API: Menu item enablement

[bpasero]

This used to be like that in the old world I think.

[joaomoreno]

@jrieken Any thoughts on contributed menu items enablement?

[jrieken]

Yeah, there is no story for enablement yet. For now you make the when-clause more specific such that the menu item doesn't show. One idea could be to add an enablement-clause when defining a command. It could use the when-syntax but define enablement of a command.

[joaomoreno]

Renamed for clarity.

[garyking]

It would be great to have this, so that the Open Changes button can be greyed out when there are no changes for the current file.

[jrieken]

cc @rebornix

[jrieken]

most work actually already happened via #41103, exposing this to extensions is the missing piece

[jrieken]

Idea would be to allow for a precondition with the command definition. That would allow to define the condition that must be fulfilled so that this command can be run, the UX is enablement/disablement.

"contributes": {
    "commands": [
      {
        "command": "someCommand",
        "title": "My Some Command",
        "precondition": "myContext == 42",
        "category": "Something"
      },

[jrieken]

This happened via: #74017

[jrieken]

@rebornix While revising #74017 I missed that enablement isn't a menu property but a command property. Commands should be enable/disabled independent of their UX location. I have pushed a change for this. After discussing we have also concluded that enablement is the better name for this. Sample a command that is only enabled when having a selection in the editor

{
  "command": "extension.sayHello1",
  "title": "Hello Enablement",
  "enablement": "editorHasSelection"
}