Added bash completion and fzf support

[jonasfj]

This adds:

• Bash completion
  • Renames internal functions to be prefixed _ so they don't show up in dv<tab><tab>
  • dvm use <tab><tab> will show list of installed versions and --default
  • dvm use --default <tab><tab> will show list of installed versions
  • dvm install <tab><tab> will show list of stable versions (this seems like the thing most used will need).
• Fuzzy matching with fzf
  • dvm install will open fzf with stable versions
  • dvm use will option fzf with installed versions
  • dvm use --default will option fzf with installed versions

To make bash completion and fuzzy matching fast, the list of versions for stable, beta and dev will be saved to:

• $DVM_ROOT/cache/versions-stable
• $DVM_ROOT/cache/versions-beta
• $DVM_ROOT/cache/versions-dev

If older than 5 minutes the list of versions will be refreshed. According to man date this should work on Mac OS too, but I only tested it on Linux.

---

warning: it's entirely possible that I made a typo in some of this code, I renamed quite a few things -- and I have yet to figure out what dvm alias is good for 🙈

[jonasfj]

I think we should consider a dvm default command for setting the default version... possibly even a dvm install [--use] [--default] command, so that updating to the latest version is easy. But that's something we can do later.

For now bash completion and fzf will make most interactions with dvm much smoother.

[cbracken]

We should probably guard this behind a conditional so as not to cause errors for anyone using other shells. Maybe something like:

if [[ "$(basename $SHELL)" == "bash" ]]; then
  complete -F _dvm_completions dvm
fi

Alternatively, this could be a case statement, and I could add zsh support when I get a moment. :)

[cbracken]

Actually, come to think of it, another alternative would be to break out a separate completions file; that would allow us to keep the shell-specific code separate.

e.g. https://github.com/scop/bash-completion/tree/master/completions

and

https://github.com/zsh-users/zsh-completions/tree/master/src

[jonasfj]

That's a good idea! :D

[jonasfj]

Note: stackoverflow suggested using BASH_VERSION instead of $SHELL because $SHELL is the users default shell, not necessarily the shell currently running.

[cbracken]

I think we should consider a dvm default command for setting the default version.

Something like this? 😉

$ dvm --help |grep use
   use        Select a Dart version to use (--default to set as default)

I'd actually forgotten this feature existed until a couple weeks ago. #12. Perhaps the bug was to actually create an alias symlink, rather than writing the file to be sourced which IIRC is what it does now. That's probably actually still a good idea.

[cbracken]

Oh I see, I misread what you'd written; you actually included the above in your completions list. Sounds like you're saying we should add a dvm default command that would allow the user to swing the default version, rather than dvm use --default VERSION?

[cbracken]

I think it'd be nice to use fzf if it's installed, but not require it. I actually hadn't heard of it till today, but it looks pretty nice!

That raises the question of how we advertise to the user that dvm makes use of fzf if available. Perhaps we could break out a dvm doctor command and have it list all dependencies (required and optional) with their install status. We'd show a scary red X if a required dependency is missing (currently just unzip), a yellow warning sign or something if fzf is missing, otherwise a green check.

That would entail breaking out _dvm_check_required_deps and _dvm_check_optional_deps functions and then pull the two together in _dvm_doctor. We'd then run _dvm_check_required_deps on line 497 below instead of _dvm_doctor.

What do you think?

[jonasfj]

We only call _dvm_check_fzf if we are about to use fzf.

So if you do: dart use <version> you'll never notice... If you do dart use it'll error saying that you need fzf.

I did consider improving the error message to say that dart use <version> works without fzf, but looking at how widely fzf is available I think most users will just install it.

---

In either case, we could explicitly support --help for all commands, but I think that's a separate issue :D

[jonasfj]

Sounds like you're saying we should add a dvm default command that would allow the user to swing the default version, rather than dvm use --default VERSION?

Yeah, or something like that.. I frequently find that what I want to do is:

• Install a Dart SDK version, and,
• Set it to be used by default.

There is many ways we could do this. Maybe dvm without any arguments should do:
V=$(dvm listall | fzf); dvm install $V; dvm use $V --default;

Just because, listall + install + use + --default is the most common thing to do. But we can consider that later.

[jonasfj]

@cbracken I assume we both forgot all about this 🤣

Should we merge... all the stuff about adding additional commands and shortcuts seems like follow up PRs, if we want to do it. With fzf and bash completion using dvm is already a lot easier :D

[cbracken]

Just adding a note to apologise for the delay! I haven't forgotten about this, but was out for three weeks starting almost exactly when you last replied and finally got caught up on all the other stuff! Will take a look!

[jonasfj]

@cbracken friendly ping :D