Bloggy Hell

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Ok, after going away and thinking about the problem, I came up with a quick and dirty (But seemingly effective and compliant) way of doing the indenting. It does require a small modification to the GeSHi code. I’m going to use an empty inline tag (ins tag - which stands for insert - how appropriate…)
Open the geshi.php file (See my previous post about code highlighting in WordPress 2.0 if you have no idea what I’m talking about) and find the indent function. Search for all the nbsp elements and replace with:

Now open the insertcode.css file and the style.css (in your theme) and add:

Voila! indenting. The output looks like this:

A few more notes: html and xml highlighting is pretty well broken unless you add a erroneous space between the angle bracket and the tag (See this example) and don’t try to use special characters. I’m currently tweaking the colour coding classes to make them look nicer too. I’ll post these when they are done.

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I have complained before about not being able to insert source code into WordPress when using the TinyMCE Rich Text Editor. Sure, I could switch to plain text mode, but frankly I would prefer an RTE as it makes entering posts much quicker. There is a TinyMCE plugin called insertcode written by by Maxime Lardenois which does exactly what I wanted. In fact, it even uses the GeSHI cde highlighter class (written in PHP) to do code highlighting. There is something like 50 different languages which are supported - Very cool.

Unfortunately, installation was not quite as simple as I hoped. Here is what I had to do (Substitute [blog_root] with the absolute path to your wordpress install):

1. Untar the GeSHI tarball and copy the geshi.php files and geshi directory to [blog_root]/wp-includes
2. Unrar (yes rar) the insertcode RAR file to [blog_root]/wp-includes/js/tinymce/plugins/insertcode (Create the insertcode directory first)
3. THe RAR file I go didn’t have a directory structure - I don’t know whether I just messed up or what, but I had to create the following directories: config, css, images, jscripts, langs, webservice
4. Copy config.php into the config directory, insertcode.css into the css directory, insertcode.gif into the images directory, insertcode.js into the jscripts directory all the php files into the webservice directory and all of the language files (e.g. en.js) into the langs directory. You should only have editor_plugin.js editor_plugin_src.js and insertcode.htm files in the insertcode dir.
5. Open get_highlighted_code.php and change the $geshi->set_header_type(GESHI_HEADER_PRE) to $geshi->set_header_type(GESHI_HEADER_DIV)
6. Open [blog_root]/wp-includes/js/tinymce/tiny_mce.gzip.php and find the line $plugins = apply_filters - add ‘insertcode’ to the array
7. Still in tiny_mce.gzip.php add ‘insertcode’ to the line that starts with $mce_buttons = apply_filters
8. Finally add the following to lines to the initArray javascript array:

content_css : “/[blog_url_path]/wp-includes/js/tinymce/plugins/insertcode/css/insertcode.css”,
encoding : “xhtml”,
This should add a new button to your toolbar with the letter “C” into. Pressing the button should pop a dialog box in which you can cut and paste code.

To make it look nice on the front end cut and paste the contents of insertcode.css into you themes’ style.css file:

That SHOULD be it.

You will notice that the indentation gets stripped - this is (I think) a Wordpress thing. I’ll post a solution once I figure one out Also, it can be a little tempermental - you have been warned. And as always: YMMV.

Edit: I’ve fixed the indent bug: check out this post.

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There is a fairly good chance that all but the most trivial dynamic sites will use sessions to emulate a stateful environment. Before the creation of sessions, the developer would have to manually pass all of the variables the next page needed via hidden input fields or cookies. As you can imagine, this is a bit of a security risk. Not to mention that cookies are limited to 4k each - if you have a large number of variables, this can quickly run out.

PHP, like most server languages can handle your sessions for you - but how does PHP keep track of sessions? There are two ways - using cookies and hidden fields. The former is the preferred way as it is easiest and is more secure (But not with out it’s risks. Check out the PHP session documentation for more info on the safe use of session variables). PHP writes a cookie which holds the PHPSESSID variable. It looks for this value when start_session() is called and if it exists, matches it to the stored session. But what happens when cookies aren’t available or are turned off? PHP is smart enough to work this out and will re-write all links and forms on the fly to ensure that the PHPSESSID is passed on every action that will refresh the page.

Well, almost. When I code, I prefer to postback to the same page, do some processing (such as error validation and storing of required session variables) and then use header(”Location: “) to re-direct the user. This makes coding much easier because all of the business logic for that page is kept in one file. Unfortunately, PHP isn’t smart enough to re-write these redirect, so we will have to help it out a bit.

append_sid

The following function will look at a URL (Whether it be relative or absolute) and append the SID if and only if PHP is in cookieless mode. I couldn’t find a PHP function that will tell you whether cookies are working, however after a bit of thought it was quite easy. PHP has a super-global called $_COOKIES. In this super-global, the PHPSESSID variable is referrenced. By checking whether it exists (After a call to session_start) we can work out whether we are in cookie or cookie-less mode:

function append_sid($link) {
    if(session_id() !== NULL && !isset($_COOKIE['PHPSESSID'])) {
        if(strpos($link, "?") === FALSE) {
            return $link . "?PHPSESSID=" . session_id();
        } else {
            return $link . "&PHPSESSID=" . session_id();
        }
    } else {
        return $link;
    }
}

Basically what happens, if the function checks to see if the session has been started - if it has, it then checks if the cookie entry exists. If it does, it just returns the link unchanged, otherwise it appends the session id. The inner most if statement checks for a ‘?’. If it exists, we can assume that the link already has some get parameters, so we will append the PHPSESSID using an ‘&’. Otherwise, just append it with a ‘?’.

