The Whiteboard

user20683

12:00 AM

@evinda it's usually O(|V| + |E|) like most graph operations

evinda

@WorldEngineer How can we find how many times the for loop:
For each list x in X:
Add [v, x] to the set Y
is executed?

user20683

@evinda how would you find out how many times any given operation is executed in anything?

user20683

Like if I had an array and I traversed that array, how would I get the computer to tell me when it had moved from one cell to the next?

evinda

@WorldEngineer So do we suppose that at each iteration we get a new list? If so, is it executed at most O(|V|^2) time? Or am I wrong?

user20683

@evinda would recommend asking on CS.SE's chat if you want a rigorous proof

evinda

12:07 AM

@WorldEngineer Ok.. And if I want to use a nxm array instead of lists, where n is the number of topological sortings and m=|V|, how could I do this?

user20683

@evinda Assuming I'm understanding you correctly, you want all possibly orderings of a graph

evinda

@WorldEngineer Right.

user20683

that's getting into NP complete territory

user20683

so O(2^|V|) or there abouts if I had to ballpark it

user20683

It's going to be very, very slow. Speeding it up is still an active area of research

user20683

12:19 AM

in any case, I need to go

user20683

best of luck

evinda

12:56 AM

Thank you :)

user55340

1:32 AM

@AshleyNunn Gotta talk to the right people.

user15026

1:49 AM

@michaelT she isn't in Canada anymore, and is a dev, so less useful for my purpose.

user15026

:)

user55340

user15026

Me? Never! I am Canadian! We are too polite for that!

psr

Which may be a flaw in this plan. Of all the peoples on Earth, Canadians might need the least moderation.

user15026

No, because if someone brings up their hockey team....

user20683

1:54 AM

@AshleyNunn or Quebec Separatism

user15026

Yikes, that too

user20683

Older Southerners sometimes speak like that

user20683

"Would you kindly"

user15026

You don't really hear it here.

Jimmy Hoffa

@AshleyNunn I love how Canadians are so polite, they don't even take offense at their being stereotyped as polite. Americans take offense at stuff they know beyond a shadow of a doubt to be true all the time

user15026

1:59 AM

@JimmyHoffa we know ourselves :p

Jimmy Hoffa

@AshleyNunn until you guys get on a hockey rink, then it's like all the stress from endless politeness gets released all over your enemies faces

user15026

Yeah, exactly! Why do you think we are so good at it? It's all that politeness.

psr

@JimmyHoffa LIAR!

Jimmy Hoffa

@psr Tuoche Mister Bond

user20683

@JimmyHoffa treason!

user20683

2:14 AM

mister bond isn't even American

user55340

2:39 AM

@WorldEngineer J.

user55340

Men In Black [1997] Agent J HD

►

Jimmy Hoffa

3:08 AM

@WorldEngineer sure he is, you think anyone else would have so many ephemeral gadgets? Pah!

gnat

10:24 AM

11

Q: Increase the Hot Network Questions randomness (proposal for testing)

Related: Ease up on the Hot Network Question Randomness. This is a recent change which resulted in a 30% increase in engagement. All of this engagement came from repeated clicks... we do have improved algorithm changes coming... Some questions appear to stick in the hot list for quite a l...

^^^ 200 meta poos wait for someone to answer

Yannis Rizos

@evinda Ναι, από Θεσσαλονίκη. Εσύ;

evinda

12:29 PM

@YannisRizos Από Κρήτη

enderland

1:11 PM

@durron597 I think it's probably a good idea, not sure the best way to do it

I"ve been trying to slowly change my lifestyle though - recognizing that changing something which for me has been a complete life pattern dramatically will be difficult to sustain

Jimmy Hoffa

1:24 PM

Colleague was asking why people don't use structs for dumb property-bag type models in web development the other day, I wrote this fun little example reminder for people of why most devs should stay the hell away from structs in .NET - not because they're bad, but because this little behaviour is something most folk never think about or expect: dotnetfiddle.net/NtBZLC

enderland

translate Ναι, από Θεσσαλονίκη. Εσύ

translate: Ναι, από Θεσσαλονίκη. Εσύ;

(from Greek) Yes, from Thessaloniki. Thou?

Ixrec

@JimmyHoffa I've never done C#, so...a struct gets pass-by-value semantics while a class gets pass-by-reference semantics?

