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• R from java with no graphics: is it worth moving to JRI

  - by LH

  I have a system set up that's been happily running R from a java servlet, spawning processed & hooking into the process's stdin, stdout, and stderr streams, as in the second andwer to this question. After a system upgrade (that included glibc), the input is no longer reaching the R process.* Until now, 'R --vanilla --slave -f [file] ...' was working fine for me. I also have no swing dependencies right now, so I'm somewhat reluctant to add them. (I may actually not be able to add swing dependencies; am I right that using REngine automatically brings swing in? The examples import all of swing.) Are there advantages to switching to JRI? What changes would I need to make to my R script? (It currently reads from stdin and writes to stdout). I'm not finding the provided examples terribly helpful for how to use JRI in this situation. Thanks for your help & comments. *I can't even tell if the problem is data being written too soon or too late, but that's a separate issue/question; if I move to JRI I'm hoping it all becomes moot.

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• Javascript Global Variable in Array

  - by user1387727

  My question may be very easy to lots of people, but I am new to Javascript. I really do not know what is wrong with the following codes. var newValue = 1; function getCurrentAmount() { return [newValue,2,3]; } var result = getCurrentAmount(); console.log(result[0] + "" + result[1] + result[2]); In the above code, the result shown in console is: undefined23 Why is the result not "123"? I am trying to use global variable because I want to increment newValue by 1 each time when the function is called. I want something like the following: var newValue = 1; function getCurrentAmount() { newValue ++; return [newValue,2,3]; } setInterval(function(){ var result = getCurrentAmount(); console.log(result[0] + "" + result[1] + result[2]); }, 1000); Also, I just tired the following codes and it works as expected. var newValue =1; function test() { newValue ++; return newValue; } console.log(test()); So I think the problem is about the Array. I hope my question is clear enough. Thanks in advance.

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• two view controllers and reusability with delegate

  - by netcharmer

  Newbie question about design patterns in objC. I'm writing a functionality for my iphone app which I plan to use in other apps too. The functionality is written over two classes - Viewcontroller1 and Viewcontroller2. Viewcontroller1 is the root view of a navigation controller and it can push Viewcontroller2. Rest of the app will use only ViewController1 and will never access Viewcontroller2 directly. However, triggered by user events, Viewcontroller2 has to send a message to the rest of the app. My question is what is the best way of achieving it? Currently, I use two level of delegation to send the message out from Viewcontroller2. First send it to Viewcontroller1 and then let Viewcontroller1 send it to rest of the app or the application delegate. So my code looks like - //Viewcontroller1.h @protocol bellDelegate -(int)bellRang:(int)size; @end @interface Viewcontroller1 : UITableViewController <dummydelegate> { id <bellDelegate> delegate; @end //Viewcontroller1.m @implementation Viewcontroller1 -(void)viewDidLoad { //some stuff here Viewcontroller2 *vc2 = [[Viewcontroller2 alloc] init]; vc2.delegate = self; [self.navigationController pushViewController:vc2 animated:YES]; } -(int)dummyBell:(int)size { return([self.delegate bellRang:size]); } //Viewcontroller2.h @protocol dummyDelegate -(int)dummyBell:(int)size; @end @interface Viewcontroller2 : UITableViewController { id <dummyDelegate> delegate; @end //Viewcontroller2.m @implementation Viewcontroller2 -(int)eventFoo:(int)size { rval = [self.delegate dummyBell:size]; } @end

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• EF Query with conditional include that uses Joins

