dependency-injection.jade, a little more translation.

This commit is contained in:
Rex 2016-04-26 12:30:30 +01:00
parent fd4f934fd5
commit 7e386533cc
1 changed files with 31 additions and 0 deletions

View File

@ -594,62 +594,93 @@ figure.image-display
img(src="/resources/images/cookbooks/dependency-injection/hero-of-month.png" alt="Hero of the month" width="300px")
:marked
It's visually simple: a few properties and the output of a logger. The code behind it gives us plenty to talk about.
它看起来很简单一些属性和一个日志output。但是后面的代码给我们很多议论点。
+makeExample('cb-dependency-injection/ts/app/hero-of-the-month.component.ts','hero-of-the-month','hero-of-the-month.component.ts')
.l-main-section
a(id='provide')
:marked
#### The *provide* function
#### *provide*函数
The imported Angular `provide` function creates an instance of
the Angular [Provider](../api/core/Provider-class.html) class.
被导入的Angular `provide`函数新建一个Angular [Provider](../api/core/Provider-class.html)类的实例。
The `provide` function takes a *token* and a *definition object*.
The *token* is usually a class but [it doesn't have to be](#tokens).
该`provide`函数需要一个*令牌*和一个*定义对象*。该*令牌*通常是一个类,但是[他不是一定是](#tokens)
The *definition* object has one main property, (e.g. `useValue`) that indicates how the provider
should create or return the provided value.
该*定义*项目有一个主要属性,(即为`userValue`)来标识该provider应该怎么新建和返回被提供的结果。
.l-main-section
a(id='usevalue')
:marked
#### useValue - the *value provider*
#### useValue - *值provider*
Set the `useValue` property to a ***fixed value*** that the provider can return as the dependency object.
把一个***固定的值**也就是该provider可以当作依赖对象返回的值赋给`userValue`属性。
Use this technique to provide *runtime configuration constants* such as web-site base addresses and feature flags.
We often use a *value provider* in a unit test to replace a production service with a fake or mock.
使用该技巧来提供*运行时间设置常量*,比如网站的基础地址和功能标志等。我们通常在单元测试中使用一个*value provider*,用一个假的或模仿的(服务)来取代一个成品服务。
The `HeroOfTheMonthComponent` example has two *value providers*.
The first provides an instance of the `Hero` class;
the second specifies a literal string resource:
`HeroOfTheMonthComponent`例子有两个*value providers*。
第一个提供了一个`Hero`类的实例;第二个指定了一个文字字符串资源:
+makeExample('cb-dependency-injection/ts/app/hero-of-the-month.component.ts','use-value')(format='.')
:marked
The `Hero` provider token is a class which makes sense because the value is a `Hero`
and the consumer of the injected hero would want the type information.
该`Hero`provider令牌是一个类这很合理因为提供的结果是一个`Hero`,而且使用这个被注入英雄的组件也想要知道这个类型信息。
The `TITLE` provider token is *not a class*.
It's a special kind of provider lookup key called an [OpaqueToken](#opaquetoken).
We often use an `OpaqueToken` when the dependency is a simple value like a string, a number, or a function.
`TITLE` provider令牌*不是一个类*。它是一个特别类型的provider查询键名叫[OpaqueToken](#opaquetoken).
The value of a *value provider* must be defined *now*. We can't create the value later.
Obviously the title string literal is immediately available.
The `someHero` variable in this example was set earlier in the file:
一个*value provider*的值必须要*立刻*定义。我们不能过后定义它的值。很显然,该标题字符串立刻可用。
该例中的`someHero`变量是于早先,在下面的文件里面定义的:
+makeExample('cb-dependency-injection/ts/app/hero-of-the-month.component.ts','some-hero')
:marked
The other providers create their values *lazily* when they're needed for injection.
其他providers只在注入需要他们的时候才创建他们值 - *延迟加载*
.l-main-section
a(id='useclass')
:marked
#### useClass - the *class provider*
#### useClass - *类provider*
The `useClass` provider creates and returns new instance of the specified class.
`userClass` provider创建并返回一个特定类的新实例。
Use this technique to ***substitute an alternative implementation*** for a common or default class.
The alternative could implement a different strategy, extend the default class,
or fake the behavior of the real class in a test case.
We see two examples in the `HeroOfTheMonthComponent`:
+makeExample('cb-dependency-injection/ts/app/hero-of-the-month.component.ts','use-class')(format='.')
:marked