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  • In what order do people build websites?

    - by Corey
    For a website, you need to have an idea, you need to have a design and you need to have data, events and output, right? Whether it be a blog, web app, Q&A site, search engine... Anyway, that is only slightly related to my question. My question is, when designing a website, providing I know the purpose, what should I start with? Should I start with the CSS, design and look&feel using dummy data first, or should I program in the logic, events and output, and style it later? What is the design process of most websites that are built from the ground up?

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  • Expected time for lazy evaluation with nested functions?

    - by Matt_JD
    A colleague and I are doing a free R course, although I believe this is a more general lazy evaluation issue, and have found a scenario that we have discussed briefly and I'd like to find out the answer from a wider community. The scenario is as follows (pseudo code): wrapper => function(thing) { print => function() { write(thing) } } v = createThing(1, 2, 3) w = wrapper(v) v = createThing(4, 5, 6) w.print() // Will print 4, 5, 6 thing. v = create(7, 8, 9) w.print() // Will print 4, 5, 6 because "thing" has now been evaluated. Another similar situation is as follows: // Using the same function as above v = createThing(1, 2, 3) v = wrapper(v) w.print() // The wrapper function incestuously includes itself. Now I understand why this happens but where my colleague and I differ is on what should happen. My colleague's view is that this is a bug and the evaluation of the passed in argument should be forced at the point it is passed in so that the returned "w" function is fixed. My view is that I would prefer his option myself, but that I realise that the situation we are encountering is down to lazy evaluation and this is just how it works and is more a quirk than a bug. I am not actually sure of what would be expected, hence the reason I am asking this question. I think that function comments could express what will happen, or leave it to be very lazy, and if the coder using the function wants the argument evaluated then they can force it before passing it in. So, when working with lazy evaulation, what is the practice for the time to evaluate an argument passed, and stored, inside a function?

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  • Using T[1] instead of T for functions overloaded for T(&)[N]

    - by Abyx
    The asio::buffer function has (void*, size_t) and (PodType(&)[N]) overloads. I didn't want to write ugly C-style (&x, sizeof(x)) code, so I wrote this: SomePacket packet[1]; // SomePacket is POD read(socket, asio::buffer(packet)); foo = packet->foo; But that packet-> looks kinda weird - the packet is an array after all. (And packet[0]. doesn't look better.) Now, I think if it was a good idea to write such code. Maybe I should stick to unsafe C-style code with void* and sizeof? Upd: here is another example, for writing a packet: SomePacket packet[1]; // SomePacket is POD packet->id = SomePacket::ID; packet->foo = foo; write(socket, asio::buffer(packet));

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  • How to access functions in extended classes efficiently?

    - by nischayn22
    In PHP I have classes as below class Animal { //some vars public function printname(){ echo $this->name; } } class AnimalMySql extends Animal { static public function getTableFields(){ return array(); } } class AnimalPostgreSql extends Animal { static public function getTableFields(){ return array(); } } Now I have an object $lion = new Animal(); and I want to do if($store == mysql) //getTableFields from class AnimalMySql else //getTableFields form class AnimalPostgreSql I am new to OOP and not sure what is the best way to call the method from the specific class P.S. Please leave a note with the answer to explain the efficiency of the approach

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  • Order of executions in C++ streams

    - by Krzysztof Bzowski
    It is obvious that first cout prints 7 7 but why the second one prints 8 8 7 ? Why not 7 8 8? How does such constructions work in c++? int ink(int *x){ *x += 1; return *x; } int main(){ int *a; int b = 6; a = &b; cout << ++b << " " << b << endl; cout << b << " " << ink(a) << " " << b; return 0; }

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  • What can I do in order to inform users of potential errors in my software in order to minimize liability?

    - by phobitor
    I'm an independent software developer that's spent the last few months creating software for viewing and searching map data. The software has some navigation functionality as well (mapping, directions,etc). The eventual goal is to sell it in mobile app markets. I use OpenStreetMap as my data source. I'm concerned about liability for erroneous map data / routing instructions, etc that might result when someone uses the application. There are a lot of stories on the internet where someone gets into an accident or gets stuck or gets lost because of their GPS unit/Google Maps/mapping app... I myself have come across incorrect map data as well in a GPS unit I have in my car. While I try to make my own software as bug free as possible, no software is truly bug free. And moving beyond what I can control, OpenStreetMap data (and street map data in general) is prone to errors as well. What steps can I take to clearly inform the user that results from the software aren't always perfect, and to minimize my liability?