  - by makerofthings7

  This is a follow up to another user's question. I have 5 tables CompanyDetail CompanyContacts FK to CompanyDetail CompanyContactsSecurity FK to CompanyContact UserDetail UserGroupMembership FK to UserDetail How do I return all companies and include the contacts in the same query? I would like to include companies that contain zero contacts. Companies have a 1 to many association to Contacts, however not every user is permitted to see every Contact. My goal is to get a list of every Company regardless of the count of Contacts, but include contact data. Right now I have this working query: var userGroupsQueryable = _entities.UserGroupMembership .Where(ug => ug.UserID == UserID) .Select(a => a.GroupMembership); var contactsGroupsQueryable = _entities.CompanyContactsSecurity;//.Where(c => c.CompanyID == companyID); /// OLD Query that shows permitted contacts /// ... I want to "use this query inside "listOfCompany" /// //var permittedContacts= from c in userGroupsQueryable //join p in contactsGroupsQueryable on c equals p.GroupID //select p; However this is inefficient when I need to get all contacts for all companies, since I use a For..Each loop and query each company individually and update my viewmodel. Question: How do I shoehorn the permittedContacts variable above and insert that into this query: var listOfCompany = from company in _entities.CompanyDetail.Include("CompanyContacts").Include("CompanyContactsSecurity") where company.CompanyContacts.Any( // Insert Query here.... // b => b.CompanyContactsSecurity.Join(/*inner*/,/*OuterKey*/,/*innerKey*/,/*ResultSelector*/) ) select company; My attempt at doing this resulted in: var listOfCompany = from company in _entities.CompanyDetail.Include("CompanyContacts").Include("CompanyContactsSecurity") where company.CompanyContacts.Any( // This is concept only... doesn't work... from grps in userGroupsQueryable join p in company.CompanyContactsSecurity on grps equals p.GroupID select p ) select company;

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• Is this a bad indexing strategy for a table?

  - by llamaoo7

  The table in question is part of a database that a vendor's software uses on our network. The table contains metadata about files. The schema of the table is as follows Metadata ResultID (PK, int, not null) MappedFieldname (char(50), not null) Fieldname (PK, char(50), not null) Fieldvalue (text, null) There is a clustered index on ResultID and Fieldname. This table typically contains millions of rows (in one case, it contains 500 million). The table is populated by 24 workers running 4 threads each when data is being "processed". This results in many non-sequential inserts. Later after processing, more data is inserted into this table by some of our in-house software. The fragmentation for a given table is at least 50%. In the case of the largest table, it is at 90%. We do not have a DBA. I am aware we desperately need a DB maintenance strategy. As far as my background, I'm a college student working part time at this company. My question is this, is a clustered index the best way to go about this? Should another index be considered? Are there any good references for this type and similar ad-hoc DBA tasks?

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• Why should I install Python packages into `~/.local`?

  - by Matthew Rankin

  Background I don't develop using OS X's system provided Python versions (on OS X 10.6 that's Python 2.5.4 and 2.6.1). I don't install anything in the site-packages directory for the OS provided versions of Python. (The only exception is Mercurial installed from a binary package, which installs two packages in the Python 2.6.1 site-packages directory.) I installed three versions of Python, all using the Mac OS X installer disk image: Python 2.6.6 Python 2.7 Python 3.1.2 I don't like polluting the site-packages directory for my Python installations. So I only install the following five base packages in the site-packages directory. For the actual method/commands used to install these, see SO Question 4324558. setuptools/ez_setup distribute pip virtualenv virtualenvwrapper All other packages are installed in virtualenvs. I am the only user of this MacBook. Questions Given the above background, why should I install the five base packages in ~/.local? Since I'm installing these base packages into the site-packages directories of Python distributions that I've installed, I'm isolated from the OS X's Python distributions. Using this method, should I be concerned about Glyph's comment that other things could potentially break (see his comment below)? Again, I'm only interested in where to install those five base packages. Related Questions/Info I'm asking because of Glyph's comment to my answer to SO question 4314376, which stated: NO. NEVER EVER do sudo python setup.py install whatever. Write a ~/.pydistutils.cfg that puts your pip installation into ~/.local or something. Especially files named ez_setup.py tend to suck down newer versions of things like setuptools and easy_install, which can potentially break other things on your operating system. Previously, I asked What's the proper way to install pip, virtualenv, and distribute for Python?. However, no one answered the "why" of using ~/.local.

