Every day I wake up thinking that The Horde is not there anymore. The dreams are good but few, and only make everything worse. I usually dream about The Horde. During sleep, my breathing is improved and more relaxed. I dream of a calendar without symbols.

When there's an inspiration, so I write. Delete everything afterward. A professional told me that's is a compulsion. The compulsion for the perfect word removes me from language itself. The enjoyment comes from excising something from myself, which makes me feel a bit closer to perfection.

Every once in awhile I forget The Horde is there. The writing becomes looser, I sip my coffee and take the lunch out of the freezer. The Horde is still there. The whistle makes my blood run cold.

I forgot when The Horde arrived, but since then my days are covered of night and dust. To me, The Horde has no color, they're covered in filth and dark cloth. They get a bit closer by dawn. But The Horde never comes.

They seem to enjoy tormenting me. Twice a crow's carcass hit my window. At least we were communicating. I had to open the window to clean the blood. The Horde did nothing. There's courtesy between me and The Horde. I never complain of their tiny advances, they never impale me alive and eat my viscera.

The worst consequence of The Horde was to remove my visitors. I had friends and a girlfriend, before The Horde. They came here regularly. On the other hand, there's something cozy about being surrounded by The Horde. I'm never alone.

I talked to them on a few occasions but never got an answer. I invited them to lunch and asked what they like The Walking Dead (seems like a relevant question for The Horde). Because, you see, The Horde may be savage, but they did not cut my internet. I keep telling everyone about The Horde, but no one believes me. They think I'm some internet phenomenon, an internal joke from a group they don't know about. They don't believe The Horde can come for them too, knocking on their armor of bronze and recycled aluminum.

Sometimes The Horde's shrieks seem to gain shape and order as if they obeyed a hidden commander. But this doesn't last, and they soon resume their lurid racket.

I don't know for how long I've lived with The Horde, nor for how long they'll stay. I'm afraid of waking up someday to find them gone. Because, in a certain way, I learned to love The Horde. I feel safe in their post-apocalyptic embrace.

This morning they got closer than normal. I can see it better now. They all have the same face, they're both one and The Horde. Their mouths are frozen in a permanent smile, salivating like rabid animals. One more step. They look like neanderthals. The Horde approaches slowly, with steady paces, and arrive with the furor of the sound of metal and drums. The house is hit by numerous rocks — the roof is about to give in. My crumbled body will soon become an ensign for their future marches. Or maybe become mush after being punctured by one thousand spears.

I'm only sure that this is going to end soon. Their petite steps, the threats, crows in the window. Everything is ending — finally, everything is ending. I'll never be again and so will The Horde. Nevermore.

Update 12/03/2020: this is not a telemetry, but a kill switch from Colombian carrier - confirmed by HMD. Kill switch will be removed from most devices soon. I updated an article and posted it here.

Original article below:

I have recently purchased Nokia 6.2 and wanted to check if it sends any data somewhere, considering what happened with previous models

First, I noticed approx. daily connection to dapi.hmdglobal.net
This is a Google Cloud that could belong to a company behind Nokia - HMD Global.
But the Privacy policy in my phone only speaks of "activation" process, not of daily diagnostics data.
So I used developer tools to remove the following packages (warning: this may break your device, I am not responsible for any consequences)

    com.hmdglobal.enterprise.api
    com.qualcomm.qti.qms.service.telemetry
    com.qualcomm.qti.qmmi
    com.qualcomm.qti.qdma

Before removing them, I used APK Extractor to save APK files just in case it breaks my phone and I may be able to attempt reinstall. This part comes into play later.
The first was my blind guess about what exactly connects to dapi.hmdglobal.net
The next 3 I found mentioned in various forums for other devices as "safe to remove", however, I have not seen any telemetry sent to Qualcomm or anywhere else, except what I mention next.

