Writer versus Constructor

What’s the favorite toy from your childhood? For me, both my sisters and pretty much everyone I know that would be Lego. If you could only afford it (and in the times when I was a kid, that wasn’t so easy in the post-soviet Poland), there was no greater fun, than the joy of unlimited freedom to create whatever you can only imagine. And the fact, that you had limited resources wasn’t a real obstacle. It was a challenge.

Nearly all the programmers I know, fell in love with programming because of the same reason. To be able to put pure ideas to life, to create something meaningful out of nothing. Truth is, no other matter is so flexible, as the stuff we work with.

We are developers because we love to construct things that work. To give soul to the machine. To make it act on our behalf. It’s like magic.

That’s why it is so difficult for us to understand, that a real software craftsman is a writer, not a constructor.

Uncle Bob is talking about it at the beginning of “Clean Code”. When you are writing code, you are actually reading a lot more. How is that possible? Let’s have a look at an example: you have a project going, and you take a new feature from the Scrum/Kanban wall of features. And you:

  1. read the code to find a place where putting some more code will give you the result you seek
  2. read the code to better understand the surroundings, to eliminate potential side effects of your changes
  3. write the test and the code that does what the feature is expected to do

You can start with an acceptance test first, but that only changes the order, not the fact, that the proportions of reading to writing, are always in favor of reading. Big time.

So, if reading takes so much time, how important is to make things readable?

People are working hard to learn how to write faster, how not to use mouse in their IDE, they memorize all the keyboard shortcuts, use templates and so on, but the speed up is not significant in real work. Why? Because we are only writing code 1/10 of our time. The rest is spent on reading and thinking.

A good craftsman is a good writer, because he makes the code readable, easy to grasp, easy to understand. There is a huge shift in mentality, between a constructor and a writer. Above all, the constructor’s goal is to make things work. The writer’s goal, on the other hand, is to make things easy to understand.

The question is, who are we writing code for? The computer? Hell no. If that was true, we would be still writing in an assembly language (or maybe even in a machine code). The whole point of procedural, functional, object oriented languages was to make it easier for us to understand the code. And that’s because we don’t write the code for the computer.

We write it for other programmers.

To make the shift in mentality easier, let mi show you the differences in mindsets, between the constructor and the writer.


The Constructor

The constructor is in love with technology for the sake of technology. He likes to “technologically masturbate” himself with new toys. He thinks that simplicity is for pussies, the real thing is always complex. He never removes anything, always adds more. He doesn’t care that he cannot understand how his earlier solutions work, if they work why would he want to change them? He creates monsters like EJB1/2, that can do pretty much everything, but nobody is able to handle them. The he writes software to be able to use/confgure the software he has written before, because it’s already too complex for anybody (maybe except for him) to understand how to use it directly.

A bigger framework is a solution to his every problem. And even if it’s a new problem, he tries to modify his beloved one-to-rule-them-all tool, to be able to solve it. He is dreaming about the day, that he will have a single, big, multipurpose, futuristic wrench that works as if by magic, and does everything, from printing log files to saving the planet.

The constructor works best alone. He gets angry at people that cannot understand his programs in a second. When he works with other programmers, he is always afraid, he doesn’t like others to play with his tools. When they try to do pretty much anything, they always blow something else up. Because of unforeseen side effects, a small change can devastate days of work. And it happens a lot. It gets messy, so he hates to work with others.

The Writer

The writer reads a lot, so he wants to make his code as readable, as simple as possible. He learns stuff like DSLs, patterns, eXtreme Programming, to make things easy. Easy is his keyword. He cares less about frameworks. He usually knows a few languages from different worlds, because he believes there is no single silver bullet, and different solutions are better for different problems. His code has few comments, because it doesn’t need them. His code is self-documenting. His code is expressive. His code is simple, simplicity is his main value. Brilliant things are simple.

The writer always thinks about his reader. He walks hand to hand with his readers. He guides them, he cares for them. He never leaves them in the dark. His skills are in communication: he wants his intentions to be understood.

The writer works like a sniper. His changes (whether bug fixes or new features) are minimal, but the effects are exactly as expected. He never does Shotgun Surgery. He doesn’t violate DRY. He is a precise man and he works with a scalpel. His code is side-effect free, simple and readable, so he knows where and how to hit. He knows what the effects will be. He keeps accidental complexity low.

The writer is agile. He doesn’t set up traps, and he doesn’t fall into traps. He works hard to master basic skills. He believes that without those basic skills, no framework can save him anyway.

