please see [PR #181](https://github.com/strongloop/loopback-boot/pull/181) for full details of change.