After removing these packages, I noticed that there are some remaining unknown connections my device attempts several times per day.
They are all done in same order, one right after the other:

    www.pppefa.com
    www.ppmxfa.com
    www.forcis.claro.com.co

After some investigation, I found that the first two domains point to some Microsoft Cloud servers rented in US.
The last one most probably belongs to Colombian telecom company, and this is where it becomes interesting.
After many hours of fruitless removing of different apps in my attempt so stop it, I suddenly remembered something.
When I used APK Extractor previously, there was an empty first line with some generic icon where an app icon should have been.
I went there again and indeed, this is a hidden system app, that you can not see in the list of all apps in Settings, normally. But it turns out, you can see it in Data usage (after it successfully sends some data using your mobile connection).
The name of the app is deliberately left empty to hide it, but if you click it in Data usage, you can see that this app is co.sitic.pp , which can receive SMS, can make calls, and has access to internet.
As with all Android apps, you can reverse read the name to guess what it is.
Turns out, http://sitic.com.co is a Colombian company, who "are leaders in innovation and create mobile and WEB applications for new products and services." (credit goes to Google Translate)

screenshot of the app with permissions

In other words, this app is a 3rd party telemetry, hidden from user, not mentioned in the Privacy policy, that has access to SMS.
This looks very bad and I really hope this is a malware injected by factory and not something knowingly distributed by Nokia, HMD Global, the EU company.

After removing the co.sitic.pp app, requests to Microsoft Cloud and Columbia stopped.
I was later pointed to a German forum, where (I believe) it was first found in a Nokia 7.2 device.
So, we have it confirmed in 2 devices in 2 different countries.

On German forum they contacted Nokia (I assume support) but got tired exchanging emails for weeks without any result.
On 02/03/2020 I have requested an official reply from Nokia and HMD Global via press.services@nokia.com and press@hmdglobal.com and waiting for reply.
Since I am not a journalist, I may never get one.

TLDR: 3rd party telemetry is found in Nokia 6.2 and 7.2 devices, is hidden from user, has access to SMS, and sends data to Microsoft Cloud in US and a server in Columbia.
It is probably supplied by SITIC S.A.S., a Colombian company, and looks more like a malware than a telemetry.

In a time of ancient legends, Androcles was a runaway slave.

He took shelter in a cave where a wounded Lion lived.

By removing a thorn from his paw Androcles cured the beast; The Lion was very pleased.

And then The Lion ate Androcles because he was a fucking lion.

Some of my favorites are:

git add -p *

This will go through your unstaged changes in chunks and allow you to stage each chunk individually in an interactive shell.

git checkout -p *

Similar to the above, this will go through your unstaged changes and allow you to undo each chunk. I almost never use Ctrl+Z anymore and go straight for this. Want to remove all of those print-debugging statements? Use this command to pluck them out one-by-one.

git commit -a --amend --no-edit && git push --force-with-lease

I alias this one to whoops in my bash profile. It will add all unstaged changes, add them to your last commit and then (safely) force-push the local branch to the tracked remote branch. This is especially useful when working with CI and you need to make constant configuration changes to get it to work. Yes, you could squash those commits afterwards as an alternative. But this is easier.

git rebase -i HEAD~5

(Change 5 to the number of previous commits you want to see)

Interactive rebases are a core part of my git flow when working on feature branches. If a co-worker gives me feedback on a code review that requires a change to a previous commit I'll go back and edit that commit using this command. You can remove individual commits, squash commits, reorder commits, and so much more.

With Pepperplate.com moving their service to an overpriced subscription (queue the exodus), I've been moving some key recipes over to Paprika¹, I figured it'd be a good time to ask for some decent recipes.

Tuck your recipe and method in a <details> with a good <summary> so the thread is easy to browse.

I'll get us started!

¹Paprika is an overpriced recipe organizer -- paprikaapp.com -- it's okay, but also kind of lame.

(You could replace FPTP with STV to keep the districts that elect representatives in the house intact.)

I'll start.

The Democratic party breaks up into the neoliberal and progressive parties.

The neoliberal party is where centrist candidates like Joe Biden and Michael Bloomberg go.

