How to implement hook_theme in drupal 7?

Question

I created a new drupal 7 theme and trying to implement hook_theme at template.php like this:

function mytheme_theme($existing, $type, $theme, $path){
    return array(
        'mytheme_header'=>array(
            'template'=>'header',
            'path'=>$path.'/templates',
            'type'=>'theme',
        ),
    );
}

then I placed header.tpl.php into templates directory and cleared all caches, and call theme function:

theme('mytheme_header', $vars);

and header.tpl.php likes this:

<?php
fb('calling header template');//the function of FirePHP to output debug info
print '<div>Header</div>';
//...

I check Firebug and it get the info 'calling header template', it mean it had called header.tpl.php, but it didn't print the html code. What's wrong with my code?

Answer 1

Try to add the variables array in hook_theme

function mytheme_theme($existing, $type, $theme, $path){
    return array(
        'mytheme_header' => array(
            'template' => 'header',
            'path' => $path . '/templates',
            'type' => 'theme',
            'variables' => array(
                'title' => NULL,
                'some_text' => NULL,
            ),
        ),
    );
}

In your header.tpl.php file:

<h1><?php print $title; ?></h1>
<p><?php print $some_text; ?></p>

Then, print it out like this:

$vars = array();
$vars['title'] = "This is a title";
$vars['some_text'] = "Some text...";
print theme('mytheme_header', $vars);