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  • Create a Task list, with tasks without executing

    - by Ernesto Araya Eguren
    I have an async method private async Task DoSomething(CancellationToken token) a list of Tasks private List<Task> workers = new List<Task>(); and I have to create N threads that runs that method public void CreateThreads(int n) { tokenSource = new CancellationTokenSource(); token = tokenSource.Token; for (int i = 0; i < n; i++) { workers.Add(DoSomething(token)); } } but the problem is that those have to run at a given time public async Task StartAllWorkers() { if (0 < workers.Count) { try { while (0 < workers.Count) { Task finishedWorker = await Task.WhenAny(workers.ToArray()); workers.Remove(finishedWorker); finishedWorker.Dispose(); } if (workers.Count == 0) { tokenSource = null; } } catch (OperationCanceledException) { throw; } } } but actually they run when i call the CreateThreads Method (before the StartAllWorkers). I searched for keywords and problems like mine but couldn't find anything about stopping the task from running. I've tried a lot of different aproaches but anything that could solve my problem entirely. For example, moving the code from DoSomething into a workers.Add(new Task(async () => { }, token)); would run the StartAllWorkers(), but the threads will never actually start. There is another method for calling the tokenSource.Cancel().

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  • Two questions on ensuring EndInvoke() gets called on a list of IAsyncResult objects

    - by RobV
    So this question is regarding the .Net IAsyncResult design pattern and the necessity of calling EndInvoke as covered in this question Background I have some code where I'm firing off potentially many asynchronous calls to a particular function and then waiting for all these calls to finish before using EndInvoke() to get back all the results. Question 1 I don't know whether any of the calls has encountered an exception until I call EndInvoke() and in the event that an exception occurs in one of the calls the entire method should fail and the exception gets wrapped into an API specific exception and thrown upwards. So my first question is what's the best way then to ensure that the remainder of the async calls get properly terminated? Is a finally block which calls EndInvoke() on the remainder of the unterminated calls (and ignores any further exceptions) the best way to do this? Question 2 Secondly when I first fire off all my asyc calls I then call WaitHandle.WaitAll() on the array of WaitHandle instances that I've got from my IAsyncResult instances. The method which is firing all these async calls has a timeout to adhere to so I provide this to the WaitAll() method. Then I test whether all the calls have completed, if not then the timeout must have been reached so the method should also fail and throw another API specific exception. So my second question is what should I do in this case? I need to call EndInvoke() to terminate all these async calls before I throw the error but at the same time I don't want the code to get stuck since EndInvoke() is blocking. In theory at least if the WaitAll() call times out then all the async calls should themselves have timed out and thrown exceptions (thus completing the call) since they are also governed by a timeout but this timeout is potentially different from the main timeout

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  • Enumerating computers in NT4 domain using WNetEnumResourceW (C++) or DirectoryEntry (C#)

    - by Kevin Davis
    I'm trying to enumerate computers in NT4 domains (not Active Directory) and support Unicode NetBIOS names. According to MSDN, WNetEnumResourceW is the Unicode counterpart of WNetEnumResource which to me would imply that using this would do the trick. However, I have not been able to get Unicode NetBIOS names properly using WNetEnumResourceW. I've also tried the C# rough equivalent DirectoryEntry using the WinNT: provider with no luck on Unicode names either. If I use DirectoryEntry on Active Directory (using the LDAP: provider) I do get Unicode names back. I noticed that during some debugging my code using DirectoryEntry and the WinNT: provider, the exceptions I saw were of type System.Runtime.InteropServices.COMException which tends to make me believe that this is just calling WNetEnumResourceW via COM. This web page implies that for some Net APIs the MS documentation is incomplete and possibly inaccurate which further confuses things. Additionally I've found that using the C# method which certainly results in cleaner, more understandable code also yields incomplete results in enumerating computers in domains\workgroups. Does anyone have any insight on this? Is it possible that computer acting as the WINS server is mangling the name? How would I determine this? Thanks

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  • Inereritance of clousure objects and overriding of methods

