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• Learning Haskell maps, folds, loops and recursion

  - by Darknight

  I've only just dipped my toe in the world of Haskell as part of my journey of programming enlightenment (moving on from, procedural to OOP to concurrent to now functional). I've been trying an online Haskell Evaluator. However I'm now stuck on a problem: Create a simple function that gives the total sum of an array of numbers. In a procedural language this for me is easy enough (using recursion) (c#) : private int sum(ArrayList x, int i) { if (!(x.Count < i + 1)) { int t = 0; t = x.Item(i); t = sum(x, i + 1) + t; return t; } } All very fine however my failed attempt at Haskell was thus: let sum x = x+sum in map sum [1..10] this resulted in the following error (from that above mentioned website): Occurs check: cannot construct the infinite type: a = a -> t Please bear in mind I've only used Haskell for the last 30 minutes! I'm not looking simply for an answer but a more explanation of it. Thanks in advanced.

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• ASP.NET AsyncPostBackTrigger disables button's OnClick function???

  - by hahuang65

  I saw another post like this: http://stackoverflow.com/questions/1795621/asyncpostbacktrigger-disables-buttons But I don't really know what to make of it. The accepted answer was poorly typed. Basically, I have a button with an OnClick function. I also have a UpdatePanel, with is AsyncPostBackTrigger set to that same button. It seems that if I do this, my Button no longer does ANYTHING. I guess it's because I have a Page_Load() event... Can anyone explain why this is? And how should I set up my webpage if I can't use the Page_Load() function? Oh and if I put my Button in a UpdatePanel, it also won't do anything, probably because of the same reason. This is a section of my code: <asp:FileUpload id="FileUploadControl" runat="server" /> <asp:Button runat="server" id="UploadButton" text="Upload" OnClick="uploadClicked" /> <br /><br /> <asp:Label runat="server" id="StatusLabel" text="Upload status: " /> <br /> <asp:UpdatePanel ID="UpdatePanel2" runat="server" updatemode="Conditional" > <ContentTemplate> <asp:DropDownList ID="songList" runat="server" /> </ContentTemplate> <Triggers> <asp:AsyncPostBackTrigger ControlID="RefreshButton" /> </Triggers> </asp:UpdatePanel> Thanks in advance.

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• Given a main function and a cleanup function, how (canonically) do I return an exit status in Bash/Linux?

  - by Zac B

  Context: I have a bash script (a wrapper for other scripts, really), that does the following pseudocode: do a main function if the main function returns: $returncode = $? #most recent return code if the main function runs longer than a timeout: kill the main function $returncode = 140 #the semi-canonical "exceeded allowed wall clock time" status run a cleanup function if the cleanup function returns an error: #nonzero return code exit $? #exit the program with the status returned from the cleanup function else #cleanup was successful .... Question: What should happen after the last line? If the cleanup function was successful, but the main function was not, should my program return 0 (for the successful cleanup), or $returncode, which contains the (possibly nonzero and unsuccessful) return code of the main function? For a specific application, the answer would be easy: "it depends on what you need the script for." However, this is more of a general/canonical question (and if this is the wrong place for it, kill it with fire): in Bash (or Linux in general) programming, do you typically want to return the status that "means" something (i.e. $returncode) or do you ignore such subjectivities and simply return the code of the most recent function? This isn't Bash-specific: if I have a standalone executable of any kind, how, canonically should it behave in these cases? Obviously, this is somewhat debatable. Even if there is a system for these things, I'm sure that a lot of people ignore it. All the same, I'd like to know. Cheers!

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• When does an ARM7 processor increase its PC register?

