I think something like this should be sufficient:

.registerGutter(name: string, priority: number) { ... }
// line numbers would have some special priority, 100 maybe?
// to add it to the right of them you'd have to specify more than that
// default would be 1
.unregisterGutter(name: string)
.clearGutter(name: string)
.setGutterMarker(name: string, line: number, marker: jQueryObj)

first two methods should probably live on EditorManager, the second two on Editor

@thehogfather let me know if you want to implement something like this, I just quickly put it together from how https://github.com/zaggino/brackets-inspection-gutters/blob/master/src/main.ts use these

@zaggino

Only thing I would say was missing is an ability to list current gutters and their priorities. So:

.getGutters():Array<{name: string, priority: number}>

This would enable extension authors to avoid/address any potential conflicts with existing gutters names and priorities. Both name and priorities should be unique - possibly throw errors on conflict.

Also is there any reason why all methods shouldn't be in Editor.js?

@thehogfather true, that method was missing.

The reason I'd put registerGutter, unregisterGutter, getRegisteredGutters on the EditorManager and not the Editor itself, it's that I'm able to just call registerGutter on startup of my extension, and there'll always be reserved place for it. I don't have to manage on which Editor's I have registered my gutter and on which not. Of course if my extension is language specific we probably don't want to have gutters on all languages and this makes it kind of complex. We could add another parameter to be array of LanguageId's of default to be all languages.

But... if you want to make it simply, they can all live on the editor.

About the conflicts, I think we should hardcode priorities for inbuilt default gutters (line numbers, code folding) and console warning when someone else tries to use them. Besides that, let extensions set which priority they want. For example all my linting extensions would probably use the same priority, whatever the number would it be.

Merging this, @thehogfather please submit a PR with the API proposal or let me know if I should work on it. I've been hitting #12726 all the time and it's quite bad side effect. It can't make it to the release.

@zaggino I'll submit a PR.

Thanks