Reimplement the depext UI with a menu

[AltGr]

Closes #5026
Additionally, also shows the hint on C-c :)

[AltGr]

Here is what it looks like:

[AltGr]

Pushing a small style update. Here are a few screenshots to show the interaction:

Trying to do it manually, then ignoring:

With depext-run-installs=false (different menu)

The code is a little spaghetti, but there is probably no better way. I have the before/after flow charts (on paper!) if you are interested ^^

[dra27]

I think is marvellous 🙂 It's not crystal clear (to me) for the sentences - I read the partial sentences w.r.t. the opening menu sentence (e.g. "Let opam run apt-get to install the required system packages? ... and abort" rather than "[quit]................. and abort"

I wonder if numbered options and a full sentence for each works more clearly:

---

opam believes some required external dependencies are missing. opam can:

1. (*) Run apt-get to install them (may need root/sudo access)
2. Display the recommended apt-get command and wait while you run it manually (e.g. in another terminal)
3. Attempt installation anyway, and permanently register that this external dependency is present, but not detectable
4. Abort the installation

[dra27]

For the manual menu, I'd suggest:

---

This command should get the requirements installed:

apt-get install libzmq3-dev

Would you like opam to:

1. Check again, as the package is now installed
2. Attempt installation anyway, and permanently register that this external dependency is present, but not detectable
3. Abort the installation

[AltGr]

I wonder if numbered options and a full sentence for each works more clearly:

Probably so, although in my display the brackets + table alignment didn't help with that, so we could have fiddled with that as well.
One of the ideas behind the y/n/i/q was to have y/n be consistent with existing questions, but I don't know if there is a point in that (keeping the same behaviour for "default" on being "y"; although n of most y/n questions would be closer to "abort" in this case.
The big plus of numbers is that it's rather obvious, and easy to read with much less clutter.

[AltGr]

[dbuenzli]

I find the > prompt slightly strange (maybe because that's my shell prompt) and a bit inconsistent with the usual way opam asks for stuff.

Just saying, I can live with that.

[AltGr]

Just saying, I can live with that.

I already had doubts about it, your input is welcome.

[AltGr]

😁

[AltGr]

I'd be happy to see how it fares on MacOS shells; but I am actually doing the minimum in terms of escape codes magic so it shouldn't be too much trouble. And at worst, there will be a little garbage on top of the menu when moving around, but it will still be readable; or the arrow keys just won't work, which is an ok fallback.

[AltGr]

(this is when depext_run_installs is disabled)

[kit-ty-kate]

On macOS the arrows work fine but some thing that throws me a bit off is that it seems that the prompt is waiting for only one character.

For example is you go and input 2 (only one character, no clicking enter) it directly does the action instead of waiting for the user to tap the enter key.

In the same kind of behaviour, if you type anything but one of the character that the prompt is waiting for, nothing happens and your character does not appear. This feels kind of stressful, even claustrophobic a little, it feels like opam just broke and froze your computer (^C still works but still)

[kit-ty-kate]

In the same kind of behaviour, if you type anything but one of the character that the prompt is waiting for, nothing happens and your character does not appear. This feels kind of stressful, even claustrophobic a little, it feels like opam just broke and froze your computer (^C still works but still)

the same freezing behaviour happens on a simple installation prompt. The y (default) character is already there but no character appears if you type anything.

I think we should keep the old [Y/n] <no character> type prompt as well

[AltGr]

Rebased; windows test broken due to last cygwin/git update (unrelated to this PR)