  - by Summer_More_More_Tea

  Hi everyone: I'm thinking about this question for a time: when does an ARM7(with 3 pipelines) processor increase its PC register. I originally thought that after an instruction has been executed, the processor first check is there any exception in the last execution, then increase PC by 2 or 4 depending on current state. If an exception occur, ARM7 will change its running mode, store PC in the LR of current mode and begin to process current exception without modifying the PC register. But it make no sense when analyzing returning instructions. I can not work out why PC will be assigned LR when returning from an undefined-instruction-exception while LR-4 from prefetch-abort-exception, don't both of these exceptions happened at the decoding state? What's more, according to my textbook, PC will always be assigned LR-4 when returning from prefetch-abort-exception no matter what state the processor is(ARM or Thumb) before exception occurs. However, I think PC should be assigned LR-2 if the original state is Thumb, since a Thumb-instruction is 2 bytes long instead of 4 bytes which an ARM-instruction holds, and we just wanna roll-back an instruction in current state. Is there any flaws in my reasoning or something wrong with the textbook. Seems a long question. I really hope anyone can help me get the right answer. Thanks in advance.

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• MVC 3, View Model for user registration process. Password validation not working properly

  - by sec_goat

  I am trying to create a user registration page using MVC 3, so that I can better understand the process of how it works, what's going on behind the scenes etc. I am running into some issues when trying to use [Compare] to check to see that the user entered the same password twice. I tried adding the ComparePassword field to my user model first, and found that would not work the way I wanted as I did not have the field in the database, so the obvious answer was to create a View Model using the same information including the ComparePassword field. So I now have created a User model and a RegistrationViewModel, however it appears that the [Compare] on the password is not returning anything, for instance no matter what I put in the two boxes, when I click create it gives no error, which seems to me to mean it was successfully validated. I am not sure what I am doing or not doing to make this work properly. I have tried updating the jQuery.Validate to the newest version as there were some bugs reported in older version, this has not helped my efforts. Below is a wall of code, that is what I am working with. } public class RegistrationViewModel { [Required] [StringLength(15, MinimumLength = 3)] [Display(Name = "User Name")] [RegularExpression(@"(\S)+", ErrorMessage = " White Space is not allowed in User Names")] [ScaffoldColumn(false)] public String Username { get; set; } [Required] [StringLength(15, MinimumLength = 3)] [Display(Name = "First Name")] public String firstName { get; set; } [Required] [StringLength(15, MinimumLength = 3)] [Display(Name = "Last Name")] public String lastName { get; set; } [Required] [Display(Name = "Email")] public String email { get; set; } [Required] [Display(Name = "Password")] [DataType(DataType.Password)] public String password { get; set; } [Required] [DataType(DataType.Password)] [Display(Name = "Re-enter Password")] [Compare("Password", ErrorMessage = "Passwords do not match.")] public String comparePassword { get; set; } }

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• Is Git ready to be recommended to my boss?

  - by Mike Weller

  I want to recomment Git to my boss as a new source control system, since we're stuck in the 90s with VSS (ouch), but are the tools and 3rd party support good enough yet? Specifically I'm talking about GUI front-ends similar to TortoiseSVN, decent visual diff/merge support, as well as stuff like email commit notifications and general support from 3rd parties like IDEs and build systems. Even though this will be used by programmers, we really need this kind of stuff in our team. I don't want to leave everyone stuck with a new tool, and even a new source control paradigm (distributed), with nothing but a command-line app and some online tutorials. This would be a step backwards. So what do you think... is Git ready? What decent tools exist for Git and what third party development apps support it? EDIT: My original question was pretty vague so I'm updating it to specifically ask for a list of available tools and 3rd party support for Git. Maybe we can get a community wiki post with a list of stuff. I also do not consider 'use subversion' to be an adequate answer. There are other reasons to use a distributed source control system other than offline editing - private and cheap branches being one of them.

