microsoft / microsoft/TypeScript

Decorators not allowed classes expressions

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#7,342 32 comments 90 reactions 0 assignees View on GitHub

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Domain: Decorators Suggestion Waiting for TC39
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Description

Not sure if this is by design or not, but the following gives a compile error of "Decorators are not valid here" with TypeScript 1.8:

let testClass = new class {
    testMethod(@myDecorator date: Date): any {
        return date;
    }
}();

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by compiling the minimal class-expression example from the issue with TypeScript 1.8 and inspect how decorator validation handles method parameters in class expressions. Check related compiler tests or parser/type-checker entry points once located. Done means the intended decorator syntax is either accepted with coverage or clearly rejected as unsupported with a documented rationale.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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