The writer likes to work with other programmers. He is using pair programming and code reviews to make sure that his code is easy to understand by others. He wants to have another mind watching his back, and catching him when he falls. He is supportive, he is friendly. He understands that no man is an island, and that the quality of his work will be measured by the number of WTFs shouted by other developers.

A good craftsman is a good writer.

And you know what one of the most successful writers of recent times, Stephen King, says?

That he’s only a craftsman.

PS: all the pictures are from Fallout games.

PS2: I’ve failed at giving appropriate credits to the author of the concept of programmer as a constructor. Let me fix that right away: the source of the idea that a programmer as a writer has opposition in programmer-constructor comes from a post by Andrzej Szczodrak that you can find in here

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Atom Feeds with Spring MVC

How to add feeds (Atom) to your web application with just two classes?
How about Spring MVC?

Here are my assumptions:
  • you are using Spring framework
  • you have some entity, say “News”, that you want to publish in your feeds
  • your "News" entity has creationDate, title, and shortDescription
  • you have some repository/dao, say "NewsRepository", that will return the news from your database
  • you want to write as little as possible
  • you don't want to format Atom (xml) by hand
You actually do NOT need to use Spring MVC in your application already. If you do, skip to step 3.


Step 1: add Spring MVC dependency to your application
With maven that will be:
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>3.1.0.RELEASE</version>
</dependency>

Step 2: add Spring MVC DispatcherServlet
With web.xml that would be:
<servlet>
    <servlet-name>dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring-mvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>dispatcher</servlet-name>
    <url-pattern>/feed</url-pattern>
</servlet-mapping>
Notice, I set the url-pattern to “/feed” which means I don't want Spring MVC to handle any other urls in my app (I'm using a different web framework for the rest of the app). I also give it a brand new contextConfigLocation, where only the mvc configuration is kept.

Remember that, when you add a DispatcherServlet to an app that already has Spring (from ContextLoaderListener for example), your context is inherited from the global one, so you should not create beans that exist there again, or include xml that defines them. Watch out for Spring context getting up twice, and refer to spring or servlet documentation to understand what's happaning.

Step 3. add ROME – a library to handle Atom format
With maven that is:
<dependency>
    <groupId>net.java.dev.rome</groupId>
    <artifactId>rome</artifactId>
    <version>1.0.0</version>
</dependency>

Step 4. write your very simple controller
@Controller
public class FeedController {
    static final String LAST_UPDATE_VIEW_KEY = "lastUpdate";
    static final String NEWS_VIEW_KEY = "news";
    private NewsRepository newsRepository;
    private String viewName;

    protected FeedController() {} //required by cglib

    public FeedController(NewsRepository newsRepository, String viewName) {
        notNull(newsRepository); hasText(viewName);
        this.newsRepository = newsRepository;
        this.viewName = viewName;
    }

    @RequestMapping(value = "/feed", method = RequestMethod.GET)        
    @Transactional
    public ModelAndView feed() {
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.setViewName(viewName);
        List<News> news = newsRepository.fetchPublished();
        modelAndView.addObject(NEWS_VIEW_KEY, news);
        modelAndView.addObject(LAST_UPDATE_VIEW_KEY, getCreationDateOfTheLast(news));
        return modelAndView;
    }

    private Date getCreationDateOfTheLast(List<News> news) {
        if(news.size() > 0) {
            return news.get(0).getCreationDate();
        }
        return new Date(0);
    }
}
And here's a test for it, in case you want to copy&paste (who doesn't?):
@RunWith(MockitoJUnitRunner.class)
public class FeedControllerShould {
    @Mock private NewsRepository newsRepository;
    private Date FORMER_ENTRY_CREATION_DATE = new Date(1);
    private Date LATTER_ENTRY_CREATION_DATE = new Date(2);
    private ArrayList<News> newsList;
    private FeedController feedController;

    @Before
    public void prepareNewsList() {
        News news1 = new News().title("title1").creationDate(FORMER_ENTRY_CREATION_DATE);
        News news2 = new News().title("title2").creationDate(LATTER_ENTRY_CREATION_DATE);
        newsList = newArrayList(news2, news1);
    }

    @Before
    public void prepareFeedController() {
        feedController = new FeedController(newsRepository, "viewName");
    }

    @Test
    public void returnViewWithNews() {
        //given
        given(newsRepository.fetchPublished()).willReturn(newsList);
        
        //when
        ModelAndView modelAndView = feedController.feed();
        
        //then
        assertThat(modelAndView.getModel())
                .includes(entry(FeedController.NEWS_VIEW_KEY, newsList));
    }