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• Mysql select - improve performance

  - by realshadow

  Hey, I am working on an e-shop which sells products only via loans. I display 10 products per page in any category, each product has 3 different price tags - 3 different loan types. Everything went pretty well during testing time, query execution time was perfect, but today when transfered the changes to the production server, the site "collapsed" in about 2 minutes. The query that is used to select loan types sometimes hangs for ~10 seconds and it happens frequently and thus it cant keep up and its hella slow. The table that is used to store the data has approximately 2 milion records and each select looks like this: SELECT * FROM products_loans WHERE KOD IN("X17/Q30-10", "X17/12", "X17/5-24") AND 369.27 BETWEEN CENA_OD AND CENA_DO; 3 loan types and the price that needs to be in range between CENA_OD and CENA_DO, thus 3 rows are returned. But since I need to display 10 products per page, I need to run it trough a modified select using OR, since I didnt find any other solution to this. I have asked about it here, but got no answer. As mentioned in the referencing post, this has to be done separately since there is no column that could be used in a join (except of course price and code, but that ended very, very badly). Here is the show create table, kod and CENA_OD/CENA_DO very indexed via INDEX. CREATE TABLE `products_loans` ( `KOEF_ID` bigint(20) NOT NULL, `KOD` varchar(30) NOT NULL, `AKONTACIA` int(11) NOT NULL, `POCET_SPLATOK` int(11) NOT NULL, `koeficient` decimal(10,2) NOT NULL default '0.00', `CENA_OD` decimal(10,2) default NULL, `CENA_DO` decimal(10,2) default NULL, `PREDAJNA_CENA` decimal(10,2) default NULL, `AKONTACIA_SUMA` decimal(10,2) default NULL, `TYP_VYHODY` varchar(4) default NULL, `stage` smallint(6) NOT NULL default '1', PRIMARY KEY (`KOEF_ID`), KEY `CENA_OD` (`CENA_OD`), KEY `CENA_DO` (`CENA_DO`), KEY `KOD` (`KOD`), KEY `stage` (`stage`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 And also selecting all loan types and later filtering them trough php doesnt work good, since each type has over 50k records and the select takes too much time as well... Any ides about improving the speed are appreciated.

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• For each <item> in CheckedListBox. <item> returns as Object and not as Control

  - by Tivie

  Hello there. I have a CheckedListBox previously populated. I want to loop with a "for each / next" through all items in the CheckedListBox and do a lot of "stuff" with each iteration element of the checkedlistbox. example code: For Each item In CheckedListBox1.Items If item.Checked = True Then 'do stuff like item.BackColor = Color.Blue Else 'do other stuff item.BackColor = Color.Brown End If Next the problem is that is an 'Object' type and not a 'Control' type. If I force the iteration var As CheckBox, it throws an InvalidCastException saying that type 'System.String' can't be associated with type 'System.Windows.Forms.CheckBox' I know I can easily work around using for i=0 to CheckedListBox.Items.Count - 1 but I want to use a for each /next loop since I have a lot of code in that loop (and With can't be used) and always poiting directly to the object is something I wish to avoid and I really need the code to be as simple as possible. I actually spent one afternoon looking for this but couldn't find any answer. If someone could be kind enough to enlight me in this, it would be extremely appreciated. Best regards

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• iPad keyboard will not dismiss if navigation controller presentation style is "form sheet".

  - by Kalle

  UPDATE: This is apparently "works as intended" classed by Apple. See accepted answer below for details. Update: this question is about a behavior discovered in the iPad keyboard, where it refuses to be dismissed if shown in a modal dialog with a navigation controller. Basically, if I present the navigation controller with the following line: navigationController.modalPresentationStyle = UIModalPresentationFormSheet; The keyboard refuses to be dismissed. If I comment out this line, the keyboard goes away fine. ... I've got two textFields, username and password; username has a Next button and password has a Done button. The keyboard won't go away if I present this in a modal navigation controller. WORKS broken *b = [[broken alloc] initWithNibName:@"broken" bundle:nil]; [self.view addSubview:b.view]; DOES NOT WORK broken *b = [[broken alloc] initWithNibName:@"broken" bundle:nil]; UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:b]; navigationController.modalPresentationStyle = UIModalPresentationFormSheet; navigationController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController:navigationController animated:YES]; [navigationController release]; [b release]; If I remove the navigation controller part and present 'b' as a modal view controller by itself, it works. Is the navigation controller the problem? WORKS broken *b = [[broken alloc] initWithNibName:@"broken" bundle:nil]; b.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController:b animated:YES]; [b release]; WORKS broken *b = [[broken alloc] initWithNibName:@"broken" bundle:nil]; UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:b]; [self presentModalViewController:navigationController animated:YES]; [navigationController release]; [b release];

