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  • C#JSON serialization

    - by Bridget the Midget
    I'm trying out the HighStock library for creating stock charts. To fill the chart with data, their example specifies this source. The first parameter is unixtime in milliseconds and the second parameter is the stock closing price. I don't know if this is valid json, but I would argue that the following would be a more appropriate way of writing json. [{"Closing":63.15000,"Date":1262559600000},{"Closing":64.75000,"Date":1262646000000}, ... I guess that I have no other option than to adapt to HighStocks syntax. I could solve this by looping and add correct syntax to a string, but that seems rudimentary. Would it be more wise to serialize C# objects to create my json, and if that's the case - how can I reach the syntax specified in the example? Lets just say this is my c# object: public class Quote { public double Date { get; set; } public decimal Closing { get; set; } } Am I making it unnecessary complex? Should I just format a json string?

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  • nedmalloc: where does mem<fm come from?

    - by Suma
    While implementing nedmalloc into my application, I am frequently hitting a situation when nedmalloc refuses to free a block of memory, claiming it did not allocate it. While debugging I have come up to the point I see a particular condition which is failing, all other (including magic numbers) succeed. The condition is this: if((size_t)mem-(size_t)fm>=(size_t)1<<(SIZE_T_BITSIZE-1)) return 0; On Win32 this seems to be equivalent to: if((int)((size_t)mem-(size_t)fm)<0) return 0; Which seems to be the same as: if((size_t)mem<(size_t)fm) return 0; In my case I really see mem < fm. What I do not understand now is, where does this condition come from. I cannot find anything which would guarantee the fm <= m anywhere in code. Yet, "select isn't broken": I doubt it would really be a bug in nedmalloc, most likely I am doing something wrong somewhere, but I cannot find it. Once I turn debugging features of nedmalloc on, the problem goes away. If someone here understands inner working of nedmalloc, could you please explain to me why is fm <= m?

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  • Need to format character precedence in Strings.

    - by Christian
    I'm currently writing a Roman Numeral Converter for the fun of it. The problem works up to the aforementioned character precedence. Since Roman Numerals are not positional, i.e. III does not symbolize 1*whatever base^2 + 1*whatever base^1 + 1*whatever base^0. That of course makes it hard when somebody types in XIV and I need to make sure that the I is not added in this case, but rather subtracted. I'm not sure how to do this. What would be the best approach to tackle this? I have both the Roman Symbols and their respective decimal numbers stored in arrays: const char cRomanArray[] = "IVXLCDM"; const int romanArray[] = { 1, 5, 10, 50, 100, 500, 1000 }; so it wouldn't be too hard for me to brute-force the damn thing by simply checking the precedence within the array, i.e. if the symbol is smaller than the next symbol, i.e. in the exampe 'XIV' if 'I' is smaller than 'V', in which case it would be because I have ordered them in the array, then I could make it subtract the value instead of add. But this seems like a very ugly solution. Are there perhaps any better ones? I was thinking something along the lines of Regular Expressions maybe( forgive me if that sounds like a horrible idea, I haven't used RegExp yet, but it sounds like it could do what I need, and that's to determine the characters in a string.)

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  • What's it like being a financial programmer?

    - by Mike
    As a student who's done an internship at a Silicon Valley company(non-financial), I'm curious to know what it's like working for a financial company doing software development. I'd expect the hours to be longer, and the pay to be higher. Specifically, I have the following questions: What's the work/life balance really like? Are you expected to work 80 hours a week most weeks? For those who have worked in non-financial software engineering jobs, how does being a financial software engineer compare in terms of work/life balance? How much does it pay? I'm curious as to starting(i.e. just got a BS) pay, as well as "top out" pay. (I'd prefer concrete numbers - ballpark is fine). Also, bonuses would be useful information. What jobs do financial programmers typically have? Are most just general software engineers, or do people typically have very specialized(i.e. AI or systems) backgrounds? Also, do most programmers have PhDs? Are programmers typically required to be at work, or are financial companies generally flexible about letting programmers work from home? When at work, do programmers have to dress formally? What are the technology environments like? Are finance companies using state-of-the-art hardware and software, or are they generally more conservative in upgrading their equipment? What programming languages are typically used? If VBA(shudder) is used, is it a large part of a finance company's workflow? If you could turn back the clock, would you still be a financial programmer? I'm going to keep this post open a little bit longer to get some more responses.