The progressive party is where progressive candidates like Bernie Sanders and Elizabeth Warren go.

The Republican party might lose a large part of their electorate to the libertarians, since many Republicans are more concerned about letting business prevail and don't really want cultural conservatism.

Andrew yang maybe also leaves the Democrats and founds his own party, the party for online reform.

The greens also become significantly more popular but they may have too much in common with the progressives.

The Senate could be changed to include as many seats as the house for proper representation.

We had a discussion here last year about "Baby, It's Cold Outside", and whether the lyrics to this song encourage rape. This came after a radio station pulled the song from its playlist after people complained it was too "rapey".

Well, John Legend has re-written this song "to remove the 'date-rape' lyrics". Here is the song and here are Legend's new lyrics.

What do you think? Did the song need to be re-written? Is this an improvement? Is this the "Christmas" song we need for a post-#metoo era?

Two asides:

I've previously written about long-running topics and I've asked about software for blogging. But I keep coming back to doing some simple blogging on Tildes. I don't think Tildes should try to compete with real blogging software, but maybe Tildes can support a minimal version of it, enough to make it worth doing it here when starting an independent blog isn't worth the effort? An example would be a project diary (like for my accordion synthesizer project). We could encourage people to start a topic for each of their creative projects that they want to talk about and to post updates as they make progress. Or, perhaps this would be a way to cover some ongoing story that they want to live-blog?

I've refined my ideas a bit about how it might work: Suppose a Tildes topic contains a list of zero or more updates in chronological order? Only the original author can post an update, but anyone can write comments responding to any update. When you post an update to one of your topics, the comment tree for each previous update gets collapsed, encouraging people to comment on the latest update.

When a topic gets an update, it reappears in the topic list with a separate set of votes, showing both the original topic's title and the update's title concatenated. Any old listing is removed, so we don't show the same topic twice. However, maybe the topic heading shows the last three updates or so if the topic is getting multiple updates in a short period of time, as might happen when live-blogging.

Just a question. Lindsey Graham, Mitch McConnell, and the rest of them saying they already have a vote against removal of Donald before a court appearance.

Sorry if this is the wrong sub tilde for this. It just pisses me off.

"'I'm not trying to pretend to be a fair juror here': Graham predicts Trump impeachment will 'die quickly'" in Senate https://edition.cnn.com/2019/12/14/politics/lindsey-graham-trump-impeachment-trial/index.html

So I bought this laptop mainly for web browsing, document editing, note taking and programming with perhaps light gaming although that's not something I've tried yet. So, really just for school work.

Specifications

Laptop Model : Acer Aspire 3 A315-42
Laptop screen : 1080p IPS (with matte finish?)
CPU : R5 3500U
RAM : 8GB DDR4 (6GB available because of iGPU)
Storage : 256GB SSD NVMe
Wireless : Qualcomm Atheros QCA9377
Wired : Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 (According to lspci)
2x USB 2.0, 1x USB 3.0, 1x HDMI port, Audio jack, 1x RJ45 Ethernet port
Battery : 36.7Wh

Linux compatibility

Everything worked out of the box, gotta modify TLP to not kill the touchpad and webcam. The touchpad seems to have a mind of its own when it comes to being detected, It seems to be a kernel bug, unsure what I'll do about it concretely but rebooting a couple of times makes it work. Nothing to install thanks to AMD's open source mesa drivers. Might need a kernel higher than 5.3 because of general Ryzen 3000 issues but I've not tried, it was already higher than that.

Operating system tested

Basically never touched Windows, directly installed Fedora 31 Silverblue.

