Anyway, feel free to see if you find anything interesting in the list of blogs i’m reading.

<?php
$isgoodapi = filter_input(INPUT_GET, 'isgoodapi', FILTER_VALIDATE_BOOLEAN);

if (is_null($isgoodapi)) { 
 echo "the 'isgoodapi' argument is missing.";
} else if ($isgoodapi === FALSE) { 
 echo "The 'isgoodapi' argument must be a valid boolean."; 
} else { 
 echo "isgoodapi is: $isgoodapi."; 
}
?>

And now you request the page with ?isgoodapi=false. The obvious problem is the fact that the function returns multiple ‘sorts’ of return values: Value of the requested variable on success, FALSE if the filter fails, or NULL if the variable_name variable is not set. If the flag FILTER_NULL_ON_FAILURE is used, it returns FALSE if the variable is not set and NULL if the filter fails.

The documentation for Filter Functions says for FILTER_VALIDATE_BOOLEAN: Returns TRUE for “1″, “true”, “on” and “yes”, FALSE for “0″, “false”, “off”, “no”, and “”, NULL otherwise. So if you try with ?isgoodapi=konijn you would expect NULL but that isn’t the case either.

<?php
function SelectMonths($name = 'selectMonths', $id = 'selectMonths') {
 $current_month = date('n');
  
 echo '<select name="' . $name .'" id="' . $id . '">';
 
 for ($i = 1; $i < 13; ++$i) {
  echo '<option value="' . $i . '"';

  if ($i == $current_month) {
   echo ' selected';
  }

 $month_name = strftime('%B', mktime(0, 0, 0, $i, 1, 2006));

  echo '>' . $month_name . '</option>';
 }
 
 echo '</select>';
}
?>

And now you can easily generate a localized menu:

<?php
include('SelectMonths.php');

SelectMonths();

// Tested on a Windows host - Read the http://be.php.net/setlocale
setlocale(LC_TIME, 'dutch');
SelectMonths();
?>

body {
        background-color: <?php echo 'yellow'; ?>;
}

Here is a simulation of what your browser recieves when it requests the file:

HTTP/1.1 200 OK
Date: Sat, 26 Aug 2006 23:36:21 GMT
Server: Apache/1.3.34 (Unix) PHP/4.4.2 mod_macro/1.1.2
X-Powered-By: PHP/4.4.2
Connection: close
Content-Type: text/html; charset=iso-8859-1

body {
        background-color: yellow;
}

Where did that content-type header come from? Well, php outputs a default content-type header (text/html) when you don’t set value explicitely. This means that your browser will try to interpret the file as html instead of css. Although it may seem weird, this behaviour is explicitely defined in RFC 2616.

So the solution is pretty simple: explicitely generate content-type header. Here is an example for css: (You’re smart enough to figure it out for csv, m3u, …)

<?php header('Content-type: text/css');?>
body {
  background-color: <?php echo 'white'; ?>
}

My solution for this problem is quite easy. For each entity in the database that can be updated by a form, we should add an attribute lastupdate. Now every time we build a form that contains data of that entity, we should also add an input of type hidden with the value of that lastupdate attribute. If the value of the lastupdate attribute in the database is more recent than the value of the posted lastupdate in the recieving script, then the posted values are invalid and this script should tell the user about this error. Offcourse, every time such an entity is updated, the lastupdate attribute of this entity should be updated too.

<?php
$result = `""c:\\my path\\prog.exe" "filename""`;
?>

In case you have to do it often you might want to wrap it into a little function like this:

<?php 
function cmd($command, $arguments = null)
{
        $commandline = '';
        foreach(func_get_args() as $word) {
                $commandline .= '"' . $word . '" ';
        }
        $commandline = rtrim($commandline, ' ');
        $commandline = '"' . $commandline . '"';
        return `$commandline`;
}

// run blah.exe
cmd('blah.exe');

// run c:\my path\blah.exe with the arguments "foo" and "bar bar" 
cmd('c:\\my path\\blah.exe', 'foo', 'bar bar');
?>

echo sprintf(__('There are %d monkeys in the %s'), $domain), $number, $location);

I started with defining the WPLANG constant in my wp-config.php:

define ('WPLANG', 'en_EN');

Then i changed the beginning of my localized plugin as following:

<?php
/*
Plugin Name: WP-SpamFilter
Version: 0.4
Plugin URI: http://timvw.madoka.be/?p=533
Description: Mark the new comment as spam if the sender is in the spammers list.
Author: Tim Van Wassenhove <timvw@users.sourceforge.net>
Author URI: http://timvw.be
*/