    @Test
    public void returnViewWithLastUpdateTime() {
        //given
        given(newsRepository.fetchPublished()).willReturn(newsList);

        //when
        ModelAndView modelAndView = feedController.feed();

        //then
        assertThat(modelAndView.getModel())
                .includes(entry(FeedController.LAST_UPDATE_VIEW_KEY, LATTER_ENTRY_CREATION_DATE));
    }

    @Test
    public void returnTheBeginningOfTimeAsLastUpdateInViewWhenListIsEmpty() {
        //given
        given(newsRepository.fetchPublished()).willReturn(new ArrayList<News>());

        //when
        ModelAndView modelAndView = feedController.feed();

        //then
        assertThat(modelAndView.getModel())
                .includes(entry(FeedController.LAST_UPDATE_VIEW_KEY, new Date(0)));
    }
}
Notice: here, I'm using fest-assert and mockito. The dependencies are:
<dependency>
 <groupId>org.easytesting</groupId>
 <artifactId>fest-assert</artifactId>
 <version>1.4</version>
 <scope>test</scope>
</dependency>
<dependency>
 <groupId>org.mockito</groupId>
 <artifactId>mockito-all</artifactId>
 <version>1.8.5</version>
 <scope>test</scope>
</dependency>

Step 5. write your very simple view
Here's where all the magic formatting happens. Be sure to take a look at all the methods of Entry class, as there is quite a lot you may want to use/fill.
import org.springframework.web.servlet.view.feed.AbstractAtomFeedView;
[...]

public class AtomFeedView extends AbstractAtomFeedView {
    private String feedId = "tag:yourFantastiSiteName";
    private String title = "yourFantastiSiteName: news";
    private String newsAbsoluteUrl = "http://yourfanstasticsiteUrl.com/news/"; 

    @Override
    protected void buildFeedMetadata(Map<String, Object> model, Feed feed, HttpServletRequest request) {
        feed.setId(feedId);
        feed.setTitle(title);
        setUpdatedIfNeeded(model, feed);
    }

    private void setUpdatedIfNeeded(Map<String, Object> model, Feed feed) {
        @SuppressWarnings("unchecked")
        Date lastUpdate = (Date)model.get(FeedController.LAST_UPDATE_VIEW_KEY);
        if (feed.getUpdated() == null || lastUpdate != null || lastUpdate.compareTo(feed.getUpdated()) > 0) {
            feed.setUpdated(lastUpdate);
        }
    }

    @Override
    protected List<Entry> buildFeedEntries(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
        @SuppressWarnings("unchecked")
        List<News> newsList = (List<News>)model.get(FeedController.NEWS_VIEW_KEY);
        List<Entry> entries = new ArrayList<Entry>();
        for (News news : newsList) {
            addEntry(entries, news);
        }
        return entries;
    }

    private void addEntry(List<Entry> entries, News news) {
        Entry entry = new Entry();
        entry.setId(feedId + ", " + news.getId());
        entry.setTitle(news.getTitle());
        entry.setUpdated(news.getCreationDate());
        entry = setSummary(news, entry);
        entry = setLink(news, entry);
        entries.add(entry);
    }

    private Entry setSummary(News news, Entry entry) {
        Content summary = new Content();
        summary.setValue(news.getShortDescription());
        entry.setSummary(summary);
        return entry;
    }

    private Entry setLink(News news, Entry entry) {
        Link link = new Link();
        link.setType("text/html");
        link.setHref(newsAbsoluteUrl + news.getId()); //because I have a different controller to show news at http://yourfanstasticsiteUrl.com/news/ID
        entry.setAlternateLinks(newArrayList(link));
        return entry;
    }

}

Step 6. add your classes to your Spring context
I'm using xml approach. because I'm old and I love xml. No, seriously, I use xml because I may want to declare FeedController a few times with different views (RSS 1.0, RSS 2.0, etc.).

So this is the forementioned spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="mediaTypes">
            <map>
                <entry key="atom" value="application/atom+xml"/>
                <entry key="html" value="text/html"/>
            </map>
        </property>
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver"/>
            </list>
        </property>
    </bean>

    <bean class="eu.margiel.pages.confitura.feed.FeedController">
        <constructor-arg index="0" ref="newsRepository"/>
        <constructor-arg index="1" value="atomFeedView"/>
    </bean>

    <bean id="atomFeedView" class="eu.margiel.pages.confitura.feed.AtomFeedView"/>
</beans>

And you are done.

I've been asked a few times before to put all the working code in some public repo, so this time it's the other way around. I've describe things that I had already published, and you can grab the commit from the bitbucket.

Hope that helps.

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