explain xkcd - User contributions [en]

Talk:1638: Backslashes

2016-02-03T19:06:14Z

162.158.252.227: more speculation on the nature of the title-text regexp; this time: is it meant to be searching out.txt for malformed regular expressions?

...Maybe it's meant to search for all Game Grumps transcripts which make mention of the "[http://gamegrumps.wikia.com/wiki/Grep Grep]" gag? [[Special:Contributions/108.162.216.55|108.162.216.55]] 15:53, 3 February 2016 (UTC)

It should be noted that this also occurs in almost every programming language where "\" is the escape character. i.e.
print("Hello")
> Hello
print("\"Hello\"")
> "Hello"
print("\\Hello\\")
> \Hello\
Oh, and by the way, isn't this the third comic to mention "Ba'al, the Soul Eater"? Maybe we should start a category. (Others are [http://www.explainxkcd.com/wiki/index.php/1246:_Pale_Blue_Dot 1246] (title text) and [http://www.explainxkcd.com/wiki/index.php/1419:_On_the_Phone 1419].)
[[Special:Contributions/173.245.54.29|173.245.54.29]] 06:14, 3 February 2016 (UTC)
:[[:Category:Ba'al|Did that]] before seeing you comment, so yes I agree. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:47, 3 February 2016 (UTC)

The last entry may also be an oblique reference to the infinitely-expandable recursive acronym "GOD = GOD Over Djinn" mentioned in Richard Hofstadter's Gödel, Escher, Bach.[[User:Taibhse|Taibhse]] ([[User talk:Taibhse|talk]]) 16:42, 3 February 2016 (UTC)

;I don't think the regex is invalid

According to <tt>man grep</tt> you need to specify the <tt>-E</tt> option to use extended regex; without it unescaped parentheses are not interpreted, so they don't need to match.

My - very wild - guess is that it was the command he used to find the line with the most special characters, but I am not confident enough to edit the article (if someone can confirm?). {{unsigned ip|141.101.66.83}}

If it was supposed to do that, it doesn't work. Running it on my bash history matches no lines, and I have lots of special characters in there [[Special:Contributions/197.234.242.243|197.234.242.243]] 07:12, 3 February 2016 (UTC)

Explain it to me like I'm dumb. What is this comic going on about? I think the explanation needs more examples like that hello, above, because that's almost understandable. --[[Special:Contributions/198.41.238.231|198.41.238.231]] 07:47, 3 February 2016 (UTC)
:I agree. But I cannot help either.--[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)

This is the third time Randall has mentioned Ba'al the Soul Eater xD [[User:International Space Station|International Space Station]] ([[User talk:International Space Station|talk]]) 08:26, 3 February 2016 (UTC)
:Yes, that was already mentioned a few hours before you comment, see the first comment. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)

After passing the regex through bash, you get <nowiki>\\[[(].*\\[\])][^)\]]*$</nowiki> That is, the literal character \, followed by [ or (, followed by any number of any characters, followed by \, followed by ] or ), followed by any number of characters that aren't ) or ], until the end of the line. [[Special:Contributions/108.162.216.44|108.162.216.44]] 08:33, 3 February 2016 (UTC)
:It sounds like you know what you are talking about. Anyone who can explain it good enough for the explanation, and correct the explanation of the title text if it is wrong to say that it would not work. I have added this as the reason for incomplete. But maybe also examples are needed for people with not programming skills/knowledge. We also enjoy xkcd ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 09:51, 3 February 2016 (UTC)

For fun:
cat ~/.bash_history | xargs -d "\n" -n 1 -I {} bash -c 'chars="$(echo "$1" | grep -o "[a-zA-Z0-9 ]" | wc -l)"; echo "$(( 100 - $(( $chars * 100 / ${#1} )) )) $1"' _ {} | sort -nrk 1 | less

Outputs your bash_history, ordered by relative gibberishness. This was copied by hand from desktop to mobile, might well have a few typos.--[[Special:Contributions/162.158.90.208|162.158.90.208]] 10:04, 3 February 2016 (UTC)

The problem in the comic is not with regexes per se but with situations when the entered text or expression passes through several interpreters, like bash -> grep/sed/awk, or program text -> external shell command. In such cases, you have to escape backslashes for each program in the sequence, and it gets worse if you have 'real' backslashes in the final text that you're processing with the utilities (Windows' file paths, for example). See https://en.wikipedia.org/wiki/Leaning_toothpick_syndrome.
Feel free to lift this to the explanation page, since I'm not good at longer and more careful explanations than this one.
Also, gotta notice that Feedly stripped paired backslashes in the title text (probably passed it through some 'interpreter' embedded in its scripts). [[User:Aasasd|Aasasd]] ([[User talk:Aasasd|talk]]) 10:13, 3 February 2016 (UTC)

:A funny comment about the MediaWiki software, which is even worse than this comic: <code><nowiki><Nikerabbit> I looked the code for rlike and didn't find where it does this. Can you point me to it? <vvv> $pattern = preg_replace( '!(\\\\\\\\\\\\\\\\)*(\\\\\\\\)?/!', '$1\\/', $pattern ); <Nikerabbit> I thought that was ascii art :)</nowiki></code> ([https://phabricator.wikimedia.org/P110$275 source]) --[[Special:Contributions/162.158.91.215|162.158.91.215]] 10:18, 3 February 2016 (UTC)