// If this function does not exist it means that the file is accessed directly.
// Accessing this file directly is not allowed.
if (!function_exists('load_plugin_textdomain')) {
  exit;
}

load_plugin_textdomain('wp_spamfilter', 'wp-content/plugins/wp-spamfilter');

In wp-includes/wp-l10n.php you see that the result of this call is that the locale and the path are used to determine the mo-file to be loaded. Because this function uses ABSPATH it’s impossible to use dirname(__FILE__) as path parameter

The _e($string, $domain) function echos a localized string and the __($string, $domain) function returns a localized string that you can use in function calls etc… Below you can see an example of the original version and the updated version with localization support:

<h2>some string</h2>
<?php echo('some other string'); ?>

<h2><?php _e('some string', 'wp_spamfilter'); ?></h2>
<?php echo(__('some other string', 'wp_spamfilter')); ?>

Then i used xgettext to extract all the strings that should be localized into wp_spamfilter-en_EN.po:

After that i editted the po file and i compiled a mo file with it using msgfmt:

Once i had made sure that wp_spamfilter-en_EN.mo was readable by my webserver i was ready.

<?php
/*
Plugin Name: %plugin_name%
Version: %plugin_version%
Plugin URI: %plugin_uri%
Description: %plugin_description%
Author: %plugin_author_name% <%plugin_author_mail%>
Author URI: %plugin_author_uri%
*/

// Direct access is not allowed.
if (!function_exists('load_plugin_textdomain')) {
  exit;
} else {
  require('%plugin_name%.php');
  $plugin_name = substr(basename(__FILE__), 0, -4);

  // You can add optional parameters to the constructor, eg: the wpdb instance.
  $%plugin_class% = new %plugin_class%($plugin_name);
}
?>

Now it’s time to implement the %plugin_class%. Here is the template for %plugin_name%/%plugin_class%.php:

<?php

class %plugin_class% {
  var $_plugin_name;

  var $_localization_domain;
  var $_localization_path;

  function %plugin_class%($plugin_name = '%plugin_name%') {
    $this->_plugin_name = $plugin_name;

    $this->_localization_domain = $plugin_name;
    $this->_localization_path = 'wp-content/plugins/' . $plugin_name;

    // You can add additional hooks and filters here.
    add_action('activate_' . $plugin_name . '/' . $plugin_name . '.php', array(&$this, 'OnActivation'));
    add_action('admin_menu', array(&$this, 'OnAdminMenu'));
}

  function OnAdminMenu() {
    load_plugin_textdomain($this->_localization_domain, $this->_localization_path);
    add_options_page(__('%plugin_name% Options', $this->_localization_domain), __('%plugin_name%', $this->_localization_domain), 'manage_options',$this->_plugin_name . '/' . $this->_plugin_name . '-options.php', array(&$this, 'OnDisplayOptions'));
  }

  function OnDisplayOptions() {
    $%plugin_class% = "";
    require( dirname(__FILE__) . '/' . $this->_plugin_name . '-options.php');
  }

  function OnActivation() {
    // This code is executed when the plugin is activated.
    // I prepend all my option names with $this->_plugin_name.
    add_option($this->_plugin_name . '_somevar', 'foo');
  }
}
?>

The code above requires that you create a %plugin_name%/%plugin_name%-options.php file to administrate the options. Here is the template for that file:

<?php
// Direct access is not allowed.
if (!isset($%plugin_class%)) {
  exit;
}                                                                                                                     

load_plugin_textdomain($%plugin_class%->_localization_domain, $%plugin_class%->_localization_path);

// Handle post action.
if ($_POST['stage'] == 'process') {
  // All the names of form variables start with %plugin_class%_plugin_name.
  if (isset($_POST[$%plugin_class%->_plugin_name . '_somevar'])) {
    // Do processing here.
  }
}

?>
<form method="post" action="">
  <input type="hidden" name="stage" value="process"/>
  <input type="text" name="<?php echo $%plugin_class%->_plugin_name . '_somevar'; ?>"/>
  <input type="submit" value="<?php _e('Submit', $%plugin_class%->_localization_domain); ?>"/>
</form>

The only thing that we still have to do is generate a po file with xgettext, translate it and compile a %plugin_name%/%plugin_name%-en_EN.mo file.

do_action('activate_' . trim( $_GET['plugin'] ));

So it appears that you simply have to use the path of your plugin relative to /wp-content/plugins. Eg: you have a plugin in /wp-content/plugins/wp-spamfilter/wp-spamfilter.php then you have to call add_action as following:

add_action('activate_wp-spamfilter/wp-spamfilter.php', 'somefunction');