<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hi Tom,<div><br></div><div>I enjoyed reading the article until this point: </div><div><pre><code class="ruby"><span class="line"> <span class="kp">private</span>
</span><span class="line">
</span><span class="line"> <span class="k">def</span> <span class="nf">send_emails_for</span><span class="p">(</span><span class="n">grouper</span><span class="p">)</span>
</span><span class="line"> <span class="no">LeaderMailer</span><span class="o">.</span><span class="n">grouper_confirmed</span><span class="p">(</span><span class="ss">member</span><span class="p">:</span> <span class="n">grouper</span><span class="o">.</span><span class="n">leader</span><span class="o">.</span><span class="n">id</span><span class="p">)</span><span class="o">.</span><span class="n">deliver</span>
</span><span class="line"> <span class="no">WingMailer</span><span class="o">.</span><span class="n">grouper_confirmed</span><span class="p">(</span><span class="ss">wings</span><span class="p">:</span> <span class="n">grouper</span><span class="o">.</span><span class="n">wings</span><span class="o">.</span><span class="n">map</span><span class="p">(</span><span class="o">&</span><span class="ss">:id</span><span class="p">))</span><span class="o">.</span><span class="n">deliver</span>
</span><span class="line"> <span class="no">AdminMailer</span><span class="o">.</span><span class="n">grouper_confirmed</span><span class="p">(</span><span class="ss">grouper</span><span class="p">:</span> <span class="n">grouper</span><span class="o">.</span><span class="n">admin</span><span class="o">.</span><span class="n">id</span><span class="p">)</span><span class="o">.</span><span class="n">deliver</span>
</span><span class="line"> <span class="k">end</span>
</span><span class="line">
</span><span class="line"> <span class="k">def</span> <span class="nf">assign_bar_for</span><span class="p">(</span><span class="n">grouper</span><span class="p">)</span>
</span><span class="line"> <span class="c1"># Asynchronous job because it’s a little slow</span>
</span><span class="line"> <span class="no">AssignBarForGrouper</span><span class="o">.</span><span class="n">enqueue</span><span class="p">(</span><span class="n">grouper</span><span class="o">.</span><span class="n">id</span><span class="p">)</span>
</span><span class="line"> <span class="k">end</span>
</span></code></pre><div>You can't test this class in isolation (you need to require all 3 mailers and AssignBarForGrouper). Maybe it seems ok now, but if there is in future another email with simple logic, you end up mocking every hard coded dependency for different scenarios. Plus I don't like passing ids to mailers, then in your mailer class you need to query for email ... I would suggest make both private methods public and introduce new object for sending emails</div></div><div><br></div><div><pre><code class="ruby"><span class="line"> <span class="k">def</span> <span class="nf">send_emails_for</span><span class="p">(</span><span class="n">confirm_grouper_mailer: ConfirmGrouperMailer.new(leader_email: grouper.leader.email, wings_emails: grouper.wings.collect(&:email), admin_email: grouper.admin_email</span><span class="p">)</span></span></code></pre><pre><code class="ruby"><span class="line"><span class="p"><pre><code class="ruby"><span class="line"> confirm_grouper_mailer.deliver</span></code></pre></span></span></code></pre><pre><code class="ruby"><span class="line"> <span class="k">end</span></span></code></pre><div>I don't think you need to test successful interactor, this scenario should be covered by end-to-end test </div></div><div><br></div><div><pre><code class="ruby"><span class="line"><span class="n"> context</span> <span class="err">“</span><span class="k">when</span> <span class="n">the</span> <span class="n">interactor</span> <span class="n">is</span> <span class="n">a</span> <span class="n">success</span><span class="err">”</span> <span class="k">do</span>
</span><span class="line"> <span class="n">let</span><span class="p">(</span><span class="ss">:success</span><span class="p">)</span> <span class="p">{</span> <span class="kp">true</span> <span class="p">}</span>
</span><span class="line">
</span><span class="line"> <span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">redirect_to</span> <span class="n">home_path</span> <span class="p">}</span>
</span><span class="line"> <span class="k">end</span>
</span></code></pre><div>The HN's discussion reminds of similar one here <a href="https://gist.github.com/justinko/2838490">https://gist.github.com/justinko/2838490</a> </div></div><div><br></div><div>You can find DHH's opinions on architecture etc on Ruby Rogues episode 056 <a href="http://rubyrogues.com/056-rr-david-heinemeier-hansson/">http://rubyrogues.com/056-rr-david-heinemeier-hansson/</a></div><div><br></div><div>Thank you for your article,</div><div><br></div><div>Erich</div><div><br></div><div><br><div><div>On 4 Mar 2014, at 15:36, Najaf Ali <<a href="mailto:ali@happybearsoftware.com">ali@happybearsoftware.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><i>> <span style="font-family:arial,sans-serif;font-size:13px">Using modules to mix in behaviour is the same as inheritance and the composition over inheritance argument has already been had.</span></i><div>
<i><span style="font-family:arial,sans-serif;font-size:13px"><br></span></i></div><div><font face="arial, sans-serif">I don't think I'm quite clever enough to follow the whole service objects vs. modules vs. objects vs. dependency injection debate, but this line in particular weakens your argument a little.</font></div>
