This Ember addon lets you use the decorator syntax for declaring/configuring ember-concurrency tasks.
Requirements:
- At least
ember-cli-babel@^7.7.2
- At least
@babel/core@^7.5.0
(as a transitive dependency viaember-cli-babel
) - At least
ember-cli-typescript@^2.0.0
, if you want to use it with TypeScript @ember-decorators/babel-transforms
is not installed- The rest of
@ember-decorators
, if present, is^6.0.0
- Below Ember v3.10:
ember-decorators-polyfill
Then install the latest
release:
ember install ember-concurrency-decorators
If you are still using stage 2 decorators, I recommend that you refactor away from them as soon as possible.
Requirements:
- at least
ember-cli-babel@^7.7.2
@ember-decorators/babel-transforms
is installed- The rest of
@ember-decorators
, if present, is^5.0.0
(below6.0.0
)
Then install the legacy
version:
ember install ember-concurrency-decorators@legacy
The following documentation will not be accurate. Instead refer to the docs for stage 2 decorators.
@task
: turns a generator method into a task@restartableTask
@dropTask
@keepLatestTask
@enqueueTask
@taskGroup
: creates a task group from a property@restartableTaskGroup
@dropTaskGroup
@keepLatestTaskGroup
@enqueueTaskGroup
@lastValue
: alias a property to the result of a task with an optional default value
import Component from '@ember/component';
import { task } from 'ember-concurrency-decorators';
export default class ExampleComponent extends Component {
@task
*doStuff() {
// ...
}
// and then elsewhere
executeTheTask() {
// `doStuff` is still a `Task` object that can be `.perform()`ed
this.doStuff.perform();
console.log(this.doStuff.isRunning);
}
}
You can also pass further options to the task decorator:
@task({
maxConcurrency: 3,
restartable: true
})
*doStuff() {
// ...
}
For your convenience, there are extra decorators for all concurrency modifiers:
Shorthand | Equivalent |
---|---|
@restartableTask |
@task({ restartable: true }) |
@dropTask |
@task({ drop: true }) |
@keepLatestTask |
@task({ keepLatest: true }) |
@enqueueTask |
@task({ enqueue: true }) |
You can still pass further options to these decorators, like:
@restartableTask({ maxConcurrency: 3 })
*doStuff() {
// ...
}
Encapsulated Tasks behave just like regular tasks, but with one crucial difference: the value of
this
within the task function points to the currently running TaskInstance, rather than the host object that the task lives on (e.g. a Component, Controller, etc). This allows for some nice patterns where all of the state produced/mutated by a task can be contained (encapsulated) within the Task itself, rather than having to live on the host object.
import Component from '@ember/component';
import { task } from 'ember-concurrency-decorators';
export default class ExampleComponent extends Component {
@task
doStuff = {
privateState: 123,
*perform() {
// ...
}
};
// and then elsewhere
executeTheTask() {
// `doStuff` is still a `Task` object that can be `.perform()`ed
this.doStuff.perform();
console.log(this.doStuff.isRunning);
}
}
Encapsulated Tasks do not work with ember-cli-typescript@1
. See the
TypeScript section for more details.
import Component from '@ember/component';
import { task, taskGroup } from 'ember-concurrency-decorators';
export default class ExampleComponent extends Component {
@taskGroup
someTaskGroup;
@task({ group: 'someTaskGroup' })
*doStuff() {
// ...
}
@task({ group: 'someTaskGroup' })
*doOtherStuff() {
// ...
}
// and then elsewhere
executeTheTask() {
// `doStuff` is still a `Task `object that can be `.perform()`ed
this.doStuff.perform();
// `someTaskGroup` is still a `TaskGroup` object
console.log(this.someTaskGroup.isRunning);
}
}
You can also pass further options to the task group decorator:
@taskGroup({
maxConcurrency: 3,
drop: true
}) someTaskGroup;
As for @task
, there are extra decorators for all concurrency modifiers:
Shorthand | Equivalent |
---|---|
@restartableTaskGroup |
@taskGroup({ restartable: true }) |
@dropTaskGroup |
@taskGroup({ drop: true }) |
@keepLatestTaskGroup |
@taskGroup({ keepLatest: true }) |
@enqueueTaskGroup |
@taskGroup({ enqueue: true }) |
You can still pass further options to these decorators, like:
@dropTaskGroup({ maxConcurrency: 3 }) someTaskGroup;
This decorator allows you to alias a property to the result of a task. You can also provide a default value to use before the task has completed.
import Component from '@ember/component';
import { task } from 'ember-concurrency-decorators';
import { lastValue } from 'ember-concurrency-decorators';
export default class ExampleComponent extends Component {
@task
*someTask() {
// ...
}
@lastValue('someTask')
someTaskValue;
@lastValue('someTask')
someTaskValueWithDefault = 'A default value';
}
The specification for decorators in broader JavaScript has been in flux. Unfortunately, that means if you have been an early adopter of decorators in your Ember application, you may need to deal with some API churn.
(You can read an excellent discussion on decorators here.)
Check the above requirements to see what version you need to install.
If you are sure, that you fulfilled the requirements correctly, but are still
experiencing weird errors, install
ember-cli-dependency-lint
to ensure that you are
not accidentally including outdated versions of ember-decorators
as transitive
dependencies.
If it's still not working after that, please create an issue.
You can use this package with ember-cli-typescript@2
. But unfortunately
decorators cannot yet change the type signature of the decorated element. This
is why you are getting type errors like:
import { task } from 'ember-concurrency-decorators';
export default class Foo {
@task
*doStuff(this: Foo) {
// ...
}
executeTheTask() {
this.doStuff.perform();
}
}
TS2339: Property 'perform' does not exist on type '() => IterableIterator<any>'.
Check issue #30 for more details.
Very soon, you will be able to use the following syntax instead with TypeScript:
import { task } from 'ember-concurrency-decorators';
export default class Foo {
@task
doStuff = task(function*(this: Foo) {
// ...
});
executeTheTask() {
this.doStuff.perform();
}
}
This might not be using a fancy generator method, but it is ๐ฏ type-safe! ๐
Check the PR #56 for progress.
No! If you are using Ember v3.10.0 or above, you can use ember-concurrency
directly, like this:
import { task } from 'ember-concurrency';
class Foo {
@(task(function*() {
// ...
}).restartable())
doStuff;
executeTheTask() {
this.doStuff.perform();
}
}
However:
- This syntax will not continue to work with the new "static decorators" proposal that is set to replace the stage 1 decorators eventually.
- This does not properly type-check with TypeScript. See TypeScript Support for more details.
- I think this looks hideous, but that is just an opinion.
Eventually, all work in ember-concurrency-decorators
will likely flow back
into ember-concurrency
at some point. Until then, we want to mature and
test-drive the API here first.
This project is licensed under the MIT License.