Interestingly, I first looked at this on my phone (using <strike>Chrome</strike> Feedly for Android), but the title text did not display correctly in that the backslashes didn't appear (which was a little confusing!). In Chrome on my Windows desktop, the title text appeared correctly. [[User:Jdluk|Jdluk]] ([[User talk:Jdluk|talk]]) 11:36, 3 February 2016 (UTC)

enough with the harry potter fancruft. "elder" is a [[Wiktionary:elder|perfectly good word]]. just because you came across it for the first time in harry potter means you are *typing carefully* the kind of person that likes harry potter. unless this is a ''harry potter reference'' wiki, of course. in which case i'll prepare a complete list of every word that appears both here and there and put a list on every page. oh, right, no i won't. --[[Special:Contributions/141.101.106.161|141.101.106.161]] 12:41, 3 February 2016 (UTC)

Remember that "Elder" is used in a lot of RPGs to denote high level enemies or items. I feel like that's what Randall's referring to here, more than Harry Potter or the general sense of the term "Elder."
* +1. Between the fact that harry potter (, ages, or tribes) aren't mentioned anywhere else in the text and the comic being a progressive list, I see this being the most likely explanation. Plus the metion of demons, which are easily the most* common usage of the modifier.
** (*) or second most, after "elder gods", who are, let's face it, also demons. [[Special:Contributions/162.158.180.125|162.158.180.125]] 14:41, 3 February 2016 (UTC)
*** I'm pretty sure that "Elder backslash" is in reference to the "Elder gods" of Lovecraft. [[Special:Contributions/173.245.54.35|173.245.54.35]] 16:51, 3 February 2016 (UTC)

Attempting to add to the discussion: This regex is not necessarily invalid or incomprehensible. It looks like he was looking for a line with a regular expression or definitely some code. You just have to work your way through the backslashes. Although it might be invalid depending on the precise rules. He has some unescaped closing brackets and closing parenthesis. If these have to always be escaped then the regex is invalid. If however you don't have to escape a closing bracket with no opening bracket, then things are fine. I'm not familiar enough with grep's regex parser to know how it handles that edge case. Presuming those unescaped paren and brackets are fine, his regex searches for:

1. A backslash

2. An opening bracket

3. An opening parenthesis (this is a character set but the only character in it is an opening paren)

4. Any number of any characters

5. A backslash

6. An opening bracket

7. A closing bracket

8. A closing paren (presuming it doesn't have to be escaped when there is no opening paren)

9. A closing bracket (presuming it doesn't have to be escaped when there is no opening bracket)

10. Any number of character that are not a closing paren or closing bracket

11. The end of the line

Basically he is looking for a string that looks like:

\[(AAAAA\[])]AAAAA

Looks like a regex to me, and it looks like this regex also doesn't escape closing paren/brackets that don't have an opening paren/bracket, so I'm guessing that he knows what he is doing and his regex is fine. Maybe he was playing regex golf?
[[User:Cmancone|Cmancone]] ([[User talk:Cmancone|talk]])cmancone

Ninjaed by Cmancone, above. I agree with that result in every respect except for the start-of-string being potentially anything, but putting my own analysis in here because it took long enough to type!
Depth-of-backslash might depend upon depth of utility. In Perl, <nowiki>''</nowiki>-quotes (among others) treat everything within as literal whilst ""-quotes (and variations) interpolates any special characters, variables, etc that you put in it. (Search for "Quote and Quote-like operators" in your favourite PerlDocs source.) '\sss' is a literal backslash followed by three 's' characters , while "\sss" is the special \s escape (a whitespace) followed by two further regular characters. You might need to define the first when you need to use it to provide a not-previously-escaped \s so that it might be escaped within another context. ''Or'' you define it as "\\sss" (escaped-\) the first time, as equivalent to '\sss'. But '\\sss' would be a literal that, later, could be interpreted as an escaped-\ to the input of a further context where the \s finally becomes 'match a whitespace'.

'\\\sss' would be literal, whilst "\\\sss" could be equivalent to '\ ss' (literal backslash, literal space, rest of characters). Then, instead of literal '\\sss', for some purpose, you could interpolate two escaped-backslashes "\\\\sss"... and so on.

Meanwhile I ''think'', just from visual inspection, "'''\\\[[(].*\\\[\])][^)\]]*$'''" in Bash should obey the interpolation rules quite nicely. The first two characters must be a literal backslash (from the escaped-backslash) and a literal open-square bracket (again, escaped). The next open-square and the close-square shortly after depict a character class that contains only an open-parenthesis, and could have been written as '''$'''.

The '''.*''' indicates zero-or-more (the asterix) instances of ''any'' character (the dot). There is then a literal backslash (from the next '''\\''' duo) and a literal open-square (the '''\[''' pair) and close-square (the '''\]''' pair). The ''')''' is literal and does not need escaping (as a parenthesis group had not yet been opened), as is the next ''']''' character. To be sure, I would have written these two as the pair escapes '''$\]''', but horses for courses...

