Summary:
We've decided to move the syntax for asynchronously requiring async dependencies. The new syntax works better with promises and therefore withe async/await as well. The new syntax looks like this: `System.import('moduleA').then(moduleA => {...});` or if you're using async/await you could simply do:
let moduleA = await System.import('moduleA');
new moduleA().someFunction();
If you need to require multiple dependencies just do:
Promise
.all([System.import('moduleA'), System.import('moduleB')])
.then((moduleA, moduleB) => {...})
or the equivalent using async/await
Summary:
This is the first step to add support for splitting the JS bundle into multiple ones. This diff adds support for keeping track of the async dependencies each module has. To do so we introduce the following syntax:
require.ensure(['dep1', 'dep2, ..., 'depN'], callback);
Where the callback function is asynchronously invoked once all the indicated modules are loaded.
Internally, the packager keeps track of every set of async dependencies a module has. So for instance if a module looks like this:
require.ensure(['dep1'], () => {...});
require.ensure(['dep2'], () => {...});
the `Module` object will keep track of each set of dependencies separately (because we might want to put them on separate bundles).
Summary:
@public
Fixes#773, #1055
The resolver was getting a bit unwieldy because a lot has changed since the initial writing (porting node-haste).
This also splits up a large complex file into the following:
* Makes use of classes: Module, AssetModule, Package, and AssetModule_DEPRECATED (`image!` modules)
* DependencyGraph is lazy for everything that isn't haste modules and packages (need to read ahead of time)
* Lazy makes it fast, easier to reason about, and easier to add new loaders
* Has a centralized filesystem wrapper: fast-fs (ffs)
* ffs is async and lazy for any read operation and sync for directory/file lookup which makes it fast
* we can easily drop in different adapters for ffs to be able to build up the tree: watchman, git ls-files, etc
* use es6 for classes and easier to read promise-based code
Follow up diffs will include:
* Using new types (Module, AssetModule etc) in the rest of the codebase (currently we convert to plain object which is a bit of a hack)
* using watchman to build up the fs
* some caching at the object creation level (we are recreating Modules and Packages many times, we can cache them)
* A plugin system for loaders (e.g. @tadeuzagallo wants to add a native module loader)
Test Plan:
* ./runJestTests.sh react-packager
* ./runJestTests.sh PackagerIntegration
* Export open source and run the e2e test
* reset cache
* ./fbrnios.sh run and click around