JavaScript

Don’t forget that if you are re-directing client using javascript or using sessions when making AJAX calls you need to pass the session id as well. The best way to do that is client side, especically if you are generating parameters on the fly. The same theory applies, except we will use JavaScript this time:

function append_sid(link) {
    < ?php if(session_id() !== NULL && !isset($_COOKIE['PHPSESSID'])) { ?>
        var session_id = '< ?php echo session_id ?>';
            if(link.indexOf('?') == -1) {
                return link + '?PHPSESSID=' + session_id;
            } else {
                return link + '&amp;PHPSESSID=' + session_id;
           }
    < ?php } else { ?>
        return link;
    < ?php } ?>
}

The reason there is PHP code interleaved (I know. I hate it too) is because we need to work out whether the session has actually been started and we need the session_id. However, we don’t want to display the session id UNLESS there is a requirement for it as it can be a security risk.

A caveat - passing session id by URL requires the session.session.use_trans_sid tio be set to 1. Most shared hosts turn this off, but you can usually override it by putting:

ini_set('session.use_trans_sid', '1')

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I quick entry today, as I really should be working.

I came across a PHP MVC (Model/View/Controller) framework for PHP 5 - You can think of it as the Rails bit of Ruby on Rails. It is this sort of stuff that will continue to push PHP into the spotlight and allow it to compete with the big boys…

It is called Agavi PHP MVC Framework

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I was going thorugh the posts from my old, now-defunct blog, seeing if there was anything I could bring over here — it is amazing how much can change in a year. There was an article I wrote about over use of cool techniques. In that article, I made mention to some new fangled technique called “Design Patterns”. At that point, I had no idea what they were and frankly couldn’t care.

Well, after being forced to look at them more closely for a uni assignment, I’m kind of a little hooked.

Design patterns are abstract solutions to common problems. Huh? Yeah, that is what I said. Many programmers strive towards code re-use. Design Patterns encourage thought re-use. Why re-invent the wheel? And because they are abstract (i.e. no code), they can be “ported” to different languages easily.

The Gang of Four introduced 23 of the things. They have put the challenge out for the discovery of more, and they haven’t been too successful as it is believed that almost all problems can be broken down to fit a composition of these rules.

To implement many of these design patterns correctly, you really need OOP features such as Abstraction and Interfacing. As I have pointed out many times, PHP4 doesn’t have these. PHP5 does. However! if you think about it, you can still use design patterns in PHP4 — you just need to be a little bit careful.

I won’t go through ever design pattern just now, but, I’ll outline one, and maybe add to them in the future. [By the way — an awesome book to use for getting your head around design patterns is “Head First Design Patterns” — look it up on Amazon]

The Stategy Pattern

Programmers often get into the habit of extending classes to change functionality — maybe because it is the easiest OOP function to understand. It can lead to problems though when you need to change implementations in a base class. I’ll use an example from a system I was writing the other day: the ubiquitous PHP email sender. The job I was doing required two types of email to be sent — a run-of-the-mill text email and a text email with an attachment.

Because I’m always trying to build my code libraries up, I decided to create set of classes that will do the job. Now, pre-design patterns, something like this may have happened:

Nothing wrong so far, but what happens if we want to add a HTML email? We could probably add another class below the attachments, because the HTML component is an attachment I guess, so we add the HTML file as one of the attachments at design time. This isn’t a great solution though, because one of the necessary bits to a HTML email is the HTML content, and you could theoretically remove it. How about we add another variable specifically for the HTML copy? That would also work, but what if the client decided that they wanted to select between HTML and text emails dynamically at run time? You would end up with something like this code wise:

switch($mailType) {
case “text”:
$email->setBody($text);
break;
case “html”:
$email->setHTMLBody($htmlText);
break;
}

(This is a bit of a contrived example, so run with me here)

now what happens if you want to add another type of email? You have to modify the case statement and test the whole thing all over again. Everyone hates testing - especially code that you know used to work that you had to change. Two keywords: CHANGE and TESTING. Minimise both and we as programmers are happy.

Now my solution was to create a class that has everything an email needs - To, From , Subject and a repository for headers (Plus a few other bits and pieces, which I won’t mention to reduce clutter). It also has a function called send(). Wow, ground breaking. Where the design gets a little strange, is there is another variable, called $emailType. This variable stores reference to a class of type EmailType (Well it pretends to, PHP4 doesn’t support interfaces). So, any class that implements EmailType can be stored in that variable. One of the abstract classes (again, let’s pretend it is abstract, PHP4 won’t understand) is the createMessage() function. This is where the magic occurs…

Each class that implements that interface know exaclty how it message needs to be contructed. The base email class doesn’t care - as long as it gets a string to tack on to the email it is happy. The creation of messages is de-coupled, meaning you can create a new email class without changing any exisiting code (As long as it implements the interface correctly).

This is an implementation of the strategy pattern!

Formal Description [Ganf of Four]: The strategy pattern defines a family of algorithms, encapsulates each one, and makes them interchangable. Strategy lets the algorithm vary independently from clients that use it.

Which is what we just did… More on design patterns later.