receive pitfall

[HEINRICH VENTER]

Hi again List

A pitfall I have stepped in twice now, and I thought I'd share :)

Be careful of a general term in your receive statements!  Your general term WILL catch anything and everything, including messages that might be intended for the same process in a different "state".  This is something you have to be especialy weary of when you have more than one receive statement in the same process, but perhaps in different functions.

For example

a() ->
   receive
      cmd_1 -> b(), a();
      cmd_2 -> a();
      Else -> error
   end.

b() ->
   receive
      stuff -> ok;
      Else -> b()
   end.

In this case if the messages that are sent are cmd_1, cmd_2, stuff it will seem to work correctly, but the cmd_2 message will be lost.  Even worse, if you are trapping EXIT messages, you might throw that away inadvertandly!

I presume the best practice would be to rather use an after clause in a receive than a generic term in case something unexpected happens?

-]-[einrich



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