Then there's another character class (the next '''[''' and the final ''']''') required zero-or-more times (the asterix) to use up all the rest of the characters to the end (the ending '''$''' character). As there was no '''^''' character (a.k.a. caret/circumflex/etc) at the start, the match isn't bothered about what unmatched characters appear before the original '''\('''. This character class, however, starts with a '''^''' which in this context (the very first character of a character-class definition, not somewhere where an entire match-string starts) indicates negation of the following selection, so it is all characters ''but'' those specified, which is the regular close-parenthesis and (because it needs to be contained within a '''[]''' pair) the escaped close-square.

So, all matching strings must start with '''\[(''', i.e. the backslash, open-square and open-paren. They can continue with ''any'' further text, before then having a '''\[])]''', i.e. backslash, open-and-close-squares and close-paren, close-square. After this, the match continues just as long as there are no non-closing square/classic brackets before the ending.

The minimum matching literal string would be '''\[(\[])]''' with longer variants being of the form '''X\[(Y\[])]Z''' where X and Y can be replaced by anything (or be absent), and Z can be replaced by anything (or absent!) ''so long as it doesn't contain possibly relevent close-brackets!''. The latter stipulation is likely because the Y (and X) ''is'' allowed to contain these characters, and for some reason you don't want to confuse the test by finding some other '''\[])]''' segment within the X/Y-zones. (In this context, it doesn't actually seem to matter too much. But it might do in ways I haven't spotted or just be a hang-over from a prior permutation of the test.)

The "grep -o" function is working on the output to the file being '''cat'''ed (there are alternate ways of doing this that some people might prefer), to only accept the lines in the file that match the '''X\[(Y\[])]Z''' string. These lines would appear to be lines of out.txt (a fairly generic name that reveals little to its original purpose) that are well-formed for some other purpose. A safety-escaped (i.e. not to be taken literally by any simple parser) '''[]'''-grouping containing a '''()'''-group (''not'' escaped, perhaps reasonably in context) containing potentially random text followed by an empty '''[]''' pair (again, safety-escaped). Depending on the source, the empty '''[]'''-pair could mean many things, as with the other layers. And the lines may end with any further text.

The "out.txt" file might be the result of a prior Grep (string-search function) quote possibly scanning code for lines of particular importance by another pattern and dumping the results to out.txt for further perusal. And then Randall finds the need to dig further into the first result by extracting just those already selected that all have the '''X\[(Y\[])Z]'''-ish pattern to them.

But I could be wrong, and that's way too long for an official explanation.
(Perhaps just something like the penultimate paragraph, if we're not entirely mistaken?) [[Special:Contributions/162.158.152.89|162.158.152.89]] 14:14, 3 February 2016 (UTC)

The regex is supposed to be looking for:
\\\ backslash
[[(] [ or (
.* any character (repeated 0 or more times)
space space
\\\ backslash
[[\])] probably meant to match either [, ] or ). However, it's not correct, it instead matches the literal characters [)]
[^)\]]* probably meant to match any character that isn't ) or ], repeated. Instead it means one character that's not a ), and then a ] zero or more times
$ end of string

The first problem is that you're not supposed to escape ] in a [...], and it also has to be first in the grouping (unless negated with a ^) It should be [][)] or something similar.
The second problem is the same. The last bit should be [^])]*$ and not [^)\]]*$. [[User:Khris|Khris]] ([[User talk:Khris|talk]]) 14:24, 3 February 2016 (UTC)

I was reading through the regex, if using grep you run into an error with an unmatched ")". Removing this gets a string such as \[(AAAAA\[]]AAAAA$ http://regexr.com/3cng8 [[Special:Contributions/162.158.214.230|162.158.214.230]] 14:42, 3 February 2016 (UTC)

The regex relies on several special cases (*surprise*).
First: bash double-quote expansion (see [https://www.gnu.org/software/bash/manual/html_node/Double-Quotes.html#Double-Quotes]). Perhaps non-intuitively, \\\ followed by a character that \ doesn't escape is an escaped backslash followed by a literal backslash, effectively the same as \\\\ followed by that same non-escaped character. After bash double-quote expansion, this results in:

\\[[(].*\\[\])][^)\]]*$

grep interprets this as:

# any leading non-\ characters
# literal backslash
# character class containing [ and (
# zero or more *any* characters
# another literal backslash
# yet another literal backslash, via a character class containing only a backslash. Note this does not contain an escaped ], as it might appear at first glance. See [http://www.gnu.org/software/grep/manual/html_node/Character-Classes-and-Bracket-Expressions.html]
# literal )
# literal ]
# character class of anything except ), \
# zero or more ]
# end of line

Matching examples:
*echo 'asdf\[asdfasdf\\)]a]]]]]]' | grep -o "\\\[[(].*\\\[\])][^)\]]*$"
*echo '$\$]P' | grep -o "\\\[[(].*\\\[\])][^)\]]*$"

