List_to_port in OTP < 20.0

Hey all,

I recently needed to get a port() from a string representation of it for…reasons. I discovered a handy little function in OTP 20.0 called list_to_port but quickly found out that ONLY works in 20.0+.

I mashed together an elixir version of term_to_port() from recon which I thought might be useful to others (not sure if this is even a common problem, common enough to be added to OTP I suppose):

  def term_to_port(<<"#Port<0.", id :: binary>> ) do
    n = id |> String.trim_trailing(">") |> String.to_integer()
  def term_to_port(n) when is_integer(n) do
    name   = Node.self() |> Atom.to_charlist() |> :erlang.iolist_to_binary()
    length = :erlang.iolist_size(name)
    self   = :erlang.term_to_binary(self())
    vsn    = :binary.last(self)

   <<131, 102, 100,
     length :: size(2)-unit(8),
     name :: size(length)-binary,
     n :: size(4)-unit(8),
     vsn :: size(8)>> 
   |> :erlang.binary_to_term

It’s very rough around the edges but useful nonetheless.

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