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  • Class initialization and synchronized class method

    - by nybon
    Hi there, In my application, there is a class like below: public class Client { public synchronized static print() { System.out.println("hello"); } static { doSomething(); // which will take some time to complete } } This class will be used in a multi thread environment, many threads may call the Client.print() method simultaneously. I wonder if there is any chance that thread-1 triggers the class initialization, and before the class initialization complete, thread-2 enters into print method and print out the "hello" string? I see this behavior in a production system (64 bit JVM + Windows 2008R2), however, I cannot reproduce this behavior with a simple program in any environments. In Java language spec, section 12.4.1 (http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html), it says: A class or interface type T will be initialized immediately before the first occurrence of any one of the following: T is a class and an instance of T is created. T is a class and a static method declared by T is invoked. A static field declared by T is assigned. A static field declared by T is used and the reference to the field is not a compile-time constant (§15.28). References to compile-time constants must be resolved at compile time to a copy of the compile-time constant value, so uses of such a field never cause initialization. According to this paragraph, the class initialization will take place before the invocation of the static method, however, it is not clear if the class initialization need to be completed before the invocation of the static method. JVM should mandate the completion of class initialization before entering its static method according to my intuition, and some of my experiment supports my guess. However, I did see the opposite behavior in another environment. Can someone shed me some light on this? Any help is appreciated, thanks.

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  • adding Json to mutable array resolves in crash

    - by user2957713
    Hello guys I am new to Xcode/iOS developing I trying to add json data to the mutable array , and it results in app crash :( so far here is my code: if(! [defaults objectForKey:@"Person1"]) [defaults setObject:[PersonsFromSearch objectAtIndex:index] forKey:@"Person1"]; else { NSMutableArray *Array = [[NSMutableArray alloc]init]; id object = [defaults objectForKey:@"Person1"]; Array = [object isKindOfClass:[NSArray class]] ? object : @[object]; [Array addObject:[PersonsFromSearch objectAtIndex:index]];//crash here :(( [Array moveObjectFromIndex:[Array count] toIndex:0]; } Crash Dump: * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFDictionary addObject:]: unrecognized selector sent to instance 0xbf98dc0' what is wrong here ? can you please help me to resolve this issue Array contains this (Json?) { Address = "\U05d3\U05e8\U05da \U05d4\U05e9\U05dc\U05d5\U05dd 53"; CellPhone = "052-3275381"; EMail = "[email protected]"; EnglishPerson = "Yehuda Konfortes"; FaceBookLink = ""; Fax1 = "03-7330703"; Fax2 = ""; FileNAme = "100050.jpg"; HomeEMail = ""; HomeFax = ""; HomePhone1 = ""; HomePhone2 = ""; PersonID = 100050; PersonName = "\U05d9\U05d4\U05d5\U05d3\U05d4 \U05e7\U05d5\U05e0\U05e4\U05d5\U05e8\U05d8\U05e1"; Phone1 = "03-7330733"; Phone2 = ""; ZipCode = ""; }

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  • Natural problems to solve using closures

    - by m.u.sheikh
    I have read quite a few articles on closures, and, embarassingly enough, I still don't understand this concept! Articles explain how to create a closure with a few examples, but I don't see any point in paying much attention to them, as they largely look contrived examples. I am not saying all of them are contrived, just that the ones I found looked contrived, and I dint see how even after understanding them, I will be able to use them. So in order to understand closures, I am looking at a few real problems, that can be solved very naturally using closures. For instance, a natural way to explain recursion to a person could be to explain the computation of n!. It is very natural to understand a problem like computing the factorial of a number using recursion. Similarly, it is almost a no-brainer to find an element in an unsorted array by reading each element, and comparing with the number in question. Also, at a different level, doing Object-oriented programming also makes sense. So I am trying to find a number of problems that could be solved with or without closures, but using closures makes thinking about them and solving them easier. Also, there are two types to closures, where each call to a closure can create a copy of the environment variables, or reference the same variables. So what sort of problems can be solved more naturally in which of the closure implementations?