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• memcached: which is faster, doing an add (and checking result), or doing a get (and set when returni

  - by Mike Sherov

  The title of this question isn't so clear, but the code and question is straightforward. Let's say I want to show my users an ad once per day. To accomplish this, every time they visit a page on my site, I check to see if a certain memcache key has any data stored on it. If so, don't show an ad. If not, store the value '1' in that key with an expiration of 86400. I can do this 2 ways: //version a $key='OPD_'.date('Ymd').'_'.$type.'_'.$user; if($memcache->get($key)===false){ $memcache->set($key,'1',false,$expire); //show ad } //version b $key='OPD_'.date('Ymd').'_'.$type.'_'.$user; if($memcache->add($key,'1',false,$expire)){ //show ad } Now, it might seem obvious that b is better, it always makes 1 memcache call. However, what is the overhead of "add" vs. "get"? These aren't the real comparisons... and I just made up these numbers, but let's say 1 add ~= 1 set ~= 5 get in terms of effort, and the average user views 5 pages a day: a: (5 get * 1 effort) + (1 set * 5 effort) = 10 units of effort b: (5 add * 5 effort) = 25 units of effort Would it make sense to always do the add call? Is this an unnecessary micro-optimization?

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• scala 2.8 CanBuildFrom

  - by oxbow_lakes

  Following on from another question I asked, I wanted to understand a bit more about the Scala method TraversableLike[A].map whose signature is as follows: def map[B, That](f: A => B)(implicit bf: CanBuildFrom[Repr, B, That]): That Notice a few things about this method: it takes a function turning each A in the traversable into a B it returns That and takes an implicit argument of type CanBuildFrom[Repr, B, That] I can call this as follows: > val s: Set[Int] = List("Paris", "London").map(_.length) s: Set[Int] Set(5,6) What I cannot quite grasp is how the fact that That is bound to B (i.e. it is some collection of B's) is being enforced by the compiler. The type parameters look to be independent in both the signature above and in the signature of the trait CanBuildFrom itself: trait CanBuildFrom[-From, -Elem, +To] How is the scala compiler ensuring that That cannot be forced into something which does not make sense? > val s: Set[String] = List("Paris", "London").map(_.length) //will not compile EDIT - this question of course boils down to: How does the compiler decide what implicit CanBuildFrom objects are in scope for the call?

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• How to store arbitrary data for some HTML tags

  - by nickf

  I'm making a page which has some interaction provided by javascript. Just as an example: links which send an AJAX request to get the content of articles and then display that data in a div. Obviously in this example, I need each link to store an extra bit of information: the id of the article. The way I've been handling it in case was to put that information in the href link this: <a class="article" href="#5"> I then use jQuery to find the a.article elements and attach the appropriate event handler. (don't get too hung up on the usability or semantics here, it's just an example) Anyway, this method works, but it smells a bit, and isn't extensible at all (what happens if the click function has more than one parameter? what if some of those parameters are optional?) The immediately obvious answer was to use attributes on the element. I mean, that's what they're for, right? (Kind of). <a articleid="5" href="link/for/non-js-users.html"> In my recent question I asked if this method was valid, and it turns out that short of defining my own DTD (I don't), then no, it's not valid or reliable. A common response was to put the data into the class attribute (though that might have been because of my poorly-chosen example), but to me, this smells even more. Yes it's technically valid, but it's not a great solution. Another method I'd used in the past was to actually generate some JS and insert it into the page in a <script> tag, creating a struct which would associate with the object. var myData = { link0 : { articleId : 5, target : '#showMessage' // etc... }, link1 : { articleId : 13 } }; <a href="..." id="link0"> But this can be a real pain in butt to maintain and is generally just very messy. So, to get to the question, how do you store arbitrary pieces of information for HTML tags?

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• What constitutes explicit creation of entities in LINQ to SQL? What elegant "solutions" are there to

  - by Marcelo Zabani

  Hi SO, I've been having problems with the rather famous "Explicit construction of entity type '##' in query is not allowed." error. Now, for what I understand, this exists because if explicit construction of these objects were allowed, tracking changes to the database would be very complicated. So I ask: What constitutes the explicit creation of these objects? In other terms: Why can I do this: Product foo = new Product(); foo.productName = "Something"; But can't do this: var bar = (from item in myDataContext.Products select new Product { productName = item.productName }).ToList(); I think that when running the LINQ query, some kind of association is made between the objects selected and the table rows retrieved (and this is why newing a Product in the first snippet of code is no problem at all, because no associations were made). I, however, would like to understand this a little more in depth (and this is my first question to you, that is: what is the difference from one snippet of code to another). Now, I've heard of a few ways to attack this problem: 1) The creation of a class that inherits the linq class (or one that has the same properties) 2) Selecting anonymous objects And this leads me to my second question: If you chose one of the the two approaches above, which one did you choose and why? What other problems did your approach introduce? Are there any other approaches?