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  • Poor LLVM JIT performance

    - by Paul J. Lucas
    I have a legacy C++ application that constructs a tree of C++ objects. I want to use LLVM to call class constructors to create said tree. The generated LLVM code is fairly straight-forward and looks repeated sequences of: ; ... %11 = getelementptr [11 x i8*]* %Value_array1, i64 0, i64 1 %12 = call i8* @T_string_M_new_A_2Pv(i8* %heap, i8* getelementptr inbounds ([10 x i8]* @0, i64 0, i64 0)) %13 = call i8* @T_QueryLoc_M_new_A_2Pv4i(i8* %heap, i8* %12, i32 1, i32 1, i32 4, i32 5) %14 = call i8* @T_GlobalEnvironment_M_getItemFactory_A_Pv(i8* %heap) %15 = call i8* @T_xs_integer_M_new_A_Pvl(i8* %heap, i64 2) %16 = call i8* @T_ItemFactory_M_createInteger_A_3Pv(i8* %heap, i8* %14, i8* %15) %17 = call i8* @T_SingletonIterator_M_new_A_4Pv(i8* %heap, i8* %2, i8* %13, i8* %16) store i8* %17, i8** %11, align 8 ; ... Where each T_ function is a C "thunk" that calls some C++ constructor, e.g.: void* T_string_M_new_A_2Pv( void *v_value ) { string *const value = static_cast<string*>( v_value ); return new string( value ); } The thunks are necessary, of course, because LLVM knows nothing about C++. The T_ functions are added to the ExecutionEngine in use via ExecutionEngine::addGlobalMapping(). When this code is JIT'd, the performance of the JIT'ing itself is very poor. I've generated a call-graph using kcachegrind. I don't understand all the numbers (and this PDF seems not to include commas where it should), but if you look at the left fork, the bottom two ovals, Schedule... is called 16K times and setHeightToAtLeas... is called 37K times. On the right fork, RAGreed... is called 35K times. Those are far too many calls to anything for what's mostly a simple sequence of call LLVM instructions. Something seems horribly wrong. Any ideas on how to improve the performance of the JIT'ing?

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  • How best to use XPath with very large XML files in .NET?

    - by glenatron
    I need to do some processing on fairly large XML files ( large here being potentially upwards of a gigabyte ) in C# including performing some complex xpath queries. The problem I have is that the standard way I would normally do this through the System.XML libraries likes to load the whole file into memory before it does anything with it, which can cause memory problems with files of this size. I don't need to be updating the files at all just reading them and querying the data contained in them. Some of the XPath queries are quite involved and go across several levels of parent-child type relationship - I'm not sure whether this will affect the ability to use a stream reader rather than loading the data into memory as a block. One way I can see of making it work is to perform the simple analysis using a stream-based approach and perhaps wrapping the XPath statements into XSLT transformations that I could run across the files afterward, although it seems a little convoluted. Alternately I know that there are some elements that the XPath queries will not run across, so I guess I could break the document up into a series of smaller fragments based on it's original tree structure, which could perhaps be small enough to process in memory without causing too much havoc. I've tried to explain my objective here so if I'm barking up totally the wrong tree in terms of general approach I'm sure you folks can set me right...

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  • How to create minidump of a .NET process when a certain first chance exception occurs.

    - by mark
    Dear ladies and sirs. My application throws InvalidCastException in the QA environment, something I cannot reproduce in development. I wish to obtain the minidump at the exception moment. I know about adplus, but I am not sure how to use it so that it creates the minidump when InvalidCastException is thrown. Apparently, it does not distinguish one .NET exception from another. May be I am wrong and there is a way. Or, there is another tool to do it. Preferably free one. Anyway, can anyone advice how to handle this issue? Thanks. UPDATE The build is a Debug build in both QA and dev. However, QA runs complex scenarios made possible in the lab, which devs cannot reproduce. Hence I need an ability to make dump when running in QA. I can modify the code and create minidump from code. However, I wish for a more flexible solution, the one not requiring to modify the code every time an issue like this occurs.