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• In C++, what is the scope resolution ("order of precedence") for shadowed variable names?

  - by Emile Cormier

  In C++, what is the scope resolution ("order of precedence") for shadowed variable names? I can't seem to find a concise answer online. For example: #include <iostream> int shadowed = 1; struct Foo { Foo() : shadowed(2) {} void bar(int shadowed = 3) { std::cout << shadowed << std::endl; // What does this output? { int shadowed = 4; std::cout << shadowed << std::endl; // What does this output? } } int shadowed; }; int main() { Foo().bar(); } I can't think of any other scopes where a variable might conflict. Please let me know if I missed one. What is the order of priority for all four shadow variables when inside the bar member function?

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• implement SIMD in C++

  - by Hristo

  I'm working on a bit of code and I'm trying to optimize it as much as possible, basically get it running under a certain time limit. The following makes the call... static affinity_partitioner ap; parallel_for(blocked_range<size_t>(0, T), LoopBody(score), ap); ... and the following is what is executed. void operator()(const blocked_range<size_t> &r) const { int temp; int i; int j; size_t k; size_t begin = r.begin(); size_t end = r.end(); for(k = begin; k != end; ++k) { // for each trainee temp = 0; for(i = 0; i < N; ++i) { // for each sample int trr = trRating[k][i]; int ei = E[i]; for(j = 0; j < ei; ++j) { // for each expert temp += delta(i, trr, exRating[j][i]); } } myscore[k] = temp; } } I'm using Intel's TBB to optimize this. But I've also been reading about SIMD and SSE2 and things along that nature. So my question is, how do I store the variables (i,j,k) in registers so that they can be accessed faster by the CPU? I think the answer has to do with implementing SSE2 or some variation of it, but I have no idea how to do that. Any ideas? Thanks, Hristo

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• Adding web reference on client when using Net.TCP

  - by Marko

  Hi everyone... I am trying to using Net.TCP in my WCF Service, which is self hosted, when i try to add this service reference through web reference to my client, i am not able access the classes and methods of that service, can any have any idea to achieve this... How I can add web references in this case. My Service has one method (GetNumber) that returns int. WebService: public class WebService : IWebService { public int GetNumber(int num) { return num + 1; } } Service Contract code: [ServiceContract] public interface IWebService { [OperationContract] int GetNumber(int num); } WCF Service code: ServiceHost host = new ServiceHost(typeof(WebService)); host.AddServiceEndpoint(typeof(IWebService), new NetTcpBinding(), new Uri("net.tcp://" + Dns.GetHostName() + ":1255/WebService")); NetTcpBinding binding = new NetTcpBinding(); binding.TransferMode = TransferMode.Streamed; binding.ReceiveTimeout = TimeSpan.MaxValue; binding.MaxReceivedMessageSize = long.MaxValue; Console.WriteLine("{0}", Dns.GetHostName().ToString()); Console.WriteLine("Opening Web Service..."); host.Open(); Console.WriteLine("Web Service is running on port {0}",1255); Console.WriteLine("Press <ENTER> to EXIT"); Console.ReadLine(); This works fine. Only problem is how to add references of this service in my client application. I just want to send number and to receive an answer. Can anyone help me?