My Silverblue configuration is :

● ostree://fedora:fedora/31/x86_64/silverblue
                   Version: 31.20191213.0 (2019-12-13T00:42:11Z)
                BaseCommit: a5829371191d0a3e26d3cced9f075525d2ea73679bd255865fcf320bd2dca22a
              GPGSignature: Valid signature by 7D22D5867F2A4236474BF7B850CB390B3C3359C4
       RemovedBasePackages: gnome-terminal-nautilus gnome-terminal 3.34.2-1.fc31
           LayeredPackages: camorama cheese eog fedora-workstation-repositories gedit gnome-calendar gnome-font-viewer gnome-tweaks hw-probe libratbag-ratbagd lm_sensors nano neofetch
                            powertop radeontop sysprof systemd-swap tilix tlp

Kernel : 5.3.15
Gnome : 3.34.1

Body and Looks

The screen back has metal, I believe it feels quite sturdy. The rest is reasonable feeling plastic. The material used just loves to imprint grease / fingers which kinda sucks - the keys being the exception thankfully. There was also stickers on the inside which well, are somewhat standard but I thought they were pretty obnoxious so I removed them.

Typing experience

It's nothing amazing but it's good enough. I'm not really knowledgeable on keyboards so that's as much as I can say on it, really.

Performance

Everything feels quite snappy but I don't game at all on this machine so I'm not pushing it too much other than while I'm compiling or doing other things. The temperature does go up to 75°C and the fans get a little loud but it's not that bad. It's mostly the bottom getting hot so it's not something you notice too much while typing. It also cold boots quite fast, in about 10-20seconds I want to say but I've not benchmarked that. It's my first computer with an SSD so there's that.

Battery life

I get about 5hours with tlp installed doing web browsing, some programming occasionally, listening to music on the speakers and chatting. Personally I was kind of expecting more from this considering it's an APU but it seems to be what other people are getting on similar setups so It'll do.

Conclusion

Overall, I'm pretty happy with this laptop considering how I bought it for 575$ on sale. I made this review mostly because I wasn't finding much information about this laptop on Linux and well, I don't know, I guess I felt like it. If you have any questions, ask up!

I usually don't mind my tags getting erased and someone putting a more appropriate tag, but I want to know what is wrong with people.doing.something, or someone doing something, or someone.doing.something. I tried various ways today, and each one got removed, and I would like to know why.

I have lots of thoughts about Tildes that I end up forgetting. This post is my attempt to put them to good use. Some of those were already stated elsewhere.

Introduction

Just to make it very clear: I am extremely happy with the way things are going on Tildes. If that was not the case, instead of drawing criticism I would simply not be here. So, please, let's be civil and avoid taking things personally ;)

I'm also a regular user, so please be gentle with my ignorance regarding the technical reasons why some things are either impossible or unpractical.

1. An Answer To A Common Objection

Some of these suggestions may encounter the following answer: "this should be an extension, not a core feature". To which I might respond:

1. Extensions impact performance and it's good practice to keep them at a minimum
2. Not everyone uses the same browser.
3. Features implemented by the actual developers will probably be of a better quality

2. Golden Rule

Unless explicit or clearly unpractical, all suggestions should be interpreted as to be as optional (and preferably opt-in) as possible for the user. I'll also make frequent use of the imperative mood: please understand that those are still suggestions. The imperative mood is just more practical. Also, notice that this is not my first language.

3. Suggestions

3.1 Keyboard Shortcuts

The majority of Tildes users would probably welcome a good set of keyboard shortcuts. I apologize if such keyboard shortcuts already exist: if they do, there should be a page listing them all.

3.1.1 Vim-like and Emacs-like keybindings

There should be Vim-like and Emacs-like (you could choose which one!) keys all around. Even with things like Vimium, not everyone uses them, and a well-thought-out set of keybindings would be extremely beneficial.

This also applies to text fields.

4. Open Calls For Moderators

Right now, I'm not sure what criteria are being used to give someone moderator powers. I think being a developer or contributor is the main criterion, which makes a lot of sense. But other participants might be up to the task, and giving them a chance could be beneficial.

5. Moderation Action Should Always Present Reason

This may seem obvious and even unfair, but I think when a moderator is in no condition to dedicate the time to justify their moderation action (such as locking threads, removing contents or banning users), then the moderator should wait until this condition is met in order to take action.

