Why is using a Global Variables class (singleton) bad practise?
What is so bad about singletons?
How do I make a bootable Ubuntu USB? I'm trying to create an item that can break certain blocks, but also has a colored name in 1.13.2   Here's the command I'm using.  /give iAugust minecraft:shears{display:{Name:"[{\"text\":\"Arcane Shears\",\"color\":\"aqua\",\"italic\":false,\"bold\":false}]CanDestroy:[minecraft:iron_bars]"}}   But it only has a colored name, and it can't break specific blocks. Are confidence intervals open or closed intervals? I have a service (kado-demo.service) that a normal user (kado) should be able to restart without entering any password.   I created /etc/sudoers.d/user_restart and added  kado ALL=NOPASSWD: /bin/systemctl restart kado-demo.service   Permissions:  -r--r-----   1 root root   585 Mar  5 10:47 user_restart   As user k, I now should be able to execute the given command, but this happens:  /bin/systemctl restart kado-demo.service  ==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===  Authentication is required to restart 'kado-demo.service'.   Multiple identities can be used for authentication:   (...)   Which is the same result as before I added the file.   The /etc/sudoers contains  #includedir /etc/sudoers.d   And I even get the same result when I add content of the user_restart file directly to /etc/sudoers.  I'm running out of ideas... See these three pages:          All three of them say:     Earned at least X total score for at least 20 answers in the  tag.   This same text also appears on the tooltip for the tag badge:   Also note the double colon after 'gold badge'  As well as on these pages:          But the  clearly states:        Bronze Badge:  You must have a total score of 100 in at least 20 non-community wiki answers to achieve this badge.   Silver Badge: You must have a total score of 400 in at least 80 non-community wiki answers to achieve this badge.   Gold Badge: You must have a total score of 1000 in at least 200 non-community wiki answers to achieve this badge.        Edit:  It has been noted in the comments that other users see different numbers in these pages, but in all cases it appears they see the same number of answers are required for all tag badge description, regardless of the badge's type. How can I use asymmetric encryption, such as RSA, to encrypt an arbitrary length of plaintext? RSA is not designed to be used on long blocks of plaintext like a block cipher, but I need to use it to send a large (encrypted) message.  How can I do this? How do you install Google Chrome on Ubuntu? Confirming that my own question is a duplicate by voting to close should have immediate effect I recently flagged a question as "very low quality", just like I've flagged many questions in the past. However, my flag was found to be unhelpful this time. The same thing happened when I recently flagged a post as not an answer.  Are the moderators being more strict when it comes to handling quality related flags? If so, why? LED accent light that slowly dims when removed from power source We've all played with different transformers and power supplies that have an LED indicator that dims before going out entirely when the power supply is unplugged.  I'm working on designing an accent light which would involve a translucent crystal light source (probably made of resin or glass if I can find a cheap supplier) containing LEDs and certain electronics, and a base which would supply electrical current. For gamers, it might appear somewhat like a Welkynd Stone. My question is what is the simplest way to cause the LEDs to dim slowly (say over 2-10 seconds) when the crystal is removed from the base? Similar to the unplugged transformer, but with an intentional and controlled dimming.  I just purchased some LEDs and plan to build a test system over the next month or two. These LEDs are in a 5 meter strip divided into 3 LED series run in parallel and rated at 12v. I do not know the amp rating of the LEDs, but I'm guessing in the 20ma range (what I've read is average for bright white). I will probably use 4 series totaling 12 LEDs in the test build.   If I have the transformer from AC power built into the base, I was guessing I could use a number of capacitors in parallel with a resistor to store electricity and slowly discharge it into the LEDs. But I'm a self-taught enthusiast so I honestly don't know if this would actually work. Nor do I know the number and ratings of capacitors and resitor that I would need.  If I have the transformer built into the crystal, the transformer and rectifier would retain a small amount of electricity, but I don't think it would be nearly enough to provide the effect I'm looking for, so something else would have to be added to make it last for several seconds.  A nicad battery with control electronics is literally my last resort for achieving this effect, and I'll probably give up on the idea before I go programming my own circuit board.  That's my main question. If anyone wants to toss in some thoughts on how to connect the crystal to the base, I'm open to suggestions. My original plan was to simply have a direct copper to copper connection with the base. But I've recently been considering an EM charging system (akin to a powermat or  my dad has). The concern with the wireless is providing consistent power to the LEDs, though it is safer. I've also learned quite a bit already about constructing the power supply from perusing this SE site, but if anyone has any suggestions for that, too, I'm all ears. For the test build I'll probably hook it up to a computer power supply, or a laptop power supply if I can find a 12v one at Goodwill or the local electronics parts store.  If I get the test model to work, I plan on building possibly a dozen of these for accent lighting around my home. This was talked about a few podcasts ago. And they referenced some other site that does this.  Currently location is a string but adding a country dropdown (and for the usa a state drop down) could be a great addition to the site.  