akkartik/template-live-editor - Change 5WHW3IDOHOBXY3M3QPXNMHFFNXXD6RR5B2WL6TB5TTVNZJYCN2AQC

fix initialization errors using driver.love

Changes inside on.initialize are minefields. Until now, if you made a mistake when modifying on.initialize, you could end up in a situation where the app would fail irrecoverably on the next startup. You'd have to go dig up a text editor to fix it.

After this commit, errors in on.initialize wait for commands from driver.love just like any other error.

Recovering from errors during initialization is a little different than normal. I don't know how much of initialization completed successfully, so I redo all of it.

I think this should be safe; the sorts of things we want to do on startup tend to be idempotent just like the sorts of things we do within an event loop with our existing error handling.

Things are still not ideal. Initialization by definition happens only when the app starts up. When you make changes to it, you won't find out about errors until you restart the app[1], which can be much later and a big context switch. But at least you'll be able to fix it in the usual way. Slightly more seamless[2].

One glitch to note: at least on Linux, an app with an initialization error feels "sticky". I can't seem to switch focus away from it using Alt-tab. Hitting F4 on the driver also jarringly brings the client app back in focus when there was an initialization error. But the mouse does work consistently. This feels similar to the issues I find when an app goes unresponsive sometimes. The window manager really wants me to respond to the dialog that it's unresponsive.

Still, feels like an improvement.

[1] I really need to provide that driver command to restart the app! But there's no room in the menus! I really need a first-class command palette like pensieve.love has!

[2] https://lobste.rs/s/idi1wt/open_source_vs_ux

Created by akkartik on November 17, 2023

5WHW3IDOHOBXY3M3QPXNMHFFNXXD6RR5B2WL6TB5TTVNZJYCN2AQC

Dependencies

In channels

main

Change contents

Replacement in main.lua at line 240 [8.2]

∅:D[6.1268] → [7.1084:1101]

B:BD[7.1084] → [7.1084:1101]

    Mode = 'run'

[6.1268]

[7.1101]

    if Redo_initialization then
      Redo_initialization = nil
      love.run()  -- won't actually replace the event loop;
                  -- we're just running it for its initialization side-effects
    else
      Mode = 'run'
    end

Replacement in live.lua at line 36 [10.722]

∅:D[4.32] → [9.12:53]

B:BD[10.1754] → [9.12:53]

  live.freeze_all_existing_definitions()

[4.32]

[9.53]

  if Live.frozen_definitions == nil then  -- a second run due to initialization errors will contain definitions we don't want to freeze
    live.freeze_all_existing_definitions()
  end

Insertion in live.lua at line 85 [10.722]

[5.97]

        if Redo_initialization then
          Redo_initialization = nil
          love.run()  -- won't actually replace the event loop;
                      -- we're just running it for its initialization side-effects
        end

Insertion in live.lua at line 402 [10.722]

[3.377]

function live.handle_initialization_error(err)
  Redo_initialization = true
  live.handle_error(err)
end

Replacement in app.lua at line 39 [12.2]

B:BD[11.190] → [11.190:435]

  -- Stash current state of App for tests
  App_for_tests = {}
  for k,v in pairs(App) do
    App_for_tests[k] = v
  end
  -- there's one nested table
  App_for_tests.screen = {}
  for k,v in pairs(App.screen) do
    App_for_tests.screen[k] = v

[11.190]

[11.435]

  -- Stash initial state of App (right after loading files) for tests
  if App_for_tests == nil then
    App_for_tests = {}
    for k,v in pairs(App) do
      App_for_tests[k] = v
    end
    -- there's one nested table
    App_for_tests.screen = {}
    for k,v in pairs(App.screen) do
      App_for_tests.screen[k] = v
    end

Replacement in app.lua at line 145 [12.2]

B:BD[13.8513] → [13.8513:8569]

  App.initialize(love.arg.parseGameArguments(arg), arg)

[13.8513]

[12.170]

  xpcall(function() App.initialize(love.arg.parseGameArguments(arg), arg) end, live.handle_initialization_error)

Insertion in Manual_tests.md at line 65 [15.1]
[14.1426]
[14.1426]
```
Driver can connect to app on errors in on.initialize.
```

Insertion in Manual_tests.md at line 67 [15.1]

[14.1501]

  driver, define on.initialize with a run-time error:
    ```
    on.initialize = function()
        foo = bar+1
    end
    ```
  Hit F4.
  Quit the client app and restart. App shows an error.
  Edit `on.initialize` in the driver and remove the error:
    ```
    on.initialize = function()
    end
    ```
  Hit F4. The error disappears from the app and driver.
* clone this repo to a new client app, clear its save dir, run it, run the
  driver, define on.initialize with a run-time error:
    ```
    on.initialize = function()
        foo = bar+1
    end
    ```
  Hit F4.
  Quit the client app and restart. App shows an error.
  Hit F4 again in the driver (without fixing the error).
  The client app continues to show the error.
* clone this repo to a new client app, clear its save dir, run it, run the