[erlang-questions] New module syntax and semantics?

Christian S chsu79@REDACTED
Wed Jul 2 02:06:50 CEST 2008

2008/7/1 Juan Jose Comellas <juanjo@REDACTED>:
> The good thing about this feature is that it provides a way to have an
> "encapsulated" record replacement.

> The code that receives the events is unnecessary cumbersome because it needs
> to work with a record within a record. If this was encapsulated within a
> parameterized module, it would become much cleaner.

Nested records are not nice, no. For the record:

make_stuff() ->
set_stuff(Ex) ->
  Ex2 = Ex#fs_channel_event{extra=(Ex#fs_channel_event.extra)#fs_channel_answer_event{read_codec_name=leetspeak}}.

So the verbose syntax to do the above is what you want to avoid.

Did you consider using an approach like the following instead?

AnswerEvent = {#fs_channel_event{}, #fs_answer_event{}}
HangupEvent = {#fs_channel_event{}, #fs_hangup_event{}}

It's easy to deconstruct a tuple in pattern matching. You dont get the
nesting above.

make_stuff() ->
  {#fs_channel_event{}, #fs_channel_answer_event{write_codec_name=rot13}}.
set_stuff({A, B}) ->
   {A, B#fs_channel_answer_event{read_codec_name=leetspeak}}.

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