Arguments to PHP template functions
This is more of a style question. I have a template file header.php in which I define a PrintHeader() function.
Callers of this function can specify, via global variables, the title of the page and any Javascript scripts to include when printing the header (because surely not every page will have the same title or want to include the same scripts). I chose to use global variables rather than function arguments because the latter would require the interface to change when adding new arguments.
Is this considered "good" style, and is there a "better" way to do what I'm trying to do?
header.php (simplified)
<?php
function PrintHeader()
{
global $pageTitle, $scripts; // Set by the caller of this function
echo <<<HEADER
<html>
<head>
<title>$pageTitle</title>
HEADE开发者_如何学GoR;
if( !empty($scripts) )
{
foreach($scripts as $script)
{
echo " <script type=\"text/javascript\" src=\"$script.js\"></script>\n";
}
}
echo " </head>\n";
}
?>
index.php (simplified)
<?php
$pageTitle = 'Welcome';
$scripts = array('script1', 'script2');
require('header.php');
PrintHeader();
// Print the rest of the page
?>
is there a "better" way to do what I'm trying to do?
sure.
I see no point in defining and calling a function at all. as well as in using heredoc.
header.php (dramatically simplified):
<html>
<head>
<title><?=$pageTitle?></title>
<? if( !empty($scripts) ): ?>
<? foreach($scripts as $script): ?>
<script type="text/javascript" src="<?=$script?>.js"></script>
<? endforeach ?>
<? endif ?>
</head>
index.php:
<?php
$pageTitle = 'Welcome';
$scripts = array('script1', 'script2');
require('header.php');
?>
but still it's not the best way, as it seems you're not using a template where it most valuable - to output page contents itself.
So, I'd make it in three parts:
links.php (simplified):
<?
//include our settings, connect to database etc.
include dirname($_SERVER['DOCUMENT_ROOT']).'/cfg/settings.php';
//getting required data
$DATA = getdata("SELECT * FROM links");
$pagetitle = "Links to friend sites";
//etc
//and then call a template:
$tpl = "links.tpl.php";
include "main.tpl.php";
?>
where main.tpl.php is your main site template, including common parts, like header, footer, menu etc:
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>My site. <?=$pagetitle?></title>
</head>
<body>
<div id="page">
<? include $tpl ?>
</div>
</body>
</html>
and finally links.tpl.php is the actual page template:
<h2><?=$pagetitle?></h2>
<ul>
<? foreach($DATA as $row): ?>
<li><a href="<?=$row['link']?>" target="_blank"><?=$row['name']?></a></li>
<? endforeach ?>
<ul>
notice native HTML syntax, which is highlighted, readable and centralized in one place instead of being split between numerous functions and files
The point is in having separate template for the every PHP page as well as main site template for them all. With such setup you'll get a lot of advantages such as custom error pages, multiple representations of the same data (say, HTML, JSON or XML) by switching only templates without changing the code and many more
The use of global variables is certainly not advisable, and I question the necessity of using heredoc as you have - not that there is anything inherently wrong with heredoc, just that you seem to have rather arbitrarily utilized it in this sample template.
It is not elegant to use a return-value of a function as the output of each template - this defeats one of the purposes of templates which is re-usability.
Take a look at smarty, if not to directly use it (after all, why re-invent the wheel), at least to get an idea of how a rendering class is used to shuttle in the variables that a template needs without resorting to messy globals.
Here's a very quick overview of a way to do templating:
You have a template class that you can assign data to and then render a template.
Template.php:
class Template
{
protected $data = array();
public function assign($key, $value)
{
$this->data[$key] = $value;
}
public function render($file)
{
extract($this->data);
require $file;
}
}
You then have your template, header.php:
<html>
<head>
<title><?php echo $pageTitle; ?></title>
....
In index.php, you then use the template class to assign data and render your template.
$tpl = new Template;
$tpl->assign('pageTitle', 'My page title!');
$tpl->render('header.php');
This is just a simple example to demonstrate the idea, and could give you a good starting point.
While "better" may be in the eye of the beholder, I would suggest having some sort of functions that set the page bits rather than exposing raw variables. For instance, instead of doing $pageTitle = 'Welcome'; you could have set_page_title('Welcome');.
For JavaScript you could have a function that adds to the current script set -- rather than possibly replacing it all -- such as add_javascript($code);. This will allow a developer to set all of these without having to keep track of what the variable name was, and also without needing to global it as well if they want to set it from within a function.
This is an alternative using output buffering.
p/example_page/index.php is one of your pages:
<?php
ob_start() ?>
<h1>Example</h1>
<p>This is the page content</p>
<?php $main = ob_get_clean();
ob_start() ?>
<script defer src="js/example_page/example.js"></script>
<?php $script = ob_get_clean();
$title = 'Example page';
include 'templates/base.php';
templates/base.php is your reusable layout:
<!doctype html>
<html>
<head>
<script defer src="js/main.js"></script>
<?php echo $script ?>
<title><?php echo $title ?> - Example website</title>
</head>
<body>
<header>
<nav aria-label="Main menu"></nav>
</header>
<main><?php
echo $main;
?></main>
<footer>Example footer</footer>
</body>
</html>
Global variables are generally considered bad, and should be avoided if possible.
Rather than listing every variable in the interface, as you said things could change, pass a single array to the PrintHeader() functions:
<?php
function PrintHeader($opts=array()) {
if(!isset($opts['title'])) $opts['title'] = 'Default Title';
echo <<<HEADER
<html>
<head>
<title>$opts['title']</title>
HEADER;
if(!empty($opts['scripts'])) {
foreach($opts['scripts'] as $script) {
echo " <script type=\"text/javascript\" src=\"$script.js\"></script>\n";
}
}
echo " </head>\n";
}
$opts = array('title'=>'Welcome',
'scripts'=>array('script1', 'script2'));
require('header.php');
PrintHeader($opts);
?>
This way, you can add new capabilities in the function without breaking old code.
加载中,请稍侯......
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