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  • How to use jQuery .live() with ajax

    - by kylemac
    Currently I am using John Resig's LiveQuery plugin/function - http://ejohn.org/blog/jquery-livesearch/ - to allow users to sort through a long unordered-list of list-items. The code is as follows: $('input#q').liveUpdate('ul#teams').focus(); The issue arises when I use ajaxified tabs to sort the lists. Essentially I use ajax to pull in different lists and the liveUpdate() function doesn't have access to the new li's. I assume I would need to bind this using the .live() function - http://api.jquery.com/live/. But I am unclear how to bind this to an ajax event, I've only used the "click" event. How would I bind the new liveUpdate() to the newly loaded list-items? EDIT: The ajax tabs is run through the wordpress ajax api so the code is fairly complex, but simplified it is something like this: $('div.item-list-tabs').click( function(event) { var target = $(event.target).parent(); var data = {action, scope, pagination}; // Passes action to WP that loads my tab data $.post( ajaxurl, data, function(response) { $(target).fadeOut( 100, function() { $(this).html(response); $(this).fadeIn(100); }); }); return false; }); This is simplified for the sake of this conversation, but basically once the $.post loads the response in place .liveUpdate() doesn't have access to it. I believe the .live() function is the answer to this problem, I'm just unclear on how to implement it with the $.post()

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  • NullPointerException in javax.swing.text.SimpleAttributeSet.addAttribute

    - by Paul Reiners
    Has anyone ever seen an exception like this?: ERROR: java.lang.NullPointerException: null at java.util.Hashtable.put(null:-1) at javax.swing.text.SimpleAttributeSet.addAttribute(null:-1) at javax.swing.text.SimpleAttributeSet.addAttributes(null:-1) at javax.swing.text.StyledEditorKit.createInputAttributes(null:-1) at javax.swing.text.StyledEditorKit$AttributeTracker.updateInputAttributes(null:-1) at javax.swing.text.StyledEditorKit$AttributeTracker.caretUpdate(null:-1) at javax.swing.text.JTextComponent.fireCaretUpdate(null:-1) at javax.swing.text.JTextComponent$MutableCaretEvent.fire(null:-1) at javax.swing.text.JTextComponent$MutableCaretEvent.mouseReleased(null:-1) at java.awt.AWTEventMulticaster.mouseReleased(null:-1) at java.awt.AWTEventMulticaster.mouseReleased(null:-1) at java.awt.Component.processMouseEvent(null:-1) at javax.swing.JComponent.processMouseEvent(null:-1) at java.awt.Component.processEvent(null:-1) at java.awt.Container.processEvent(null:-1) at java.awt.Component.dispatchEventImpl(null:-1) at java.awt.Container.dispatchEventImpl(null:-1) at java.awt.Component.dispatchEvent(null:-1) at java.awt.LightweightDispatcher.retargetMouseEvent(null:-1) at java.awt.LightweightDispatcher.processMouseEvent(null:-1) at java.awt.LightweightDispatcher.dispatchEvent(null:-1) at java.awt.Container.dispatchEventImpl(null:-1) at java.awt.Window.dispatchEventImpl(null:-1) at java.awt.Component.dispatchEvent(null:-1) at java.awt.EventQueue.dispatchEvent(null:-1) at java.awt.EventDispatchThread.pumpOneEventForFilters(null:-1) at java.awt.EventDispatchThread.pumpEventsForFilter(null:-1) at java.awt.EventDispatchThread.pumpEventsForHierarchy(null:-1) at java.awt.EventDispatchThread.pumpEvents(null:-1) at java.awt.EventDispatchThread.pumpEvents(null:-1) at java.awt.EventDispatchThread.run(null:-1) I wish I could tell you an easy way to reproduce this, but I can’t. It’s happening in a Java Swing application I maintain. It happens infrequently and the application is quite complex. I know it’s a bit of a long shot just showing this stack trace, but I thought I’d try.

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  • Handling conflicting priorities and expectations in project development

    - by jasonk
    There are any number of situations in the standard day where priority conflicts exist for projects. Management wants maximum productivity from employees. Marketing wants maximum salability and fast turnaround. Ownership wants maximum profit. Customers want usability and low cost. Regardless of the origin of the demands, time and money are always the limiting factor in business. Sometimes project elements have intrinsic or goodwill benefits for which there is not a hard, fast way to measure with monetary means (e.g. arguments for an attractive UI appeal vs. functional but plain). Other elements of software may have a method of providing “mental breaks” or motivating “cool factor” for developers that can get them back on track on other bigger, complex issues. While they may sidetrack the project short term they may have greater results long term through improved job satisfaction, etc. Continued training is a must, but working it in can setup back progress. What are your suggestions for setting priorities? How do you evaluate requests/demands on your projects? What are your suggestions for communicating and passing those on to your team in a way that they stay focused?