<div><font face="arial, sans-serif"><br></font></div><div><font face="arial, sans-serif">The composition over inheritance argument has indeed already been had: the primary reason that composition is better than inheritance is that inheritance needlessly couples type to implementation. Mixing in a module doesn't do that. There are other problems with modules (in particular when you have a lot of them, implicit dependencies can creep in between them) but "they are the same as inheritance therefore bad" strikes me as a little lazy.</font></div>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Mar 4, 2014 at 2:15 PM, Stephen Best <span dir="ltr"><<a href="mailto:bestie@gmail.com" target="_blank">bestie@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">@Riccardo Using decorators over extend gives you<div><br></div><div>* No method / instance variable naming collisions (counts for private methods too)</div>
<div>* Separate state</div><div>* Very obvious which decorations have been applied</div>
<div>* You can unwrap the decorators and get the original object back</div><div><br></div><div>The annoying this really is that the difference in effort is negligible yet the module approach is widely cargo-culted.<br><div>
<div><br></div><div>Using modules to mix in behaviour is the same as inheritance and the composition over inheritance argument has already been had.</div><div><div class="h5"><div class="gmail_extra">
<br><br><div class="gmail_quote">On 4 March 2014 10:24, Riccardo Tacconi <span dir="ltr"><<a href="mailto:rtacconi@gmail.com" target="_blank">rtacconi@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">I created this project (very incomplete) to try few things and one was DCI: <a href="https://github.com/rtacconi/scriptrunner/blob/master/app/contexts/runner_on_project.rb" target="_blank">https://github.com/rtacconi/scriptrunner/blob/master/app/contexts/runner_on_project.rb</a>. Yes I used 'extend' but it is 'expensive' and using mixins seems okay to me. What's the advantage of using decorators?</div>
<div>
<div class="gmail_extra"><br><br><div class="gmail_quote">On 4 March 2014 09:37, Stephen Best <span dir="ltr"><<a href="mailto:bestie@gmail.com" target="_blank">bestie@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Also why do Ruby developers insist on implementing DCI by mixing in modules at runtime? It's just completely unnecessary, why not decorate?<div><div class="gmail_extra"><div><br clear="all"><div>
<div dir="ltr">
<br>Stephen Best<br><br><a href="tel:%2B44%207745%20790523" value="+447745790523" target="_blank">+44 7745 790523</a><br><div><a href="http://theaudaciouscodeexpiment.com/" target="_blank">theaudaciouscodeexpiment.com</a><br>
<a href="http://github.com/bestie" target="_blank">github.com/bestie</a><br>
@thebestie</div></div></div>
<br><br></div><div><div class="gmail_quote">On 4 March 2014 09:35, Stephen Best <span dir="ltr"><<a href="mailto:bestie@gmail.com" target="_blank">bestie@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">DHH as usual saying the best way to design your objects is don't. GOOD LUCK WITH THAT.<br><div class="gmail_extra"><br clear="all"><div><div dir="ltr"><br>Stephen Best<br><br><a href="tel:%2B44%207745%20790523" value="+447745790523" target="_blank">+44 7745 790523</a><br>
<div><a href="http://theaudaciouscodeexpiment.com/" target="_blank">theaudaciouscodeexpiment.com</a><br>
<a href="http://github.com/bestie" target="_blank">github.com/bestie</a><br>@thebestie</div></div></div><div>
<br><br><div class="gmail_quote">On 3 March 2014 23:09, Mark Burns <span dir="ltr"><<a href="mailto:markthedeveloper@gmail.com" target="_blank">markthedeveloper@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">It's kind of similar, but DCI is kind of like a run-time only ActiveSupport::Concern.<div>It's still a big bag o' methods, but a big dynamic bag of methods. Maybe less chance of collisions, but</div>
<div>the principle is still the same as AS::Concern.</div><div>Interactors in the sense of the interactor gem are cleaner as you're not polluting a potentially already</div><div>overloaded domain model/persistence object hybrid.</div>
</div><div><div class="gmail_extra"><br><br><div class="gmail_quote">On 3 March 2014 22:18, Riccardo Tacconi <span dir="ltr"><<a href="mailto:rtacconi@gmail.com" target="_blank">rtacconi@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Hi Tom,<div><br></div><div>Your interactor reminds me the I part (interaction) of DCI, am I wrong? I see few similarities.</div></div><div class="gmail_extra"><br><br><div class="gmail_quote"><div>
On 3 March 2014 20:38, Tom Blomfield <span dir="ltr"><<a href="mailto:tomblomfield@gmail.com" target="_blank">tomblomfield@gmail.com</a>></span> wrote:<br>
</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div dir="ltr">Hi all,<div><br></div><div>I wrote a blog post on Interactors in Rails - <a href="http://eng.joingrouper.com/blog/2014/03/03/rails-the-missing-parts-interactors" target="_blank">http://eng.joingrouper.com/blog/2014/03/03/rails-the-missing-parts-interactors</a></div>
<div><br></div><div>You might enjoy the discussion on HN, with DHH wading in <a href="https://news.ycombinator.com/item?id=7335211" target="_blank">https://news.ycombinator.com/item?id=7335211</a></div><span><font color="#888888"><div>
<br></div><div>Tom</div></font></span></div>
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