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01bec1736f
function, rename it _init(), plumb that through AutomaticMetadata, and move @tagname and Element.tagname to a new frameworks.md file that has stuff that wouldn't actually be part of core Sky Review URL: https://codereview.chromium.org/946513006
32 lines
1.1 KiB
Markdown
32 lines
1.1 KiB
Markdown
Frameworks
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----------
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Sky is intended to support multiple frameworks. Here is one way you
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could register a custom element using Dart annotations:
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```dart
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// @tagname annotation for registering elements
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// only useful when placed on classes that inherit from Element
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class tagname extends AutomaticMetadata {
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const tagname(this.name);
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final String name;
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void init(DeclarationMirror target, Module module, ScriptElement script) {
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assert(target is ClassMirror);
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if (!(target as ClassMirror).isSubclassOf(reflectClass(Element)))
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throw new UnsupportedError('@tagname can only be used on descendants of Element');
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module.registerElement(name, (target as ClassMirror).reflectedType);
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}
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}
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```
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A framework that used the above code could use the following code to
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get the tag name of an element:
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```dart
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String getTagName(Element element) { // O(N) in number of annotations on the class
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// throws a StateError if the class doesn't have an @tagname annotation
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var tagnameClass = reflectClass(tagname);
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return (reflectClass(element.runtimeType).metadata.singleWhere((mirror) => mirror.type == tagnameClass).reflectee as tagname).name;
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}
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```
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