What is the Dependency Injection Container (DIC)?

If you’re coding for the web, you almost certainly have encountered frameworks that make use of the Dependency Injection Container. Incredibly useful – but what is it?

In the most simplistic way – it’s just a great big bag of stuff. That’s it. There’s nothing magical about the container, it’s simply an object that stores references to other objects. Combined with a liberal use of Interfaces, this allows for a high level of abstraction and therefore also aids in unit testing smaller code parts.

For example, if you’re injecting the entire DIC into a component, you are metaphorically handing that component a great big bag of stuff and saying “here’s what we have to work with. Ask for it by name.” The component may then access the container and all configured dependencies.

You may well now be saying “well that sounds a bit like code soup” – and you’d be right. Normally, you’d only inject the dependencies that a component requires (and not the whole bag). The major frameworks (e.g. Laravel, Symfony, Zend) feature Dependency Injection Containers and an associated service locator and dependency manager. These are no longer simply “great big bags of stuff“, but true DI systems that allow for a high level of abstraction.

For a super simple Dependency Injection Container, see Pimple (by Sensio Labs). This is a great place to get started with understanding how a system will utilise a DIC. It is super simple, and forces you to understand how things are bootstrapped and provided for your system.

For more detailed information on dependency injection, see these links:

Features image (with modifications):
Coffee Bag W” by DaveBleasdale. Licensed under CC BY 2.0

Installing Intl on PHP and MAMP

Compiling the Intl extension for PHP under MAMP is actually quite simple. I explain how and include a few solutions to “gotcha” problems along the way.

If needed, download the relevant ICU package, and extract it. Ensure your MAMP PHP binary is in your $PATH environment string. Snippet from StackOverflow:

Opening a Terminal to the extracted directory, I then compiled the code:

As I did not have autoconf, I installed it using Brew. Alternatively, you can compile it from source if you do not have Brew.

The next few steps are where I had some problems. I was getting strange errors:

fatal error: 'php.h' file not found
"ERROR: `phpize' failed"

Digging around, it turns out there’s a bit of a strange bug here. It can be quite simply solved by downloading/updating XCode from the App Store and symlinking the XCode SDK headers to the MAMP directory:

After this, simply install Intl using PECL:

If you’ve downloaded and installed XCode just now, you may get the error:

This is simply a MacOSX/XCode licensing issue. You can solve it by launching XCode or just typing:

to trigger the licence terms and agreements prompts. Afterwards, run the pecl install command again to install the extension.

Once that’s done, add the extension to your PHP config. In MAMP, this can be found under File > Edit Template > PHP > PHP 5.6.10. Add extension=intl.so to the list of loaded extensions.

MAMP should be restarted for this to take effect.

If you have any comments/questions, please leave them below!

Updates and Other News

Wow, that was a long hiatus, wasn’t it?

I don’t always plan what I’m going to write about. Usually I just plod along in my daily grind and problems present themselves. I spend time figuring out what’s going on, and if the solution is somewhat weird, I try to explain why I thought so.

In the last twelve months or so, I’ve taken up residence at a Berlin startup called Arzttermine.de. They specialise in taking appointments for doctors online. It also lets me forget about agency work for a while and instead focus on developing a single piece of software.

…Aaand still here we are. The problem with the platform we had was that it was… old. It was built in about 14(!) days from scratch using a very old (scratch-built) CMS platform. A miracle by any stretch of investor imagination. After number of, let’s say, less-than-qualified contractors worked on it, it became a staggeringly bloated mess full of untestable spaghetti-code.

At the moment, it feels like I’m poking my head up from underwater, as the codebase is somewhat refactored and new features can be developed again without big if/else blocks wrapping method calls. I wish I worked on something interesting in the last twelve months. I like breaking down my problems into dumb little pieces and then explaining it online. I’ve been told more than a few times that my posts are helpful, and that is amazing to know.

Due to this lack of work-related creativity, I’ve started producing trite little YouTube videos that some people appear to like. If this is your thing, give it a quick look and say hi. If it isn’t, well come to Twitter and say hi anyway. I welcome the distraction from work.

– Neill

Save Snapchat files (Android) – Part 2

SnapchatTake the headache out of saving your Snapchat files from Part 1 by automating the entire process using Tasker.

Edit: This post is now obsolete! Snapchat have upgraded their app, and since the time of writing, many free apps have appeared on the Google Play and Apple App Stores.

