Today I came across this excellent analogy by a gentleman named "DavidWolfire" describing the initialisation, use and discarding of dynamically-allocated memory in C-like languages.
It stemmed from a question that had been interpreted to request a way to destruct a dynamically-allocated object and completely zero-out the memory underneath it, without actually losing the allocation itself.
Here it is:
If you call delete(ptr[5]), it is telling the OS that you no longer need the memory pointed to by ptr[5]. However! delete() will not re-initialize that memory for you. You can think of it like a sand castle — when you call new(), you draw a square on the beach to mark off the area you will use for your castle. Inside the square, the sand starts out in some random state, all lumpy with footprints from everyone else walking all over the beach. Then you use a constructor or initializer to shape the memory, forming your sand castle. Since you have your lines drawn in the sand, everyone else avoids your sand castle, and only you are allowed to touch it.
When you call delete(), you erase the lines in the sand. Your sand castle is still there, and you can still point to it, but it is no longer marked as off limits for others. Eventually people will start walking through it and claiming that sand for themselves, and moving pieces of your castle around to make their own. You can still point to the spot your castle used to be at, but your castle may or may not still be there — it could also contain bits and pieces of random castles created by other people.
In this metaphor, your question would be "How do I make my sand castle perfectly flat when I'm done with it?"
The tap in my bathroom sink had been getting rather "sticky" of late. I don't mean sticky to the touch on the exterior, but as a mixer tap its vertical movements were no longer smooth and thus controlling water flow had become difficult. This condition had been deteriorating over the last year or so, and I decided that now would be a great time to do something about it.
I rent an apartment and have little to no documentation of the major fittings, though there is a pack of assembly instructions for a few furnishings hidden away at the back of one of the kitchen draws, enough to identify my tap as a "Mixer Tap with Pop-up Waste" from Bristan's "Matrix" range.
(Apparently the unit is also sold under the Vado name, and pop-up waste means that there is a push/pull lever at the rear of the assembly for raising and lowering the plug.)
The web contains a few descriptions of how to change the "cartridge" (the actual interior mixer mechanism) for various models, but I had little joy trying to find specific instructions for this model, and was less than keen to play around blindly. A water leak or broken tap is the last thing I need, and I'd have a hard time explaining to my landlord how such a thing could have happened without my direct intervention.
Disliking the phone in general, I emailed Bristan's customer service directly:
I have a Bristan Matrix Mixer Tap with pop-up waste (see attached image) and no idea how to service it. The handle no longer moves "smoothly", which I attribute to a build-up of debris and/or limescale on the inside of the mechanism. I have been unable to find detailed instructions on how to disassemble, clean then re-assemble the tap.
Can you advise?
Experience tells me that companies tend not to respond to such specific inquiries, especially for models that do not appear to be sold any longer, when plumber-level documentation is already available on their website for similar units.
I knew that at the very least, having sent my message late on Friday, I'd have to wait until at least Monday to receive nothing back.
Come Monday, before 10am, imagine my surprise…
Good Morning Tom,
Thank you for your email.
Please find attached an exploded spares diagram for your Matrix tap which I hope will assist you in disassembling your product. As you will see, there is a small grub screw located beneath the blue & red indice (which will prise out). This will be removed usually with an allan key and then the handle will lift away from the tap.
The shroud beneath the handle will unscrew to reveal the cartridge beneath.
Please do not hesitate to contact us should you require any further assistance.
Well, how about that! The key to the whole endeavour was the new certainty that the blue/red "indice" would "prise out"; I'd suspected this but didn't want to go stick screwdrivers in things unless I was sure.
So now, armed with an IKEA "FIXA" toolkit (plus random Stanley knife I acquired somewhere along the way) and Bristan's diagram for reference and peace of mind, I was ready to go.
First thing's first, though; from my original web browsing I'd discovered the easiest way to safe the sink — isolate the water supply to the taps, leaving other supplies in the flat enabled so that I could still use them to clean individual components as I went along.
One half-turn of the screw on the hot water pipe then the same on the adjacent cold water pipe behind the sink is enough — when horizontal the water is cut-off, and when vertical it flows. This made it easy to discover which screw to turn, as I would have been uncomfortable turning any of them more than a few rotations during my guesswork for fear of springing a nice big leak in the pipework.
Checking that there were no evident leaks anywhere — I didn't want a nasty surprise when moving on to pulling various components out of the assembly — I prised out the "indice", which actually popped out quite easily with help from a strong fingernail, and found a tiny grub screw barely visible behind it as promised.
