Reposted from my site at www.vbcodex.com (http://www.vbcodex.com)

Following my previous article, I want to give some information about the new template tags in vBulletin 4. The use of template tags is not a new concept to vBulletin 4 developers and designers. We have been using them for years for conditional statements and building phrases that had parameters.

In vBulletin 4, Phrase parsing has been moved to the variable parsing system but conditional usage has been improved and several new tags have been added to make things easier. Like the variable system I talked about earlier, tags are in their own namespace so all tags are prefixed with 'vb:'. This actually provides several benefits but the primary one is that you can program scriptable web editors like Dreamweaver or Expressions Web to parse these conditionals and provide output based on values you provide. They also allow proper syntax highlighting to occur in most web editors.

Template Conditionals
Everyone who has worked with vBulletin templates in the past should be familiar with template conditionals. They provide a wide range of use in determining what information to show depending on various conditions. In vBulletin 3.X, the IF conditional was simple and easy to use. In fact, you can still use pretty much the same format in vBulletin 4. However a couple of new tags were added to make conditionals more robust.

Here is an example:

<vb:if condition="$show['guest']">
<div class="alert">You are a guest, no soup for you.</div>
<vb:elseif condition="$is_member_of($bbuserinfo,6)" />
<div class="adminalert">Hello {vb:raw bbuserinfo.musername}! Let's get to work.</div>
<vb:else />
<div class="useralert">Welcome Back {vb:raw bbuserinfo.musername}!</div>
</vb:if>
The new thing here is the <vb:elseif /> tag. It allows you to branch your conditions better and reduce the number of nested conditions you may need to make.

Conditionals also have a new shorthand using a curly brace syntax. In today's templates, you see a lot of code that looks like this:

<a href="somepage.php<if condition="$album['albumid']">album=$album[albumid]<else />group=$group[groupid]</if>">link text</a>
That is a brief example but makes a real mess of syntax highlighting and can't even be validated. With the new shortform notation it would look like this:

<a href="somepage.php{vb:if $album['albumid'] : album=$album[albumid] ? group=$group[groupid]}">link text</a>
As you can see the second examples looks a lot cleaner and maintains syntax highlighting.


Each
For a long time, users have wanted a way to do loops in templates. Heck, I have wanted to be able to do loops in templates. vBulletin 4.0 includes the <vb:each> tag which accomplishes just that. While it is not being used for the default templates at this time, it will probably be used in the future to eliminate some of the many 'bit' templates in the system. The Each tag will allow you to easily process an array and apply formatting to its elements.

Example:

Welcome this week's new users: <ul>
<vb:each from="newusers" key="userid" value="newuserinfo">
<li><a href="member.php?u={vb:var userid}">{vb:var newuserinfo.username}</a></li>
</vb:each></ul>
If the array looked like:

$newusers = array(
1 => array('username' => 'Adam', 'email' => 'adam@adam.com'),
2 => array('username' => 'Ben', 'email' => 'ben@ben.com'),
3 => array('username' => 'Chris', 'email' => 'chris@chris.com')
);
The output could look like:

Welcome this week's new users: Adam Ben Chris

Comment
How many times have you wanted to leave commented notes in a template so you can understand why you did what you did? Or you work on a team so others need to know what is being done in a template? Before now, you would have had to use HTML comments that would have been output to the Browser and visible in the page's source code. vBulletin 4.0 introduces the comment tag so you can add your comments and not worry about them being sent to the client. Comments will be stripped when the template is compiled into PHP. Can also be used for hiding code blocks from being output to the user.

Example:

<vb:comment>This is a comment and won't be shown in page source code.</vb:comment>

Literals
The final new tag is the literal tag. It allows you to stop the parsing of any nested tags or variable syntax within the tags. It works similar to the noparse BB Code. It is handy when you want the template to simply output the raw HTML instead of putting it through the template parser.

Example:

<vb:literal>This will output exactly like this {vb:raw somevariable}</vb:literal>

Summary
While the changes to tags are not as extensive as variable handling, the new tags provide new ways of handling templates and will provide better abilities to create addon products in the future. The Each and Comment tags will come in especially handy while doing customizations in the future. I hope this gives you another good glimpse into the vBulletin 4.0 template system.