Telastyn

yeh

evinda

1:44 PM

@enderland Google translate? ;)

Jimmy Hoffa

@Ixrec yeah, but structs are so rare in .NET that pass-by-value semantics are extremely unexpected by the vast majority of folk; usually structs in .NET are created by people who don't know the difference between structs and objects and have some errant thought that tells them "This thing is real simple, structs are simpler than classes right? So I should create this thing as a struct right?" without any knowledge of what you just described

Ixrec

I guess it doesn't help that in C++ they actually are almost identical

Jimmy Hoffa

@Ixrec in .NET they are too, but people have this idea that objects are somehow extended with greater OO-mojo over structs

Ixrec

I would consider pass-by-value versus reference a pretty huge difference

Jimmy Hoffa

so they assume structs are for simple things, when in fact there's nothing you can do in an object you can't in a struct that I can think of offhand (@Telastyn that right?)

@Ixrec it is, but I mean in what you can create with a struct. They can have generics, they can have interfaces, they can have publics and privates and methods and complex inheritance hierarchies

.NET folk tend to presume structs can't do all of that stuff because that's "OO" and structs are pre-OO, right? right?

Ixrec

1:52 PM

yeah

iirc virtual methods are the only thing that actually adds something to the "shape" of the class/struct in memory, right?

Jimmy Hoffa

@Ixrec not sure I understand the comment? Also don't think I'm familiar with virtual methods having some interesting effect?

Ixrec

I'm thinking of C++ where virtual methods require the implementation to add a vtable to every object

and every other OOP feature is just compile-time magic which doesn't cause the object itself to contain anything new or special

Jimmy Hoffa

@Ixrec oh, in .NET every object has a vtable I believe

Ixrec

ah right

is there a way to ask it not to do that?

Jimmy Hoffa

@Ixrec you can do interesting things with structs, you might be able to do that? Actually I'm not certain structs have them off hand.. you can fiddle with the alignment and packing on structs if you really want I know

16

A: Performance of "direct" virtual call vs. interface call in C#

I think the article at http://msdn.microsoft.com/en-us/magazine/cc163791.aspx will answer your questions. In particular, see the section Interface Vtable Map and Interface Map, and the following section on Virtual Dispatch. It's probably possible for the JIT compiler to figure things out and opt...

Interfaces are the one special case I know about for that sort of thing as described there

but there's links in there that describe the vtable behaviours better than I know, what I know of internal layouts is just from debugging memory dumps

not really information that you need to rely on much

Telastyn

2:10 PM

Yeah, there are limitations on structs. I don't remember exactly what they are though.

Mostly on inheritance and constructors.

Not like Scala traits and stuff like that which are really constrained.

Jimmy Hoffa

@Telastyn oh, maybe they can't inherit objects?

Telastyn

They cannot be inherited from
You cannot define your own nullary ctor.

Jimmy Hoffa

and constructors? hmm I don't get that one. Must have parameterless because they're value types and thus don't need initialization?

Telastyn

So says the Internet.

Jimmy Hoffa

@Telastyn oh that makes sense, they have a default value type nullary ctor

Telastyn

2:14 PM

Yeh, which iirc is just "bzero this block of memory"

Jimmy Hoffa

yeah exactly

ah no inheritance, only interfaces...really? I thought I remembered seeing someone do inheritance with structs before, whatever

Duga

3:45 PM

Probably more on-topic at programmers.stackexchange.com — cfh 49 secs ago

I'm voting to close this question as off-topic because it isn't a technical programming question. It would probably be too broad on Programmers too... — Jon Skeet 1 min ago

user55340

4:02 PM

-2

Q: working from home as a programmer

ok, this might be a dumb question and probably not the right place to ask, but I couldn't find a better option. I wanted to know about all kinds of programming jobs one can do from home (or any other place on the globe for that matter). I'm not talking about a full time job or a regular job where...

jobs

user55340

Umm... No.