6. Heated Discussions Should Be Allowed in More Circumstances

I understand Tildes is, and should always be, a place for politeness, even affectionate discussion, but sometimes heated language, including irony and sarcasm, are necessary to stress a point and take the discussion forward. I understand that's a fine line, and that is usually better err on the side of caution, but I also feel the need to caution my fellow Tilders and Tildes administration against excessive moderation, which could stifle the discussion of sensitive subjects

7. There Should Be a Page Explaining How to Collaborate

This page should be short and to the point, with lots of links. I, for instance, wanna collaborate in the documentation, but the information telling how to do so was in a comment I cannot find anymore.

8. Table of Contents

Tildes markdown should support the automated creation of a simple table of contents, which would be very useful for longer posts. Preferably, there should be a limited set of options, such as:

• title of the table of contents ("TOC", "Table of Contents", "Contents" etc)
• numbered vs unnumbered
• depth of the numbering

9. Search own content

I find very hard to search my own content. Sometimes I must reference something I said earlier, or adapt a previous response to a question I already answered. On these occasions, I have to manually Ctrl+f page after page of my user page, which is tedious and inefficient.

10. Sort my own content

I wish I could sort my own content in the same manner I can with other pages. This would help with item 9, and also help answer faster to comments that were recently made.

11. Notifications

I wish it was possible to op-in desktop notifications for Tildes to show me whenever I get an answer to a thread, a comment or a private message.

Correction: I'm not referring to Email notifications, but desktop notifications. The ones that appear occasionally on your browser or screen.

12. There Should Be Space for Comedy

I'm not saying Tildes should become a place for lazy memes and endless puns, but comedy is valuable content and I don't like the idea of Tildes being a more conversational version of Stack Overflow. I fully agree with @deimos vision for a website for meaningful interactions with a focus on privacy. I just don't think comedy is necessarily a menace to this and all the other Tildes' stated goals. Right now, we're a very serious bunch of folks. There should be a place for humor in Tildes. How would that work? IDK. I leave this open for discussion.

13. Link to Excerpt

It would be awesome being able to link not just to a particular comment, but to a selection of that particular comment. After linking to the excerpt, I would go to the full comment, but the excerpt would be highlighted.

Conclusion

This is more of a collection of thoughts than an article, therefore I cannot offer a proper conclusion. But I'd like to kindly ask my fellow Tilders to give some considerations to my ideas. And please understand that they are not complaints. It's just may to contribute to this great community.

Cheers ;)

It is was a tedious task to mention users: copy, type, paste. This script makes it a single step: drag and drop any username on to the comment you're composing, and tada! It's there.

Here is the script:

// ==UserScript==
// @name     tildesDragNDropUsernameForMention
// @version  1
// @grant    none
// @namespace   tildes.net
// ==/UserScript==

var userLinks = document.querySelectorAll('a.link-user');

var dragstartHandler = function (event) {
  var text = event.target.innerText;
  if(!text.startsWith('@')){
    text = "@" + text;
  }
  event.dataTransfer.setData("text", text);
  event.dataTransfer.dropEffect = 'copy';
}

userLinks.forEach(function (each) {
  each.setAttribute('draggable', true);
  each.ondragstart = dragstartHandler;
});

Patches welcome!

Edit: remove useless code

News article: Gay artist 'devastated' to have THIS artwork 'censored' by Llandudno gallery after 'homophobia' complaint to police

Direct link to the artwork on Paul Yore's Instagram: https://www.instagram.com/p/Bz2OF2EA4mR/

Is it homophobic to depict homophobia in art?

This was written for a themed flash fiction contest (the theme was Technological Dystopia) and ended up losing, but I figured it wouldn't hurt to share it here. It's not my proudest work but, as flash fiction, I think it works well enough. I hope you enjoy!

She was three floors from the bottom of the sunken tower when the crying first reached her. A quick swipe earned her a pair from the rack nearby and she continued her descent.

