TypeScript 1.5 - Metadata Annotations / Interfaces #2305

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1. Dan Quirk (danquirk)

   added

   QuestionAn issue which isn't directly actionable in codeAn issue which isn't directly actionable in code

   on Mar 11, 2015
2. DanielRosenwasser commented on Mar 11, 2015

   

   Daniel Rosenwasser (DanielRosenwasser)

   on Mar 11, 2015

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   See #2249 and the proposal for decorators in ES7.

   As for type serialization, interfaces will actually not carry any metadata (they will just represented as the Object constructor function); however, classes will be serialized. You can see the specifics for our the scheme here. Keep note that this is a work in progress and we're ironing out the details.
3. giancarloa commented on Mar 12, 2015

   

   giancarloa

   on Mar 12, 2015

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   Thanks Daniel Rosenwasser (@DanielRosenwasser) for the info!!! I think I understand a little better now what's happening...

   it all looks great EXCEPT the interfaces... don't you think it's a serious problem that there's no way to query metadata for interfaces? In my case for example I would never ever do the first example I gave above. Instead I would always do the second which is program against an interface, and I would dare say this is usually the norm rather than the exception among devs. At the very least you guys could write out the fully qualified name of the interface. I never really understood why you guys don't produce a JS function for TS interface declarations.

   One other question I have... is TS going to always automatically generate basic metadata about TS classes OR do we always have to create and use decorators for this? For example, I believe AtScript was going to always generate metadata about the constructor function's parameter types without the developer having to do anything (see "Metadata Annotations" section of https://docs.google.com/document/d/11YUzC-1d0V1-Q3V0fQ7KSit97HnZoKVygDxpWzEYW0U/mobilebasic?viewopt=127). Is TS going to do the same? I hope so....

   Thanks again
4. giancarloa commented on Mar 16, 2015

   

   giancarloa

   on Mar 16, 2015

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   since i got no response i guess it's best to close this item and ask my follow up questions in a new item.
5. giancarloa

   closed this as completedon Mar 16, 2015
6. bparadie commented on May 7, 2015

   

   Bernd Paradies (bparadie)

   on May 7, 2015

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   giancarloa I found this article very helpful: https://smellegantcode.wordpress.com/2015/04/02/typescript-1-5-get-the-decorators-in/

   Here is the example in Playground:

   // https://smellegantcode.wordpress.com/2015/04/02/typescript-1-5-get-the-decorators-in/
   
   class C {
       @log
       foo(n: number) {
           return n * 2;
       }
   }
   
   function log(target: Function, key: string, value: any) {
       return {
           value: (...args: any[]) => {
   
               var a = args.map(a => JSON.stringify(a)).join();
               var result = value.value.apply(this, args);
               var r = JSON.stringify(result);
   
               console.log(`Call: ${key}(${a}) => ${r}`);
   
               return result;
           }
       };
   }
   
   var c = new C();
   console.log(c.foo(23));
   
7. Ciantic commented on Jun 2, 2015

   

   Jari Pennanen (Ciantic)

   on Jun 2, 2015

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   Maybe this should be renamed as asking for documentation for annotations?

   I tried to find annotations from handbook, there is no mention of "@", "decorator" or "annotations". Also noticed the language spec is TS 1.4 so it wasn't helpful either.
8. DanielRosenwasser commented on Jun 2, 2015

   

   Daniel Rosenwasser (DanielRosenwasser)

   on Jun 2, 2015

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   Jari Pennanen (@Ciantic) I agree that we need to improve our documentation - the handbook is fairly outdated. We're currently fixing it up, and decorators are one of the new topics we intend to write about.
9. microsoft

   locked and limited conversation to collaborators on Jun 18, 2018