Then allow for user filtering by country / state. is there any uncertainty on the free particle with a definite momentum $\vec p$? The probability amplitude for a free particle with momentum $\ p$ and energy $E$ is the complex wave function: $$\psi_{(\vec x , t)}=e^{i(\vec k\cdot \vec x -\omega t)}$$  is there any uncertainty on the free particle with a definite momentum $\vec p$!? Equation number in aligned environment after last line I'm using aligned inside align as follows   \documentclass{article} \usepackage{amsmath} \begin{document} \begin{align} x =&22+2 \nonumber\\   =& \begin{aligned}[t]     &5+3\\     &-3+4\\     &+15-0   \end{aligned} \end{align} \end{document}   I want to have just one equation number after the very last line.  However, I'm getting the number at the beginning of the first split line (after the second = ),    and I cannot figure out how to move this equation number to the bottom. Any help will be appreciated. What is the difference between user and service account? I would like to know difference between user and service account.  I know that e.g. Jenkins installed to ubuntu is not a user, .    What is use of service account? When we need them? How can I create service account? Image a phone and browse on computer emulator? I have a galaxy nexus (stock OS). During its use I have used WeChat and WhatsApp, and would like to save my chat and voice histories within these programs.  Does a way exist to image my current phone as it is, so I can load it onto some PC emulator and browse these apps on my PC? This would allow me to save everything as it is, but also start fresh on my phone with a format. I do not want to format my phone then load back on WeChat for instance, yet I still want to be able to browse my old WeChat chats and voice clips (using a PC).  Thanks I've seen lately that new question editing is stored somewhere for later use if we wander off the new question without posting it and then return back to the page. Which is a good functionality addition in it's own right.  What I'd like to also have is the Discard this draft functionality that would clear form data and forget it. Somehow we find an answer in the meantime and the question isn't valid any more.  So having a Discard saved draft or something similar would be a nice contra-functionality to auto-save to remove stored data. The way it's implemented now seems too hidden hidden and unpredictable to users.  Additional edit  When adding hidden auto functionality usually means creating the opposite as well by either giving the possibility to preference of not having automatism at all or giving the possibility to clear what's been auto saved.  Let's see how GMail doesn't work (and I think we all agree that from UX perspective it does the job as expected:   User clicks Compose message User starts writing a new email message User decides to not send the message and checks their inbox User clicks Compose message again A clean form is presented to user (old one being part of drafts)   I'm not suggesting we should have something like Saved drafts but we surely should have the possibility to clear previous question draft.  Since this new functionality was introduced I should point out that I would use the discard functionality more frequently than the saved one. I do welcome saving messages, but discarding of saved drafts is anything but a rare situation one might want to do. It wouldn't be a problem if this was a 1% against 99%. To me it's more like 50/50.  Best possible solution  When providing saved drafts there should (from the UX perspective) be the opposite functionality as well. Namely discarding of it. But first thing we should be asking ourselves is:    do users more frequently need pre-filled saved question draft or do users more frequently need empty form with the possibility to populate it with a saved draft   User testing should provide the usage frequency between the two and the one that's more likely to happen (my guess is that there would be a big difference between the two) should be implemented. So one of these:   Pre-populate question fields with saved draft on question form load, while also providing a button to clear the draft and start writing anew without the need to manually clear all the fields (which would be the optimal solution in case of a single field form) Question form should always load empty while also having a button that would pre-populate it with a saved draft.   I think this would be the best consensus related to saved question drafts and their usage. But as we've seen this issue has been swept under the rug for an indefinite time. Would anyone can help me how to show that a finitely generated projective module over a local ring and PID are free?    What I know about a finitely generated projective module $M$ over a PID $R$ is isomorphic to $R^k\oplus R/(a_1)\oplus\dots\oplus R/(a_n)$, and for the local ring case I don't know how to start. What are my options if I need to move a database from SQL Server 2012(32bit) to SQL Server 2005(64bit)?  I know I cannot:   restore a backup of the database on SQL Server 2005 detach &amp; attach   I know I can:   use import data wizard, and I tried it on one database, but it only moves data, and even that was troublesome as I needed to do a lot of work creating temp tables to maintain identity columns, recreating all FKs, indexes etc.    Is there an easier option? Notify-send ignores timeout? Maybe I'm doing something wrong, but shouldn't the commands (run separately) notify-send -t 1 &quot;test&quot; notify-send -t 1000 &quot;test&quot; notify-send -t 10000 &quot;test&quot;  have different timeouts? The first being nearly instantaneous, the second taking 1 sec and the third 10 seconds? In all cases it seems to take about six seconds for me. Is there a way around this behaviour? As the developers label this as a &quot;feature&quot; instead of a bug, I would like some alternatives. How to get Drupal 7 installed in a sub-folder / sub-directory properly? Currently i'm trying to installing a drupal 7 installation in a subfolder of another drupal public_html folder, but it doesnt seem to work. I am getting a redirect loop error in chrome. I already modified the .htaccess in the parent drupal installation to ignore the sub-folder and i also set the $base_url in the sub-directory drupal installation.