chore: add a mixin for disabled and apply it to md-button (#3944)

src/lib/button/button.ts

@@ -10,6 +10,7 @@ import {
   ViewEncapsulation
 } from '@angular/core';
 import {coerceBooleanProperty, FocusOriginMonitor} from '../core';
+import {mixinDisabled, CanDisable} from '../core/common-behaviors/disabled';
 
 
 // TODO(kara): Convert attribute selectors to classes when attr maps become available
@@ -79,6 +80,11 @@ export class MdFabCssMatStyler {}
 export class MdMiniFabCssMatStyler {}
 
 
+// Boilerplate for applying mixins to MdButton.
+export class MdButtonBase { }
+export const _MdButtonMixinBase = mixinDisabled(MdButtonBase);
+
+
 /**
  * Material design button.
  */
@@ -89,14 +95,15 @@ export class MdMiniFabCssMatStyler {}
             'button[mat-button], button[mat-raised-button], button[mat-icon-button],' +
             'button[mat-fab], button[mat-mini-fab]',
   host: {
-    '[disabled]': 'disabled',
+    '[disabled]': 'disabled || null',
   },
+  inputs: ['disabled'],
   templateUrl: 'button.html',
   styleUrls: ['button.css'],
   encapsulation: ViewEncapsulation.None,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
-export class MdButton implements OnDestroy {
+export class MdButton extends _MdButtonMixinBase implements OnDestroy, CanDisable {
   private _color: string;
 
   /** Whether the button is round. */
@@ -107,20 +114,15 @@ export class MdButton implements OnDestroy {
 
   /** Whether the ripple effect on click should be disabled. */
   private _disableRipple: boolean = false;
-  private _disabled: boolean = null;
 
   /** Whether the ripple effect for this button is disabled. */
   @Input()
   get disableRipple() { return this._disableRipple; }
   set disableRipple(v) { this._disableRipple = coerceBooleanProperty(v); }
 
-  /** Whether the button is disabled. */
-  @Input()
-  get disabled() { return this._disabled; }
-  set disabled(value: boolean) { this._disabled = coerceBooleanProperty(value) ? true : null; }
-
   constructor(private _elementRef: ElementRef, private _renderer: Renderer,
               private _focusOriginMonitor: FocusOriginMonitor) {
+    super();
     this._focusOriginMonitor.monitor(this._elementRef.nativeElement, this._renderer, true);
   }
 
@@ -179,10 +181,11 @@ export class MdButton implements OnDestroy {
   selector: `a[md-button], a[md-raised-button], a[md-icon-button], a[md-fab], a[md-mini-fab],
              a[mat-button], a[mat-raised-button], a[mat-icon-button], a[mat-fab], a[mat-mini-fab]`,
   host: {
-    '[attr.disabled]': 'disabled',
+    '[attr.disabled]': 'disabled || null',
     '[attr.aria-disabled]': '_isAriaDisabled',
     '(click)': '_haltDisabledEvents($event)',
   },
+  inputs: ['disabled'],
   templateUrl: 'button.html',
   styleUrls: ['button.css'],
   encapsulation: ViewEncapsulation.None

src/lib/core/common-behaviors/disabled.spec.ts

@@ -0,0 +1,18 @@
+import {mixinDisabled} from './disabled';
+
+
+describe('MixinDisabled', () => {
+  it('should augment an existing class with a disabled property', () => {
+    class EmptyClass { }
+
+    let classWithDisabled = mixinDisabled(EmptyClass);
+    let instance = new classWithDisabled();
+
+    expect(instance.disabled)
+        .toBe(false, 'Expected the mixed-into class to have a disabled property');
+
+    instance.disabled = true;
+    expect(instance.disabled)
+        .toBe(true, 'Expected the mixed-into class to have an updated disabled property');
+  });
+});

src/lib/core/common-behaviors/disabled.ts

@@ -0,0 +1,22 @@
+import {coerceBooleanProperty} from '../coercion/boolean-property';
+
+
+/** @docs-private */
+export type Constructor<T> = new(...args: any[]) => T;
+
+/** @docs-private */
+export interface CanDisable {
+  disabled: boolean;
+}
+
+/** Mixin to augment a directive with a `disabled` property. */
+export function mixinDisabled<T extends Constructor<{}>>(base: T): Constructor<CanDisable> & T {
+  return class extends base {
+    private _disabled: boolean = false;
+
+    get disabled() { return this._disabled; }
+    set disabled(value: any) { this._disabled = coerceBooleanProperty(value); }
+
+    constructor(...args: any[]) { super(...args); }
+  };
+}

src/lib/core/common-behaviors/index.ts

@@ -0,0 +1 @@
+export {CanDisable, mixinDisabled} from './disabled';