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  • Spring Security 3.0- Customise basic http Authentication Dialog

    - by gav
    Rather than reading; A user name and password are being requested by http://localhost:8080. The site says: "Spring Security Application" I want to change the prompt, or at least change what the "site says". Does anyone know how to do this via resources.xml? In my Grails App Spring configuration, my current version is as follows; <?xml version="1.0" encoding="UTF-8"?> <beans:beans xmlns="http://www.springframework.org/schema/security" xmlns:beans="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.0.xsd"> <http auto-config="true" use-expressions="true"> <http-basic/> <intercept-url pattern="/**" access="isAuthenticated()" /> </http> <authentication-manager alias="authenticationManager"> <authentication-provider> <user-service> <user name="admin" password="admin" authorities="ROLE_ADMIN"/> </user-service> </authentication-provider> </authentication-manager> </beans:beans>

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  • Determining what action an NPC will take, when it is partially random but influenced by preferences?

    - by lala
    I want to make characters in a game perform actions that are partially random but also influenced by preferences. For instance, if a character feels angry they have a higher chance of yelling than telling a joke. So I'm thinking about how to determine which action the character will take. Here are the ideas that have come to me. Solution #1: Iterate over every possible action. For each action do a random roll, then add the preference value to that random number. The action with the highest value is the one the character takes. Solution #2: Assign a range of numbers to an action, with more likely actions having a wider range. So, if the random roll returns anywhere from 1-5, the character will tell a joke. If it returns 6-75, they will yell. And so on. Solution #3: Group all the actions and make a branching tree. Will they take a friendly action or a hostile action? The random roll (with preference values added) says hostile. Will they make a physical attack or verbal? The random roll says verbal. Keep going down the line until you reach the action. Solution #1 is the simplest, but hardly efficient. I think Solution #3 is a little more complicated, but isn't it more efficient? Does anyone have any more insight into this particular problem? Is #3 the best solution? Is there a better solution?

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  • Sitecore development. Sitecore.Web.UI.WebControl.GetCacheKey() throws NullReferenceException

    - by user344010
    I just click submit button and got an exception. Unable to debug, because this happens before the submit event handler work. I tried to clear sitecore caches, browser caches and cookies... nothing helps. here the stack trace. [NullReferenceException: Object reference not set to an instance of an object.] Sitecore.Web.UI.WebControl.GetCacheKey() +242 Sitecore.Web.UI.WebControl.Render(HtmlTextWriter output) +61 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +134 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19 System.Web.UI.HtmlControls.HtmlHead.RenderChildren(HtmlTextWriter writer) +17 System.Web.UI.HtmlControls.HtmlContainerControl.Render(HtmlTextWriter writer) +32 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +134 System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19 System.Web.UI.Page.Render(HtmlTextWriter writer) +29 System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27 System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99 System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1266

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  • Alignment in assembly

    - by jena
    Hi, I'm spending some time on assembly programming (Gas, in particular) and recently I learned about the align directive. I think I've understood the very basics, but I would like to gain a deeper understanding of its nature and when to use alignment. For instance, I wondered about the assembly code of a simple C++ switch statement. I know that under certain circumstances switch statements are based on jump tables, as in the following few lines of code: .section .rodata .align 4 .align 4 .L8: .long .L2 .long .L3 .long .L4 .long .L5 ... .align 4 aligns the following data on the next 4-byte boundary which ensures that fetching these memory locations is efficient, right? I think this is done because there might be things happening before the switch statement which caused misalignment. But why are there actually two calls to .align? Are there any rules of thumb when to call .align or should it simply be done whenever a new block of data is stored in memory and something prior to this could have caused misalignment? In case of arrays, it seems that alignment is done on 32-byte boundaries as soon as the array occupies at least 32 byte. Is it more efficient to do it this way or is there another reason for the 32-byte boundary? I'd appreciate any explanation or hint on literature.

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  • How can you get the call tree with python profilers?

