/**
 * This is a directive to store data in a local variable
 * I developped it from angular's ngIf directive.
 * https://github.com/angular/angular/blob/6.1.1/packages/common/src/directives/ng_if.ts
 *
 * ## Storing result in a variable
 *
 * A common pattern is that we need to show a set of properties from the same object. If the
 * object is undefined, then we have to use the safe-traversal-operator `?.` to guard against
 * dereferencing a `null` value. This is especially the case when waiting on async data such as
 * when using the `async` pipe as shown in following example:
 *
 * ```
 * Hello {{ (userStream|async)?.last }}, {{ (userStream|async)?.first }}!
 * ```
 * There are several inefficiencies in the above example:
 *  - We create multiple subscriptions on `userStream`. One for each `async` pipe, or two in the
 *    example above.
 *  - We have to use the safe-traversal-operator `?.` to access properties, which is cumbersome.
 *  - We have to place the `async` pipe in parenthesis.
 *
 * A better way to do this is to use `ngIf` and store the result of the condition in a local
 */
import { TemplateRef, ViewContainerRef } from '@angular/core';
export declare class NgLetDirective {
    private _viewContainer;
    private _context;
    private _thenTemplateRef;
    private _thenViewRef;
    constructor(_viewContainer: ViewContainerRef, templateRef: TemplateRef<NgLetContext>);
    ngLet: any;
    private _updateView;
}
export declare class NgLetContext {
    $implicit: any;
    ngLet: any;
}
export declare class NgLetModule {
}