Microsoft/TypeScript

Language service: open Type.id

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#5,687 opened on Nov 16, 2015

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Domain: APIHelp WantedSuggestion

Description

I am using language service to "traverse" the program, and I would like very much to "remember" which types and symbols I already saw, and to cache my computation results for them. Performance boost and avoiding infinite loops.

The compiler very helpfully supplies id for Type, Symbol and Node, and it seems to be "really, really" unique for symbols and nodes, and "relatively unique" (i.e. within a given typechecker) for types.

The problem is, however, that, unlike nodes and symbols, types hide their ids behind the "internal" qualifier and the lack of accessor function, making them not legally visible to me as a consumer of the language service. Of course, this being JavaScript, nothing prevents me from accessing them anyway, and that is what I currently do, but this is not ideal, because I am not protected from the code evolution in the future.

So it seems to me that nothing stands in the way of adding a getTypeId method to the typechecker, unless I'm missing something very important.

Contributor guide

Tech stack
typescript
Domain
tooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScript compiler internalsFamiliarity with checker.ts and types.ts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Look at TypeScript source files src/compiler/checker.ts and src/compiler/types.ts. The issue requests adding a public method getTypeId to the type checker that exposes the already existing internal id property of Type. Check if there are any existing methods like getSymbolId or getNodeId for consistency. Propose implementation: add a new method in checker.ts similarly to how other id accessors are defined. Ensure to handle the case where type might be undefined. Write tests for the new method. Also consider whether the method should be part of the language service public API. Since the issue is old, verify that no similar change has been made in later versions. If not, create a PR with the change.
Language service: open Type.id · Microsoft/TypeScript#5687 | Good First Issue