The Ewelike Blog

We’ve been experimenting over the past year with various Templating engines in PHP, and we decided on our winner: Smarty

Originally we’d planned to use the HTML_TEMPLATE_IT package from PEAR, but Smarty just gives us more power (and thus makes the templating cleaner). HTML_TEMPLATE_IT seems to be the templating system most illustrated in books and examples, so for many it’s a good choice.

Smarty will also allow us to cache pages and “compile” the templates into a quicker rendering form - both of which will be an advantage for us as this new application is released.

Templating allows the “presentation” to be seperated from the code and this is (almost always) a good thing. For a start there will be no more horrible echo statements all over the PHP code, secondly you can “include” templating files so that you have more consistent commonality between the pages. Best of all using this system means that you can quickly create an output HTML file from a template, this can then be used by your designers when they construct the CSS. This is especially important to me as design is not my strong point and we either hire in graphics people as required, or we use external agencies. When using external agencies they can have sample HTML (and the templates with a brief explanation) for them to skin, so they understand the structure and they have something concrete to work upon. If for some reason CSS can’t handle some of the HTML structure (this is amazingly still an issue as the CSS implementations for various browsers are still broken) then you can always amend the template if required. But, importantly design never holds up the development process, it works in parallel.

Using a templating system shouldn’t be overlooked for any site. Today, without changing a single line of code in PHP, we were able to add additional fields to a page, and change the structure of what was generated. Of course we don’t use the templating system for look and feel, instead that’s all done with the other front-end layer - CSS. This essentially creates a “two tier presentation tier”, something which Martin Fowler has written about in the past. It’s true power is that your back-end (that does the business logic) is seperated from how the front-end PHP works, which is again seperated from the templating system which then only has to use the data it is given. CSS can then take the templating system’s data and turn it into something visually appealling.

Lots of books advocate the “classic 3 tier” application structure (roughly; presentation layer, business logic layer, and data layer), don’t be pushed by this though as just 10 years ago a large number of publications would tell you how you need a 2-tier (also known as client-server) application structure - the 2 tier people turned out to have industrial-class blinkers on and didn’t notice all the issues it caused.

The truth is that the number of layers/tiers depends on the application you’re creating. A HelloWorld program needs 1 layer (and no more! ), Fat client systems can work admirably as 2 tier applications (although you must bear in mind the issues with having fat clients, and bandwidth concerns), 3 tiers is normally the usual for anything web-based (CSS and the HTML generated are often seen as the same layer in this model as the two are so intricately tied and both contain presentation information). Our application uses 5 tiers - Database, Data Objects, Business Objects, Templates, CSS and all are well seperated by contracts between them - but that doesn’t make it a solution for all.

You can learn more about Smarty from the crash course on the smarty.php.net site. I’d encourage you to take a look even if you’re sure you’ll never need templating.

For many new PHP users my advice would be to build the templates first (in a similar manner to how design is performed using the Catalysis OO design method), that way you understand what pages require and how they act together. Best of all, it means that your templates can be simple and avoid (too many) UI tags - such as; p (for paragraphs of course), ul (lists) and tables, and thus just rely on the CSS to perform the rendering.For some this may be difficult as the resulting templated HTML is extremely ugly until the CSS is in place to style it appropriately. If you can live with the ugly but functional HTML while developing (which shouldn’t be a major problem - after all you are unit testing right? That way you’ll be sure you’re only debugging your templates, not the other php that gets it) then you’ll love Templates. Be a Smarty - download it today and have a go.