In the previous instalment, we set up our rooted device to save Snapchat files using a handy little script. Although this works, it’s quite tedious to repeatedly have to call the script whenever you receive a snap. To save ourselves some time, we’re going to set up our script to run automatically using Tasker.

What you’ll need

Set up
I recommend reading through this guide before starting. The process is rather long but quite simple.

  1. Open up Tasker. Click “+” to create a new Task and select the “Application” context option. Find Snapchat from the list and tap to select it. Click “App selection” in the corner to go back to the main screen once that’s selected.
  2. Now that we have a context specified, we need to tell Tasker what to do when the app launches. Click “New Task” to open up the task creator, then click “+” to add an action.

  3. From the popup, select “Plugin” from the list of available actions, then choose Secure Settings.
  4. We now need to configure exactly what our Secure Settings action is doing. Click “Edit”, then find “Run Command”. On the “Run Command” configuration screen, enter the path of your script from part 1. In my example, this is /data/snapchat.sh. Note: I’ve since updated the path due to some people having difficulties with /etc.

    DO NOT FORGET to check the box labelled “Use Root”, as this is responsible for ensuring that the script runs with the proper permissions (and actually does something). Also, I like to enable “Show Notification” so I know that the action is running.

    After naming the action, you can save your configuration by clicking the save icon (bottom left) or by tapping the “Run Command”/back header in the top corner and selecting the save option from the popup dialog.

  5. Click the headers in the corner to go back to the main screen. This will also serve to save your changes. Once this is done, you should be able to boot up Snapchat for a test run.

If you didn’t run into any trouble throughout the guide, Snapchat should now trigger your script, saving any downloaded snaps to your specified directory.

There is some weird behaviour that may pop up when using the script/Tasker combo. Here are some things I’ve encountered during my time with the script and how to work around them.

  • The script is not saving snaps
    This is either because 1) the script is faulty; or 2) Snapchat has not downloaded your files. As there is occasionally a delay, I like to load Snapchat, wait for the files to load, then check my gallery for the files. The usual culprit is poor phone reception.
  • The saved snaps are not showing in the gallery
    This is the most annoying “bug” that I encounter. Android caches the thumbnails for the gallery, and the script bypasses any media refresh hooks. You can manually refresh the gallery by rebooting the phone, taking a photo, or use an app. I used SD Card Rescan and it works amazingly. It can take a while to scan fully, depending on the size of your card, so bear that in mind.
    Due to the nature of the script, it is very indiscriminate when it comes to saving files. It will always attempt to save whatever it finds, duplicate or not. I just delete them.

These are the three main things I run into regularly. I’m happy to investigate any other weird things posted to the comments.

Hopefully this guide made sense, and you are now happily (read: sneakily) saving your incoming Snapchats. Feel free to leave a note below if this worked/did not work for you.

Happy snapping!

Get the topmost category in WordPress

If you’re using WordPress, here’s a quick snippet of code to get the oldest ancestor (topmost parent) of a category or subcategory.

This can just go in functions.php.

The only caveat to the snippet is that it will always return only a single category, so if that’s not a problem, you should be fine.

Save Snapchat files (Android) – Part 1

SnapchatIf you’re using Snapchat, chances are you want to save some of the pictures and/or videos you receive. Now you can.

Edit: This post is now obsolete! Snapchat have upgraded their app, and since the time of writing, many free apps have appeared on the Google Play and Apple App Stores.

I should start with a preface: You probably shouldn’t do this. Half the fun of Snapchat is knowing it’s a one-off, and there’s a sort of “honour among thieves” type of policy between users. That being said, I do like a challenge, even if a solution does make me look creepy.

What you’ll need

  1. I assume that if you’re reading this, you have Snapchat. If you don’t, you can grab it from one of the links on their website.
  2. An Android phone. So far, this solution only applies to Android. I’m currently playing around with a solution for Apple devices.
  3. A rooted phone. I probably haven’t thought hard enough about the problem, but from what I can tell, you need to have root access for this to work.
  4. The most useful tool of all – a Terminal Emulator. There are heaps of apps out there for changing permissions and fiddling with the filesystem, but nothing is better than the ol’ terminal.