One key thing to understand is that \ is not a special character when it's in a bracket expression - you can't escape characters in bracket expressions. So [^)\] simply means any character other then ) or \. Also, ( and ) are just regular characters unless they are escaped in basic regular expressions - extended regular expressions reverse this rule.
----
[[Special:Contributions/108.162.216.34|108.162.216.34]] 16:14, 3 February 2016 (UTC)rb

I don't know about the regular expression in the title text, but I think the explanation is incorrect in that it starts off talking about regular expressions. Escaping backslashes is an issue with strings in programming in general. [[Special:Contributions/173.245.54.46|173.245.54.46]] 17:12, 3 February 2016 (UTC)
----
I suspect that Randall may have used the regexp in the title text to *find* malformed regular expressions in a file (out.txt) that he (or someone) had previously filled with output from some error message (or collection of error messages, or at least the output of something where a regular expression had been expected to work but had not worked as expected). [[Special:Contributions/162.158.252.227|162.158.252.227]] 19:06, 3 February 2016 (UTC)

Talk:1637: Salt Mine

2016-02-01T17:40:43Z

162.158.252.227: Appreciating how someone salted the page with salt jokes about how the explanation and the comic should be taken. With salt.

I don't think that the exotic restaurants relate, here. As well, I think that Ponytail says "Yes, that is definitely why" because she is saying "Yes, we definitely built the detector here to block out cosmic rays, and definitely *not* to eat the delicious salt." You know what I mean? Thoughts? [[Special:Contributions/173.245.54.21|173.245.54.21]] 06:46, 1 February 2016 (UTC)
: I agree. The comment about restaurants only adds to the potential confusion around the comic. [[Special:Contributions/108.162.216.59|108.162.216.59]] 08:05, 1 February 2016 (UTC)BK201
The science facility in a salt mine made me think of [https://en.wikipedia.org/wiki/Portal_2 Portal 2]. Now i'm wondering if the IMB served as an inspiration for Portal 2. [[Special:Contributions/141.101.104.25|141.101.104.25]] 08:36, 1 February 2016 (UTC)

"The title text is intended to be absurd, and thus humorous." GLaDOS, is that you? (I can't help. As I read this sentence I imagined it spoken by GLaDOS...) [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 08:49, 1 February 2016 (UTC)

Could the salt eating be a reference to TOS: The Man Trap? {{unsigned ip|162.158.90.159}}

Maybe "salt" should taste somewhat appropriate about flavor of subatomic particles and randomness (cryptography) too. [[Rotten Brain]] [[Special:Contributions/162.158.150.221|162.158.150.221]] 14:35, 1 February 2016 (UTC)

Even assuming that's 'low grade' rock-salt, mostly inert rock, the intake would probably exceed the regulatory advice (6g/day over here, I think, but I'd have to look it up to be sure - and that's mostly used up/exceeded with the ''hidden'' salt in prepared meals!). I think that's because of the danger of the sodium excess (hence sodium-free salts, sometimes called "salt-free salt" as it has a different formula to NaCl, sold as being a healthier option). But raw salt ingestion like this would (assuming it doesn't already overload the tastebuds, perhaps because of an extremely over-riding craving?) likely also create problems of extreme and ''active'' dehydration... i.e. like being mummified from the inside-out.

I do know that there ''are'' cravings for minerals (coal, clays, chalk, etc), which can be life-long habits without too many apparent ill effects (perhaps tooth-wearing, primarily) - if not just a strange reaction to pregnancy. If anyone knows of a similarly extreme salt-craving, though, it would probably be worth linking it in so I'm not left thinking that it's a typical "taken to extremes" XKCD comic. [[Special:Contributions/162.158.152.89|162.158.152.89]] 16:42, 1 February 2016 (UTC)

The lines about salt at the end of the explanation ("This explanation should be taken with a grain of salt. This comic should be taken with a grain of salt. Salt.") are the best part, not only of the explainer page but of this comic. The only time I laughed, and I laughed aloud. [[Special:Contributions/162.158.252.227|162.158.252.227]] 17:40, 1 February 2016 (UTC)

1636: XKCD Stack

2016-02-01T00:08:28Z

162.158.252.227:

{{comic
| number = 1636
| date = January 29, 2016
| title = XKCD Stack
| image = xkcd_stack.png
| titletext = This site requires Sun Java 6.0.0.1 (32-bit) or higher. You have Macromedia Java 7.3.8.1¾ (48-bit). Click here [link to java.com main page] to download an installer which will run fine but not really change anything.
}}

==Explanation==
{{incomplete|Needs more detail. The table is great but should be corrected to not refer to a person's view or feelings. ''I think'' phrases are used more than once at the moment.}}

In software engineering, a tech stack is the set of technology platforms and tools that a company or app uses. A common tech stack is LAMP, composed of a Linux operating system, an Apache web server, a MySQL database, and the PHP programming language. In this comic, the XKCD stack is introduced. The technologies comprising it are either non-existent, unreliable, or outdated.