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  • Telephone Number to Geolocation UK

    - by David Toy
    Is there a service that provides latitude and longitude for UK phone numbers? For example: Query: 0141 574 xxx, Returns: (55.8659829, -4.2602205) [Glasgow City Centre] Allow me to stress that I am not looking for a reverse-directory-enquires. I am more interested in 'local area' for things like weather by phone or "Where's my nearest Pizza Shop?" If this service doesn't exist your suggestions on how to implement it or where to get data from would also be incredibly useful. I am aware that Ofcom provides a list of area codes with a place name [1] suitable for geolocation, but I have my concerns about resolution. I see this as a particular problem in smaller towns and rural areas where an area code will cover a large geographical area. Second Example: Area Code: 01555, Ofcom: Lanark However: 01555 860xxx is Crossford (4 miles W of Lanark) 01555 77xxxx is Carluke (5 miles NW) 01555 89xxxx is Lesmahagow (5 miles SW) 01555 840xxx is Carnwath (7 miles NE) Therefore 01555 covers about ~80 sq miles. That's not particularly local. [1] Ofcom Area Code Tool: http://www.ofcom.org.uk/consumer/2009/09/telephone-area-codes-tool/

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  • Counter that will remember it's value

    - by owca
    I have a task to operate on complex number. Each number consists of double r = real part, double i = imaginary part and String name. Name must be set within constructor, so I've created int counter, then I'm sending it's value to setNextName function and get name letter back. Unfortunately incrementing this 'counter' value works only within costructor and then it is once again set to 0. How to deal with that?Some constant value? And second problem is that I also need to provide setNextNames(char c) function that will change the counter current value. The code : public class Imaginary { private double re; private double im; private String real; private String imaginary; private String name; private int counter=0; public Imaginary(double r, double u){ re = r; im = u; name = this.setNextName(counter); counter++; } public static String setNextName(int c){ String nameTab[] = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N", "O","P","Q","R","S","T","U","W","V","X","Y","Z"}; String setName = nameTab[c]; System.out.println("c: "+c); return setName; } public static String setNextName(char c){ // //don't know how to deal with this part // }

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  • MVC Paging and Sorting Patterns: How to Page or Sort Re-Using Form Criteria

    - by CRice
    What is the best ASP.NET MVC pattern for paging data when the data is filtered by form criteria? This question is similar to: http://stackoverflow.com/questions/1425000/preserve-data-in-net-mvc but surely there is a better answer? Currently, when I click the search button this action is called: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Search(MemberSearchForm formSp, int? pageIndex, string sortExpression) {} That is perfect for the initial display of the results in the table. But I want to have page number links or sort expression links re-post the current form data (the user entered it the first time - persisted because it is returned as viewdata), along with extra route params 'pageIndex' or 'sortExpression', Can an ActionLink or RouteLink (which I would use for page numbers) post the form to the url they specify? <%= Html.RouteLink("page 2", "MemberSearch", new { pageIndex = 1 })%> At the moment they just do a basic redirect and do not post the form values so the search page loads fresh. In regular old web forms I used to persist the search params (MemberSearchForm) in the ViewState and have a GridView paging or sorting event reuse it.

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  • How to use routing in a ASP MVC website to localize in two languages - But keeping exiting URLs

    - by Anders Pedersen
    We have a couple ASP MVC websites just using the standard VS templates default settings - Working as wanted. But now I want to localize these website ( They are now in Dutch and I will add the English language ) I would like to use routing and not Resource because: 1. Languages will differ in content, numbers of pages, etc. 2. The content is mostly text. I would like the URLs to look some thing like this - www.domain.com/en/Home/Index, www.domain.nl/nl/Home/Index. But the last one should also work with - www.domain.nl/Home/Index - Witch is the exciting URLs. I have implemented Phil Haacks areas ViewEngine from this blogpost - http://haacked.com/archive/2008/11/04/areas-in-aspnetmvc.aspx. But only putting the English website in the areas and keeping the Dutch in old structure. Witch are served as Phils default fallback. But the problem is here that I have to duplicate my controllers for both language's. So I tried the work method described in this tread - http://stackoverflow.com/questions/1712167/asp-net-mvc-localization-route. It works OK with the ?en? and /nl/ but not with the old URLs. When using this code in the global.asax the URL without the culture isn't working. public static void RegisterRoutes(RouteCollection routes) { //routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{culture}/{controller}/{action}/{id}", // URL with parameters new { culture = "nl-NL", controller = "Home", action = "Index", id = "" } // Parameter defaults ); routes.MapRoute( "DefaultWitoutCulture", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = "" } // Parameter defaults ); } I properly overlooking some thing simple but I can't get this to work for me. Or are there a better way of doing this?