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• Joining tables, if percentage is above certain value

  - by CluelessGerman

  My question is similar to this one: Compare rows and get percentage However, little different. I adapted my question to the other post. I got 2 tables. First table: user_id | post_id 1 1 1 2 1 3 2 12 2 15 And second table: post_id | rating 1 1 1 2 1 3 2 1 2 5 3 null 3 1 3 4 12 4 15 1 So now I would like to count the rating for each post, in the second table. If the rating has more than, lets say, 50% positive ratings than I want to get the post_id and going it to the post_id from table one and add 1 to the user_id. At the end it would return the user_id with the number of positive posts. The result for above table would be: user_id | helpfulPosts 1 2 2 1 The post with post_id 1 and 3 have positive rating, because more than 50% have ratings of 1-3. The post with id = 2 is not positive, because the rating is exactly 50%. How would I achieve this? For clarification: It's a mysql rdbm and a positive post, is one where the number of rating_ids with 1, 2 and 3 are more than half of the overall rating. Basically the same thing, from the other thread I posted above.

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• Is there such a thing as a MemberExpression that handles a many-to-many relationship?

  - by Jaxidian

  We're trying to make it easy to write strongly-typed code in all areas of our system, so rather than setting var sortColumn = "FirstName" we'd like to say sortOption = (p => p.FirstName). This works great if the sortOption is of type Expression<Func<Person, object>> (we actually use generics in our code but that doesn't matter). However, we run into problems for many-to-many relationships because this notation breaks down. Consider this simple code: internal class Business { public IQueryable<Address> Addresses { get; set; } public string Name { get; set; } } internal class Address { public State MyState { get; set; } } internal class State { public string Abbreviation { get; set; } public int StateID { get; set; } } Is it possible to have this sort of MemberExpression to identify the StateID column off of a business? Again, the purpose of using this is not to return a StateID object, it's to just identify that property off of that entity (for sorting, filtering, and other purposes). It SEEMS to me that there should be some way to do this, even if it's not quite as pretty as foo = business.Addresses.SomeExtension(a => a.State.StateID);. Is this really possible? If more background is needed, take a look at this old question of mine. We've since updated the code significantly, but this should give you the general detailed idea of the context behind this question.

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• How is machine code understood by the machine

  - by Kraken

  I have a very naive question here, and I would like you to correct me on whatever wrong concepts I put out here. The question is as follows: I have ubuntu installed on my machine, now I write a helloWorld.c program in C language. Now, on the operating system I have a compiler installed, when I execute my helloWorld.c program, the OS schedules the compiler and that basically compiles my code into machine code, which eventually, I execute. Now my kernel code is written in C, then how does my machine interprets that code? Say my kernel code is helloWorld.c, now would not I require any compiler, to compile this code. Also, if I hardcode a compiler in maybe ROM or something, then what language is it written in? Assembly language? Let me know if I have made myself clear with the problem. Thanks. EDIT: By kernel code I mean, the code for operating system. Operating System code. I guess it is written in C right?

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• How can I write output to a new external file with Perl?

  - by Structure

  Maybe I am searching with the wrong keywords or this is a very basic question but I cannot find the answer to my question. I am having trouble writing the result of my whois command to a new external file. My code is below. It takes $readfilename, which is a file name which has a list of IPs, and $writefilename, which is the destination file for output. Both are user-specified. For my tests, $readfilename contains three IP addresses on three separate lines so there should be three separate whois results in the user specified output file. if ($readfilename) { open (my $inputfile, "<", $readfilename) || die "\n Cannot open the specified file. Please double check your file name and path.\n\n"; open (my $outputfile, ">", $writefilename) || die "\n Could not create write file.\n\n"; while (<$inputfile>) { my $iplookupresult = `whois $_`; print $outputfile $iplookupresult; } close $outputfile; close $inputfile; } I can execute this script and end up with a new external file, but over half of the file has binary garbage data (running on CentOS) and only one (or a portion of one) of the whois lookups is readable. I have no idea how half of my file is ending up binary... but my approach must be incorrect. Is there a better way to achieve the same result?