===Explanation of steps===
{| class="wikitable"
| | Layer
| | Explanation
|-
| |
EBNF/CSS
| |
BNF or {{w|Backus–Naur Form}} is a syntax used for describing {{w|context-free grammars}}.
{{w|Extended Backus–Naur Form|EBNF}} is "Extended BNF", it is the same thing as BNF with a few more syntactic constructs intended to ease its use in the most common cases. [[1343: Manuals]] mentionned EBNF.

CSS or {{w|Cascading Style Sheets}} are a language used to describe what a web page should look like. Web pages are usually written in {{w|HTML}}, which describes the ''structure'' of the page (i.e. divides the document into paragraphs, lists, etc.) complemented with CSS which describes the ''look and feel'' of the page (colors, fonts, margins, etc.). EBNF/CSS would suggest CSS with strange syntax.
|-
| |
Broken Java Applet
| |
In recent years it has become more difficult to run {{w|Java (programming language)|Java}} {{w|Applet|applets}} in several browsers. {{w|Google Chrome|Chrome}} 45 stopped supporting {{w|NPAPI}}, {{w|Mozilla Firefox|Firefox}} will drop support by 2016, and {{w|Microsoft Edge|Edge}} does not support NPAPI plugins at all. Furthermore, two days before this comic was published {{w|Oracle Corporation|Oracle}} (the developer of Java) announced plans to officially end support of Java applets in an upcoming version.
|-
| |
Archive.org Mirror
| |
{{incomplete|It could simply man that archive.org is the mirror}}

{{w|Internet Archive|Archive.org}} is a website which archives websites, and created the {{w|Wayback Machine}}.An Archive.org mirror would be the copy of xkcd on Archive.org.
|-
| |
Hypercard.js
| |
{{w|HyperCard}} can be considered as a kind of predecessor for the world wide web developed at {{w|Apple Inc.|Apple}}. The file extension .js indicates that is was rewritten in {{w|JavaScript}}. A similar reference to JavaScript is found in [[1508: Operating Systems]]. The .js extension also refers to node.js, where most library names end in .js
|-
| |
QBasic on Rails
| |
A mix between {{w|QBasic}} and {{w|Ruby on Rails}}. {{w|BASIC}} is a programming language that was very widespread during the 80s. QBasic is an implementation of BASIC created by Microsoft in early 90s, that, among other things, added support for {{w|structured programming}}. QBasic, lacking several of the things present on modern computer languages, is known for its spaghetti code. {{w|Ruby (programming language)|Ruby}} is a rather modern language, often used with Ruby on Rails web application {{w|Software framework |framework}}. QBasic on Rails would likely mean a port of Ruby on Rails, replacing Ruby with QBasic. QBasic no longer runs on modern computers, however there are a couple of free {{w|open source}} implementation of QBasic, one being [http://www.qb64.net/ QB64] and the other [http://www.freebasic.net/ FreeBASIC], which are available for Windows, Linux, Mac, and Android. There also exists a webserver on BASIC called [http://www.runbasic.com/ RunBasic].

|-
| |
[Blocked by AdBlocker]
| |
{{w|Ad blocking}} software are extensions to browsers that try to remove ads from web pages, so the user is not distracted by them. [[624: Branding]] shows what "browsing without adblock" looks like. The joke is that AdBlocker is preventing us from seeing what makes up this portion of the stack. Additionally, some websites insert advertisements in the middle of their lists and tables, so an AdBlocker would remove such advertisements, leaving a blank space in the middle of the table.
|-
| |
MongoDB/Excel
| |
{{w|MongoDB}} is a modern {{w|NoSQL}} {{w|Database|database}} system, {{w|Microsoft Excel}} is a {{w|Spreadsheet|spreadsheet}} program from Microsoft, which is sometimes misused as a database system.

|-
| |
Some piece that works so nobody asks any questions
| |
Writing any non-trivial piece of software always require a phase of {{w|debugging}}, which consists in finding and fixing {{w|Software bug|bugs}}. With complex software, this is a long and tiring process, so when the product is finally finished no one dares to modify it any further for fear that it will fail in unexpected ways. After some time passes, it is even worse because nobody really remembers how the software was ''supposed'' to work, so the product becomes some kind of godlike treasure which must be treated with the utmost respect and reverence because, you know, if it stops working we're all doomed ([[1421: Future Self]]). After completion, {{w|Refactoring}} is the process of rewriting code for greater efficiency or reliability. However, if the performance is not 'too bad' (i.e. not unusably terrible in normal use) there is a great temptation to avoid this, in favour of the 'if it ain't broke, don't fix it' methodology. This could lead, for example, to a trained monkey and an abacus being used to crunch numbers. It works, but could be done far better. However, nobody wishes to change it, for fear of breaking a presently functional, if inefficient, system.
|-
| |
Triply-Nested Docker
| |
{{w|Docker (software)|Docker}} is a {{w|Operating-system-level virtualization|software container}}, which is a way that allows a complete operating system to run under different operating system (OS) (as long they share the same kernel, among other things). Triply-nested docker would mean OS A running under OS B running under OS C running under OS D (running under OS E?). That would likely be a performance and management nightmare
|-
| |
Paravirtual Boy®
| |
This is a reference to the {{w|Virtual Boy}}, a failed portable console created by {{w|Nintendo}}. {{w|Paravirtualization}} is a common buzzword in the virtualization community these days. "Virtual X" means simulated X. "Paravirtual X" means X is simulated, but is aware of simulation and cooperating, for faster performance.
|-
| |
A dev typing real <nowiki>[sic]</nowiki> fast
| |
A dev is a {{w|Software developer|software developer}}. This is possibly a reference to [[341: 1337: Part 1]], where [[Mrs. Roberts]] edits the {{w|Transmission Control Protocol|TCP}} stream live while wearing oven mitts and baking cookies. Such a feat would require really
fast typing. It looks like the xkcd Webserver is not a computer after all -- we have a person manually replying to HTTP protocol queries. Such a feat would indeed require real fast typing.