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  • R plot- SGAM plot counts vs. time - how do I get dates on the x-axis?

    - by Nate
    I'd like to plot this vs. time, with the actual dates (years actually, 1997,1998...2010). The dates are in a raw format, ala SAS, days since 1960 (hence as.date conversion). If I convert the dates using as.date to variable x, and do the GAM plot, I get an error. It works fine with the raw day numbers. But I want the plot to display the years (data are not equally spaced). structure(list(site = c(928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L, 928L), date = c(13493L, 13534L, 13566L, 13611L, 13723L, 13752L, 13804L, 13837L, 13927L, 14028L, 14082L, 14122L, 14150L, 14182L, 14199L, 16198L, 16279L, 16607L, 16945L, 17545L, 17650L, 17743L, 17868L, 17941L, 18017L, 18092L), y = c(7L, 7L, 17L, 18L, 17L, 17L, 10L, 3L, 17L, 24L, 11L, 5L, 5L, 3L, 5L, 14L, 2L, 9L, 9L, 4L, 7L, 6L, 1L, 0L, 5L, 0L)), .Names = c("site", "date", "y"), class = "data.frame", row.names = c(NA, -26L)) sgam1 <- gam(sites$y ~ s(sites$date)) sgam <- predict(sgam1, se=TRUE) plot(sites$date,sites$y,xaxt="n", xlab='Time', ylab='Counts') x<-as.Date(sites$date, origin="1960-01-01") axis(1, at=1:26,labels=x) lines(sites$date,sgam$fit, lty = 1) lines(sites$date,sgam$fit + 1.96* sgam$se, lty = 2) lines(sites$date,sgam$fit - 1.96* sgam$se, lty = 2) ggplot2 has a solution (it doesn't mind the as.date thing) but it gives me other problems...

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  • Cleaner/more effective way to use modulus and creating columned lists

    - by WmasterJ
    I currently have a list (<ul>) of people that I have divided up into two columns. But after finishing the code for it I keept wondering if there is a more effective or clean way to do the same thing. echo "<table class='area_list'><tr>"; // Loop users within areas, divided up in 2 columns $count = count($areaArray); for($i=0 ; $i<$count ; $i++) { // get the modulus value + ceil for uneven numbers $rowCalc = ($i+1) % ceil($count/2); if ($rowCalc == 1) echo "<td><ul>"; // OUTPUT the actual list item echo "<li>{$users[$uid]->profile_lastname}</li>"; if ($rowCalc == 0 && $i!=0) echo "</ul></td>"; } echo "</table>"; Any ideas of how to make this cleaner or do it in another way?

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  • Algorithm to determine which points should be visible on a map based on zoom

    - by lgratian
    Hi! I'm making a Google Maps-like application for a course at my Uni (not something complex, it should load the map of a city for example, not the whole world). The map can have many layers, including markers (restaurants, hospitals, etc.) The problem is that when you have many points and you zoom out the map it doesn't look right. At this zoom level only some points need to be visible (and at the maximum map size, all points). The question is: how can you determine which points should be visible for a specified zoom level? Because I have implemented a PR Quadtree to speed up rendering I thought that I could define some "high-priority" markers (that are always visible, defined in the map editor) and put them in a queue. At each step a marker is removed from the queue and all it's neighbors that are at least D units away (D depends on the zoom levels) are chosen and inserted in the queue, and so on. Is there any better way than the algorithm I thought of? Thanks in advance!