With the aid of technology this process had been streamlined and systematized such that these checks were only needed once a month, but everyone dreaded them. She had drawn the short straw this time and, though it had been years since last she’d ventured to The Lab, she still remembered her last haunting experience. It wasn’t that she was a dissenter or rebelled against that which needed to be done. This was a necessary evil to save their species, but she was still a human being. Seeing them all like that, all tubes and tapes running from frail flesh, was enough to turn any stomach.

A pair of heavy iron doors sat ominously in her way as she bottomed out. She could see the white, crisp interior of The Lab beyond and pushed forward, swallowing her hesitance as best she could.

Before her lay a large room with clean white tile, walls and harsh, flourescent light. It smelled and looked like a hospital because that’s exactly what it was. 10 rows and columns of small, clear, plastic boxes stretched between her and the far wall. The muffs were doing their job exceedingly well, but she could still hear the awful racket bouncing around her memory. She took a deep breath, steadied herself, and started working.

Her primary duty was to make sure the machines were functioning correctly, mostly the arm that glided to and fro above the boxes, administering medicine or changing bags of various fluids as need be. She would also be checking the tubes for clogs that may have been missed by any old or worn out sensors; this was the part she dreaded the most. She flipped the lid on the nearest box and checked the left, then the right, and lastly the tube running into its belly button, and closed the box quickly.

It couldn’t have taken her more than 5 seconds but that short time was enough for the anguished face to plaster itself onto her mind. Everyone does their part, she reminded herself, from the start to the end. It didn’t serve a purpose to bemoan that which she could not change. She moved on to the next crib, hoping this would go by faster than she expected.

Halfway through her checks she hit a snag. There was a clog in Crib 54. She could register the fault in the system and it would fix it on its next hourly cycle, as were her orders, but it was such a small clog. The tube simply needed to be changed, and as a nurse she was well-versed in the procedure. In that moment it was decided.

The tubes themselves were specially designed to be thin and flexible, but rigid enough to fit the shape of a tear duct. Her first task, after finding a pair of gloves, was to gently remove the tube currently in the eye. She hovered over the crib and gently pulled the tube out of the right tear duct. It came slowly, millimeter by millimeter, each bit covered in more goop and mucus than the last. It wound its way up into the sinuses which meant, by the end of it, she had pulled at least five inches of tubing. This she discarded.

Next she had to insert the new tube (these were kept in abundance in a draw underneath the crib). She grabbed one, snipped it to length with a pair of scissors hanging from the IV stand, and took a moment to recent herself. Inserting the tube while the child was crying would be much more difficult than removing it.

As gently as she could she reached down and, with her index finger and thumb, pried open the eye of the little one. With one came the other, the muscles young and unwilling to work independently, and she found herself staring into a pair of brilliant green pools. Her heart melted and, for the briefest moment, she thought of taking it. She could smuggle it out. The bed being empty would trip the system but she could clear the error and explain it away somehow. But no, that was silly. This wasn’t a decision for her to make; things were done this way because there was no other choice.

She pushed the tip of the tube into the tear duct confidently, shoving the traitorous thoughts from her mind as the child’s cries were renewed with pain. She was here to do a job, cold and emotionless. It wasn’t her place to question the way things were done. The tube went in without a hitch and the child’s eyes snapped closed again once she released them. The little bundle of agony before her squirmed and she saw the tears begin to flow anew. With swift, definite movement she closed and latched the lid.

The rest of her checks went smoothly, but she couldn’t shake the uneasy feeling that now ran rampant in her gut. She hated Lab duty, and she expected that would always be the way. With a heavy heart she signed the documents needed to record her visit, noted the tube change in the work log, and left The Lab through its heavy iron doors. The trip upstairs would be long and tiring, but at least she could try and forget ever having been here.