Duga

@JonSkeet yes, this question is a very poor fit for Programmers - it would be quickly voted down and closed over there, see meta.programmers.stackexchange.com/a/6488/40980 Recommended reading: What goes on Programmers.SE? A guide for Stack Overflow — gnat 6 secs ago

user55340

4:17 PM

So, what are the best Webmaster tools... lets ask Bing: bing.com/search?q=webmaster+tools

Ixrec

4:39 PM

when someone posts a late answer that basically repeats an existing high-quality accepted answer, are we supposed to tell them that's not helpful in some way or just leave it alone? (I normally do the latter)

...oh, it was an audit based on one of the original high-quality answers

ugh

MetaFight

I typically find their snail mail address and send them some of my dirty laundry. Once a day. For about a year.

gnat

@Ixrec I for one add a comment, "that basically repeats an existing high-quality accepted answer" and link to the earlier answer (to make it easier for other readers check after me). After that, I vote down. Sometimes I also flag but it's often difficult to decide whether particular case is flag-worthy (of course except for clear plagiarism)

Ixrec

@gnat sounds good, even if I accidentally told Doc Brown off for plagerizing his own answer I could easily undo that after the audit reveals itself

evinda

5:15 PM

@YannisRizos Είσαι προγραμματιστής;

Jimmy Hoffa

@MichaelT I just read this

29

A: What goes on Programmers.SE? A guide for Stack Overflow

What is a good question? A good question on Programmers.SE would be a good question on Stack Overflow. This isn't to say that if it is on topic on Stack Overflow it is on topic here. Rather that it's not too broad, not opinion, and not unclear. If you have the slightest inkling of closing the ...

Really great

One of the clearest things I've read describing what does belong on P.SE in a short concise way

Yannis Rizos

@evinda I pretend to be ;) (let's switch to English for the benefit of our non Greek speaking friends in here)

user55340

@JimmyHoffa I've got that section in there about it... we far too often get "not code, migrate to programmers" suggestions via Duga... so I wrote that.

user55340

5:31 PM

@YannisRizos I thought you were writing Haskell code there.

user55340

@YannisRizos btw if you handled that "maybe two accounts" flag...

user55340

-6

Q: What does `void` mean in Java?

I'm currently learning Java and learned about int and double. Those are numbers, and I get them. However, I stumbled upon void, and I don't really know what this means. So what does void mean in Java?

java

Yannis Rizos

Nope.

user55340

Oh well... you had the final vote on the delete for this programmers.stackexchange.com/questions/280544/…

user55340

Which had a revision of:

user55340

5:34 PM

> What does void means. Sorry for asking this question because I'm just a beginner

user55340

by:

user55340

Noor Shiha

1 3

user55340

And the first post is from:

user55340

Noor Shiha

4

java

user55340

That really looks like the same user to me.

Yannis Rizos

5:35 PM

It probably is.

user55340

I know there was at least one other post from the first linked account...

user55340

(has the peer pressure badge, the post I see isn't deleted by OP)

user55340

I suspect the second account was created to get around a question ban here

user55340

(thats what I was referring to in the flag on the deleted post)

gnat

5:49 PM

@MichaelT this reminds me a guy who complained at MSO that he created five (five) accounts in the row and all of them quickly bumped in question ban

Yannis Rizos

That would be my guess as well. Deleted that -7 question and If he posts again from the second account, he'll probably get banned again (assuming his question is of similar quality to the previous ones).

Yannis Rizos

In other news, I passed 1k rep on Myth.SE. Not bad for a 5 day old site...

user20683

7:46 PM

@GlenH7 humblebundle.com/books

user20683

current bundle is kid's comics

durron597

8:20 PM

I was in the middle of typing my answer when a google employee answered :-/

2

Q: how Gson TypeToken works?

I understand that in Java contrary to, for example, C# generics are compile-time feature and is removed via type erasure. So, how does Gson's TypeToken really work? How does it get the generic type of an object?

java generics gson erasure

user114359

8:58 PM

@durron597 I'm still trying to figure out what is going on in his profile picture: Louis Wasserman

durron597

@Snowman One person is blue skirt maroon shirt he other is red shirt orange skirt

Ixrec

9:27 PM

is anyone else unable to access the Mythology beta's meta site? for the last few days it's always given me a redirect loop error

user114359

@Ixrec I am not in the private beta, I have no idea.

Yannis Rizos

@Ixrec There seem to be some ssl related issues with beta sites. SE didn't quite get https support right.

durron597

@Ixrec I have 15% of the questions in the mythology meta beta... no problems.

Yannis Rizos

What url are you using to access it?

Ixrec

the help > meta link in the top right, typing "meta." into the front of the url in my omnibar, and clicking the meta.mythology link on the main page all do the same thing

ah wait the link on the main page just worked now

so random

durron597

10:23 PM

@YannisRizos grats on being the first to get the ~~10k~~ 1k tools on mythology

Yannis Rizos

11:24 PM

@durron597 Heh, I'm out of deletion votes for the day ;)

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