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  • weighted matching algorithm in Perl

    - by srk
    Problem : We have equal number of men and women.each men has a preference score toward each woman. So do the woman for each man. each of the men and women have certain interests. Based on the interest we calculate the preference scores. So initially we have an input in a file having x columns. First column is the person(men/woman) id. id are nothing but 0.. n numbers.(first half are men and next half woman) the remaining x-1 columns will have the interests. these are integers too. now using this n by x-1 matrix... we have come up with a n by n/2 matrix. the new matrix has all men and woman as their rows and scores for opposite sex in columns. We have to sort the scores in descending order, also we need to know the id of person related to the scores after sorting. So here i wanted to use hash table. once we get the scores we need to make up pairs.. for which we need to follow some rules. My trouble is with the second matrix of n by n/2 that needs to give information of which man/woman has how much preference on a woman/man. I need these scores sorted so that i know who is the first preferred woman/man, 2nd preferred and so on for a man/woman. I hope to get good suggestions on the data structures i use.. I prefer php or perl. Thank you in advance

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  • Is there any way to combine transparency and "ajax usability" with HTML templates

    - by Sam
    I'm using HTML_Template_Flexy in PHP but the question should apply to any language or template library. I am outputting a list of relatively complex objects. In the beginning I just iterated over a list of the objects and called a toHtml method on them. When I was about to have my layout designer look over the template I noticed that it was too opaque and that he would have ended up looking through and/or editing many additional php source files to see what really gets generated by the toHtml method. So I extracted most of the HTML strings in the php classes up to the template which made for one clear file where you can see the whole page structure at once. However this causes problems when you want to add an object to the list using javascript. Then I have to keep the old toHtml method and maintain both the main template and the html strings at the same time, so I can output just the HTML for a new object that should be added to the page. So I'm back to the idea of using smaller templates for the objects that make up the page, but I was wondering if there was some easy way of having my cake and eating it too by having one template that shows the whole page but also the mini-templates for smaller objects on the page. Edit: Yes, updating the page is not a problem at all. My concern is with having both maintainability and transparency of the template files. If I have one single template for the whole page, then I must maintain mini-templates of the objects that are shown on the page. If I just have the mini-templates and include them from the higher-level template it becomes more difficult to look at the top-level html and imagine what the end result will look like.

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  • How much business logic belongs in RIA services layer?

    - by jkohlhepp
    I have been experimenting recently with Silverlight, RIA Services, and Entity Framework using .NET 4.0. I'm trying to figure out if that stack makes sense for use in any of my upcoming projects. It certainly seems like these technologies can be very productive for developing applications, but I'm struggling to decide how an application on top of this stack should be architected. The main issue I have is that in most of the demos I've seen most of the business logic ends up as DataAnnotations and custom validations in the RIA Services domain service class. This seems inappropriate to me. I view the domain service as basically a glorified web service that happens to make it easy to push information to the client. But most of what I've seen seems to orient the domain service as the main source of business logic in the application. So, my questions: What is the best location for business logic (rules, validations, behaviors, authorization) in an application using this stack? Are there any guidelines published at an architectural level for using this stack? My questions pertain to large, complex, and long-lived applications. Obviously for an application of only a few screens this is less of a concern. Edit: Another thing I meant to mention is that obviously you can make the domain service class stupid, but then you lose a lot of the automagic entity information (e.g. validations) being pushed to the client. And then if you lose that is there any point to using RIA services?

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  • List of objects or parallel arrays of properties?

    - by Headcrab
    The question is, basically: what would be more preferable, both performance-wise and design-wise - to have a list of objects of a Python class or to have several lists of numerical properties? I am writing some sort of a scientific simulation which involves a rather large system of interacting particles. For simplicity, let's say we have a set of balls bouncing inside a box so each ball has a number of numerical properties, like x-y-z-coordinates, diameter, mass, velocity vector and so on. How to store the system better? Two major options I can think of are: to make a class "Ball" with those properties and some methods, then store a list of objects of the class, e. g. [b1, b2, b3, ...bn, ...], where for each bn we can access bn.x, bn.y, bn.mass and so on; to make an array of numbers for each property, then for each i-th "ball" we can access it's 'x' coordinate as xs[i], 'y' coordinate as ys[i], 'mass' as masses[i] and so on; To me it seems that the first option represents a better design. The second option looks somewhat uglier, but might be better in terms of performance, and it could be easier to use it with numpy and scipy, which I try to use as much as I can. I am still not sure if Python will be fast enough, so it may be necessary to rewrite it in C++ or something, after initial prototyping in Python. Would the choice of data representation be different for C/C++? What about a hybrid approach, e.g. Python with C++ extension?

