I am learning OOP with Python and I am trying to figure how to get the accessor and mutator method for class level variables. I have no issues with instance level variables but I am having trouble with the class level ones. from abc import ABC, abstractmethod  class Book(ABC):     #Class Variable     _libraryLoanDuration = 14      def __init__(self, bookName, yearPublished, cost):         self._title = title         self._yearPublished = yearPublished         self._cost = cost       #Accessor for class variable     @property     def libraryLoanDuration(cls):         return cls._libraryLoanDuration      #Mutator for class variable     @classmethod     def libraryLoanDuration(cls, newlibraryLoanDuration):         cls._libraryLoanDuration = newlibraryLoanDuration
I have a class with two class methods (using the classmethod() function) for getting and setting what is essentially a static variable.  I tried to use the property() function with these, but it results in an error.  I was able to reproduce the error with the following in the interpreter: class Foo(object):     _var = 5     @classmethod     def getvar(cls):         return cls._var     @classmethod     def setvar(cls, value):         cls._var = value     var = property(getvar, setvar)  I can demonstrate the class methods, but they don't work as properties: &gt;&gt;&gt; f = Foo() &gt;&gt;&gt; f.getvar() 5 &gt;&gt;&gt; f.setvar(4) &gt;&gt;&gt; f.getvar() 4 &gt;&gt;&gt; f.var Traceback (most recent call last):   File &quot;&lt;stdin&gt;&quot;, line 1, in ? TypeError: 'classmethod' object is not callable &gt;&gt;&gt; f.var=5 Traceback (most recent call last):   File &quot;&lt;stdin&gt;&quot;, line 1, in ? TypeError: 'classmethod' object is not callable  Is it possible to use the property() function with @classmethod decorated functions?
A geometric sequence has its first term equal to $12$ and its fourth term equal to $-96$.   How do I find the common ratio? And find the sum of the first $14$ terms How is the passage of time handled in Pokemon? I stopped following the Pokemon anime a while ago, but I know the series has had Ash go through many regions, including retreading at least one of them.  When Ash was about to get his eight badge, Misty mentioned that they'd been on the road for a year at that point.  I saw some recent episodes, and Ash looks nearly identical to when he first started as a trainer.  Normally I'd attribute that to cartoon sitcom logic, where the characters never age; but in a series with continuity and references to earlier seasons, this makes no sense.  What's the official word on a timeline for the Pokemon anime? How to prove this $\pi$ formula? I am hoping to find out where the formula  $$\frac{\pi}{2}=\sum_{k=0}^{\infty}\frac{k!}{\left(2k+1\right)!!}$$ comes from. I can't see how one could begin to prove it. Inner join using an array column Having trouble indexing and executing a query in O (log n) time.  The query includes an INNER JOIN, an ORDER BY, and an equality operation. If I understand the laws of databases correctly, a query can be indexed and executed in O (log n) time (or thereabouts) if a non-equality operator is not used on more than one column. In this case, I believe the INNER JOIN does count as an equality operator and the non-equality operator would be the ORDER BY portion of the query. This table has upwards of 10,000,000 rows and needs to handle several reads and writes per second.  Using PostgreSQL. This is what the table looks like. As you can see, the column 'Names' is a list property and it is the column that the INNER JOIN goes against:  Age Names                       Date 34  ['carla', 'john', 'sam']    3/13/2011 26  ['json', 'cindy', 'joel']   3/13/2011 72  ['beth', 'amber', 'susie']  3/13/2011 14  ['john', 'jim', 'debie']    3/13/2011   This is the query that we are trying to do:  SELECT * FROM the_table WHERE Age==26 AND Names=='john' ORDER BY Date   My background is from using App Engine's Big Table, so I've used equality operators here to indicate that 'john' should be one of the names in the Names column. This would be an acceptable query in GAE's big table, it would execute in O (log N) time as all Big Table queries are reqyured to do. I am assuming there is a way to do this in PostgreSQL as well since PostgreSQL accepts list data types as columns.  Is this possible to do in PostgreSQL?  If so, how should the index be set up (we can't figure out how to set up an index that takes into account the three properties)? Were there any canon examples of Harry being an innately powerful wizard? Was Harry Potter an innately powerful/skillful Wizard in any way, based on canon?  