message passing

   1: -module(play).

   2: -export([headstrip/1,message/1,start/0,receiver/0,sender/1]).

   3:  

   4: sender(RxPid) ->

   5:     RxPid ! {hey, self()}.

   6:  

   7: receiver() ->

   8:     io:format("in receiver ~p~n",[self()]),     

   9:     receive

  10:         {hey, TxPid} -> io:format("rx: ~p ~p~n",[hey, TxPid])

  11:     end.

  12:  

  13: start() ->

  14:     RxPid = spawn(play, receiver, []),

  15:     spawn(play, sender, [RxPid]).

28> play:start().
in receiver
rx: hey
<0.150.0>

receive blocks, and handles one message

If you want your receiver to hang around, call it again. e.g. add a call to receiver() just before end in the code above. But then – whole process finishes. Is something running in the background still? How do I check? [see http://timbar.blogspot.com/2009/09/process-management.html]

remember to export

Remember that every function called must be exported – not just the bootstrap function you use to kick things off. In this context the error

=ERROR REPORT==== 25-Sep-2009::16:51:33 ===
Error in process <0.98.0> with exit value: {undef,[{play,sender,[<0.97.0>]}]}

indicates that you've forgotten to export the function "sender".

unhandlable messages are just dropped

Messages that receive doesn’t know how to handle are just forgotten. How to do a default response? Try sending eef instead of hey in the code above.