    - by Oliver
    I used to use a nice Apple profiler that is built into the System Monitor application. As long as your C++ code was compiled with debug information, you could sample your running application and it would print out an indented tree telling you what percent of the parent function's time was spent in this function (and the body vs. other function calls). For instance, if main called function_1 and function_2, function_2 calls function_3, and then main calls function_3: main (100%, 1% in function body): function_1 (9%, 9% in function body): function_2 (90%, 85% in function body): function_3 (100%, 100% in function body) function_3 (1%, 1% in function body) I would see this and think, "Something is taking a long time in the code in the body of function_2. If I want my program to be faster, that's where I should start." Does anyone know how I can most easily get this exact profiling output for a python program? I've seen people say to do this: import cProfile, pstats prof = cProfile.Profile() prof = prof.runctx("real_main(argv)", globals(), locals()) stats = pstats.Stats(prof) stats.sort_stats("time") # Or cumulative stats.print_stats(80) # 80 = how many to print but it's quite messy compared to that elegant call tree. Please let me know if you can easily do this, it would help quite a bit. Cheers!

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  • Linq In Clause & Predicate building

    - by Michael G
    I have two tables. Report and ReportData. ReportData has a constraint ReportID. How can I write my linq query to return all Report objects where the predicate conditions are met for ReportData? Something like this in SQL: SELECT * FROM Report as r Where r.ServiceID = 3 and r.ReportID IN (Select ReportID FROM ReportData WHERE JobID LIKE 'Something%') This is how I'm building my predicate: Expression<Func<ReportData, bool>> predicate = PredicateBuilder.True<ReportData>(); predicate = predicate.And(x => x.JobID.StartsWith(QueryConfig.Instance.DataStreamName)); var q = engine.GetReports(predicate, reportsDataContext); reports = q.ToList(); This is my query construction at the moment: public override IQueryable<Report> GetReports(Expression<Func<ReportData, bool>> predicate, LLReportsDataContext reportDC) { if (reportDC == null) throw new ArgumentNullException("reportDC"); var q = reportDC.ReportDatas.Where(predicate).Where(r => r.ServiceID.Equals(1)).Select(r => r.Report); return q; }

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  • WCF REST adding data using POST or PUT 400 Bad Request

    - by user55474
    HI How do i add data using wcf rest architecture. I dont want to use the channelfactory to call my method. Something similar to the webrequest and webresponse used for GET. Something similar to the ajax WebServiceProxy restInvoke Or do i always have to use the Webchannelfactory implementation I am getting a 400 BAD request by using the following Dim url As String = "http://localhost:4475/Service.svc/Entity/Add" Dim req As WebRequest = WebRequest.Create(url) req.Method = "POST" req.ContentType = "application/xml; charset=utf-8" req.Timeout = 30000 req.Headers.Add("SOAPAction", url) Dim xEle As XElement xEle = <Entity xmlns:i="http://www.w3.org/2001/XMLSchema-instance"> <Name>Entity1</Name> </Entity> Dim sXML As String = xEle .Value req.ContentLength = sXML.Length Dim sw As New System.IO.StreamWriter(req.GetRequestStream()) sw.Write(sXML) sw.Close() Dim res as HttpWebResponse = req.GetResponse() Sercice Contract is as follows <OperationContract()> _ <WebInvoke(Method:="PUT", UriTemplate:="Entity/Add")> _ Function AddEntity(ByVal e1 As Entity) DataContract is as follows <Serializable()> _ <DataContract()> _ Public Class Entity private m_Name as String <DataMember()> _ Public Property Name() As String Get Return m_Name End Get Set(ByVal value As String) m_Name = value End Set End Property End Class thanks

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  • DataGridView with row-specific DataGridViewComboBoxColumn contents