It seems that whenever Harry Potter performed some unusually potent bit of magic (potent as far as require raw power AND/OR skill), most of the time we find that it wasn’t innately Harry’s skill, but a combination of:   some extraneous magic forces/rules/powers circumstance great reaction time (which is obviously extraordinary from his Quidditch playing; and is likely a larger factor in his dueling than the strength of his magic) general smartness or (the part that Harry’s detractors, including Voldemort missed) Harry’s strength of character/personality   The only two counter-examples I can think of which show him as having extraordinary or at least obviously above average magical abilities are:   His skill at flying brooms - while a part of it is pure physical skill, at least part is magical. His (corporeal) Patronus charm   As far as examples of his unusual feats being due to reasons listed above:   Obviously, surviving Avada Kedavra as an infant - due to Lily’s sacrifice Parselmouth talent - proxied via Voldemort’s piece of soul. Ability to see the Sorcerer’s Stone in the Mirror of Erised - due to purity of his character, nothing magical. Obvious lack of talent at potion making throughout all of the books (sans cheating in HBP) His win over the Basilisk - due to Hermione’s research, character traits, and as a consequence of the last one, getting Fawkes and Gryffindor’s Sword’s help.  Just to be clear, before someone flames me - what he did was obviously super extraordinary, BUT IMHO he would have achieved the same result if he was turned into a Squib for the duration of Chamber of Secrets fight. TriWizard Tournament entry - wasn’t him, it was Barty Crouch TriWizard Tournament second challenge - a combination of character and outside help (someone told him about Gillyweed) TriWizard Tournament third challenge - Mostly, Barty Crouch’s cheating  Note that I’m omitting the first challenge, since that one was the aforementioned Broom flying skills. His survival in the cemetery after Voldemort’s return - again, a combination of superior strength of character and super powerful wandlore magic that had nothing to do with his skill as a Wizard. The whole “last Horcrux” thing when surviving the second Avada Kedavra from Voldemort His ownership of the Elder Wand in the very last duel with Voldemort.   So, to paraphrase my original question, was there any canon/JKR evidence that Harry was anything but a completely average/mediocre wizard in any way, shape, or form if you take into account only his own magical abilities and skills? Custom command does not reference a label created with a previous custom command Trying to remap my left SUPER key (also called WINDOWS key) to left or right CONTROL key, with xkg I feel like someone made a comment as an answer on a question with a bounty just so they could reap the "auto bounty" since they are the only answer on it.   I've flagged the bad/useless answer (as a non-answer) for moderator review but the bounty will be assigned automatically in less than 24hrs and I feel like this guy/gal is just trying to cheat the system.   All I'm trying to do is ensure the bounty simply expires and the guy/gal that was trying to cheat the system by putting down a useless guess doesn't get it.   I've answered my own question (properly) and marked it as the accepted answer, not sure if that makes a difference though in this person still cheating the system since I'm the OP and created the accepted answer.   Here is the post: A 10x10 table filled with 0 to 9 numbers UV Unwrapping a Modified Model I modified an existing model by removing unwanted vertices, then selecting surrounding vertices and creating faces one triangle at a time (By pressing 'F').  On UV unwrapping the mesh, the faces which were added by me seem to stretch from the very bottom left of the map, shown below.    How do I create a face so it appears on the UV map as expected? Using special auto start servlet to initialize on startup and share application data I installed Ubuntu alongside Windows but I did not disable secure boot as someone told me it could cause problems with boot loader. So when installation finished and I rebooted, the system went straight into Windows. I went to Ubuntu IRC Support and they told me to turn off the secure boot and reinstall Ubuntu. I did that but my system still boot into windows.  This is a picture of partitions on my system:    This is my first Ubuntu install on my new laptop. I followed everdaylinux guide to install it and I used something else option. Determining possible minimal polynomials for a rank one linear operator I have come across a question about determining possible minimal polynomials for a rank one linear operator and I am wondering if I am using the correct proof method.  I think that the facts needed to solve this problem come from the section on Nilpotent operators from Hoffman and Kunze's "Linear Algebra".     