ex_early_ret

An Elixir macro for limited early return (expands to nested if-else).

Limited in that you can't return from nested blocks, it's strictly for this kind of thing:

if some_check(a, b)
  return -1
end

some_var = a + b

if other_check(some_var) && aaaaa
  return -2
end

some_other_vars = 123 # ...

You could sort of use cond for this kind of validation code, but cond does not let you define the some_var above.

Installation

Add ex_early_ret to your project's dependencies in mix.exs:

def deps do
  [
    {:ex_early_ret, "~> 0.1.0"}
  ]
end

And fetch your project's dependencies:

$ mix deps.get

Usage

Some examples:

defearlyret fetch(url, check_mention: check_mention) do
  u = URI.parse(url)

  ret_if u.scheme != "http" && u.scheme != "https", do: {:non_http_scheme, u.scheme}

  host = u.host

  ret_if host == nil || host == "localhost" do
    {:local_host, host}
  end

  resp = HttpClient.get!(url, headers: [{"accept", "text/html"}])
  Floki.parse(resp.body)
end

{status, body} =
  earlyret do
    redir = conn.body_params["redirect_uri"]

    ret_if is_nil(redir) or !String.starts_with?(redir, "http"),
      do: {:bad_request, "No valid redirect URI"}

    clid = conn.body_params["client_id"]

    ret_if is_nil(clid), do: {:bad_request, "No client ID"}

    ret_if is_nil(conn.body_params["code"]), do: {:bad_request, "No code"}

    tempcode = TempCode.get_if_valid(conn.body_params["code"])

    ret_if is_nil(tempcode), do: {:bad_request, "Code is not valid"}

    ret_if tempcode.redirect_uri != redir,
      do:
        {:bad_request,
         "redirect_uri does not match: '#{redir}' vs '#{tempcode.redirect_uri}'"}

    ret_if tempcode.client_id != clid,
      do: {:bad_request, "client_id does not match: '#{clid}' vs '#{tempcode.client_id}'"}

    TempCode.use(tempcode.code)

    Jason.encode(%{
      me: Process.get(:our_home_url)
    })
  end

Contributing

Please feel free to submit pull requests!

By participating in this project you agree to follow the Contributor Code of Conduct.

The list of contributors is available on GitHub.

License

This is free and unencumbered software released into the public domain.
For more information, please refer to the UNLICENSE file or unlicense.org.