41 lines
1.1 KiB
Plaintext
41 lines
1.1 KiB
Plaintext
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.l-main-section
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h2(class="function export") forwardRef
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pre.prettyprint
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code.
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forwardRef(forwardRefFn: ForwardRefFn) : Type
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p.location-badge.
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exported from <a href='../di'>angular2/di</a>
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defined in <a href="https://github.com/angular/angular/tree/3a0410a/modules/angular2/src/di/forward_ref.ts#L3-L35">angular2/src/di/forward_ref.ts (line 3)</a>
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:markdown
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Allows to refer to references which are not yet defined.
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This situation arises when the key which we need te refer to for the purposes of DI is declared,
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but not yet defined.
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## Example:
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```
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class Door {
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// Incorrect way to refer to a reference which is defined later.
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// This fails because `Lock` is undefined at this point.
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constructor(lock:Lock) { }
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// Correct way to refer to a reference which is defined later.
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// The reference needs to be captured in a closure.
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constructor(@Inject(forwardRef(() => Lock)) lock:Lock) { }
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}
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// Only at this point the lock is defined.
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class Lock {
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}
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```
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