Make mix help list aliases

[Sihui]

ref: https://trello.com/c/9DzdXbp4/4-make-mix-help-list-aliases

cc @michalmuskala

[Sihui]

Not sure why the latest build failed: https://travis-ci.org/elixir-lang/elixir/jobs/397193995.
The second latest build also failed but on a different test: https://travis-ci.org/elixir-lang/elixir/jobs/397182429. 😞

Does the new code introduce something flaky? 😨

[smorin]

I was just wanting this exact functionality. Thanks for doing the pull request.

[michalmuskala]

The build failure seems unrelated. I rested the failed suite.

[michalmuskala]

I wonder about the format here with the list, but I'm not really sure what would be better.

[josevalim]

I would say we should just call inspect. It is the simplest implementation and it would be similar to what we have today. But I am not sure.

I guess the formatting was the biggest concern for including aliases in the mix help, as they can get quite verbose. Another option is to just have a simple text: "# Alias defined in mix.exs" and call it a day.

Thoughts?

[fertapric]

I think in order for this feature to be complete, this PR should supportmix help ALIAS. It might be confusing to be able to run mix help TASK on some of the names listed but not on others.

This might also simplify the formatting of the aliases in mix help. As @josevalim suggested, mix help can just display my_alias # Alias defined in mix.exs; and mix help my_alias could display a more verbose description:

Alias for ["run my/really/long/path.exs", "cmd another_long_cmd"]

Thoughts?

[michalmuskala]

I like this solution.

[smorin]

I like: my_alias # Alias defined in mix.exs as a solution but why not also allow.

defp aliases do
    [
      help_make: [alias: "cmd make", description: "my description", new_option: "asdf"]
    ]
  end

OR

defp aliases do
    [
      help_make: %{alias: "cmd make", description: "my description", new_option: "asdf"}
    ]
  end

[josevalim]

@smorin If you want to add descriptions and what not, then I would say you should just go ahead and define a proper task.

[smorin]

@josevalim Why force someone to write a task for something that takes 3 words. It's using a sledge hammer to drive a nail. Especially in cases, where the command is 2 or 3 separate words and the description is the longest part. Why clutter a code base, adding steps for a developer, and more lines of code to maintain.

npm does it will good effect: https://docs.npmjs.com/misc/scripts

[whatyouhide]

We try to avoid single pipes. I would suggest to refactor this with a for comprehension:

aliases = 
  for {alias_name, _} = alias <- load_aliases(),
      String.contains?(alias_name, pattern),
      do: alias

[Sihui]

why do we try to avoid single pipes?

[josevalim]

@Sihui mostly because if we don't have multiple expressions, the pipeline ends up being more noise than helping readability. We know it is subjective but that's why we decided to add a "rule", so it is a clear path and we remove subjectivity. :)

[Sihui]

@josevalim
A (weak) counter argument will be using single pipe makes adding additional pipe easier. But that's for another discussion.

I don't think we should avoid Enum.filter b/c of avoiding single pipes though. I think Enum.filter expresses our intention clearer than the for comprehension. How about

Enum.filter(load_aliases, &String.contains?(elem(&1, 0), pattern))

A side note, we have quite a few usages of single pipes throughout the file (and the codebase), does it mean we want to replace all of them?

[whatyouhide]

Eventually we want to replace all pipes, but we try to avoid small changes like that in the codebase in order to keep the number of changes down. Enum.filter/2 is also very much fine with me, I just don't love elem/2 since it hides what the tuple looks like. What about:

Enum.filter(load_aliases(), fn {name, _} -> String.contains?(name, pattern) end)

[Sihui]

good call! I not a fan of elem either.

[whatyouhide]

We try to avoid single pipes and single-letter variables. Maybe rewrite this as:

defp load_aliases() do
  for {name, value} <- Mix.Project.config()[:aliases] do
    {Atom.to_string(name), value}
  end
end

[Sihui]

updated to

  defp load_aliases() do
    Mix.Project.config()[:aliases]
    |> Enum.map(fn {k, v} -> {Atom.to_string(k), v} end)
    |> Map.new()
  end

to make verbose_doc easier. (turning it to a map also makes more sense.)