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  • mdadm raid5 recover double disk failure - with a twist (drive order)

    - by Peter Bos
    Let me acknowledge first off that I have made mistakes, and that I have a backup for most but not all of the data on this RAID. I still have hope of recovering the rest of the data. I don't have the kind of money to take the drives to a recovery expert company. Mistake #0, not having a 100% backup. I know. I have a mdadm RAID5 system of 4x3TB. Drives /dev/sd[b-e], all with one partition /dev/sd[b-e]1. I'm aware that RAID5 on very large drives is risky, yet I did it anyway. Recent events The RAID become degraded after a two drive failure. One drive [/dev/sdc] is really gone, the other [/dev/sde] came back up after a power cycle, but was not automatically re-added to the RAID. So I was left with a 4 device RAID with only 2 active drives [/dev/sdb and /dev/sdd]. Mistake #1, not using dd copies of the drives for restoring the RAID. I did not have the drives or the time. Mistake #2, not making a backup of the superblock and mdadm -E of the remaining drives. Recovery attempt I reassembled the RAID in degraded mode with mdadm --assemble --force /dev/md0, using /dev/sd[bde]1. I could then access my data. I replaced /dev/sdc with a spare; empty; identical drive. I removed the old /dev/sdc1 from the RAID mdadm --fail /dev/md0 /dev/sdc1 Mistake #3, not doing this before replacing the drive I then partitioned the new /dev/sdc and added it to the RAID. mdadm --add /dev/md0 /dev/sdc1 It then began to restore the RAID. ETA 300 mins. I followed the process via /proc/mdstat to 2% and then went to do other stuff. Checking the result Several hours (but less then 300 mins) later, I checked the process. It had stopped due to a read error on /dev/sde1. Here is where the trouble really starts I then removed /dev/sde1 from the RAID and re-added it. I can't remember why I did this; it was late. mdadm --manage /dev/md0 --remove /dev/sde1 mdadm --manage /dev/md0 --add /dev/sde1 However, /dev/sde1 was now marked as spare. So I decided to recreate the whole array using --assume-clean using what I thought was the right order, and with /dev/sdc1 missing. mdadm --create /dev/md0 --assume-clean -l5 -n4 /dev/sdb1 missing /dev/sdd1 /dev/sde1 That worked, but the filesystem was not recognized while trying to mount. (It should have been EXT4). Device order I then checked a recent backup I had of /proc/mdstat, and I found the drive order. md0 : active raid5 sdb1[0] sde1[4] sdd1[2] sdc1[1] 8790402048 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU] I then remembered this RAID had suffered a drive loss about a year ago, and recovered from it by replacing the faulty drive with a spare one. That may have scrambled the device order a bit...so there was no drive [3] but only [0],[1],[2], and [4]. I tried to find the drive order with the Permute_array script: https://raid.wiki.kernel.org/index.php/Permute_array.pl but that did not find the right order. Questions I now have two main questions: I screwed up all the superblocks on the drives, but only gave: mdadm --create --assume-clean commands (so I should not have overwritten the data itself on /dev/sd[bde]1. Am I right that in theory the RAID can be restored [assuming for a moment that /dev/sde1 is ok] if I just find the right device order? Is it important that /dev/sde1 be given the device number [4] in the RAID? When I create it with mdadm --create /dev/md0 --assume-clean -l5 -n4 \ /dev/sdb1 missing /dev/sdd1 /dev/sde1 it is assigned the number [3]. I wonder if that is relevant to the calculation of the parity blocks. If it turns out to be important, how can I recreate the array with /dev/sdb1[0] missing[1] /dev/sdd1[2] /dev/sde1[4]? If I could get that to work I could start it in degraded mode and add the new drive /dev/sdc1 and let it resync again. It's OK if you would like to point out to me that this may not have been the best course of action, but you'll find that I realized this. It would be great if anyone has any suggestions.