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• Merging Three or More Images -- PHP

  - by bballer13sn

  Before I ask my question, I'd like to thank you all in advance for helping me with this. So here's the question: So, for my website, I've been trying to make it so people's characters (which are currently composed of several pictures that are moved by CSS) are merged into one image as to make my life easier. The chunk of code that currently doesn't work is as follows: $template = $charRow['template']; $gender = $charRow['gender']; $shirt = $charRow['shirt']; $pants = $charRow['pants']; $hat = $charRow['hat']; $templatePic = imagecreatefrompng("Templates/".$template); if (!empty($shirt)) { $shirtPic = imagecreatefrompng($shirt); imagecopy($templatePic,$shirtPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } if (!empty($pants)) { $pantsPic = imagecreatefrompng($pants); imagecopy($templatePic,$pantsPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } if (!empty($hat)) { $hatPic = imagecreatefrompng($hat); imagecopy($templatePic,$hatPic,0,0,0,0,imagesx($templatePic),imagesy($templatePic)); } imagePNG($templatePic, 'Images/'); //Problem line... This is the error PHP is giving me: Warning: imagepng() [function.imagepng]: Unable to open 'Images/' for writing: Is a directory in PathToParentFolderOfFollowingFile/testFile.php on line 139 What exactly does this error mean and how can it be fixed? NOTE: $charRow is not the problem. The query to get that is just not being displayed to all of you.

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• Dependency Injection: How to pass DB around?

  - by Stephane

  Edit: This is a conceptual question first and foremost. I can make applications work without knowing this, but I'm trying to learn the concept. I've seen lots of videos with related classes and that makes sense, but when it comes to classes wrapping around other classes, I can't seem to grasp where things should be instantiated/passed around. =-=-=-=-=-=-= Question: Let's say I have a simple page that loads data from a table, manipulates the result and displays it. Simple. I'm going to use '=' for instantiating a class and '-' for passing a class in using constructor injection. It seems to me that the database has to be passed from one end of the application to the other which doesn't seem right. Here's how I would do it if I wanted to separate concerns: index =>Controller =>Model Layer =>Database =>DAO->Database I have this rule in my head that says I'm not supposed to create objects inside other objects. So what do I do with the Database? Or even the Model for that matter? I'm obviously missing something so basic about this. I would love a simplified example so that I can move forward in my code. I feel really hamstrung by this.

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• Basic SQL Query, I am newbie

  - by user3530547

  I just started my database and query class on Monday. We met on Monday and just went over the syllabus, and on Wednesday the network at school was down so we couldn't even do the power point lecture. Right now I am working on my first homework assignment and I am almost finished but I am having trouble on one question. Here is is... Write a SELECT statement that returns one column from the Customers table named FullName that joins the LastName and FirstName columns. Format the columns with the last name, a comma, a space, and the first name like this: Doe, John Sort the result set by last name in ascending sequence. Return only the contacts whose last name begins with letters from M to Z. Here is what I have so far... USE md0577283 SELECT FirstName,LastName FROM Customers ORDER BY LastName,FirstName My question is how do I format is Lastname, FirstName like the professor wants and how do I only select names M-Z? If someone could point me in the right direction I would greatly appreciate it. Thank you. PS With all do respect, I didn't ask for the answer I asked for a nudge in the right direction so why the down vote guys?

