breaking-out-of-the-box

# Breaking out of the Box

Up until now, we've highlighted cool features of Hobo, and made
everything look easy.  You can't blame us, can you?

Hobo makes the first 90% of your application really easy, but we
cannot anticipate everything.  That last 10% is what makes your
application special, and cannot be included in any toolkit.

Most rapid application generators put you inside a box -- if you stay
inside the box, everything is easy.  Some won't let you break out of
the box, and others make it very difficult.

With Hobo there is no box.  More and more customization is required the
further you stray away from what has been anticipated, but the border
is not sharp.

In essence, Hobo and DRYML support five different ways of customizing
a widget, page or action.

## Parametrization

Most of what you have seen so far in this tutorial has been
parametrization.  In DRYML you can set the attributes or parameters of
a tag you invoke, in Ruby you can change the parameters to functions
you invoke.

## Extension

In DRYML, there is a tag called
[extend](/manual/dryml-guide#customising_and_extending_tags).  Extend
allows you to redefine an existing tag while reusing the existing
definition.  This allows you to add to the tag or change its default
parametrization.

You saw an example of extension in DRYML in [Customizing
Views](#customising_views).

## Redefinition

The next level of customization is to redefine a tag or function.
`app/views/taglibs/application.dryml` gets loaded after the RAPID
library and the auto-generated DRYML, so if you redefine a tag, your
definition will be used instead of the library definition.

Perhaps the first thing that many developers customize is the
navigation bar.  In our little tutorial, we want to remove the "Story
Status" tab.

The nice thing about redefining a tag is that you can use the existing
definition for a little bit of cut and paste.  Cutting and pasting is
generally frowned upon -- DRYML includes "don't repeat yourself",
after all, but sometimes we do it anyways.  In our case, we'll be
cutting and pasting from the top of `view/taglibs/auto/rapid/pages.dryml`.

SHOW_PATCH

You will notice that we've removed the StoryStatus line.  We've also
removed the "param" attributes.  Nobody is going to be parameterzing
our redefinition, so let's make it a little simpler.

## Defining new tags

Creating new tags is outside of the scope of this tutorial.  Creating
new tags lets you avoid cutting and pasting, and lets you reuse your
code throughout your project and into other projects.  For more
information on DRYML, see the [manual](/manual).

## Replacement

When you want to do something completely different, you can completely
bypass the existing tags.   `app/views/projects/show.dryml` can
contain raw HTML with little or no DRYML.  You can also bypass DRYML
and create `app/views/projects/show.html.erb` and use standard Ruby on
Rails techniques.  Hobo models and controllers follow standard Rails
conventions, so completely custom views can be used without defining
custom controllers and models or vice versa.

app/views/taglibs/application.dryml

@@ -33,3 +33,8 @@
   </old-card>
 </extend>
 
+<def tag="main-nav">
+  <navigation class="main-nav" merge-attrs>
+    <nav-item href="#{base_url}/">Home</nav-item>
+  </navigation>
+</def>