Installing Haml 1.5.2Edit

Created , updated

These notes were made while installing Haml for the first time.

Installing

The official Haml download page states that Haml can be installed from the top-level of an existing Rails application by executing this command:

script/plugin install http://svn.hamptoncatlin.com/haml/tags/stable

This command, however, results in the plug-in being installed in a folder called stable when it really should be called haml. So I instead installed as follows:

svn export http://svn.hamptoncatlin.com/haml/tags/stable vendor/plugins/haml

My bug report for this posted to the Haml Google group can be found here. This page suggests that an alternative which might work would be:

# use undocumented optional target name parameter
script/plugin install http://svn.hamptoncatlin.com/haml/tags/stable haml

Out of curiosity I tried that out and as of Rails 1.2.3 it no longer works:

Plugin not found: ["http://svn.hamptoncatlin.com/haml/tags/stable", "haml"]

First template conversion

I started off by taking a simple view template, index.rhtml:

<% for user in @users %>
<div id="userlist">
  <div class="<%= cycle('odd', 'even') %>">
    <div class="label"><%= _('Login name:') %></div>
    <div class="info"><%=h user.login_name %></div>
    <div class="label"><%= _('Display name:') %></div>
    <div class="info"><%=h user.display_name %></div>
    <div class="label"><%= _('Email address:') %></div>
    <div class="info"><%=h user.email_address %></div>
  </div>
</div>
<% end %>

And converting it to Haml:

- for user in @users
  [/tags/userlist #userlist]
    %div{:class => cycle('odd', 'even')}
      .label= _('Login name:')
      .info= h user.login_name
      .label= _('Display name:')
      .info= h user.display_name
      .label= _('Email address:')
      .info= h user.email_address

The Haml version is 3 lines shorter, and its character count is 269 (compared with 439 for the original version).

It is easy to migrate to Haml because Haml templates coexist with RHTML templates. In the current example the index.haml file will be used, if present, otherwise Rails will fall back to index.rhtml. If the changes don’t work out, you can easily switch back to RHTML.

Because I’m doing Behaviour-Driven Development using RSpec I was able to immediately confirm that the output continues to pass all specs; this is again confirmed by visual inspection of the output:

<div id='userlist'>
  <div class='odd'>
    <div class='label'>Login name:</div>
    <div class='info'>example login name 1</div>
    <div class='label'>Display name:</div>
    <div class='info'>example display name 1</div>
    <div class='label'>Email address:</div>
    <div class='info'>example email address 1</div>
  </div>
</div>
<div id='userlist'>
  <div class='even'>
    <div class='label'>Login name:</div>
    <div class='info'>example login name 2</div>
    <div class='label'>Display name:</div>
    <div class='info'>example display name 2</div>
    <div class='label'>Email address:</div>
    <div class='info'>example email address 2</div>
  </div>
</div>

See also