[erlang-questions] gproc Help

Andrew Berman <>
Fri Jun 22 23:36:17 CEST 2012


Ahhhhh, of course!  Stupid me.  Thanks for your help, Bob!

On Fri, Jun 22, 2012 at 2:35 PM, Bob Ippolito <> wrote:

> You call gproc_ps:subscribe(l, test) from the spawned process instead of
> from the shell process.
>
> For example:
>
> new() ->
>     spawn_link(fun () -> gproc_ps:subscribe(l, test), ?MODULE:apply() end).
>
>
> On Fri, Jun 22, 2012 at 5:33 PM, Andrew Berman <> wrote:
>
>> Yes, but how do I have my new process subscribe to it?
>>
>> Thanks,
>>
>> Andrew
>>
>> On Fri, Jun 22, 2012 at 2:26 PM, Bob Ippolito <> wrote:
>>
>>> On Fri, Jun 22, 2012 at 5:19 PM, Andrew Berman <>wrote:
>>>
>>>> I'm trying to use gproc as a very basic pub/sub.  Here is example code
>>>> I have (very basic):
>>>>
>>>> -module(test).
>>>>
>>>> -compile([export_all]).
>>>>
>>>> new() ->
>>>>     Pid = spawn_link(?MODULE, apply, []),
>>>>     gproc_ps:subscribe(l, test),
>>>>     Pid.
>>>>
>>>> apply() ->
>>>>     receive
>>>>         {gproc_ps_event, test, Msg} -> io:put_chars(Msg),
>>>>         apply()
>>>>     end.
>>>>
>>>> publish() ->
>>>>     gproc_ps:publish(l, test, "My test message").
>>>>
>>>> In the shell I then do:
>>>>
>>>>  Pid = test:new().
>>>> test:publish().
>>>>
>>>> My expectation was that I would get an output of "My test message", but
>>>> all I get is {gproc_ps_event,test,"My test message"}.  When I do a flush(),
>>>> I do get the Shell got {gproc_ps_event,test,"My test message"}.  What am I
>>>> doing wrong?  I obviously don't understand something, can someone explain
>>>> how to get this simple example to work.  I know I can do Pid ! {....} in
>>>> this example, but I'm trying to play with gproc.
>>>>
>>>> Thanks for any help!
>>>>
>>>
>>> You're subscribing to 'test' from the shell process, not from Pid, so
>>> that is why the shell is receiving the message.
>>>
>>> -bob
>>>
>>>
>>
>
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