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• Stream buffering issue

  - by Kolyunya

  The mod_rewrite documentation states that it is a strict requirement to disable in(out)put buffering in a rewrite program. Keeping that in mind I've written a simple program (I do know that it lacks the EOF check but this is not an issue and it saves one condition check per loop): #include <stdio.h> #include <stdlib.h> int main ( void ) { setvbuf(stdin,NULL,_IOLBF,4200); setvbuf(stdout,NULL,_IOLBF,4200); int character; while ( 42 ) { character = getchar(); if ( character == '-' ) { character = '_'; } putchar(character); } return 42 - 42; } After making some measurements I was shocked - it was over 9,000 times slower than the demo Perl script provided by the documentation: #!/usr/bin/perl $| = 1; # Turn off I/O buffering while (<STDIN>) { s/-/_/g; # Replace dashes with underscores print $_; } Now I have two related questions: Question 1. I believe that the streams may be line buffered since Apache sends a new line after each path. Am I correct? Switching my program to setvbuf(stdin,NULL,_IOLBF,4200); setvbuf(stdout,NULL,_IOLBF,4200); makes it twice as fast as Perl one. This should not hit Apache's performance, should it? Question 2. How can one write a program in C which will use unbuffered streams (like Perl one) and will perform as fast as Perl one?

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• nothrow or exception ?

  - by Muggen

  I am a student and I have small knowledge on C++, which I try to expand. This is more of a philosophical question.. I am not trying to implement something. Since #include <new> //... T * t = new (std::nothrow) T(); if(t) { //... } //... Will hide the Exception, and since dealing with Exceptions is heavier compared to a simple if(t), why isn't the normal new T() not considered less good practice, considering we will have to use try-catch() to check if a simple allocation succeeded (and if we don't, just watch the program die)?? What are the benefits (if any) of the normal new allocation compared to using a nothrow new? Exception's overhead in that case is insignificant ? Also, Assume that an allocation fails (eg. no memory exists in the system). Is there anything the program can do in that situation, or just fail gracefully. There is no way to find free memory on the heap, when all is reserved, is there? Incase an allocation fails, and an std::bad_alloc is thrown, how can we assume that since there is not enough memory to allocate an object (Eg. a new int), there will be enough memory to store an exception ?? Thanks for your time. I hope the question is in line with the rules.

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• How to make smooth movements in OpenGL?

  - by thyrgle

  So this kind of on topic to my other OpenGL question (not my OpenGL ES question but OpenGL the desktop version). If you have someone press a key to move a square how do you make the square movement naturally and less jumpy but also at the same speed I have it now? This is my code for the glutKeyboardFunc() function: void handleKeypress(unsigned char key, int x, int y) { if (key == 'w') { for (int i = 0; i < 12; i++) { if (i == 1 || i == 7 || i == 10 || i == 4) { square[i] = square[i] + 1; } } glutPostRedisplay(); } if (key == 'd') { for (int i = 0; i < 12; i++) { if (i == 0 || i % 3 == 0) { square[i] = square[i] + 1; } } glutPostRedisplay(); } if (key == 's') { for (int i = 0; i < 12; i++) { if (i == 1 || i == 7 || i == 10 || i == 4) { square[i] = square[i] - 1; } } glutPostRedisplay(); } if (key == 'a') { for (int i = 0; i < 12; i++) { if (i == 0 || i % 3 == 0) { square[i] = square[i] - 1; } } glutPostRedisplay(); } } I'm sorry if this doesn't quite make sense I'll try to rephrase it in a better way if it doesn't make sense.

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• Objective C : UIButton image with NSArray in a random order

  - by Sarah

  Brief Idea about the flow : I have say minimum 1 and maximum 18 records in my database with a text and an image from which I have to fetch images and place any 3 of the same randomly to 3 UIButtons among which one image should match with my question. i.e. 1 is the answer and other 2 are the distractors. For Example : Question is : where is Apple? Now among the bunch of images, I want to place any 3 images on the 3 UIButtons(1 answer i.e. An Apple and 2 distractors) in a random order and on selecting the UIButton it should prompt me if it's a right answer or not. I am implementing below code for placing the UIImages in a random order : -(void) placeImages { NSMutableArray *images = [NSMutableArray arrayWithArray:arrImg]; NSArray *buttons = [NSArray arrayWithObjects:btn1,btn2,btn3, nil]; for (UIButton *btn in buttons) { int randomIndex= random() % images.count; UIImage *img = [images objectAtIndex:randomIndex]; [btn setImage:img forState:UIControlStateNormal]; [images removeObjectAtIndex:randomIndex]; } } But I am stuck at a point that how should I get 1 UIButton image with an answer and other as distractors also that how should i maintain the index of the image from the NSArray? Kindly guide me. Thank you.

