You know what annoys me? People with crazy ideas. Especially when they pimp them like crazy.
That's why this tutorial on "code separation" from a web forum I occasionally visit annoys me so much. The author links to this thing like his life depends on it. Whenever somebody has the nerve to post a code snippet that has both HTML and PHP in it, he brings it up. Even if the code is just echoing a variable inside an HTML block. It's ridiculous.
Don't get the wrong idea - separation of concerns is obviously a good thing. If you're outputting HTML and querying the database in the same file, you're doing things wrong. But this guy takes it to absurd lengths and insists that you should never have any PHP code mixed in with your HTML. Not even echo statements.
The real kicker is the content of this "tutorial". It's basically a half-baked template system that does nothing but string replacement of pre-defined placeholders. At best, it grossly over simplifies the problem. I suppose it does demonstrate that it's possible to output a page without having HTML and PHP in the same file (as if anyone really doubted that), but that's about it.
The thing that really bothers me about this approach is that the author promotes it results in code that's easier to understand than code that has both PHP and HTML in it. Except that it's not. The guy apparently just has a pathological fear of having two different languages in the same file. it's completely irrational.
The problem with his approach is that it doesn't actually solve the problem, but just moves it. Sure, basic replacement like that it's fine for simple cases, but as soon as the requirements for your markup get more complicated, things blow up. For example, how do you do conditionals? Well, you have another template file and you do a check in your controller for which one to inject into the page. What about loops? Well, you have a template file for the loop content and you run the actual loop in your controller, build up the output, and inject that into the page.
The net result? What would normally be a fairly simple page consisting of one template with a loop and two conditionals is now spread across six template (one main template, one for the loop body, and two for each if statement) and pushes all the display logic into the controller. So instead of one "messy" template to sort through, you now have a seven-file maze that accomplishes the same thing.
I find it difficult to see how this is any sort of improvement. At best, it's just trading one type of complexity for another in the name of some abstract principle that mixing code and markup is evil. Of course, if you want to follow that principle, you could always go the sane route and just use something like Smarty instead. But let's be honest - that's just using PHP code with a slightly different syntax. It may be useful in some cases, but it's not really fundamentally different from just writing your template files in PHP.
Personally, I've come to be a believer in keeping things simple. PHP is a template system. It was originally designed as a template system. It's good at it. So there's no need to introduce additional layers of template abstraction - just stick with PHP. There may be cases where things like Smarty are useful, but they're far from necessary. And the half-baked templating systems like those advocated in that tutorial are just intellectual abortions. There's no need to reinvent a less functional version of the wheel when you can just use a working, tested wheel.
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