Preface

It's not uncommon for a written piece of code to be both brief and functionality correct, yet difficult to reason about. This is especially true of recursive algorithms, which can require some amount of simulating the algorithm mentally (or on a whiteboard) on smaller problems to try to understand the underlying logic. The more you have to perform these manual simulations, the more difficult it becomes to track what exactly is going on at any stage of computation. It's also not uncommon that these algorithms can be made easier to reason about with relatively small changes, particularly in the way you conceptualize the solution to the problem. Our goal will be to take a brief tour into what these changes might look like and why they are effective at reducing our mental overhead.

Background

We will consider the case of the subset sum problem, which is essentially a special case of the knapsack problem where you have a finite number of each item and each item's value is equal to its weight. In short, the problem is summarized as one of the following:

• Given a set of numbers, is there a subset whose sum is exactly equal to some target value?

• Given a set of numbers, what is the subset whose sum is the closest to some target value without exceeding it?

For example, given the set of numbers {1, 3, 3, 5} and a target value of 9, the answer for both of those questions is {1, 3, 5} because the sum of those numbers is 9. For a target value of 10, however, the first question has no solution because no combination of numbers in the set {1, 3, 3, 5} produces a total of 10, but the second question produces a solution of {1, 3, 5} because 9 is the closest value to 10 that those numbers can produce without going over.

A Greedy Example

We'll stick to the much simpler case of finding an exact match to our target value so we don't have to track what the highest value found so far is. To make things even simpler, we'll consider the case where all numbers are positive, non-zero integers. This problem can be solved with some naive recursion--simply try all combinations until either a solution is found or all combinations have been exhausted. While more efficient solutions exist, naive recursion is the easiest to conceptualize.

An initial assessment of the problem seems simple enough. Our solution is defined as the set of array elements whose total is equal to our target value. To achieve this, we loop through each of the elements in the array, try combinations with all of the remaining elements, and keep track of what the current total is so we can compare it to our target. If we find an exact match, we return an array containing the matching elements, otherwise we return nothing. This gives us something like the following:

function subsetSum($target_sum, $values, $total = 0) {
    // Base case: a total exceeding our target sum is a failure.
    if($total > $target_sum) {
        return null;
    }

    // Base case: a total matching our target sum means we've found a match.
    if($total == $target_sum) {
        return array();
    }

    foreach($values as $index=>$value) {
        // Recursive case: try combining the current array element with the remaining elements.
        $result = subsetSum($target_sum, array_slice($values, $index + 1), $total + $value);

        if(!is_null($result)) {
            return array_merge(array($value), $result);
        }
    }

    return null;
}

Your Scope is Leaking

This solution works. It's functionally correct and will produce a valid result every single time. From a purely functional perspective, nothing is wrong with it at all; however, it's not easy to follow what's going on despite how short the code is. If we look closely, we can tell that there are a few major problems:

• It's not obvious at first glance whether or not the programmer is expected to provide the third argument. While a default value is provided, it's not clear if this value is only a default that should be overridden or if the value should be left untouched. This ambiguity means relying on documentation to explain the intention of the third argument, which may still be ignored by an inattentive developer.

• The base case where a failure occurs, i.e. when the accumulated total exceeds the target sum, occurs one stack frame further into the recursion than when the total has been incremented. This forces us to consider not only the current iteration of recursion, but one additional iteration deeper in order to track the flow of execution. Ideally an iteration of recursion should be conceptually isolated from any other, limiting our mental scope to only the current iteration.

• We're propagating an accumulating total that starts from 0 and increments toward our target value, forcing us to to track two different values simultaneously. Ideally we would only track one value if possible. If we can manage that, then the ambiguity of the third argument will be eliminated along with the argument itself.

Overall, the amount of code that the programmer needs to look at and the amount of branching they need to follow manually is excessive. The function is only 22 lines long, including whitespace and comments, and yet the amount of effort it takes to ensure you're understanding the flow of execution correctly is pretty significant. This is a pretty good indicator that we probably did something wrong. Something so simple and short shouldn't take so much effort to understand.