The Script

Most of what does the work is inside this shell script:

When executed (before viewing anything), the script checks the two storage locations for Snapchat (images and video), loop through the list of files, and copies the data to a safe location (a place the app can’t touch). The unusual part of the script is the use of the cat command, which we need due to some filesystem limitations within Android. Also, keep in mind that the paths above are for my device (Samsung Galaxy SIII, running Jelly Bean 4.1). You may need to update them if the script is returning errors.

Setting up the script

If you are Unix-savvy, you probably already know how to do this. You can jump down to the “how-to” section below for some notes.

If you’re a little Unix-rusty, here’s what you need to do to get this script working.

  1. First, copy/paste the script above into a new text file. Save it as whatever you like and add the extension .sh. I called mine snapchat.sh.
  2. Transfer the script onto your phone using Android File Transfer (Mac) or just in Explorer (Windows). I usually just stick it in the sdcard’s “Downloads” folder. It actually doesn’t matter, as this location is temporary anyway.
  3. Open the Terminal Emulator. First switch to the root user by running the su command.

    Then, make the internal system writable by running:

    If this step isn’t working, you can try this app instead. It’s what I use, as it offers a one-click solution.

  4. Now that you’re root, we need to move the script to a place on the system to allow us to execute it without any permission errors. Thanks to an Android limitation, this will need to be done using cat. Note: Some people appeared to be having problems copying to /etc. I’m now using /data instead to avoid any difficulties. Everything except the path is the same.

    This outputs the contents of the script into a new copy located in /data. Feel free to change this location to basically anything on the phone’s internal storage.

  5. Remove the temporary copy of the script (not essential, just tidy):

  6. Once this is done, navigate to the folder you copied the script into (on the phone’s storage), and add execute permissions using chmod.

  7. All that’s left is a bit of cleanup:

    This will remount the internal storage as read-only (as it was before).

As far as set-up is concerned, that’s (thankfully) it!

How to

Now for the best part – saving files. You will need to use Terminal Emulator (or equivalent) to do this. Be aware that you need to use su, otherwise the script won’t find the files due to permission restrictions.

  1. “Snap received!”
  2. Open Snapchat and wait until your snaps are loaded. Do not open them. I can’t stress this enough. If you open them, the script will not find them.
  3. Jump to your Terminal Emulator and run:

    This will execute the script and tell you what it does (as it’s doing it).

  4. Once that’s complete (assuming no errors), you can view your snaps as normal. A copy should have been made in the location specified by the script (in my example, this is /storage/extSdCard/snapchat/)

And that’s all there is to it! Unfortunately, this process needs to be repeated every time new snaps come in. However, in part 2, we’ll be automating the whole process using Tasker, meaning that once you open the app, your files are saved. Very sneaky.

Update: Part 2 is now available!

Note: Feel free to add comments/suggestions or point out errors in the comments section below. I will be maintaining this post.

Remove extra RSS feeds in WordPress

Here’s a WordPress snippet to remove RSS feeds for comments while keeping the main one available.

RSS Icon

RSS is super nifty. It’s a great way to keep on top of breaking news and articles from your favourite blogs and/or aggregators (I’ve got over 100 subscriptions in my feedly reader).

So it’s a wonder then that WordPress offers RSS feeds for comments on all your posts. I presume there’s a group of people who really like to track conversations, but in my experience, it’s the minority. This functionality should really be an additional (and not core) part of WordPress. If you want to prevent your site serving pointless additional RSS feeds, you’ll need to remove them from wp_head.

Removing them, however, is a two-step process. Add the following to your functions.php file:

And that’s it. The first two actions strip the RSS using remove_action with a high priority. The final add_action call tells WordPress to load our function when processing wp_head. This will go through and reinsert the main feed, leaving the comment feed out.

Congratulations! Your post conversations are now untrackable.

WordPress: Add page slug to body class (including parents!)

Are you using WordPress as a CMS? Do you want to style pages with CSS logically? You might want to try this.

By default, WordPress will inject the page and its ID into the body class. That’s great if you’re only running a single install, or if you really really don’t care what your CSS looks like.

Let’s face it – you care. Otherwise, you wouldn’t be here. Here’s a snippet that will inject the current page’s slug and all slugs of its parents into the body class of your HTML.

Add this to functions.php

And that’s it! You can then start chaining together page classes to target little overrides that your clients are probably hassling you about.

Help! register_activation_hook isn’t working!

