Web Development - The Line Between Code and Content?

markmcb asks: "I help design a LAMP web site and I'm constantly plagued by trying to decide on what level should I separate functional code and markup. Depending on what you read, some say embedding HTML in your PHP scripts [or Perl, or Java, or Ruby, or Python, etc] is bad while others say it's no big deal. However, seldom are any practical applications of such code cited. How is your site built? Do you mix HTML with your code? If not, how do you overcome the simple and easy method of doing so? Lastly, what performance gains/losses have you noticed by doing so?"

Comments

Simple

[neoform]

Seperated: If you want something modular and scalable (but slower)

Embedded: If you want something faster and easy to write (but not as scalable)

Logic vs Presentation

[illuminatedwax]

People will always tell you to "separate logic from presentation" and that is good advice - to a certain extent. I don't think that this is correct all the time, however, because it is not a correct statement per se because the two cannot always be separated. However, they usually can and usually are, and web pages are a good example of this. But what does "separate" mean? Does it mean physically moving your presentation to another file, generating it, etc.? There are many different ways, all of which work best in certain situations.

Here's what you should worry about instead:
1) Is the program readable?
2) Can you easily make changes in the program without having to change too many other parts of it?
3) Are you having to rewrite the same code too much?

Those are some pretty basic computer programming design concepts, and if you apply those, you'll find that the answer should be pretty clear. Just keep everything clean and life will be happier.

Separation good

[legLess]

Separation is good. I can trot out the old "let coders code and designers design," but I often do both, and there are other benefits. You should look at model view controller. You don't have to drink all the MVC kool-aid to get good ideas from it.

Wonder why Slashdot looks like ass? I've spent a lot of time hacking Slash source and, until their recent refactors (and maybe even now) there was markup everywhere in the Perl. It made a redesign impossible without actually writing code, and possible introducing bugs.

MVC says that the presentation layer should be separate from the rest of the application. If you think about it, that's the same idea as keeping presentation (e.g. CSS) separate from content (e.g. XHTML). That idea has clearly won out.

Performance can be a factor for smaller systems, but if you cache your templates or have them precompiled (e.g. JSP) it helps. Also, programmer efficiency is almost always more important than code efficiency. Keeping the controller code and the view separate allows you to find and fix code bugs without wading through all sorts of presentation logic. Who cares about how a nested list is constructed in XHTML when you're trying to find out why your app is barfing?

Re:Matter of Personal Preference?

[jalefkowit]

Wait until your project grows to a point where you're not the only person working on it, and then come back and tell us if you still feel this way.

Keeping markup out of your code means that you can, for example, bring in a graphic designer to change the look and feel your site/app without requiring that they know Perl (or PHP, or whatever) -- very few designers know, or care, about programming. And it means that you can bring in other programmers to fix bugs/add features without worrying that their changes will muck up the UI.

Re:I never like this method

[MaoTse]

The point is: PHP does not support content/logic separation ;-)

Your designer wanted to delete the code because it was breaking his design tool. Fuck ...

Zope Page Templates do not have this problem.