Patching the Leak

Now that we've assessed the problems, we can see that our original solution isn't going to cut it. We have a couple of ways we could approach fixing our function: we can either attempt to translate the abstract problems into tangible solutions or we can modify the way we've conceptualized the solution. With that in mind, let's take a second crack at this problem by trying the latter.

We've tried taking a look at this problem from a top-down perspective: "given a target value, are there any elements that produce a sum exactly equal to it?" Clearly this perspective failed us. Instead, let's try flipping the equation: "given an array element, can it be summed with others to produce the target value?"

This fundamentally changes the way we can think about the problem. Previously we were hung up on the idea of keeping track of the current total sum of the elements we've encountered so far, but that approach is incompatible with the way we're thinking of this problem now. Rather than incrementing a total, we now find ourselves having to do something entirely different: if we want to know if a given array element is part of the solution, we need to first subtract the element from the problem and find out if the smaller problem has a solution. That is, to find if the element 3 is part of the solution for the target sum of 8, then we're really asking if 3 + solutionFor(5) is valid.

The new solution therefore involves looping over our array elements just as before, but this time we check if there is a solution for the target sum minus the current array element:

function subsetSum($target_sum, $values) {
    // Base case: the solution to the target sum of 0 is the empty set.
    if($target_sum === 0) {
        return array();
    }

    foreach($values as $index=>$value) {
        // Base case: any element larger than our target sum cannot be part of the solution.
        if($value > $target_sum) {
            continue;
        }

        // Recursive case: do the remaining elements create a solution for the sub-problem?
        $result = subsetSum($target_sum - $value, array_slice($values, $index + 1));

        if(!is_null($result)) {
            return array_merge(array($value), $result);
        }
    }

    return null;
}

A Brief Review

With the changes now in place, let's compare our two functions and, more importantly, compare our new function to the problems we assessed with the original. A few brief points:

• Both functions are the same exact length, being only 22 lines long with the same number of comments and an identical amount of whitespace.

• Both functions touch the same number of elements and produce the same output given the same input. Apart from a change in execution order of a base case, functionality is nearly identical.

• The new function no longer requires thinking about the scope of next iteration of recursion to determine whether or not an array element is included in the result set. The base case for exceeding the target sum now occurs prior to recursion, keeping the scope of the value comparison nearest where those values are defined.

• The new function no longer uses a third accumulator argument, reducing the number of values to be tracked and removing the issue of ambiguity with whether or not to include the third argument in top-level calls.

• The new function is now defined in terms of finding the solutions to increasingly smaller target sums, making it easier to determine functional correctness.

Considering all of the above, we can confidently state that the second function is easier to follow, easier to verify functional correctness for, and less confusing for anyone who needs to use it. Although the two functions are nearly identical, the second version is clearly and objectively better than the original. This is because despite both being functionally correct, the first function does a poor job at accurately defining the problem it's solving while the second function is clear and accurate in its definition.

Correct code isn't necessarily accurate code. Anyone can write code that works, but writing code that accurately defines a problem can mean the difference between understanding what you're looking at, and being completely bewildered at how, or even why, your code works in the first place.

Final Thoughts

Accurately defining a problem in code isn't easy. Sometimes you'll get it right, but more often than not you'll get it wrong on the first go, and it's only after you've had some distance from you original solution that you realize that you should've done things differently. Despite that, understanding the difference between functional correctness and accuracy gives you the opportunity to watch for obvious inaccuracies and keep them to a minimum.

In the end, even functionally correct, inaccurate code is worth more than no code at all. No amount of theory is a replacement for practical experience. The only way to get better is to mess up, assess why you messed up, and make things just a little bit better the next time around. Theory just makes that a little easier.

I started using wine in about 2013 and I remember back then it was quite patchy and only worked on some programs/games. I used to have a rule that I stuck hard to that I would not buy any games that did not have a linux version. But now in 2019 I have found that everything I have tried to run in wine has been so seamless and close to flawless that I hardly know its running in wine. I semi regularly buy games that only have windows version because I am mostly sure it will work and can get a refund if it doesn't.

What does everyone else think about this?