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• Travelling software. Is that a concept?

  - by Bubba88

  Hi! This is barely a sensible question. I would like to ask if there existed a program, which were intended to travel (for example following some physical forces) across the planet, possibly occupying and freeing computational resources/nodes. Literally that means that some agent-based system is just regularly changing it's location and (inevitably to some extent) configuration. An example would be: suppose you have external sensors, and free computers - nodes - across the space; would it make sense to self-replicate agents to follow the initializers from sensors, but in such restrictive manner that the computation is only localized at where the physical business is going on. I want to stress that this question is just for 'theoretical' fun, cause I cannot see any practical benefits of the restrictions mentioned, apart from the optimization of 'outdated' (outplaced?) agent disposal. But maybe it could be of some interest. Thank you! EDIT: It's obvious that a virus is fitting example, although the deletion of such agents is rarely of concern of the developers. More precisely, I'm interested in 'travelling' software - that is, when the count (or at least order) of the agents is kind of constant, and it's just the whole system who travels.

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• Managing modes in Windows application working directly with SQL Server 2008

  - by hgulyan

  Hi, I have a MS Access 97 application (but the question is general) working directly with SQL Server 2008 (without application server or anything). Numbers of users can be up to 1000. Windows Authentication is used. The question is: How to handle modes, so some users will be allowed to work in read-only mode some users won't have access to db for some time My versions: Using a table with a mode id for every group of users, that will work the same way. On Form Load application will query that table for mode id. Using trigger on the tables, that must work according to that mode. The trigger will query mode value and doesn't work if access is closed or it's in read-only mode I know it's not these are not the best solutions, that's why I'm asking for your advice. There's one more point. If the mode is changed to "access-is-closed" for a group of users, that group must not be able to query to DB starting that moment. With first solution I wrote it won't work, because user can be in application at that moment and no form load event will work. How can I do this? Is there any optimal solution? Thank you. Any help would be appreciated.

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• Template Syntax in C++

  - by Crystal

  I don't understand templates really and was trying to run a simple find the minimum for ints, doubles, chars. First question, why is template<typename T> sometimes used, and other times template<>? Second question, I do not know what I am doing wrong with the following code below: #include <iostream> template <typename T> T minimum(T arg1, T arg2) { return arg1 < arg2 ? arg1 : arg2; } template <typename T> // first I tried template <> instd of above, but wasn't sure the difference T minimum<const char *>(const char *arg1, const char *arg2) { return strcmp(arg1, arg2) ? arg2 : arg1; } int main() { std::cout << minimum<int>(4, 2) << '\n'; std::cout << minimum<double>(2.2, -56.7) << '\n'; std::cout << minimum(2.2, 2) << '\n'; } Compile Errors: error C2768: 'minimum' : illegal use of explicit template arguments error C2783: 'T minimum(const char *,const char *)' : could not deduce template argument for 'T' : see declaration of 'minimum' : error C2782: 'T minimum(T,T)' : template parameter 'T' is ambiguous : see declaration of 'minimum' Third, in getting familiar with separating .h and .cpp files, if I wanted this minimum() function to be a static function of my class, but it was the only function in that class, would I have to have a template class as well? I originally tried doing it that way instead of having it all in one file and I got some compile errors as well that I can't remember right now and was unsure how I would do that. Thanks!

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• I can't find the homepage for my ASP.NET MVC site :(

  - by Pure.Krome

  Hi folks, really simple question here. when I remove the default route, I returns an empty page to the browser :- routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = UrlParameter.Optional } ); Now before everyone starts shouting "that's because that's the default route to access all action methods, etc.." .. i know that. My question is - what code / routes does the default framework try and call .. which makes that Default Route get used/kick in? Why? I don't wish to make that my default route regex (don't ask why - this is some R&D) but I still need the main home page .. ie. Home/Index . If i try and just add that route, it doesn't get called and an empty page is returned. So -- what does the framework try and call when a user doesn't provide any urls? It's like there's some secret default document stuff set up? Cheers :)

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