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  • java RMI connection to server

    - by user85116
    I have a very simple rmi client / server application. I don't use the "rmiregistry" application though, I use this to create the server: server = new RemoteServer(); registry = LocateRegistry.createRegistry(PORT); registry.bind("RemoteServer", server); The client part is: registry = LocateRegistry.getRegistry(IPADDRESS, PORT); remote = (IRemoteServer) registry.lookup("RemoteServer"); Here is the fascinating problem: The application works perfectly when both server and client are running in my (private) local network. As soon as I put the server on a public server, the application hangs for a minute, then gives me the following error: java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: java.rmi.ConnectException: Connection refused to host: 192.168.x.y; nested exception is: java.net.ConnectException: Connection timed out: connect at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source) at sun.rmi.transport.Transport$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.Transport.serviceCall(Unknown Source) at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Source ... (the rest is truncated) The key I think is that the client (running on my private network) cannot connect to myself (my address is 192.168.x.y where x.y is some other numbers, but the real error message shows my ip address listed there) If I kill the rmi server on the public internet, then I instantly get a "connection refused to host: a.b.c.d") message, so I know that something at the server end is at least working. Any suggestions? EDIT: just to make this a little more clear: 192.168.x.y is the client address, a.b.c.d is the server address. The stacktrace shows the client cannot connect to the client.

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  • When virtual inheritance IS a good design?

    - by 7vies
    EDIT3: Please be sure to clearly understand what I am asking before answering (there are EDIT2 and lots of comments around). There are (or were) many answers which clearly show misunderstanding of the question (I know that's also my fault, sorry for that) Hi, I've looked over the questions on virtual inheritance (class B: public virtual A {...}) in C++, but did not find an answer to my question. I know that there are some issues with virtual inheritance, but what I'd like to know is in which cases virtual inheritance would be considered a good design. I saw people mentioning interfaces like IUnknown or ISerializable, and also that iostream design is based on virtual inheritance. Would those be good examples of a good use of virtual inheritance, is that just because there is no better alternative, or because virtual inheritance is the proper design in this case? Thanks. EDIT: To clarify, I'm asking about real-life examples, please don't give abstract ones. I know what virtual inheritance is and which inheritance pattern requires it, what I want to know is when it is the good way to do things and not just a consequence of complex inheritance. EDIT2: In other words, I want to know when the diamond hierarchy (which is the reason for virtual inheritance) is a good design

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  • Time complexity with bit cost

    - by Keyser
    I think I might have completely misunderstood bit cost analysis. I'm trying to wrap my head around the concept of studying an algorithm's time complexity with respect to bit cost (instead of unit cost) and it seems to be impossible to find anything on the subject. Is this considered to be so trivial that no one ever needs to have it explained to them? Well I do. (Also, there doesn't even seem to be anything on wikipedia which is very unusual). Here's what I have so far: The bit cost of multiplication and division of two numbers with n bits is O(n^2) (in general?) So, for example: int number = 2; for(int i = 0; i < n; i++ ){ number = i*i; } has a time complexity with respect to bit cost of O(n^3), because it does n multiplications (right?) But in a regular scenario we want the time complexity with respect to the input. So, how does that scenario work? The number of bits in i could be considered a constant. Which would make the time complexity the same as with unit cost except with a bigger constant (and both would be linear). Also, I'm guessing addition and subtraction can be done in constant time, O(1). Couldn't find any info on it but it seems reasonable since it's one assembler operation.

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  • How can i use complextype class or multi type class is it generic collection?

    - by programmerist
    i need a complex returning type. i have 4 class returning types COMPLEXTYPE must include Company, Muayene, Radyoloji, Satis because i must return data switch case situation how can i do? Maybe i need generic collections How can i do that? public class GenoTipController { public COMPLEXTYPE Generate(DataModelType modeltype) { _Company company = null; _Muayene muayene = null; _Radyoloji radyoloji = null; _Satis satis = null; switch (modeltype) { case DataModelType.Radyoloji: radyoloji = new Radyoloji(); return radyoloji; break; case DataModelType.Satis: satis = new Satis(); return satis; break; case DataModelType.Muayene: muayene = new Muayene(); return muayene; break; case DataModelType.Company: company = new Company(); return company; break; default: break; } } } public class CompanyView { public static List GetPersonel() { GenoTipController controller = new GenoTipController(); _Company company = controller.Generate(DataModelType.Company); return company.GetPersonel(); } } public enum DataModelType { Radyoloji, Satis, Muayene, Company }

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