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  • Common practice for higher-order-polymorphism in scala

    - by raichoo
    Hi, I'm trying to grasp higher-order-polymophism in scala by implementing a very basic interface that describes a monad but I come across a problem that I don't really understand. I implemented the same with C++ and the code looks like this: #include <iostream> template <typename T> class Value { private: T value; public: Value(const T& t) { this->value = t; } T get() { return this->value; } }; template < template <typename> class Container > class Monad { public: template <typename A> Container<A> pure(const A& a); }; template <template <typename> class Container> template <typename A> Container<A> Monad<Container>::pure(const A& a) { return Container<A>(a); } int main() { Monad<Value> m; std::cout << m.pure(1).get() << std::endl; return 0; } When trying to do the same with scala I fail: class Value[T](val value: T) class Monad[Container[T]] { def pure[A](a: A): Container[A] = Container[A](a) } object Main { def main(args: Array[String]): Unit = { val m = new Monad[Value] m.pure(1) } } The compiler complains about: [raichoo@lain:Scala]:434> scalac highorder.scala highorder.scala:5: error: not found: value Container Container[A](a) ^ one error found What am I doing wrong here? There seems to be a fundamental concept I don't seem to understand about scala typeconstructors. Regards, raichoo

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  • Unordered list appears higher than div

    - by LordArmadillo
    I am trying to create a simple page, which I normally can without any trouble. However, the unordered list appears higher up the page than the div. I do know a solution for this, however I cannot remember it. The page goes like this: <style> ul.menu { list-style-type: none; margin:150; margin-bottom:30px; padding:0; display: block; width: 708px; margin-left: auto; margin-right: auto; } li.menu { float:left; display: block; width: 118px; } a.menu:link,a.menu:visited { color:black; display:block; border:1px solid black; background-color:#FFFF00; width:118px; text-align:center; text-decoration:none; font-family:"Courier New", Courier, monospace } a.menu:hover { background-color:#FFBB11; } </style> <div id="head"> My images here & such</div> <ul class="menu"> <li class="menu"> <a class="menu">Main</a> </li> </ul> Normally I welcome suggestions to change my code, but I have a deadline today! So, quick & simple help would be appreciated! Thanks! LordArmadillo

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  • Higher-order type constructors and functors in Ocaml

    - by sdcvvc
    Can the following polymorphic functions let id x = x;; let compose f g x = f (g x);; let rec fix f = f (fix f);; (*laziness aside*) be written for types/type constructors or modules/functors? I tried type 'x id = Id of 'x;; type 'f 'g 'x compose = Compose of ('f ('g 'x));; type 'f fix = Fix of ('f (Fix 'f));; for types but it doesn't work. Here's a Haskell version for types: data Id x = Id x data Compose f g x = Compose (f (g x)) data Fix f = Fix (f (Fix f)) -- examples: l = Compose [Just 'a'] :: Compose [] Maybe Char type Natural = Fix Maybe -- natural numbers are fixpoint of Maybe n = Fix (Just (Fix (Just (Fix Nothing)))) :: Natural -- n is 2 -- up to isomorphism composition of identity and f is f: iso :: Compose Id f x -> f x iso (Compose (Id a)) = a

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  • Using the "naked" attribute for functions in GCC

    - by Art Spasky
    GCC documentation (http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html) states in 6.29 Declaring Attributes of Functions "naked Use this attribute on the ARM, AVR, IP2K, RX and SPU ports to indicate that the specified function does not need prologue/epilogue sequences generated by the compiler. It is up to the programmer to provide these sequences. The only statements that can be safely included in naked functions are asm statements that do not have operands. All other statements, including declarations of local variables, if statements, and so forth, should be avoided. Naked functions should be used to implement the body of an assembly function, while allowing the compiler to construct the requisite function declaration for the assembler." Can I safely call functions using C syntax from naked functions, or only by using asm?

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  • 3 hash functions to best hash sliding window strings for a bloom filter with minimum collisions

    - by Duaa
    Hi all: I need 3 hash functions to hash strings of a sliding window moving over a text, to be used later to search within a bloom vector. I'm using C# in my programming I read something about rolling hash functions and cyclic polynomials, they are used for sliding window applications. But really, I did not find any codes, they are just descriptions So please, if anyone have any idea about 3 best C# hash functions to use with sliding window strings of fixed size (5-char), that consume less time and have minimum number of collisions, either they are rolling hash functions or others, please help me with some C# codes or links to hash functions names Duaa

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  • How would I order a table by the number of matching params in the where clause of an sql statement?