Question: Let $V$ be a vector space of dimension $n$ over the field $F$ and consider a linear operator $T$ on $V$ such that $\mathrm{rank}(T) = 1$.  List all possible minimal polynomials for $T$.   Sketch of Proof:   If $T$ is nilpotent then the minimal polynomial of $T$ is $x^k$ for some $k\leq n$.  So suppose $T$ is not nilpotent, then we can argue that $T$ is diagonalizable based on the fact that $T$ must have one nonzero eigenvalue otherwise it would be nilpotent (I am leaving details of the proof of diagonalization but it is the observation that the characteristic space of the nonzero eigenvalue is the range of T and has dimension $1$).  Thus the minimal polynomial of $T$ is just a linear term $x-c$.    Did I make a mistake assuming that $T$ can have only one nonzero eigenvalue?  Thanks for your help How to sort an array of integers correctly Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)? Looking around Amazon, it seems that different types of batteries are measured differently:  Does anyone know why?   Li-ion are measured in mWh    (Cheap-Os)  3000mWh AmpTorrent  NiMH are measured in mAh      Alkalines are typically not measured   "Long Lasting" Duracell "Longest Lasting" Energizer    I assume that Alkalines are not measured for some sort of historical reason with marketing departments?  ... or is it that alkalines so mystical and unreliable that giving them a measurement is too aggressive? Or that switching to non-toxic / non-mercury was such a bad move in performance that measurements had to be removed in the 90s so people wouldn't know?  Perhaps NiMH are measured in mAh because the voltage can very so greatly and mWh doesn't make sense?  Are Li-ion measured in mWh because that's more consistent with non-battery measurements and they do deliver reliable voltage? How do I determine which graphics card I'm using? How to prevent nginx redirecting from HTTPS to HTTP on AWS? I have a website served by nginx behind an AWS ELB Load Balancer. Only HTTPS is enabled on the load balancer.  Requesting individual files, or directories with a trailing slash, work fine. However, requesting directories without a trailing slash don't work.  The reason is, when I request the directory without the trailing slash, nginx does a redirect to the path with the trailing slash (that's OK), but it also changes from HTTPS to HTTP. The load balancer is configured to only allow HTTPS, so that doesn't work (timeout).  On the nginx logfile, I can see that the request reaches nginx, and that it's nginx that responds with the 301 Permanent Redirect (so it's not e.g. a problem with the load balancer setup).  10.100.10.15 - - [24/Nov/2017:15:41:08 +0000] "GET /admin HTTP/1.1" 301 178 "-" "Wget/1.18 (darwin16.0.0)"   When I request the URL via curl I see the redirect:  $ curl -v https://example.com/admin *   Trying 1.2.3.4... * TCP_NODELAY set * Connected to example.com (1.2.3.4) port 443 (#0) * TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 * Server certificate: example.com * Server certificate: Amazon * Server certificate: Amazon Root CA 1 * Server certificate: Starfield Services Root Certificate Authority - G2 &gt; GET /admin HTTP/1.1 &gt; Host: example.com &gt; User-Agent: curl/7.54.0 &gt; Accept: */* &gt;  &lt; HTTP/1.1 301 Moved Permanently &lt; Date: Mon, 27 Nov 2017 09:19:05 GMT &lt; Content-Type: text/html &lt; Content-Length: 178 &lt; Connection: keep-alive &lt; Server: nginx &lt; Location: http://example.com/admin/ &lt; X-UA-Compatible: IE=Edge &lt;  &lt;html&gt; &lt;head&gt;&lt;title&gt;301 Moved Permanently&lt;/title&gt;&lt;/head&gt; &lt;body bgcolor="white"&gt; &lt;center&gt;&lt;h1&gt;301 Moved Permanently&lt;/h1&gt;&lt;/center&gt; &lt;hr&gt;&lt;center&gt;nginx&lt;/center&gt; &lt;/body&gt; &lt;/html&gt; * Connection #0 to host example.com left intact   My nginx config file is just   server {     root /var/www; }   The /etc/nginx/nginx.conf is .  I have tried server_name_in_redirect off but it did not make any difference.  I would like to avoid putting the hostname in the config file, because this is packed into a Docker image which is then deployed on different hosts (QA, Prod, etc.).  I would like nginx to do this redirect, but stay on HTTPS. What can I do? Is a contradiction enough to prove a set equality to $\varnothing$? Is there a standard naming convention for XML elements? Is there any standard, de facto or otherwise, for XML documents? For example which is the "best" way to write a tag?  &lt;MyTag /&gt; &lt;myTag /&gt; &lt;mytag /&gt; &lt;my-tag /&gt; &lt;my_tag /&gt;   Likewise if I have an enumerated value for an attribute which is better  &lt;myTag attribute="value one"/&gt; &lt;myTag attribute="ValueOne"/&gt; &lt;myTag attribute="value-one"/&gt; Ubuntu 20.04 interface font too small after restart, even with high scaling factor