Dominic Sayers

HOWTO: Fix problems with Firefox extensions

I have been having problems with a Firefox extension that disappeared whenever I upgraded either Firefox or the extension itself. My specific problem was with an extension called Firebug, but I'm betting this affects other add-ons too. After extensive searching I eventually came up with an answer that worked for me. I'm posting it here so other people might avoid the hot tears of frustration that I cried trying to fix this.

The symptom

You choose a Firefox extension by clicking on the install link, the extension downloads and installs. You click the button to restart Firefox and the extension is simply not there. No error message, no indication why it failed. Just stubborn, passive-aggressive refusal to install. Arms folded, lips pursed, the extension just won't do what you want. Gah.

The solution

Yes, it's the old favourite - your virus checker. In my case all I had to do was open the AVG Anti-Virus control panel, double-click Resident Shield and unclick the "Resident Shield active" checkbox. Click on Save Changes. Then if you repeat the Firefox estension install you should find it installs OK. Don't forget to turn your virus checker back on afterwards.

Email address validation 1.0

Quick links: Source code | Email address validators head-to-head

OK, after some correspondence with Dave Child and Cal Henderson I have now released version 1.0 of my PHP email address validator. This version passes all 139 unit tests in the suite - tests I have collated from RFC 3696 and from articles by Dave Child, Doug Lovell and Phil Haack plus some of my own to test the IPv6 address format. The full analysis is on my website and the latest version of the source code will always be in Google Code. I would really appreciate it if you find a valid address that fails my validator, or an invalid one that passes, if you would get in touch with me and let me know. Here are the scores on the doors: Dominic Sayers: 100% validated correctly Simon Slick: 86% Dave Child: 81% Phil Haack: 79% Cal Henderson: 71% For the RFC nerds, this version now correctly validates the obsolete local form of word *("." word). In other words you can regard the local part of the address as a dot-delimited series of elements each of which can be separately quoted. This means that first."last"@example.com is now recognised as a valid address.

Quick links: Source code | Email address validators head-to-head

Email validation head-to-head

Quick links: Source code | Email address validators head-to-head

I've discovered a number of other public-domain functions that attempt to validate the format of an email address. I tried to validate my 124 test cases against these functions with the results below: Dominic Sayers: 100% correctly validated Simon Slick: 88%  Dave Child: 80% Cal Henderson: 72% Interestingly, all the other functions failed correctly to validate the example addresses given in RFC3696 (Section 3: Restrictions on email addresses). I couldn't include Doug Lovell's function in my tests because the code is copyright All Rights Reserved by Linux Journal (ironically). Some of the other functions also supply test cases; I've added these to my test suite. More analysis and commentary here: RFC-compliant email address validator. In summary, I recommend you use my function if you want totally RFC-compliant address validation.

Quick links: Source code | Email address validators head-to-head

Domain name geekery

If you're not technical, there's nothing to see here. Move along please. OK, I'm writing an email address validation function. Why? Because everybody else has and why should I be different? The catch is, I'm trying to make it RFC-compliant rather than use the same noddy regular expressions everybody else does. Ask me anything you like about RFCs 1035, 2396, 3696, 4291, 4343, 5321 & 5322. Go on. Try this one: RFC 1035 says the following:

The labels must follow the rules for ARPANET host names.  They must
start with a letter, end with a letter or digit, and have as interior
characters only letters, digits, and hyphen.

(A label is a component of a domain name, i.e. the "example" in example.com) So is 3com.com a valid domain name? No? Somebody should tell them.

Firefox "problem" turns out to be Dominic problem

Big thanks to Sig for helping me out with my Firefox CSS issue. He was dead right - it was a MIME issue that was easily fixed by setting the MIME type to text/css in the header of the dynamic CSS.

More details here: Generating Dynamic CSS with PHP

I've left the demonstration in place here: Dynamic CSS MIME demonstration but adjusted the text to make it clear I was at fault, not the browser. Why do the other browsers behave differently? Well the CSS was returned to the page within an element of the page's header that declared the contents to be text/css so it was fairly easy for a "smart" browser to guess my intention. And also quite easy for me to make the fatal assumption that that was enough. We live and learn. And Firefox is a strict mistress.

Eyebrow-raising Firefox problem

I've come across a problem with a website I'm developing. My nifty code works fine for all browsers except Firefox. Yes, that's right - Firefox fails to render the page as intended but Chrome, Internet Explorer, Safari and Opera all work fine. I've put a demonstration of the problem here. I'm surprised that Firefox behaves so differently from other browsers. We all know which browsers we think are non-standards-compliant. If I'd been posting this about an Internet Explorer behaviour then I wouldn't have expected any surprise or sympathy. But Firefox. I'm getting cramp in my eyebrows - they've been permanently raised since I discovered this. I'm hoping there's a way I can code round the problem. The latest version of Firefox (3.0.2) still exhibits this odd behaviour.

Where should where I go go?

Dopplr or TripIt? All the cool kids use Dopplr. Blackbelt Jones is a team member and I am a fan. On the other hand, I can just forward my email confirmations to TripIt and it does everything for me! 1-0 to TripIt at the moment*. * Except my emails from Monarch Airlines, Thomsonfly and National Express East Coast weren't recognised. So maybe 0.5-0

Stephen Fry technology videos

Just a link you might be interested in: http://www.videojug.com/tag/stephen-fry Six videos featuring Stephen Fry pontificating on technology and learning and stuff.

The next layer, and the 64-bit tipping point.

2008 is a hard deadline for the adoption of 64-bit computing, according to Eric S. Raymond (author of The Cathedral and the Bazaar). He made this claim in 2006 based on historical trends of memory use by personal computers. As far as I know, there is no reason why this could not be come to pass - next year you will be buying a 64-bit processor and more than 4GB of RAM in your personal computer. It's never been easy to predict in advance what triggers the need for this extra horsepower, but in the past it has been the addition of layers of software underneath whatever programming language that software developers were using. If you're writing in assembler for a particular processor then you can squeeze a lot of functionality and performance into quite a small space, but your application won't run on anybody else's processor and won't be able to use a wide range of peripherals. When you start to abstract those incompatibilities away, that's what starts to slow down your application and make it consume lots of memory. What's the next layer of abstraction that will push us over into the 64-bit world? Joel Spolsky thinks he has identified it: in his Strategy Letter VI he writes about a hypothetical application platform that will let you forget about the incompatibilities between different browsers' interpretation of Cascading Style Sheets and their different object models. Moreover it will let you forget about different ways of publishing your online status and journal (Facebook or Twitter? Who cares? I publish to all of them). For me, it's one of those eye-opening articles that makes the world seem like a slightly different place. GMail is today's Wordperfect? Obvious when you think about it.

And while you’re not paying attention, everybody starts writing NewSDK apps, and they’re really good, and suddenly businesses ONLY want NewSDK apps, and all those old-school Plain Ajax apps look pathetic and won’t cut and paste and mash and sync and play drums nicely with one another. And Gmail becomes a legacy. The WordPerfect of Email. And you’ll tell your children how excited you were to get 2GB to store email, and they’ll laugh at you. Their nail polish has more than 2GB.

Somebody must be working on this application platform, surely? Any ideas who? And when can I play with it?

Fanboys

It's a waste of time having emotions about technology. It sure as hell won't love you back. Not yet anyway.