    - by XXXXX
    So I have something like the following data structure (constructors omitted) class Child { public string Name { get; set; } public int Age { get; set; } } class Parent { public string Name { get; set; } public List <Child> Children { get; private set; } // never null; list never empty public Child FavoriteChild { get; set; } // never null; always a reference to a Child in Children } List < Parent > Parents; What I want to do is show a DataGridView where each row is a Parent from Parent list. Each row should have two columns: a text box showing the parent's name and a DataGridViewComboBoxColumn containing that parent's children, from which the user can select the parent's favorite child. I suppose I could do the whole thing manually, but I'd like to do all this with more-or-less standard Data Binding. It's easy enough to bind the DataGridView to the list of parents, and easy enough to bind the selected child to the FavoriteChild property. The part that's giving me difficulty is that it looks like the Combo Box column wants to bind to one data source for all the combo-box's contents on all rows. I'd like each instance of the combo box to bind to the list of each parent's children. I'm fairly new to C#/Windows Forms, so I may well be missing something obvious. Or it could be that "you can't get there from here." It's not too tough to make a separate list of all the children and filter it by parent; I'm looking into that possibility right now. Is this feasible, or is there a better way?

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  • Zend Form - how do I create these custom form elements?

    - by Jeremy Hicks
    This is a very specific instance where I'm having difficulty getting Zend Form to produce the correct output and supply the correct validation. I may have to go create a composite element but thought I'd ask here first. Here is the HTML I'm trying to get Zend Form to produce. I'd like this to be able to work where if the validation doesn't pass that the error messages still show up inline with the field that produced the error. <tr> <td>Budget</td> <td> <input type="radio" name="budget" value="unlimited" /> unlimited <br /> <input type="radio" name="budget" value="limited" /> $ <input type="text" name="budget_amount" /> every <select name="budget_period"> <option value="day">day</option> <option value="week">week</option> <option value="month">month</option> <option value="year">year</option> </select> </td> </tr> <tr> <td></td> <td><input type="checkbox" name="include_weekends" value="yes" /> include weekends?</td> </tr> The user can choose either unlimited or limited for the budget value, however, if they choose limited, then they are required to enter a value for the budget amount field and choose a value from the select for the budget period field.

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  • Compilation errors calling find_if using a functor

    - by Jim Wong
    We are having a bit of trouble using find_if to search a vector of pairs for an entry in which the first element of the pair matches a particular value. To make this work, we have defined a trivial functor whose operator() takes a pair as input and compares the first entry against a string. Unfortunately, when we actually add a call to find_if using an instance of our functor constructed using a temporary string value, the compiler produces a raft of error messages. Oddly (to me, anyway), if we replace the temporary with a string that we've created on the stack, things seem to work. Here's what the code (including both versions) looks like: typedef std::pair<std::string, std::string> MyPair; typedef std::vector<MyPair> MyVector; struct MyFunctor: std::unary_function <const MyPair&, bool> { explicit MyFunctor(const std::string& val) : m_val(val) {} bool operator() (const MyPair& p) { return p.first == m_val; } const std::string m_val; }; bool f(const char* s) { MyFunctor f(std::string(s)); // ERROR // std::string str(s); // MyFunctor f(str); // OK MyVector vec; MyVector::const_iterator i = std::find_if(vec.begin(), vec.end(), f); return i != vec.end(); } And here's what the most interesting error message looks like: /usr/include/c++/4.2.1/bits/stl_algo.h:260: error: conversion from ‘std::pair, std::allocator , std::basic_string, std::allocator ’ to non-scalar type ‘std::string’ requested Because we have a workaround, we're mostly curious as to why the first form causes problems. I'm sure we're missing something, but we haven't been able to figure out what it is.

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  • Why are my event listeners firing more than once?

    - by Arms
    In my Flash project I have a movieclip that has 2 keyframes. Both frames contain 1 movieclip each. frame 1 - Landing frame 2 - Game The flow of the application is simple: User arrives on landing page (frame 1) User clicks "start game" button User is brought to the game page (frame 2) When the game is over, the user can press a "play again" button which brings them back to step 1 Both Landing and Game movieclips are linked to separate classes that define event listeners. The problem is that when I end up back at step 1 after playing the game, the Game event listeners fire twice for their respective event. And if I go through the process a third time, the event listeners fire three times for every event. This keeps happening, so if I loop through the application flow 7 times, the event listeners fire seven times. I don't understand why this is happening because on frame 1, the Game movieclip (and I would assume its related class instance) does not exist - but I'm clearly missing something here. I've run into this problem in other projects too, and tried fixing it by first checking if the event listeners existed and only defining them if they didn't, but I ended up with unexpected results that didn't really solve the problem. I need to ensure that the event listeners only fire once. Any advice & insight would be greatly appreciated, thanks!

