Failing with grace and artistry

1 Jun 2007

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One of the problems I’ve always had with PHP error handling is catching the fatal errors. If a php script encounters a fatal error it stops, and the desired error handling code does not get executed.

So the user will (usually) be confronted with a blank screen and, worse still, since the error isn’t logged I don’t know about it and therefore can’t fix it.

It’s a rare and confident user who will report a blank page or other such glitch; people are so used to working with a certain level of pain when using a computer that they just assume it’s unavoidable or that it’s been caused by their own inadequacy in some way.

Anyway, (thank-you PHP London user group) I now have a solution using the register_shutdown_function()


// ... go and do all sorts of exciting stuff ...

$running = false;

function cleanExit() {
	if ($GLOBALS['running'])) {
		// script is still running - it's an ERROR
		// tell Bronwen about the error
		// tell user it's not their fault

Favourite error message of the week

11 Nov 2006


‘Subtitle – Study Programming and Learn New Things About Punctuation

This week, when running a Php script, I got the error message:

Parse error: syntax error, unexpected ')', expecting T_PAAMAYIM_NEKUDOTAYIM

After the “what!” reaction, I looked it up (remember, Google is your friend) and found that PAAMAYIM_NEKUDOTAYIM is Hebrew for a pair of colons.

It’s very nice that there is a word for a pair of colons (:: is used to access a static element of a class, so it can be used), but I feel that I am rather unlikely to use this term in casual conversation, or even in geeky programming-type conversations. I wonder if developers who have English as a second langauge have similar problems with the more standard and less esoteric error messages.

I’m also reminded, but not in a particularly nice way, of my first job where I wrote code for a Geac 9000 library computer in a language called ZOPL (ZOPL stands for “Version Z, Our Programming Language”). The guy who’d written the ZOPL compiler had obviously been a Pink Floyd fan and some of the error messages reflected this.

Debugging like snails

18 Oct 2006


‘My golden rule : Go slow. Don’t rush. Do one thing at a time.

On nuclear-powered subs, there’s a brass bar in front of the control panel for the power plant. When status alarms begin to go off, the engineers are trained to grab the brass bar with both hands and hold on until they’ve looked at all the dials and indicators, and understand exactly what’s going on in the system. What this does is help them overcome the temptation to start “fixing” things, throwing switches and opening valves. These quick fixes confuse the automatic recovery systems, bury the original fault beneath an onslaught of new conditions, and may cause a real, major disasters. It’s more effective to remember to do something (“Grab the bar!”) than to remember not to do something (“Don’t touch that dial!”)

Debugging: The Nine Indispensable Rules for Finding Even the Most Elusive Software and Hardware Problems

Click to activate and use this control

30 Apr 2006

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‘Microsoft has recently lost a patent dispute with Eolas Technologies, relating to “automated interactive experience” and the use of plug-ins in web browsers.

As a result Internet Explorer has been modified so users cannot directly interact with ActiveX controls which are loaded by via the APPLET, EMBED, or OBJECT elements. Instead the browser prompts users to “click to activate” before they can access the extra functionality.

This will affect any site which relies on a web-browser’s ability to automatically launch and display content via a plugin such as Flash. At the moment only Internet Explorer has been modified, but other browsers are going to have to follow its path.

Work Arounds
The updated browser only prompts users to activate object, embed and applet tags that are inline in an HTML file. So the webpages use tags which have been generated by external script files (like javascript), will continue to work normally with no change. So any page which is already using javascript to detect the flash plugin (most of mine) should be fine. Not sure how long this state of affairs will continue.

See Also

More fun and games with

23 Mar 2006


Starting to find my way around Asp.Net

I’m setting up a form for “forgotten password”. This is standard enough – give us your email address and we email you your password for the site.

This form has a single-line text input field (enter your email address here) and one button (Send Password). I want the button’s onsubmit event to be fired when if the user types in their email address and then (reasonably enough) presses the Enter key instead of groping for the mouse and clicking the big Send button. Works fine in Firefox, but not in IE. The form posts back, but I don’t get the OnSubmit event

Fix (and an excellent explanation) from the invaluable 4 Guys Obviously enough, I need to add another textbox – and since I don’t want another textbox I’ll make it invisible.

<asp:TextBox runat="server" style="visibility:hidden;display:none;" />

page_load doesn’t fire

22 Mar 2006


The Page_Load event in one of my pages was not firing – I eventually tracked this down to the InitializeComponent function (inside the “Web Form Designer generated code” block) The following line, which should have been automatically generated, was missing :

this.Load += new System.EventHandler(this.Page_Load);

The trouble is that I tend to stay away from the design view and work almost exclusively in the HTML view. And in making a new page, based on an existing one, this vital line was omitted. Much frustration.