|-
| |
Older version of our software
| |
People are often reluctant to switch to newer versions of software because, even though newer versions are supposed to have more features and fewer bugs, they end up confusing users. Users of older versions are used to doing everything with less features and circumventing old bugs. They don't know how to use the new features, which of course come with new bugs they haven't learned how to circumvent yet. It is also often the case that newer versions remove weird unused old features, breaking the workflow of users who actually did use such features and are left without a suitable replacement ([[1172: Workflow]]). Alternately, since higher parts of a stack are dependent on lower parts, this could also be a reference to how the consumer versions of Microsoft Windows (3.x, 95, 98, and ME) ran on the "older version" software Microsoft DOS until Windows XP.
|-
| |
Mystery Networking Horror
| |
Randall suggests here that the whole networking stuff behind the XKCD service is both mysterious (no one actually knows the details) and horrific (technically questionable architecture and implementation, or somehow tentacled and eldritch in nature).
|-
| |
Microsoft Bob Server®
| |
{{w|Microsoft Bob}} was a short-lived, failed attempt by Microsoft, around 1995, to provide a user-friendly interface for the {{w|Microsoft Windows|Windows}} 3.1x, Windows 95 and Windows NT operating systems. It consisted of a virtual "house" and "rooms", and the idea was that you could click on a pen and open the word processor. It was heavily criticized and was soon discontinued. Randall seems to be making the suggestion the Bob has continued to be developed and now there's a Bob Server, similarly to Windows server.
|-
| |
A giant {{w|Central processing unit|CPU}} someone built in Minecraft
| |
{{w|Minecraft}} is a popular sandbox game where you place blocks to build things. Since the introduction of Redstone objects (materials used to create basic electric circuits within the game) people have made many machines within Minecraft, including calculators and clocks. The most complex of these machines simulate simple computers, capable of storing several lines of code and performing basic mathematical operations such as division, which requires thousands of blocks and extremely complex designs.
|}

The title text contains several jokes about the Java programming language:

* First, it refers to Java both as {{w|Sun Microsystems|Sun}} Java and {{w|Macromedia}} Java. This is a pun on the fact that older documents refer to "Sun Java" where newer documents refer to "{{w|Oracle Corporation|Oracle}} Java", as if there were two different languages. The fact is that Java was designed originally by Sun and then bought by Oracle, so it "changed name" even though the language is the same. Macromedia was the company that developed Flash before it was bought by Adobe. Both Flash and Java were popular in the early WWW to have interactive web pages, but both are being deprecated in favor of JavaScript.

* Second, the version numbers: older software products used to have two version numbers: major and minor (e.g. in {{w|MS-DOS}} 6.22 the major number is 6 and the minor is 22). Newer products tend to have hundreds of minor revisions, all of them numbered, so a typical user may well find themselves updating version 6.0.0.1 to 7.3.8.1 without knowing at all the differences between both versions or which other versions are in between. The ¾ in the Macromedia Java version is a joke on complex version numbers, which (so far) have never included fractions.

* Third, the 32-bit or 48-bit version: The {{w|Intel 80386}} processor used an architecture known as {{w|IA-32}}, which implies the data bus is 32-bit wide and thus able to handle up to 4{{w|Gibibyte|GiB}} of {{w|Random-access memory|RAM}} memory. This was plenty for the early 1990s, when a typical home PC would have about 8MiB (this is 512 times less than 4GiB). However, about 10 years after that, a typical home PC could well use more than 4GiB of RAM, so several 64-bit architectures were created. These architectures are not compatible, so programs (including the Java Runtime Environment, or JRE) often have 32-bit and 64-bit versions. Furthermore, the JRE is heavily used by many web browsers, and for this to work the JRE and browser need to be the same "number of bits". This means that most people have installed both versions of the JRE to be able to use it with both 32-bit and 64-bit browsers. There's no 48-bit architecture (though some 64-bit processors including the {{w|x86-64|most common ones}} don't actually use all 64 bits everywhere, ignoring some bits so actual virtual or physical memory is smaller (in the case of the most common ones, 48bits virtual and 40bits physical), they simulate a full 64-bit environment to allow adding more bits later, so there are no specific 48-bit applications).

* Fourth, an application trying to let the user install a new version of the JRE should direct the user to the download page in the [http://java.com/ java.com site], not to the main page which deals with lots of issues with java and is not particularly helpful when trying to update the JRE.