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  • How to efficiently compare the sign of two floating-point values while handling negative zeros

    - by François Beaune
    Given two floating-point numbers, I'm looking for an efficient way to check if they have the same sign, given that if any of the two values is zero (+0.0 or -0.0), they should be considered to have the same sign. For instance, SameSign(1.0, 2.0) should return true SameSign(-1.0, -2.0) should return true SameSign(-1.0, 2.0) should return false SameSign(0.0, 1.0) should return true SameSign(0.0, -1.0) should return true SameSign(-0.0, 1.0) should return true SameSign(-0.0, -1.0) should return true A naive but correct implementation of SameSign in C++ would be: bool SameSign(float a, float b) { if (fabs(a) == 0.0f || fabs(b) == 0.0f) return true; return (a >= 0.0f) == (b >= 0.0f); } Assuming the IEEE floating-point model, here's a variant of SameSign that compiles to branchless code (at least with with Visual C++ 2008): bool SameSign(float a, float b) { int ia = binary_cast<int>(a); int ib = binary_cast<int>(b); int az = (ia & 0x7FFFFFFF) == 0; int bz = (ib & 0x7FFFFFFF) == 0; int ab = (ia ^ ib) >= 0; return (az | bz | ab) != 0; } with binary_cast defined as follow: template <typename Target, typename Source> inline Target binary_cast(Source s) { union { Source m_source; Target m_target; } u; u.m_source = s; return u.m_target; } I'm looking for two things: A faster, more efficient implementation of SameSign, using bit tricks, FPU tricks or even SSE intrinsics. An efficient extension of SameSign to three values.

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  • Any merit to a lazy-ish juxt function?

    - by NielsK
    In answering a question about a function that maps over multiple functions with the same arguments (A: juxt), I came up with a function that basically took the same form as juxt, but used map: (defn could-be-lazy-juxt [& funs] (fn [& args] (map #(apply %1 %2) funs (repeat args)))) => ((juxt inc dec str) 1) [2 0 "1"] => ((could-be-lazy-juxt inc dec str) 1) (2 0 "1") => ((juxt * / -) 6 2) [12 3 4] => ((could-be-lazy-juxt * / -) 6 2) (12 3 4) As posted in the original question, I have little clue about the laziness or performance of it, but timing in the REPL does suggest something lazy-ish is going on. => (time (apply (juxt + -) (range 1 100))) "Elapsed time: 0.097198 msecs" [4950 -4948] => (time (apply (could-be-lazy-juxt + -) (range 1 100))) "Elapsed time: 0.074558 msecs" (4950 -4948) => (time (apply (juxt + -) (range 10000000))) "Elapsed time: 1019.317913 msecs" [49999995000000 -49999995000000] => (time (apply (could-be-lazy-juxt + -) (range 10000000))) "Elapsed time: 0.070332 msecs" (49999995000000 -49999995000000) I'm sure this function is not really that quick (the print of the outcome 'feels' about as long in both). Doing a 'take x' on the function only limits the amount of functions evaluated, which probably is limited in it's applicability, and limiting the other parameters by 'take' should be just as lazy in normal juxt. Is this juxt really lazy ? Would a lazy juxt bring anything useful to the table, for instance as a compositing step between other lazy functions ? What are the performance (mem / cpu / object count / compilation) implications ? Is that why the Clojure juxt implementation is done with a reduce and returns a vector ? Edit: Somehow things can always be done simpler in Clojure. (defn could-be-lazy-juxt [& funs] (fn [& args] (map #(apply % args) funs)))

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  • Linux network stack : adding protocols with an LKM and dev_add_pack

