# Tapable

``` javascript
var Tapable = require("tapable");
```

`Tapable` is a class for plugin binding and applying.

Just extend it.

``` javascript
function MyClass() {
	Tapable.call(this);
}

MyClass.prototype = Object.create(Tapable.prototype);

MyClass.prototype.method = function() {};
```

Or mix it in.

``` javascript
function MyClass2() {
	EventEmitter.call(this);
	Tapable.call(this);
}

MyClass2.prototype = Object.create(EventEmitter.prototype);
Tapable.mixin(MyClass2.prototype);

MyClass2.prototype.method = function() {};
```

## Public functions

### apply

``` javascript
void apply(plugins: Plugin...)
```

Attaches all plugins passed as arguments to the instance, by calling `apply` on them.

### plugin

``` javascript
void plugin(names: string|string[], handler: Function)
```

`names` are the names (or a single name) of the plugin interfaces the class provides.

`handler` is a callback function. The signature depends on the class. `this` is the instance of the class.

## Protected functions

### applyPlugins

``` javascript
void applyPlugins(name: string, args: any...)
```

Synchronously applies all registered handlers for `name`. The handler functions are called with all args.

### applyPluginsWaterfall

``` javascript
any applyPluginsWaterfall(name: string, init: any, args: any...)
```

Synchronously applies all registered handlers for `name`. The handler functions are called with the return value of the previous handler and all args. For the first handler `init` is used and the return value of the last handler is return by `applyPluginsWaterfall`

### applyPluginsAsync

``` javascript
void applyPluginsAsync(
	name: string,
	args: any...,
	callback: (err?: Error) -> void
)
```

Asynchronously applies all registered handlers for `name`. The handler functions are called with all args and a callback function with the signature `(err?: Error) -> void`. The handler functions are called in order of registration.

`callback` is called after all handlers are called.

### applyPluginsBailResult

``` javascript
any applyPluginsBailResult(name: string, args: any...)
```

Synchronously applies all registered handlers for `name`. The handler function are called with all args. If a handler function returns something `!== undefined`, the value is returned and no more handlers are applied.

### applyPluginsAsyncWaterfall

``` javascript
applyPluginsAsyncWaterfall(
	name: string,
	init: any,
	callback: (err: Error, result: any) -> void
)
```

Asynchronously applies all registered handlers for `name`. The handler functions are called with the current value and a callback function with the signature `(err: Error, nextValue: any) -> void`. When called, `nextValue` is the current value for the next handler. The current value for the first handler is `init`. After all handlers are applied, `callback` is called with the last value. If any handler passes a value for `err`, the `callback` is called with this error and no more handlers are called.

### applyPluginsAsyncSeries

``` javascript
applyPluginsAsyncSeries(
	name: string,
	args: any...,
	callback: (err: Error, result: any) -> void
)
```

Asynchronously applies all registered handlers for `name`. The handler functions are called with all `args` and a callback function with the signature `(err: Error) -> void`. The handlers are called in series, one at a time. After all handlers are applied, `callback` is called. If any handler passes a value for `err`, the `callback` is called with this error and no more handlers are called.

### applyPluginsParallel

``` javascript
applyPluginsParallel(
	name: string,
	args: any...,
	callback: (err?: Error) -> void
)
```

Applies all registered handlers for `name` in parallel. The handler functions are called with all args and a callback function with the signature `(err?: Error) -> void`. The `callback` function is called when all handlers have called the callback without `err`. If any handler calls the callback with `err`, `callback` is invoked with this error and the other handlers are ignored.

### applyPluginsParallelBailResult

``` javascript
applyPluginsParallelBailResult(
	name: string,
	args: any...,
	callback: (err: Error, result: any) -> void
)
```

Applies all registered handlers for `name` in parallel. The handler functions are called with all args and a callback function with the signature `(err?: Error) -> void`. Handler functions must call the callback. They can either pass an error, pass undefined, or pass a value. The first result (either error or value) which is not undefined is passed to the `callback`. The order is defined by registration, not by the speed of the handler function.

### hasPlugins

``` js
hasPlugins(
	name: string
)
```

Returns true, if plugins are registered for this name.