[fertapric]

What do you think about these names to address the single-letter variables?

defp load_aliases() do
  Mix.Project.config()[:aliases]
  |> Enum.map(fn {alias_name, alias_tasks} -> {Atom.to_string(alias_name), alias_tasks} end)
  |> Map.new()
end

[whatyouhide]

You're doing two passes this way. I didn't know you needed a map but if you do, I'd much rather go with into: %{} in the for comprehension or just Map.new/2:

aliases = Mix.Project.config()[:aliases]
Map.new(aliases, fn {alias_name, alias_tasks} -> {Atom.to_string(alias_name), alias_tasks} end)

(also, definitely let's avoid single-letter variables!)

[Sihui]

@whatyouhide I used map b/c I couldn't find an easy way to accomplish Map.has_key?(aliases, task). If there's a way without having to use map, I would love to learn that! :)

[whatyouhide]

Instead of is_bitstring/1, maybe use is_binary/1 here?

[josevalim]

@josevalim Why force someone to write a task for something that takes 3 words. It's using a sledge hammer to drive a nail.

I would say that ad-hoc aliases would end-up being more clutter than well-structured tasks but I see your point. We should move the discussion about revamping aliases elsewhere then. Maybe a proposal to the elixir-lang-core mailing list as the scope of this particular issue is well defined based on how aliases work today and we should not go off-topic.

[Sihui]

Couldn't find an easy way to format "nested.h": [&Mix.shell().info(inspect(&1)), "h foo bar"] nicely.
Thoughts?

[josevalim]

@Sihui this is honestly good enough to me. :)

[Sihui]

^^ Updated to:

1. use my_alias # Alias defined in mix.exs in mix help
2. and add support for mix help ALIAS

[fertapric]

I think there is a typo here "prints all aliases, tasks and their shortdoc"

[Sihui]

I don't think we have shortdoc for aliases. shortdoc are marked with @shortdoc

[fertapric]

"and their summary" or "and their short description"?

[fertapric]

Minor nitpick: I would change the order of "tasks" and "aliases" here (and below). For some reason, in my head 😅 , it makes more sense to put "tasks" at the beginning as they are more relevant for this specific task :) So, "Lists all tasks and aliases or prints the documentation for a given task or alias."

[fertapric]

Minor nitpick: I think it should be "lists", and maybe "help lists all aliases"?

[fertapric]

Could this test give false positives due to the match of other tasks like mix compile?

[josevalim]

@fertapric good catch!

[fertapric]

"prints all tasks and aliases that contain PATTERN in the name"?

[Sihui]

good catch!

[fertapric]

Unfortunately, this might also give false positives with mix help itself, mix hex or any mix hex.*.

[fertapric]

I would either include a space, or match on the message live above:

assert_received {:mix_shell, :info, ["mix h" <> message]}
assert message =~ ~r/# Alias defined in mix.exs/

[smorin]

@josevalim makes sense moving to core-mailing list.

I would say that ad-hoc aliases would end-up being more clutter than well-structured tasks but I see your point. We should move the discussion about revamping aliases elsewhere then. Maybe a proposal to the elixir-lang-core mailing list as the scope of this particular issue is well defined based on how aliases work today and we should not go off-topic.

[Sihui]

@josevalim @michalmuskala @whatyouhide Can this be merged? Anything else I need to do?

[josevalim]

We need two reviews to merge, so we are waiting on the second one. :) Once somebody has some time available, they will review it and likely merge. -- *José Valimwww.plataformatec.com.br <http://www.plataformatec.com.br/>Founder and Director of R&D*

[whatyouhide]

Why not use aliases = load_aliases() here too?

[whatyouhide]

I mean that and then Enum.sort(Map.to_list(aliases) ++ tasks).

[Sihui]

Map.to_list(aliases) won't work because aliases is [{alias1, taks1}, {alias2, task2}, ...].
If we want to use load_aliases(), we might need to do

    aliases = Enum.map(load_aliases(), fn {alias_name, _} -> alias_name end)

    for info <- Enum.sort(aliases ++ tasks) do
      Mix.shell().info(info)
    end

At that point, we might as well use Mix.Project.config()[:aliases] directly, so we don't have to iterate twice.

[whatyouhide]

Oh I missed that it was just the alias name, sorry!

[whatyouhide]

Thanks @Sihui! 💟

[Sihui]

Thank you all for reviewing! ❤️ ❤️ ❤️