    - by agent0range
    Hello, I have recently been trying to familiarize myself with the Linux Networking stack and device drivers (have both similarly named O'Reilly books) with the eventual goal of offloading UDP. I have already implemented UDP on the NIC but now the hard part... Rather than ask for assistance on this larger goal I was hoping someone could clarify for me a particular snippet I found that is part of a LKM which registeres a new protocol (OTP) that acts as a filter between the device driver and network stack. http://www.phrack.org/archives/55/p55_0x0c_Building%20Into%20The%20Linux%20Network%20Layer_by_lifeline%20&%20kossak.txt (Note: this Phrack article contains three different modules, code for the OTP is at the bottom of the page) In the init function of his example he has: otp_proto.type = htons(ETH_P_ALL); otp_proto.func = otp_func; dev_add_pack(&otp_proto); which (if I understand correctly) should register otp_proto as a packet sniffer and put it into the ptype_all data structure. My question is about the dev_add_pack. Is it the case that the protocol being registered as a filter will always be placed at this layer between L2 and the device driver? Or, for instance could I make such a filtering occur between the application and transport layers (analyze socket parameters) using the same process? I apologize if this is confusing - I am having some trouble wrapping my head around the bigger picture when it comes to modules altering kernel stack functionality. Thanks

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  • Setting up Inversion of Control (IoC) in ASP.NET MVC with Castle Windsor

    - by Lirik
    I'm going over Sanderson's Pro ASP.NET MVC Framework and in Chapter 4 he discusses Creating a Custom Controller Factory and it seems that the original method, AddComponentLifeStyle or AddComponentWithLifeStyle, used to register controllers is deprecated now: public class WindsorControllerFactory : DefaultControllerFactory { IWindsorContainer container; public WindsorControllerFactory() { container = new WindsorContainer(new XmlInterpreter(new ConfigResource("castle"))); // register all the controller types as transient var controllerTypes = from t in Assembly.GetExecutingAssembly().GetTypes() where typeof(IController).IsAssignableFrom(t) select t; //[Obsolete("Use Register(Component.For<I>().ImplementedBy<T>().Named(key).Lifestyle.Is(lifestyle)) instead.")] //IWindsorContainer AddComponentLifeStyle<I, T>(string key, LifestyleType lifestyle) where T : class; foreach (Type t in controllerTypes) { container.Register(Component.For<IController>().ImplementedBy<???>().Named(t.FullName).LifeStyle.Is(LifestyleType.Transient)); } } // Constructs the controller instance needed to service each request protected override IController GetControllerInstance(Type controllerType) { return (IController)container.Resolve(controllerType); } } The new suggestion is to use Register(Component.For<I>().ImplementedBy<T>().Named(key).Lifestyle.Is(lifestyle)), but I can't figure out how to present the implementing controller type in the ImplementedBy<???>() method. I tried ImplementedBy<t>() and ImplementedBy<typeof(t)>(), but I can't find the appropriate way to pass int he implementing type. Any ideas?

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  • How to generate lots of redundant ajax elements like checkboxes and pulldowns in Django?

    - by iJames
    Hello folks. I've been getting lots of answers from stackoverflow now that I'm in Django just be searching. Now I hope my question will also create some value for everybody. In choosing Django, I was hoping there was some similar mechanism to the way you can do partials in ROR. This was going to help me in two ways. One was in generating repeating indexed forms or form elements, and also in rendering only a piece of the page on the round trip. I've done a little bit of that by using taconite with a simple URL click but now I'm trying to get more advanced. This will focus on the form issue which boils down to how to iterate over a secondary object. If I have a list of photo instances, each of which has a couple of parameters, let's say a size and a quantity. I want to generate form elements for each photo instance separately. But then I have two lists I want to iterate on at the same time. Context: photos : Photo.objects.all() and forms = {} for photo in photos: forms[photo.id] = PhotoForm() In other words we've got a list of photo objects and a dict of forms based on the photo.id. Here's an abstraction of the template: {% for photo in photos %} {% include "photoview.html" %} {% comment %} So here I want to use the photo.id as an index to get the correct form. So that each photo has its own form. I would want to have a different action and each form field would be unique. Is that possible? How can I iterate on that? Thanks! {% endcomment %} Quantity: {{ oi.quantity }} {{ form.quantity }} Dimensions: {{ oi.size }} {{ form.size }} {% endfor %} What can I do about this simple case. And how can I make it where every control is automatically updating the server instead of using a form at all? Thanks! James

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  • Why would this Lua optimization hack help?

