Initialize *args weirdness

[Kenny Stone]

I don't understand why the first arg is seeming getting removed when I inherit from EM::Connection

require 'eventmachine'

module Dude

  class Adapter < EM::Connection

    def initialize(*args)

      puts ">> #{self.class}: " << args.inspect

      super(args)

    end

  end

  class AdapterNoEM

    def initialize(*args)

      puts ">> #{self.class}: " << args.inspect

    end

  end

end

Dude::Adapter.new( 'arg1', 'arg2', arg: '3' )

Dude::AdapterNoEM.new( 'arg1', 'arg2', arg: '3' )

===>

>> Dude::Adapter: ["arg2", {:arg=>"3"}]

>> Dude::AdapterNoEM: ["arg1", "arg2", {:arg=>"3"}]

help?  where is it going?  what should it be?

[Jake Douglas]

Hi Kenny,

You don't need to call super from your initialize method. EM::Connection.new will take whatever basic arguments are required by it and pass the rest on to your initialize method.

For example:

EM.connect("127.0.0.1", 12345, SomeHandler, :foo, :bar)

will end up calling SomeHandler#initialize with :foo and :bar

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[Kenny Stone]

Thanks Jake, that's good to know; I was just following the general introduction, which has the 'super' call.

I still see "args" getting the first element removed, though, which I don't understand.

[Kenny Stone]

The reason I ask is for unit tests, where I will never call "EM::Connect"

adapter = Adapter.new( arg1, arg2, arg3, ... )

adapter.receive_data( my_data )

assert something_happened_with_my_data

Is there a better pattern you guys use for unit tests?

[Jake Douglas]

Now I understand what you mean. .new expects the first argument to be a connection 'signature', assigned to it by the reactor. You can probably just pass nil there for your unit tests.

Other folks may have better feedback in regards to methods of testing your connection handlers.

[Kenny Stone]

I was making the (poor) assumption that 'new' calls 'initialize' without anything else happening to the argument list.  Thanks!

[Jake Douglas]

It isn't very intuitive and most people either had to figure it out by asking like you or don't know about it at all. We should make it more clear somewhere in the examples.

[Kenny Stone]

It doesn't seem as though calling "new" is the way to go for unit testing.  

"post_init" is getting called at some point after initialize although I'm never calling "Connect".  The documentation says post_init is called by the event loop immediately after the network connection has been established, but no network connection is happening here.  Is "new" only supposed to be called by the reactor?  It seems like some assumptions are made when "new" is called.

Here's the simple example of "new" eventually making the call to post_init even though there was never a network connection:

---

require 'eventmachine'

module Dude

  class Adapter < EM::Connection

    def initialize(*args)

      puts "inititialize"

    end

    def post_init

      puts "post_init"

    end

  end

end

Dude::Adapter.new(nil)

==> ruby my_adapter.rb

inititialize

post_init

---

And checking 'error?' doesn't work, either.

---

module Dude

  class Adapter < EM::Connection

    def initialize(*args)

      puts "inititialize"

    end

    def post_init

      puts "post_init"

      send_data "login_msg" unless error?

    end

  end

end

Dude::Adapter.new(nil)

==> ruby my_adapter.rb

inititialize

post_init

/usr/local/lib/ruby/gems/1.9.1/gems/eventmachine-0.12.10/lib/em/connection.rb:233:in `report_connection_error_status': no implicit conversion from nil to integer (TypeError)

from /usr/local/lib/ruby/gems/1.9.1/gems/eventmachine-0.12.10/lib/em/connection.rb:233:in `error?'

from try.rb:11:in `post_init'

from /usr/local/lib/ruby/gems/1.9.1/gems/eventmachine-0.12.10/lib/em/connection.rb:45:in `block in new'

from /usr/local/lib/ruby/gems/1.9.1/gems/eventmachine-0.12.10/lib/em/connection.rb:36:in `instance_eval'

from /usr/local/lib/ruby/gems/1.9.1/gems/eventmachine-0.12.10/lib/em/connection.rb:36:in `new'

from try.rb:16:in `<main>'