There’s a limit to how much I’m willing to let my code look like it’s object oriented 
ityonemo
czrpb
czrpb
so, here is my code now: for a list of process names, get their pids from ‘tasklist’.
i love the group_by solution, seems exactly right! this is the problem with being an old imperative/python programmer trying to get the heck out! 
note, this is everything in-lined so its a bit ugly but, any suggestions on how to be more functional and/or elixir-y please!
def get_pids_for_names2(proc_names) do
proc_names = MapSet.new(proc_names)
System.cmd("tasklist", [])
|> (fn {output, 0} -> output end).()
|> String.split("\r\n") |> Enum.drop(3)
|> Enum.reject(&(String.trim(&1) == ""))
|> Enum.map(&String.split/1)
|> Enum.filter(fn [name|_] -> MapSet.member?(proc_names, name) end)
[|> Enum.map(fn [name,pid|_] -> [name, pid] end)] <-- not needed, removed in a later edit
|> Enum.group_by(
fn [name|_] -> name end,
fn [_, pid|_] -> pid end
)
end
thoughts?
1
Eiji
Please use pipe for code formatting consistency:
"tasklist"
|> System.cmd([])
For more information take a look at pipeline operator in Elixir Style Guide by @lexmag
Avoid using anonymous functions in pipe.
# shorter version:
|> elem(0)
# gets first element of `Tuple`
# longer version (more readable):
|> success_command_output()
# …
defp success_command_output({output, 0}), do: output
For more information pleast take a look at:
- Kernel.elem/2 documentation
- Don’t use anonymous functions in pipelines in
Elixir Style Guide
Just a quote:
For a multi-line pipeline, place each function call on a new line, and retain the level of indentation.
Example:
|> String.split("\r\n")
|> Enum.drop(3)
Source: GitHub - lexmag/elixir-style-guide: An opinionated Elixir style guide · GitHub
For comments please use # comment syntax.
# …
# not needed, removed in a later edit
# |> Enum.map(fn [name,pid|_] -> [name, pid] end)
# …
In this case you may want to use List.first/1 and/or Enum.at/3:
# shorter version:
|> Enum.group_by(&List.first/1, &Enum.at(&1, 1))
# longer version (more readable):
|> Enum.group_by(&get_name_from_list/1, &get_pid_from_list/1)
# …
defp get_name_from_list(list) when is_list(list), do: List.first(list)
defp get_pid_from_list(list) when is_list(list), do: Enum.at(list, 1)
Note: In case you are worried about unexpected nil values you can use Enum.fetch!/2 in first case and pattern match inside function clause in second case.
For more information please take a look at:
- Enum.at/3 documentation
- Enum.fetch!/2 documentation
- List.first/1 documentation
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