    - by Ian Boyd
    i'm looking over a document that describes various techniques to improve performance of Lua script code, and i'm shocked that such tricks would be required. (Although i'm quoting Lua, i've seen similar hacks in Javascript). Why would this optimization be required: For instance, the code for i = 1, 1000000 do local x = math.sin(i) end runs 30% slower than this one: local sin = math.sin for i = 1, 1000000 do local x = sin(i) end They're re-declaring sin function locally. Why would this be helpful? It's the job of the compiler to do that anyway. Why is the programmer having to do the compiler's job? i've seen similar things in Javascript; and so obviously there must be a very good reason why the interpreting compiler isn't doing its job. What is it? i see it repeatedly in the Lua environment i'm fiddling in; people redeclaring variables as local: local strfind = strfind local strlen = strlen local gsub = gsub local pairs = pairs local ipairs = ipairs local type = type local tinsert = tinsert local tremove = tremove local unpack = unpack local max = max local min = min local floor = floor local ceil = ceil local loadstring = loadstring local tostring = tostring local setmetatable = setmetatable local getmetatable = getmetatable local format = format local sin = math.sin What is going on here that people have to do the work of the compiler? Is the compiler confused by how to find format? Why is this an issue that a programmer has to deal with? Why would this not have been taken care of in 1993? i also seem to have hit a logical paradox: Optimizatin should not be done without profiling Lua has no ability to be profiled Lua should not be optimized

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  • DRYing out implementation of ICloneable in several classes

    - by Sarah Vessels
    I have several different classes that I want to be cloneable: GenericRow, GenericRows, ParticularRow, and ParticularRows. There is the following class hierarchy: GenericRow is the parent of ParticularRow, and GenericRows is the parent of ParticularRows. Each class implements ICloneable because I want to be able to create deep copies of instances of each. I find myself writing the exact same code for Clone() in each class: object ICloneable.Clone() { object clone; using (var stream = new MemoryStream()) { var formatter = new BinaryFormatter(); // Serialize this object formatter.Serialize(stream, this); stream.Position = 0; // Deserialize to another object clone = formatter.Deserialize(stream); } return clone; } I then provide a convenience wrapper method, for example in GenericRows: public GenericRows Clone() { return (GenericRows)((ICloneable)this).Clone(); } I am fine with the convenience wrapper methods looking about the same in each class because it's very little code and it does differ from class to class by return type, cast, etc. However, ICloneable.Clone() is identical in all four classes. Can I abstract this somehow so it is only defined in one place? My concern was that if I made some utility class/object extension method, it would not correctly make a deep copy of the particular instance I want copied. Is this a good idea anyway?

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  • VS2010 development web server does not use integrated-mode HTTP handlers/modules

    - by Domenic
    I am developing an ASP.NET MVC 2 web site, targeted for .NET Framework 4.0, using Visual Studio 2010. My web.config contains the following code: <system.webServer> <modules runAllManagedModulesForAllRequests="true"> <add name="XhtmlModule" type="DomenicDenicola.Website.XhtmlModule" /> </modules> <handlers> <add name="DotLess" type="dotless.Core.LessCssHttpHandler,dotless.Core" path="*.less" verb="*" /> </handlers> </system.webServer> When I use Build > Publish to put the web site on my local IIS7 instance, it works great. However, when I use Debug > Start Debugging, neither the HTTP handler nor module are executed on any requests. Strangely enough, when I put the handler and module <add /> tags back into <system.web /> under <httpHandlers /> and <httpModules />, they work. This seems to imply that the development web server is running in classic mode. How do I fix this?