* Fifth, and continuing with the joke of users updating from 7.3.8.1¾ to 6.0.0.1 and not knowing why they should, the new version is said to "run fine but not really change anything". This is the usual behavior for Java updates: they run fine (possibly in opposition to [[1197: All Adobe Updates]], where updating must be done several times and the user is never sure they have installed all the newest updates), but after finished updating the user can't see any difference with the previous behavior, and/or may still be told that an update is required. Considering that 7.3.8.1¾ is bigger number than 6.0.0.1, it can also refer to the fact that the test for upgrading is incorrect and 7.3.8.1¾ is actually newer version.

* Sixth, Macromedia was a multimedia software company in the 90s that originally developed Flash, a popular plug-in similar to Java. Adobe purchased Macromedia in 2005.

==Transcript==

:Introducing

:The XKCD Stack
:{| class="wikitable"
| |
EBNF/CSS
|-
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Broken Java Applet
|-
| |
Archive.org Mirror
|-
| |
Hypercard.js
|-
| |
QBasic on Rails
|-
| |
[Blocked by AdBlocker]
|-
| |
MongoDB/Excel
|-
| |
Some piece that works so nobody asks any questions
|-
| |
Triply-Nested Docker
|-
| |
Paravirtual Boy®
|-
| |
A dev typing real fast
|-
| |
Older version of our software
|-
| |
Mystery Networking Horror
|-
| |
Microsoft Bob Server®
|-
| |
A giant CPU someone built in Minecraft
|}

{{comic discussion}}

[[Category:Computers]]
[[Category:Programming]]
[[Category:Video games]]

Talk:1633: Possible Undiscovered Planets

2016-01-22T23:41:51Z

162.158.252.227:

Why is it late? — ''[[User:Tbc|tbc]] ([[User talk:Tbc|talk]]) 16:57, 22 January 2016 (UTC)''
:No idea but it's weird. [[User:SuperSupermario24|Just some random derp]] 18:08, 22 January 2016 (UTC)

Why is Earth's "Distance from me" 10000km? -- ''19:26, 22 January 2016 (UTC)''
:The diameter of Earth is ~12000km and distances are measured from the center of the object (that why there is a "Planet ruled out because I would be inside them" zone). I suppose Earth should be placed at a distance of 6000km instead of 12000k (as it is the radius, not the diameter that matter here). [[Special:Contributions/141.101.66.11|141.101.66.11]] 19:43, 22 January 2016 (UTC)
::Earth's distance seems to be to the left of the 10Mm marker on the distance line, to me, although it's hard to tell without a straightedge. Remember the plot is diameter to distance. [[Special:Contributions/108.162.238.71|108.162.238.71]] 19:52, 22 January 2016 (UTC)

This comic bothers me because the diagonal line with Earth on it cannot possibly represent what it claims. Zero cannot be plotted on the X-axis with this log scale. The entire "I would be inside of them" region is bogus. [[Special:Contributions/188.114.106.83|188.114.106.83]] 19:42, 22 January 2016 (UTC)
:Not if you're measuring to the center of the planet. [[Special:Contributions/108.162.238.71|108.162.238.71]] 19:52, 22 January 2016 (UTC)
:Also, please sign your comments. I had to sign this one for you. [[Special:Contributions/108.162.238.71|108.162.238.71]] 19:54, 22 January 2016 (UTC)
:OK, it does make sense if you take the normal convention of arrival and turn it into total core penetration. Sorry about the signing thing. I never use this and wondered where the input for it was. I see now from googling around that you just put it at the end. [[Special:Contributions/188.114.106.83|188.114.106.83]] 20:00, 22 January 2016 (UTC)

Planets ruled out because we could see them during the day = Stars? [[Special:Contributions/162.158.56.5|162.158.56.5]] 21:10, 22 January 2016 (UTC)
: Only stars that are close enough to see during the day. Actually, there's one star that ''is'' close enough that we can see it during the day, although for some reason Randall did not mark it on the chart: our Sun. (Every other star is so far away that it's off the chart.) —[[User:TobyBartels|TobyBartels]] ([[User talk:TobyBartels|talk]]) 21:34, 22 January 2016 (UTC)
::I added the stars statement before reading your comment. Feel free to edit it.
::And I agree that it's strange that Randall didn't mark the Sun. Furthermore, the Sun fits the Greek definition of planet. In fact, it fits any definition of planet better than birds or planes.--[[User:Pere prlpz|Pere prlpz]] ([[User talk:Pere prlpz|talk]]) 21:57, 22 January 2016 (UTC)

: No not stars, this is just about planets -- you can see the moon in the day when in the right position compared to the sun. You would be able to see any planet during the day if the circular surface was sufficiently big, and with a planetary body that is a function of the size over the distance squared -- the moon is just so close that it does not have to that big [[Special:Contributions/162.158.255.109|162.158.255.109]] 22:25, 22 January 2016 (UTC)

:: So shouldn't the "during the day" section be sloped, and include the moon? --[[Special:Contributions/162.158.252.227|162.158.252.227]] 23:41, 22 January 2016 (UTC)

