terminal/doc/specs/#6899 - Action IDs/#6899 - Action IDs.md

author	created on	last updated	issue id
Mike Griese @zadjii-msft	2020-07-13	2020-07-22	6899

Action IDs

Abstract

This document is intended to serve as an addition to the Command Palette Spec, as well as the New Tab Menu Customization Spec.

As we come to rely more on actions being a mechanism by which the user defines "do something in the Terminal", we'll want to make it even easier for users to re-use the actions that they've already defined, as to reduce duplicated json as much as possible. This spec proposes a mechanism by which actions could be uniquely identifiable, so that the user could refer to bindings in other contexts without needing to replicate an entire json blob.

Solution Design

This spec was largely inspired by the following diagram from @DHowett:

The goal is to introduce an id parameter by which actions could be uniquely refered to. If we'd ever like to use an action outside the list of actions, we can simply refer to the action's ID, allowing the user to only define the action once.

We'll start by renaming bindings to actions. bindings was suggested as a rename for keybindings in #6532, as a way to make the name more generic. Discussion with the team lead to the understanding that the name actions would be even better, as a way of making the meaning of the "list of actions" more obvious.

When we're parsing actions, we'll make three passes:

• The first pass will scan the list for objects with an id property. We'll attempt to parse those entries into ActionAndArgs which we'll store in the global id->ActionAndArgs map. If any entry doesn't have an id set, we'll skip it in this phase. If an entry doesn't have a command set, we'll ignore it in this pass.
• The second pass will scan for keybindings. Any entries with keys set will create a KeyChord->ActionAndArgs entry in the keybindings map. If the entry has an id set, then we'll simply re-use the action we've already parsed for the id, from the action map. If there isn't an id, then we'll parse the action manually at this time. Entries without a keys set will be ignored in this pass.
• The final pass will be to generate commands. Similar to the keybindings pass, we'll attempt to lookup actions for entries with an id set. If there isn't an id, then we'll parse the action manually at this time. We'll then get the name for the entry, either from the name property if it's set, or the action's GenerateName method.

For a visual representation, let's assume the user has the following in their actions:

We'll first parse the actions to generate the mapping of id->Actions:

Then, we'll parse the actions to generate the mapping of keys to actions, with some actions already being defined in the map of id->Actions:

When layering actions, if a later settings file contains an action with the same id, it will replace the current value. In this way, users can redefine actions, or remove default ones (with something like { "id": "Terminal.OpenTab", "command":null }

We'd maintain a large list of default actions, each with unique ids set. These are all given id's with a Terminal. prefix, to easily identify them as built-in, default actions. Not all of these actions will be given keys, but they will all be given ids.

👉 NOTE: The IDs for the default actions will need to be manually created, not autogenerated. These ids are not strings displayed in the user interface, so localization is not a concern.

As we add additional menus to the Terminal, like the customization for the new tab dropdown, or the tab context menu, or the TermControl context menu, they could all refer to these actions by id, rather than duplicating the same json.

Existing Scenarios

Keybindings will still be stored as a keys->Action mapping, so the user will still be able to override default keybindings exactly the same as before.

Similarly, commands in the Command Palette will continue using their existing name->Action mapping they're currently using. For a binding like

{ "keys": "ctrl+alt+x", "id": "Terminal.OpenDefaultSettings" },

• We'll bind whatever action is defined as Terminal.OpenDefaultSettings to ctrl+alt+x.
• We'll use whatever action is defined as Terminal.OpenDefaultSettings to generate a name for the command palette.

Future Context Menus

In New Tab Menu Customization Spec, we discuss allowing the user to bind actions to the new tab menu. In that spec, they can do so with something like the following:

{
    "newTabMenu": [
        { "type":"action", "command": { "action": "adjustFontSize", "delta": 1 }, }
        { "type":"action", "command": { "action": "adjustFontSize", "delta": -1 }, }
        { "type":"action", "command": "resetFontSize", }
        { "type":"profile", "profile": "cmd" },
        { "type":"profile", "profile": "Windows PowerShell" },
        { "type":"separator" },
        {
            "type":"folder",
            "name": "Settings...",
            "icon": "C:\\path\\to\\icon.png",
            "entries":[
                { "type":"action", "command": "openSettings" },
                { "type":"action", "command": { "action": "openSettings", "target": "defaultsFile" } },
            ]
        }
    ]
}

In this example, the user has also exposed the "Increase font size", "Decrease font size", and "Reset font size" actions, as well as the settings files in a submenu. With this proposal, the above could instead be re-written as:

{
    "newTabMenu": [
        { "type":"action", "id": "Terminal.IncreaseFontSize" },
        { "type":"action", "id": "Terminal.DecreaseFontSize" },
        { "type":"action", "id": "Terminal.ResetFontSize" },
        { "type":"profile", "profile": "cmd" },
        { "type":"profile", "profile": "Windows PowerShell" },
        { "type":"separator" },
        {
            "type":"folder",
            "name": "Settings...",
            "icon": "C:\\path\\to\\icon.png",
            "entries":[
                { "type":"action", "id": "Terminal.OpenDefaultSettings" },
                { "type":"action", "id": "Terminal.OpenSettings" },
            ]
        }
    ]
}

In this example, the actions are looked up from the global map using the id provided, enabling the user to re-use their existing definitions. If the user re-defined the Terminal.IncreaseFontSize action to mean something else, then the action in the new tab menu will also be automatically updated.

Furthermore, when additional menus are added (such as the tab context menu, or the TermControl context menu), these could also leverage a similar syntax to the above to allow re-use of the id parameter.

Discussion with the team also suggested that users shouldn't be able to define actions in these menus at all. The actions should exclusively be defined in actions, and other menus should only be able to refer to these actions by id.

UI/UX Design

There's not a whole lot of UI for this feature specifically. This is largely behind-the-scenes refactoring of how actions can be defined.

Capabilities

Accessibility

(not applicable)

Security

(no change expected)

Reliability

(no change expected)

Compatibility

(no change expected)

Performance, Power, and Efficiency

(no change expected)

Potential Issues

This won't necessarily play well with iterable commands in the Command Palette, but that's okay. For iterable commands, users will still need to define the actions manually.

Future considerations

• See the following issues for other places where this might be useful:
  • #1912 - Context Menu for Tabs
    • See also #5524, #5025, #5633
  • #3337 - Right-click menu inside TerminalControl (w/ Copy & Paste?)
    • See also #5633 and #5025, both those actions seem reasonable in either the tab context menu or the control context menu.