It was quite far behind the hole in the handle. I had been advised at this point to use an allan key, but my IKEA kit has screwdriver heads of various sizes with the same pattern, so I used the one labelled T15. T10 is a tighter fit, but I'd struggled to get initial traction with it through the tap head.
(Allan key image by Richard Wheeler (Zephyris) 2007.)
Once loose enough, the grub screw fell off inside the mechanism but, no foul; I figured I'd find it again later.
With this done, I set about finding a way to "lift out" the handle from the tap. I really didn't want to force it and found no obvious separation point, but a quick referral to Bristan's diagram showed me where it should have been, giving me the confidence to apply more force. Indeed, a firm vertical pull "clips" the handle off the base.
My first cleanable component! As expected, some water-related detritus had accumulated around the inside of the handle. There was actually less build-up here than I expected, so at this point I expected more cleaning to need doing, not least because I had read about people cleaning and even replacing mixer tap cartridges, setting a precedent for my expectations.
For now, though, I gave the inside and outside of the handle a good wipedown using a different sink and a j-cloth.
At this point the cuboid head of the cartridge was mostly exposed, and using my finger I could rotate it in the same manner that the handle does; it still felt stiff, but this could have been mostly attributable to the lack of leverage.
(I took this opportunity to reclaim the fallen grub screw, too.)
Again following the diagram, I unscrewed the "shroud" to get at the cartridge proper, using a rubber glove to get some traction.
At this point, though, I became stuck. Not physically. My kit didn't contain a spanner big enough to grip the top of the cartridge and, with it screwed in fairly firmly I couldn't remove it.
Slightly dejected, I began putting all the pieces back together with the intention of coming back another day with some extra tools. First the shroud, then the handle went back on; to replace the grub screw I placed it on the end of my T10 to keep it level as I pushed it through the hole in the handle, gently screwed it in a small way, then switched to the T15 to finish the job. Finally the "indice" got snapped back on.
To my surprise, I found that my work so far seemed to have loosened up the handle enough to effectively accomplish my goal!
With little apparent need for removing and cleaning underneath the actual cartridge, I took advantage of the isolated supply to thoroughly clean the exterior of the tap assembly, then turned the water back on. Job done.
Though I like to try things out myself, I am cautious when it comes to plumbing, and I wouldn't have managed this without Bristan's excellent customer service. It just goes to show what a difference that can make: the direct result is that Bristan will certainly be first on my list when shopping for bathroom fittings in the future.
The world fell; the ash fell faster. As thick as the leaves on which it was supposed to be landing, except those had gone. Creating a pleasant sludge to trudge through, neatly balancing out the destruction that had fell almost as completely.
All the lights still shining but nobody left to illuminate. No-one except me, anyway.
The wind would still sing in the distance, an eery reminder of noisier days, but really even the moving air dared not come too close; each flake would sit casually on my coat, just where it fell, no matter how much grace I lost trudging through that sludge.
God willing, they'd cried; God willing? You'd think God'd've gotten around to this a while ago. Not a soul in sight and the only profound thought to be mustered is that it had been inevitable; indescribably so, even. Playing with such things. Toying. The outcome certain, yet we'd never learn. Can't now. Learn what, even? The best question asked, but far too late.
Admittedly the odd taxi passes by once in a while, but not enough to make a dent in my mood, nor barely enough to get back to where we were, at that. Six, nay, seven billion lives lost or near enough and no half-fleet of city cabs is going to undo that. Where are they going, anyway?
The homes are empty and beyond the wind the only sound I can hear is, once in a while, faded remnants of "My Funny Valentine"; faded in that it must be far away and the melody drifts in and out of my perception, dancing around empty buildings and silent streets. Really, Billie wouldn't have wanted this to change, wouldn't she?
Anyway, the ash still fell, so it doesn't make much difference now. I can get to where I am going easily enough, just as I got to where I just was, easily enough. But to where next? It doesn't make much sense to have any such goals on the surface of it, but then why not? Why did we ever? There seems to be just as much purpose in trudging along deserted, ash-laden boulevards as there ever had been, commuting up those same streets when they were filled with voices, sights, smells.
In a way, this is better. Calmer. It's hard to imagine that, had the world been this way to begin with, it would ever have fallen; but then, that's rather the point, isn't it? God willing, indeed — it does rather make one wonder.
And that distantly howling wind really is quite eery.