    - by Eitan
    I'm writing sql to search a database by a number of parameters. How would I go about ordering the result set by the items that match the most parameters in the where clause. For example: SELECT * FROM users WHERE username = 'eitan' OR email = '[email protected]' OR company = 'eitan' Username | email | company 1) eitan | [email protected] | blah 2) eitan | [email protected] | eitan 3) eitan | [email protected] | blah should be ordered like: 2, 3, 1. Thanks. (ps the query isn't that easy, has a lot of joins and a lot of OR's in the WHERE) Eitan

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  • htaccess rewriterule with order in url

    - by NRoscoe
    I'm trying to put together a rewrite rule for an Apache server. It should take 'order/###' and change it to 'order.php?id=###'. For some reason it's rewriting as 'order.php/###'. If I change it to anything other than 'order' my rule works fine. Anyone know what's going on? My .htaccess file looks like this: RewriteEngine on ## tighten host RewriteCond %{HTTP_HOST} !^mydomain\.com$ [NC] RewriteRule .? http://mydomain.com%{REQUEST_URI} [R=301,L] ## Dynamic Pages RewriteRule ^order/([0-9]+)/?$ order.php?code=$1 [L,NC] ## Static Page Redirects RewriteRule ^prices$ /prices.php [L,NC] RewriteRule ^examples$ /examples.php [L,NC] I have no access to the httpd main server config file on the live server.

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  • (C++) What's the difference between these overloaded operator functions?

    - by cv3000
    What is the difference between these two ways of overloading the != operator below. Which is consider better? Class Test { ...// private: int iTest public: BOOL operator==(const &Test test) const; BOOL operator!=(const &Test test) const; } BOOL operator==(const &Test test) const { return (iTest == test.iTest); } //overload function 1 BOOL Test::operator!=(const &Test test) const { return !operator==(test); } //overload function 2 BOOL Test::operator!=(const &Test test) const { return (iTest != test.iTest); } I've just recently seen function 1's syntax for calling a sibling operator function and wonder if writing it that way provides any benefits.

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  • Moving Function With Arguments To RequireJS

    - by Jazimov
    I'm not only relatively new to JavaScript but also to RequireJS (coming from string C# background). Currently on my web page I have a number of JavaScript functions. Each one takes two arguments. Imagine that they look like this: functionA(x1, y1) { ... } functionB(x2, y2) { ... } functionC(x3, y3) { ... } Currently, these functions exist in a tag on my HTML page and I simply call each as needed. My functions have dependencies on KnockoutJS, jQuery, and some other JS libraries. I currently have Script tags that synchronously load those external .js dependencies. But I want to use RequireJS so that they're loaded asynchronously, as needed. To do this, I plan to move all three functions above into an external .js file (a type of AMD "module") called MyFunctions.js. That file will have a define() call (to RequireJS's define function) that will look something like this: define(["knockout", "jquery", ...], function("ko","jquery", ...) {???} ); My question is how to "wrap" my functionA, functionB, and functionC functions where the ??? is above so that I can use those functions on my page as needed. For example, in the onclick event handler for a button on my HTML page, I would want to call functionA and pass two it two arguments; same for functionB and functionC. I don't fully understand how to expose those functions when they're wrapped in a define that itself is located in an external .js file. I know that define assures that my listed libraries are loaded asynchronously before the callback function is called, but after that's done I don't understand how the web page's script tags would use my functions. Would I need to use require to ensure they're available, such as: require(["myfunctions"],function({not sure what to put here})] I think I understand the basics of RequireJS but I don't understand how to wrap my functions so that they're in external .js files, don't pollute the global namespace, and yet can still be called from the main page so that arguments can be passed to them. I imagine they're are many ways to do this but in reviewing the RequireJS docs and some videos out there, I can't say I understand how... Thank you for any help.

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  • Generating link-time error for deprecated functions

    - by R..
    Is there a way with gcc and GNU binutils to mark some functions such that they will generate an error at link-time if used? My situation is that I have some library functions which I am not removing for the sake of compatibility with existing binaries, but I want to ensure that no newly-compiled binary tries to make use of the functions. I can't just use compile-time gcc attributes because the offending code is ignoring my headers and detecting the presence of the functions with a configure script and prototyping them itself. My goal is to generate a link-time error for the bad configure scripts so that they stop detecting the existence of the functions.

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