Reputation: 12355

separating php and html... why?

So I have seen some comments on various web sites, pages, and questions I have asked about separating php and html.

I assume this means doing this:

<?php

myPhpStuff();

?>

<html>

<?php

morePhpStuff();

?>

Rather than:

<?php

    doPhpStuff();

    echo '<html>';

    ?>

But why does this matter? Is it really important to do or is it a preference?

Also it seems like when I started using PHP doing something like breaking out of PHP in a while loop would cause errors. Perhaps this is not true anymore or never was.

I made a small example with this concept but to me it seems so messy:

<?php

$cookies = 100;
while($cookies > 0)
{
    $cookies = $cookies -1;
?>
    <b>Fatty has </b><?php echo $cookies; ?> <b>cookies left.</b><br>

<?php

} 

?>

Are there instances when it is just better to have the HTML inside the PHP?

<?php

$cookies = 100;
while($cookies > 0)
{
    $cookies = $cookies -1;

    echo'<b>Fatty has </b> '.$cookies.' <b>cookies left.</b><br>';
} 

?>

Upvotes: 5

Answers (11)

Steve Claridge

Reputation: 11100

When people talk about separating PHP and HTML they are probably referring to the practice of separating a website's presentation from the code that is used to generate it.

For example, say you had a DVD rental website and on the homepage you showed a list of available DVDs. You need to do several things: get DVD data from a database, extract and/or format that data and maybe mix some data from several tables. format it for output, combine the DVD data with HTML to create the webpage the user is going to see in their browser.

It is good practice to separate the HTML generation from the rest of the code, this means you can easily change your HTML output (presentation) without having to change the business logic (the reading and manipulation of data). And the opposite is true, you can change your logic, or even your database, without having to change your HTML.

A common pattern for this is called MVC (model view controller). You might also want to look at the Smarty library - it's a widely used PHP library for separating presentation and logic.

Upvotes: 16

Csaba Kétszeri

Reputation: 694

Let's make it clear what is not separation

you switch from php mode to html mode
you use print or echo statements to write out html code
you use small php snipplets inside html files

If you do this, there is no separation at all, no matter if you escape from php to html blocks or do it the other way and put php code into html.

Have a look at a good templating engine, there are a plenty of reasons in the "why use ...." parts of the manuals. I'd suggert www.smarty.net especially http://www.smarty.net/whyuse.php

It will answer all your questions now you have.

Upvotes: 7

user114752

Reputation:

I find it preferable to separate application logic from the view file (done well with CodeIgniter framework with MVC) as it leaves code looking relatively tidy and understandable. I have also found that separating the two leaves less margin for PHP errors, if the HTML elements are separated from the PHP there is a smaller amount of PHP that can go wrong.

Ultimately I believe it is down to preference however I feel that separation has the following pros:

Tidier Code
Less of an Error Margin
Easy to Interpret
Easier to change HTML elements
Easier to changed Application Logic
Faster Loading (HTML is not going from Parser->Browser it goes straight to browser)

However some cons may be:

It only works in PHP5 (I Believe, could be wrong, correct if needed)
It may not be what one is used to
Untidy if done incorrectly (without indentation etc, however this is the same with anything)

But as you can see, the pros outweigh said cons. Try not to mix the two also, some separation and some intergration - this may get confusing for yourself and other developers that work with you.

I hope this helped.

Upvotes: 3

shylent

Reputation: 10086

Ouch!

All of the examples in your question are perfectly impossible to read. I'd say, you do yourself and those, who might read your code a great favour and use a template engine of sorts, say, Smarty. It is extremely easy to set up and use and it WILL separate your code from presentation. It doesn't require you to put everything in classes, it just makes sure, that your logic is in one file and presentation - in another one.

Upvotes: 1

farzad

Reputation: 8855

for pages that contain a lot of HTML, embedding PHP code into the page could be easier. this is one of the first intentions behind PHP. anyway when you are developing an application with lots and lots of logic, different types of connectivity, data manipulation, ... your PHP code gets too complicated if you want to just embed them in the same pages that are shown to users. and then the story of maintenance begins. how are you going to change something in the code, fix a bug, add a new feature?

the best way is to separate your logic (where most of the code is PHP) in different files (even directories) from your page files (where most of the code is HTML, XML, CSV, ...).

this has been a concern for developers for so many years and there are recommendations to handle these general problems, that are called design patterns.

since not everyone has the experience, and can apply these design patterns into his application, some experienced developers create Frameworks, that will help other developers to use all the knowledge and experience laying in the hear of that framework.

when you look at toady's most used PHP frameworks, you see that all of them put code into PHP Classes in special directories, make configurations, and .... in none of these files you see a line of HTML. but there are special files that are used to show the results to users, and they have a lot of HTML, so you can embed your PHP values inside those HTML pages to show to users. but remember that these values are not calculated on the same page, they are results of a lot of other PHP codes, written in other PHP files that have no HTML in them.

Upvotes: 4

Ayman Hourieh

Reputation: 137436

It is very important to separate application logic from presentation logic in projects. The benefits include:

Readability: Your code will be much easier to read if it does not mix PHP and HTML. Also, HTML can become difficult to read if its stored and escaped in PHP strings.
Reusability: If you hard-code HTML strings within PHP code, the code will be very specifc to your project and it won't be possible to reuse your code in later projects. On the other hand, if you write small functions that do one task at a time, and put HTML into separate template files, reusing your code in future projects will be possible and much easier.
Working in a team: If you are working in a team that contains developers and designers, separation of application logic and presentation templates will be advantageous to both. Developers will be able to work on the application without worrying about the presentation, and designers (who don't necessarily know PHP very will) will be able to create and update templates without messing with PHP code.

Upvotes: 4

Alexandru Trandafir Catalin

Reputation: 2658

It says that what you put in echo '' it is first processed by the programming language and then sent to the browser, but if you directly put there html code without php, that code will load faster because there is no programming involved.

And the second reason as people above said is that you should have your 'large programming code' stored separately of the html code, and in the html code just put some calls to print results like 'echo $variable'. Or use a template engine like Smarty (like I do).

Best regards, Alexandru.

Upvotes: 1

Cimplicity

Reputation: 2732

Functionally: they both will work, so ultimately it is a preference.

Yet, you might consider that comments are a preference as well, your code would compile and run exactly the same without comments. However most people would agree comments are essential to writing and maintaining good code. I see this as being a similar subject matter. In the long run it will make it easier to read and maintain the code it if the two are separated.

So is it important? I would say Yes.

Upvotes: 2

Jeff Meatball Yang

Reputation: 39057

Benefits of the first method (separating PHP and HTML):

You don't need to escape characters
It's also possible for code editors to highlight/indent the markup.
It's arguably easier to read
There is no downside to this method, compared to the second method.

Upvotes: 2

Arsen Mkrtchyan

Reputation: 50752

I don't know how in php but in asp.net separation has the following advantages. 1. separated code is easy to understand and develop 2. designer can work in html in the same time developer can write a code

Upvotes: 0

Gideon

Reputation: 18501

I kick off with: the first one you can open in a WYSIWYG editor, and still see some markup, which might makes it easier to maintain.

Upvotes: 1

separating php and html... why?

Answers (11)

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