I think Randall means "TENTH planet". 22:58, 22 January 2016 (UTC)

928: Mimic Octopus

2016-01-22T05:12:05Z

162.158.252.227: /* Explanation */

{{comic
| number = 928
| date = July 22, 2011
| title = Mimic Octopus
| image = mimic_octopus.png
| titletext = Even if the dictionaries are starting to give in, I refuse to accept 'octopi' as a word mainly because--I'm not making this up--there's a really satisfying climactic scene in the Orson Scott Card horror novel 'Lost Boys' which hinges on it being an incorrect pluralization.
}}

==Explanation==
This comic is a parody of fish and sea-life identification charts, referencing the {{w|mimic octopus}} which, as the name implies, is able to mimic other animals. The creatures the octupus mimics include tuna, a clownfish, a lionfish, a shark, what appears to be a crinoid, an angler fish, an anchor, a submarine, a scuba diver, multiple fish, and a single octopus.

The {{w|Orson Scott Card}} novel that the title text refers to is ''{{w|Lost Boys (novel)|Lost Boys}}'': "A withdrawn eight-year-old in a troubled family invents imaginary friends who bear the names of missing children" (Publisher's Weekly). The part of the story that Randall is referring to (Chapter 7, Crickets) involves a situation where the protagonist, Stewie, is given a C grade for an otherwise impeccable diorama featuring underwater animals involving clay sculptures (when only a poster would have sufficed) and a well-written presentation supposedly because the other children had destroyed the diorama before the end of the day. To make matters worse, his teacher, Ms. Jones, had made fun of his project and given the ribbon for first prize to someone else.

On enquiring about, his father, Step, found out that the principal, Dr. Mariner, had already made the decision to hand Stewie the blue ribbon for first prize as she had reviewed the project before it had been destroyed, but Ms. Jones had secretly overruled her behind her back by announcing that another child (JJ) would receive the ribbon. So, the next day he met up with Ms Jones after school to have a word on the grading of his project. Needless to say, they ended up arguing about minor issues, with Mrs Jones justifying the reason for her decision on, among other things, the definition of a 'depiction', whether or not the amount of content was defined by the word count or the number of pages and of the importance of putting the report in a plastic cover. The argument finally comes to a head when Step points out that there was only one red mark on the project report, and that concerned an 'incorrect' pluralisation of the word 'octopus'

:“But Mrs. Jones, surely you know that the plural of “octopus” is either ‘octopus’, with nothing added, or ‘octopuses’.”
:“I think not,” said Mrs. Jones.
:“Think again, Mrs. Jones.”
:She must have realized that she was not on firm ground here. “Perhaps ‘octopuses’ is an alternate plural, but I’m sure that ‘octopi’ is the preferred.”
:“No, Mrs. Jones. If you had looked it up, you would have discovered that ‘octopi’ is not the preferred spelling. It is not a spelling at all. '''The word does not exist, except in the mouths of those who are pretending to be educated but in fact are not.''' This is because the ‘us’ ending of ‘octopus’ is not a Latin nominative singular ending, which would form its plural by changing to the letter ‘i’. Instead, the syllable ‘pus’ in ‘octopus’ is the Greek word for ‘foot.’ And it forms its plural the Greek way. Therefore ‘octopoda’, not ‘octopi’. Never ‘octopi’.”
:“Well, then, octopoda. Your son’s paper said octopuses.”
:“I know,” said Step. “When he asked me the correct plural, I told him octopoda. But then he was still uncertain, because my son doesn’t think he knows something until he knows it, and so he looked it up. And to my surprise, octopoda is only used when referring to more than one species of octopus, rather than when referring to more than one actual octopus. What Stevie put in his paper is in fact the preferred dictionary usage. Which you would have known, too, if you had looked it up.”

After proving his case that his son did indeed deserve an A grade, he then threatened to bring the matter to the attention of the principal. He then warned Mrs Jones that while he wanted the grade to remain unchanged, he wanted her to inform the class that the ribbon would be awarded to Stewie, before revealing that he had been recording the conversation all along. And, after this, after Mrs Jones came crying for forgiveness before leaving, Step realised how vulnerable she was and how she was channelling her frustration at one particular student in each class to find some relief from that.

According to the [http://www.youtube.com/watch?v=wFyY2mK8pxk Merriam-Webster Dictionary], 'octopi', 'octopuses', and 'octopodes' (UK English) are all correct plural versions of "octopus." Supposedly, Randall would very much like the word 'octopi' to remain unrecognised by major dictionaries as otherwise it would lessen the magnitude of the climactic conclusion of this argument by rendering Step's mockery of Ms. Jones' perceived intellectual superiority factually invalid.

==Transcript==
:Southeast Asian Sea Life
:Identification Chart
:[There are silhouettes of eight individual fish, a school of fish, a scuba diver, an anemone, a submarine, and an anchor, each labeled "Mimic Octopus." There is also a silhouette of an octopus, labeled "Two Mimic Octopuses."]

{{comic discussion}}
[[Category:Charts]]
[[Category:Biology]]