If you’re developing a plugin, chances are you’ve been caught out by the WordPress activation/deactivation hooks.

I’ve been working on an Instagram plugin for WordPress, and in doing so have needed to use the functions register_activation_hook and register_deactivation_hook.

However, I – like many others, it seems – can’t get the hooked functions to execute. They simply don’t fire. To illustrate the problem, here’s an example from the code:

I would fully expect the system to execute the functions hooked within the constructor. Had that been the case, I wouldn’t have lost a day debugging a non-existant problem.

Finding a solution

Of course, everyone’s setup is different. There were many suggestions for fixing the problem. For the sake of usefulness, here’s the other major suggestion:

Your global variables aren’t global

If (like me), your plugin is a global, you actually need to explicitly define it as such with the global keyword. For example, the snippet

should instead by written this way:

Why? Well, for this, we need to consider how the plugin has its code loaded. After installation, your plugin has its code included “normally” with standard includes. This creates the global scope that you would expect. However, when you register a function with register_(de)activation_hook, it is called from within another function’s scope, effectively hiding your non-explicit globals.

Confused? Consider the plugin example from earlier. The variable $my_instagram is declared in the global scope, with global visibility. When your code executes, your plugin is included at the same scope, meaning you will have access to the variable (as they share the same suitably-high scope). Due to the way the hook/filter system in WordPress works, your activation/deactivation hooks are executed within a localised (not global) scope.

Screen beans - the only thing worse than scope.
Screen beans – the only thing worse than scope.

This scope-confusion applies to all functions created using create_function, or (in our specific example), functions called with call_user_func (and call_user_func_array). These functions have their own scope and are thus shielded from the cheap-and-nasty pile of implicit “globals” that haven’t been properly declared as such.

You can find a suitably more technical (and probably correct) write-up at the WordPress Codex page for register_activation_hook.

tl;dr: Explicitly declare your globals if you want them to work everywhere.

Ok, that’s great, but what’s the answer?

After having accidentally (and rather unwillingly) been given a very rough refresher on scope, I found that this was not my problem at all. Even running proxy functions (which eliminates scope issues) failed to call the functions specified in the hook.

After much trial and error (and I mean much), I found that the paths within register_(de)activation_hook were not matching the path found in plugin_dir_path. In fact, __FILE__ was returning a completely different path.

The problem? I had symlinked the theme directory in my install, meaning that __FILE__ returned a different path to plugin_dir_path. This is especially important, as the file path specified by the first parameter of register_(de)activation_hook is included before the function specified by the second parameter is called. So, if the path in the first parameter is wrong, you probably aren’t going to be executing many functions today.

The Fix

This is always my favourite part. To fix the symlinking problem, you just have to be very specific when you’re asking WordPress to execute a hook for you.

Fixing the first example, we get:

The most important changes occur on lines 1, 16, and 17. The first line fixes the definition by manually specifying the path using the base plugin directory (instead of an automagic WordPress search). Lines 16 and 17 specify the main plugin file itself as the path (instead of relying on __FILE__).

This allowed WordPress to find the plugin files without a hitch, which is especially important in the installation/uninstallation phases.

Moral of the story? Check your paths first.


LinkedIn – Lesson #1

My battle against recruiters continues with a strange and random request from LinkedIn.

I consider rejecting unsolicited LinkedIn mail my sisyphean punishment for some mysterious crime I did not commit. An ever-present tide of human ignorance washing against the grainy shore of my day, snuffing out what little hope I had left that the entire population was not – at some fundamental level – simply a dipshit.

It is no wonder, then, that I grew weary of replying to people who couldn’t do their job. The ever-persistent advance of this multi-headed hydra was eroding my enthusiasm for being a twat. Apathy was winning.

Another day, another email, and I replied with a terse “contact the manager”. A little while later, I was surprised to find the following response:

> Who is the GM?

Now, I’m no expert on LinkedIn (hell, I rarely venture from my own profile), but I certainly know how to click a link when I see one. Several, in fact. Sometimes in a row. So when the information you’re after is fewer clicks away than finding your inbox, you should probably just take the easier option. But if this is something you need to be told, I guess there is probably a greater concern here, right?

Instead of giving him a real answer, I decided to be a complete dick about it and go ahead and create this handy little video tutorial. Take note, LinkedIn trawlers.

I think my passion has returned.