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• Sequential animations in Jquery

  - by Pickels

  I see a lot people struggling with this(me included). I guess it's mostly due to not perfectly knowing how Javascript scopes work. An image slideshow is a good example of this. So lets say you have series of images, the first one fades in = waits = fades out = next image. When I first created this I was already a little lost. I think the biggest problem for creating the basics is to keep it clean. I noticed working with callbacks can get uggly pretty fast. So to make it even more complicated most slideshows have control buttons. Next, previous, go to img, pause, ... I've been trying this for a while now and this is where I got: $(InitSlideshow); function InitSlideshow() { var img = $("img").hide(); var animate = { wait: undefined, start: function() { img.fadeIn(function() { animate.middle(); }); }, middle: function() { animate.wait = setTimeout(function() { animate.end(); }, 1000); }, end: function() { img.fadeOut(function() { animate.start(); }); }, stop: function() { img.stop(); clearTimeout(animate.wait); } }; $("#btStart").click(animate.start); $("#btStop").click(animate.stop); }; This code works(I think) but I wonder how other people deal with sequentials animations in Jquery? Tips and tricks are most welcome. So are links to good resources dealing with this issue. If this has been asked before I will delete this question. I didn't find a lot of info about this right away. I hope making this community wiki is correct as there is not one correct answer to my question. Kind regards, Pickels

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• jquery autocomplete, $array source. how do i make it multiple?

  - by Toni Michel Caubet

  hello there! I'm using autocomplete so user can easly enter data on inputs, like this: <? $a = new etiqueta(0, ''); $b = $a->autocomplete_etiquetas(); ?> <script type="text/javascript"> function cargar_autocomplete_etiquetas(){ $("#tags").autocomplete({ source: [<? echo $b; ?>] }); } </script> $a = $b its an array with a result like: 'help','please',i','need','to,'be able to', 'select next item',' with autocomplete'; and i checked the ui documentation, but it doesn't fith with my source method.. any idea? I'm trying like this (edited with Bugai13 aportation): <? $a = new etiqueta(0, ''); $b = $a->autocomplete_etiquetas(); ?> <script type="text/javascript"> function cargar_autocomplete_etiquetas(){ $("#tags").autocomplete({ source: [<? echo $b; ?>], multiple: true, multipleSeparator: ", ", matchContains: true }); } </script> but i don't know how to do it.. any idea? are .push and .pop functions from the autocomplete? or shall i define, them? thanks again! PS: i'm getting adicted to this site! PS: come on dudes, i think the answer will be very usefull for many people PS: is it allowed to offer paypal reward?

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• Word characteristics tags

  - by theBlinker

  I want to do a riddle AI chatbot for my AI class. So i figgured the input to the chatbot would be : Something like : "It is blue, and it is up, but it is not the ceiling" Translation : <Object X> <blue> <up> <!ceiling> </Object X> (Answer : sky?) So Input is a set of characteristics (existing \ not existing in the object), output is a matched, most likely object. The domain will be limited to a number of objects, i could input all attributes myself, but i was thinking : How could I programatically build a database of characteristics for a word? Is there such a database available? How could i tag a word, how could i programatically find all it's attributes? I was thinking on crawling wikipedia, or some forum, but i can't see it build any reliable word tag database. Any ideas on how i could achieve such a thing? Any ideas on some literature on the subject? Thank you

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• Java webapp: how to implement a web bug (1x1 pixel)?

  - by NoozNooz42

  In the accepted answer in the following question, a SO regular with 13K+ rep suggests to use a "web bug" (non-cacheable 1x1 img) to be able to track requests in the logs: http://stackoverflow.com/questions/1784893 How can I do this in Java? Basically, I've got two issues: how to make sure the 1x1 image is not cacheable (how to set the header)? how to make sure the query for these 1x1 image will appear in the logs? I'm looking for exact piece of code because I know how to write a .jsp/servlet and I know how to serve an 1x1 image :) My question is really about the exact .jsp/servlet that I should write and how/what needs to be done so that Tomcat logs the request. For example I plan to use the following mapping: <servlet-mapping> <servlet-name>WebBugServlet</servlet-name> <url-pattern>/webbug*</url-pattern> </servlet-mapping> and then use an img tag referencing a "webbug.png" (or .gif), so how do I write the .jsp/servlet? What/where should I look for in the logs?

