Start using a union for FunctionLike things #16988
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
sandersn
approved these changes
Jul 6, 2017
Member
sandersn
left a comment
sandersn
left a comment
There was a problem hiding this comment.
Looks good. One naming suggestion, although I'm not sure it's an improvement.
src/compiler/types.ts
Outdated
| | SetAccessorDeclaration | ||
| | FunctionExpression | ||
| | ArrowFunction; | ||
| export type FunctionLikeTypes = |
ghost
mentioned this pull request
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
We have a type,
FunctionLikeDeclaration, which is used a lot internally. We also have a functionisFunctionLikewhich, prior to this PR, guarded to that type. However, what the type guard checked for and what was based on that type were not the same set of types. This PR clarifies the relationship between what that guard checks for and what is considered aFunctionLikeDeclarationby moving everything over to using unions of the correct types (isFunctionLikenow guards to a union of the type associated with the syntax kinds it actually checks) - this has the added advantage that in places where usage is correct, fewer casts are required. (Although, in many cases we unsafely check ifnode.bodyexists when the node's type indicates it should never have a body - in these places we now need a cast to assert that we'd like to check the potentially nonexistent property)It also breaks the property signature interface into two interfaces so they may be union-ed together and properly discriminated in our current checker.
I mentioned I had done this in one of my branches to @sandersn as I was working because I was becoming annoyed by lots of small gotchyas when attempting to use these types as they existed prior (and attempting to remember what was/was not safe to cast to).