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  • How do I perform this MutliArray setup in Java?

    - by Andy Barlow
    I come from a PHP background and I'm just getting my teeth into some Java. I was wondering how I could implement the following in Java as simply as possible, just echoing the results to a terminal via the usual "System.out.print()" method. <?php $Results[0]['title'] = "No Country for Old Men"; $Results[0]['run_time'] = "122 mins"; $Results[0]['cert'] = "15"; $Results[1]['title'] = "Old School"; $Results[1]['run_time'] = "88 mins"; $Results[1]['cert'] = "18"; // Will basically show the above in order. foreach($Results as value) { echo $Results[$value]['title']; echo $Results[$value]['run_time']; echo $Results[$value]['cert']; } // Lets add some more as I need to do this in Java too $Results[2]['title'] = "Saving Private Ryan"; $Results[2]['run_time'] = "153 mins"; $Results[2]['cert'] = "15"; // Lets remove the first one as an example of another need $Results[0] = null; ?> I hear there are "list iterators" or something that are really good for rolling through data like this. Perhaps it could be implemented with that? A fully working .java file would be most handy in this instance, including how to add and remove items from the array like the above. P.S. I do plan on using this for an Android App in the distant future, so, hopefully it should all work on Android fine too, although, I imagine this sort of thing works on anything Java related :).

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  • Ext JS 4.2.1 loading controller - best practice

    - by Hown_
    I am currently developing a Ext JS application with many views/controlers/... I am wondering myself what the best practice is for loading the JS controllers/views/and so on... currently i have my application defined like this: // enable javascript cache for debugging, otherwise Chrome breakpoints are lost Ext.Loader.setConfig({ disableCaching: false }); Ext.require('Ext.util.History'); Ext.require('app.Sitemap'); Ext.require('app.Error'); Ext.define('app.Application', { name: 'app', extend: 'Ext.app.Application', views: [ // TODO: add views here 'app.view.Viewport', 'app.view.BaseMain', 'app.view.Main', 'app.view.ApplicationHeader', //administration 'app.view.administration.User' ... ], controllers: [ 'app.controller.Viewport', 'app.controller.Main', 'app.controller.ApplicationHeader', //administration 'app.controller.administration.User', ... ], stores: [ // stores in there.. ] }); somehow this forces the client to load all my views and controllers at startup and is calling all init methods of all controllers of course.. i need to load data everytime i chnage my view.. and now i cant load it in my controllers init function. I would have to do something like this i assume: init: function () { this.control({ '#administration_User': { afterrender: this.onAfterRender } }); }, Is there a better way to do this? Or just an other event? Though the main thing i am questioning myself is if it is the best practice to load all the javascript at startup. Wouldnt it be better to only load the controllers/views/... which the client does need right now? Or should i load all the JS at startup? If i do want to load the controllers dynamicly how could i do this? I assume a would have to remove them from my application arrays (views, controllers, stores) and create an instance if i do need it and mby set the view in the controllers init?! What's best practice??

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  • How do I send the mutable string to the NSTextField properly?

    - by Merle
    So I have all this code that I have debugged and it seems to be fine. I made a mutable string and for some reason I can not get it to be displayed on my label. the debugger says "2010-04-22 22:50:26.126 Fibonacci[24836:10b] * -[NSTextField setString:]: unrecognized selector sent to instance 0x130150" What is wrong with this? When I just send the string to NSLog, it comes out fine. here's all my code, any help would be appreciated. "elementNum" is a comboBox and "display" is a Label. Thanks #import "Controller.h" @implementation Controller - (IBAction)computeNumber:(id)sender { int x = 1; int y = 1; NSMutableString *numbers = [[NSMutableString alloc] init]; [numbers setString:@"1, 1,"]; int num = [[elementNum objectValueOfSelectedItem]intValue]; int count = 1; while (count<=num) { int z = y; y+=x; x=z; [numbers appendString:[NSString stringWithFormat:@" %d,", y]]; count++; } [display setString:numbers]; NSLog(numbers); } @end `

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