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• How to benchmark on multi-core processors

  - by Pascal Cuoq

  I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

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• Releasing Excel after using Interop

  - by figus

  Hi everyone I've read many post looking for my answer, but all are similar to this: http://stackoverflow.com/questions/1610743/reading-excel-files-in-vb-net-leaves-excel-process-hanging My problem is that I don't quit the app... The idea is this: If a User has Excel Open, if he has the file I'm interested in open... get that Excel instance and do whatever I want to do... But I don't to close his File after I'm done... I want him to keep working on it, the problem is that when he closes Excel... The process keeps running... and running... and running after the user closes Excel with the X button... this is how I try to do it This piece is used to know if he has Excel open, and in the For I check for the file name I'm interested in. Try oApp = GetObject(, "Excel.Application") libroAbierto = True For Each libro As Microsoft.Office.Interop.Excel.Workbook In oApp.Workbooks If libro.Name = EquipoASeccionIdSeccion.Text & ".xlsm" Then Exit Try End If Next libroAbierto = False Catch ex As Exception oApp = New Microsoft.Office.Interop.Excel.Application End Try here would be my code... if he hasn't Excel open, I create a new instance, open the file and everything else. My code ends with this: If Not libroAbierto Then libroSeccion.Close(SaveChanges:=True) oApp.Quit() Else oApp.UserControl = True libroSeccion.Save() End If System.Runtime.InteropServices.Marshal.FinalReleaseComObject(libroOriginal) System.Runtime.InteropServices.Marshal.FinalReleaseComObject(libroSeccion) System.Runtime.InteropServices.Marshal.FinalReleaseComObject(origen) System.Runtime.InteropServices.Marshal.FinalReleaseComObject(copiada) System.Runtime.InteropServices.Marshal.FinalReleaseComObject(oApp) libroOriginal = Nothing libroSeccion = Nothing oApp = Nothing origen = Nothing copiada = Nothing nuevosGuardados = True So you can see that, if I opened the file, I call oApp.Quit() and everything else and the Excel Process ends after a few seconds (maybe 5 aprox.) BUT if I mean the user to keep the file open (not calling Quit()), Excel process keeps running after the user closes Excel with the X button. Is there any way to do what I try to do?? Control a open instance of excel and releasing everything so when the user closes it with the X button, the Excel Process dies normally??? Thanks!!!

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• Prevent box shadow from showing on a specific side

  - by kaile

  Is there any way to create a css box-shadow in which regardless of the blur value, the shadow only appears on the desired sides? For example if I want to create a div with shadows on left and right sides and no shadow on the top or bottom. The div is not absolutely positioned and its height is determined by the content. -- Edit -- @ricebowl: I appreciate your answer. Maybe you can help with creating a complete solution to fix the problems stated in my reply to your solution... My page setup is as follows: <div id="container"> <div id="header"></div> <div id="content"></div> <div id="clearfooter"></div> </div> <div id="footer"></div> And CSS like this: #container {width:960px; min-height:100%; margin:0px auto -32px auto; position:relative; padding:0px; background-color:#e6e6e6; -moz-box-shadow: -3px 0px 5px rgba(0,0,0,.8), 3px 0px 5px rgba(0,0,0,.8);} #header {height:106px; position:relative;} #content {position:relative;} #clearFooter {height:32px; clear:both; display:block; padding:0px; margin:0px;} #footer {height:32px; padding:0px; position:relative; width:960px; margin:0px auto 0px auto;}

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• Choosing between instance methods and separate functions?

