Eventmachine talk - Aug 2006 - Using globals

For variables that need to be defined outside of the module/class that
is called as an argument to start_server, is there any other way to
pass objects to that class that were created before calling
start_server, or should I just use global variables?  For example the
object that holds the database pool, or other variables that won''t
change for the life of the server, but need to be instantiated only
once.

Chris

On 8/23/06, snacktime <snacktime at gmail.com>
wrote:
>
> For variables that need to be defined outside of the module/class that
> is called as an argument to start_server, is there any other way to
> pass objects to that class that were created before calling
> start_server, or should I just use global variables?  For example the
> object that holds the database pool, or other variables that won''t
> change for the life of the server, but need to be instantiated only
> once.


Yes. You can use a class instead of a module to handle your protocol
requests. Using modules is preferred in general because it''s so simple,
there''s almost nothing to do. Something like this should solve it for
you,
and there is more information about this in the Rdoc.

class YourClass < EventMachine::Connection
  # here, add in all the normal methods you would have put in a module
end

EventMachine.run {
  EventMachine.start_server( addr, port, YourClass ) {|newconnection|
    # newconnection is an instance of YourClass, and this block is
    # called inside its constructor. Use instance_eval to add variables
    # to it.
  }


Is that closer to what you wanted?
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>
> class YourClass < EventMachine::Connection
>   # here, add in all the normal methods you would have put in a module
> end
>
> EventMachine.run {
>   EventMachine.start_server( addr, port, YourClass ) {|newconnection|
>     # newconnection is an instance of YourClass, and this block is
>     # called inside its constructor. Use instance_eval to add variables
>     # to it.
>   }
>
Ya that''s it, I was already using a class instead of a module, but I
didn''t see how to pass an instance of the class instead of the class
name.

Chris

I''m missing something there.  How do I set an instance or class
variable via instance_eval?  If I do something like the following @dbh
and @@dbh are both nil.

class YourClass < EventMachine::Connection

  @@ dbh = nil
  def initialize *args
    super
  end
end

  def receive_data
    p @dbh
    p @@ dbh
  end
end


EventMachine.run {
EventMachine.start_server( addr, port, YourClass ) {|newconnection|
newconnection.instance_eval {@dbh =
''test'';@@dbh=''test''}
}

I don''t think the block is being run.  If I just put a print statement
in it I see nothing.

Checking.....

On 8/23/06, snacktime <snacktime at gmail.com>
wrote:
> I don''t think the block is being run.  If I just put a print
statement
> in it I see nothing.
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>

Doesn''t look like start_server takes a block when providing a class as
the handler.

def EventMachine::start_server server, port, handler=nil
    klass = if (handler and handler.is_a?(Class))
      handler
    else
      Class.new( Connection ) {handler and include handler}
    end

    s = start_tcp_server server, port
    @acceptors[s] = klass
  end

On 8/23/06, snacktime <snacktime at gmail.com>
wrote:
> Doesn''t look like start_server takes a block when providing a
class as
> the handler.
>
> def EventMachine::start_server server, port, handler=nil
>     klass = if (handler and handler.is_a?(Class))
>       handler
>     else
>       Class.new( Connection ) {handler and include handler}
>     end
>
>     s = start_tcp_server server, port
>     @acceptors[s] = klass
>   end
> _______________________________________________
> Eventmachine-talk mailing list
> Eventmachine-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/eventmachine-talk
>

You''re right. Just fixed it, please sync to the latest and try it. Nice
catch.