  - by StackedCrooked

  Adding functionality to a class can be done by adding a method or by defining a function that takes an object as its first parameter. Most programmers that I know would choose for the solution of adding a instance method. However, I sometimes prefer to create a separate function. For example, in the example code below Area and Diagonal are defined as separate functions instead of methods. I find it better this way because I think these functions provide enhancements rather than core functionality. Is this considered a good/bad practice? If the answer is "it depends", then what are the rules for deciding between adding method or defining a separate function? class Rect { public: Rect(int x, int y, int w, int h) : mX(x), mY(y), mWidth(w), mHeight(h) { } int x() const { return mX; } int y() const { return mY; } int width() const { return mWidth; } int height() const { return mHeight; } private: int mX, mY, mWidth, mHeight; }; int Area(const Rect & inRect) { return inRect.width() * inRect.height(); } float Diagonal(const Rect & inRect) { return std::sqrt(std::pow(static_cast<float>(inRect.width()), 2) + std::pow(static_cast<float>(inRect.height()), 2)); }

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• Game architecture: modeling different steps/types of UI

  - by Sander

  I have not done any large game development projects, only messed around with little toy projects. However, I never found an intuitive answer to a specific design question. Namely, how are different types/states of UI modeled in games? E.g. how is a menu represented? How is it different from a "game world" state (let's use an FPS as an example). How is an overlaid menu on top of a "game world" modeled? Let's imagine the main loop of a game. Where do the game states come into play? It it a simple case-by-case approach? if (menu.IsEnabled) menu.Process(elapsedTime); if (world.IsEnabled) world.Process(elapsedTime); if (menu.IsVisible) menu.Draw(); if (world.IsVisible) world.Draw(); Or are menu and world represented somewhere in a different logic layer and not represented at this level? (E.g. a menu is just another high-level entity like e.g. player input or enemy manager, equal to all others) foreach (var entity in game.HighLevelEntities) entity.Process(elapsedTime); foreach (var entity in game.HighLevelEntities) entity.Draw(elapsedTime); Are there well-known design patterns for this? Come to think of it, I don't know any game-specific design patterns - I assume there are others, as well? Please tell me about them.

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• Question about decorator pattern and the abstract decorator class?

  - by es11

  This question was asked already here, but rather than answering the specific question, descriptions of how the decorator pattern works were given instead. I'd like to ask it again because the answer is not immediately evident to me just by reading how the decorator pattern works (I've read the wikipedia article and the section in the book Head First Design Patterns). Basically, I want to know why an abstract decorator class must be created which implements (or extends) some interface (or abstract class). Why can't all the new "decorated classes" simply implement (or extend) the base abstract object themselves (instead of extending the abstract decorator class)? To make this more concrete I'll use the example from the design patterns book dealing with coffee beverages: There is an abstract component class called Beverage Simple beverage types such as HouseBlend simply extend Beverage To decorate beverage, an abstract CondimentDecorator class is created which extends Beverage and has an instance of Beverage Say we want to add a "milk" condiment, a class Milk is created which extends CondimentDecorator I'd like to understand why we needed the CondimentDecorator class and why the class Milk couldn't have simply extended the Beverage class itself and been passed an instance of Beverage in its constructor. Hopefully this is clear...if not I'd simply like to know why is the abstract decorator class necessary for this pattern? Thanks. Edit: I tried to implement this, omitting the abstract decorator class, and it seems to still work. Is this abstract class present in all descriptions of this pattern simply because it provides a standard interface for all of the new decorated classes?

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• How can I tackle 'profoundly found elsewhere' syndrome (inverse of NIH)?

  - by Alistair Knock

  How can I encourage colleagues to embrace small-scale innovation within our team(s), in order to get things done quicker and to encourage skills development? (the term 'profoundly found elsewhere' comes from Wikipedia, although it is scarcely used anywhere else apart from a reference to Proctor & Gamble) I've worked in both environments where there is a strong opposition to software which hasn't been developed in-house (usually because there's a large community of developers), and more recently (with far fewer central developers) where off-the-shelf products are far more favoured for the usual reasons: maintenance, total cost over product lifecycle, risk management and so on. I think the off the shelf argument works in the majority of cases for the majority of users, even though as a developer the product never quite does what I'd like it to do. However, in some cases there are clear gaps where the market isn't able to provide specifically what we would need, or at least it isn't able to without charging astronomical consultancy rates for a bespoke solution. These can be small web applications which provide a short-term solution to a particular need in one specific department, or could be larger developments that have the potential to serve a wider audience, both across the organisation and into external markets. The problem is that while development of these applications would be incredibly cheap in terms of developer hours, and delivered very quickly without the need for glacial consultation, the proposal usually falls flat because of risk: 'Who'll maintain the project tracker that hasn't had any maintenance for the past 7 years while you're on holiday for 2 weeks?' 'What if one of our systems changes and the connector breaks?' 'How can you guarantee it's secure/better/faster/cheaper/holier than Company X's?' With one developer behind these little projects, the answers are invariably: 'Nobody, but...' 'It will break, just like any other application would...' 'I, uh...' How can I better answer these questions and encourage people to take a little risk in order to stimulate creativity and fast-paced, short-lifecycle development instead of using that 6 months to consult about what tender process we might use?

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• UIScrollView loading an image

  - by treasure

  i must say i m not very good at this. and you probably know that (cause noone bothers to answer my questions) but i will keep on trying!!! lol here it goes! i wanted to find an "easy" way to use the pinch/zoom function on my app! so i decided to use a UIScrollView. so far so good. i load my image from an sqlite db like so: - (void)loadView { self.title = @"ScrollView"; imageView = [[UIImageView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame]; imageView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; imageView.contentMode = UIViewContentModeScaleAspectFit; imageView.backgroundColor = [UIColor blackColor]; self.view = imageView;} and - (void)viewWillAppear:(BOOL)animated {imageView.image = entity.imageA} I followed a tutorial but i cnnot seem to be able to load my image at all: - (void)vieDidLoad { imageView = [[UIImageView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame]; imageView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth; imageView.contentMode = UIViewContentModeScaleAspectFit; imageView.backgroundColor = [UIColor blackColor]; //when i have this it does load the image but when i cant load my own data!! /*UIImageView *tempImageView = [[UIImageView alloc] initWithImage:[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://www.austinbull.com/clonemines.png"]]]]; [self setMyImage:tempImageView]; [tempImageView release];*/ myScrollView.contentSize = CGSizeMake(imageView.frame.size.width, imageView.frame.size.height); myScrollView.maximumZoomScale = 4.0; myScrollView.minimumZoomScale = 0.75; myScrollView.clipsToBounds = YES; myScrollView.delegate = self; [myScrollView addSubview:imageView]; self.view = scrollView; [window makeKeyAndVisible]; } (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return myImage; } any help would be appreciated! thank you for your time!

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• visual studio macro - copy a definition or declaration from/to .h to/from .cpp

  - by Michael

  Is it possible to do a macro that copies a definition of a function to a declaration, and also the opposite? For instance class Foo { Foo(int aParameter, int aDefaultParameter = 0); int someMethod(char aCharacter) const; }; from the .h file would be: Foo::Foo(int aParameter, int aDefaultParameter){ // } int Foo::someMethod(char aCharacter) const { return 0; } in the .cpp file. The opposite wouldn't work with the default value, but it would still be cool if it copied the declaration into the class in the header file. Also if it could return a default value as in someMethod (based on the return value from the declaration). Personally I tried to do macrocoding some year ago (I think it was around 2005) but the tutorials and documentation of macros was thin (or I hadn't searched enough). I ended up going through the examples that they had in the IDE but gave up when I figured it would take too long to learn. I would however like to give it a try again. So if there are anyone with knowledge of good tutorials or documentation that aims at Visual Studio .Net (and maybe also covers the above problem) I would probably accept that as an answer as well :)

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