    - by bobikk
    I need to extend a class, which is encapsulated in a closure. This base class is following: var PageController = (function(){ // private static variable var _current_view; return function(request, new_view) { ... // priveleged public function, which has access to the _current_view this.execute = function() { alert("PageController::execute"); } } })();` Inheritance is realised using the following function: function extend(subClass, superClass){ var F = function(){ }; F.prototype = superClass.prototype; subClass.prototype = new F(); subClass.prototype.constructor = subClass; subClass.superclass = superClass.prototype; StartController.cache = ''; if (superClass.prototype.constructor == Object.prototype.constructor) { superClass.prototype.constructor = superClass; } } I subclass the PageController: var StartController = function(request){ // calling the constructor of the super class StartController.superclass.constructor.call(this, request, 'start-view'); } // extending the objects extend(StartController, PageController); // overriding the PageController::execute StartController.prototype.execute = function() { alert('StartController::execute'); } Inheritance is working. I can call every PageController's method from StartController's instance. However, method overriding doesn't work: var startCont = new StartController(); startCont.execute(); alerts "PageController::execute". How should I override this method?

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  • What happens when value types are created?

    - by Bob
    I'm developing a game using XNA and C# and was attempting to avoid calling new struct() type code each frame as I thought it would freak the GC out. "But wait," I said to myself, "struct is a value type. The GC shouldn't get called then, right?" Well, that's why I'm asking here. I only have a very vague idea of what happens to value types. If I create a new struct within a function call, is the struct being created on the stack? Will it simply get pushed and popped and performance not take a hit? Further, would there be some memory limit or performance implications if, say, I need to create many instances in a single call? Take, for instance, this code: spriteBatch.Draw(tex, new Rectangle(x, y, width, height), Color.White); Rectangle in this case is a struct. What happens when that new Rectangle is created? What are the implications of having to repeat that line many times (say, thousands of times)? Is this Rectangle created, a copy sent to the Draw method, and then discarded (meaning no memory getting eaten up the more Draw is called in that manner in the same function)? P.S. I know this may be pre-mature optimization, but I'm mostly curious and wish to have a better understanding of what is happening.

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  • Hibernate is persisting entity during flush when the entity has not changed

    - by Preston
    I'm having a problem where the entity manger is persisting an entity that I don't think has changed during the flush. I know the following code is the problem because if I comment it out the entity doesn't persist. In this code all I'm doing is loading the entity and calling some getters. Query qry = em.createNamedQuery("Clients.findByClientID"); qry.setParameter("clientID", clientID); Clients client = (Clients) qry.getSingleResult(); results.setFname(client.getFirstName()); results.setLname(client.getLastName()); ... return results; Later in a different method I do another namedQuery which causes the entity manger to flush. For some reason the client loaded above is persisted. The reason this is a problem is because in the middle of all this, there is some old code that is making some straight JDBC changes to the client. When the entity manger persists the changes made by the straight JDBC are lost. The theory we have at moment is that the entity manger is comparing the entity to the underlying record, sees that it's different, then persists it. Can someone explain or confirm the behavior we're seeing?

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  • Can I get rid of this read lock?

    - by Pieter
    I have the following helper class (simplified): public static class Cache { private static readonly object _syncRoot = new object(); private static Dictionary<Type, string> _lookup = new Dictionary<Type, string>(); public static void Add(Type type, string value) { lock (_syncRoot) { _lookup.Add(type, value); } } public static string Lookup(Type type) { string result; lock (_syncRoot) { _lookup.TryGetValue(type, out result); } return result; } } Add will be called roughly 10/100 times in the application and Lookup will be called by many threads, many of thousands of times. What I would like is to get rid of the read lock. How do you normally get rid of the read lock in this situation? I have the following ideas: Require that _lookup is stable before the application starts operation. The could be build up from an Attribute. This is done automatically through the static constructor the attribute is assigned to. Requiring the above would require me to go through all types that could have the attribute and calling RuntimeHelpers.RunClassConstructor which is an expensive operation; Move to COW semantics. public static void Add(Type type, string value) { lock (_syncRoot) { var lookup = new Dictionary<Type, string>(_lookup); lookup.Add(type, value); _lookup = lookup; } } (With the lock (_syncRoot) removed in the Lookup method.) The problem with this is that this uses an unnecessary amount of memory (which might not be a problem) and I would probably make _lookup volatile, but I'm not sure how this should be applied. (John Skeets' comment here gives me pause.) Using ReaderWriterLock. I believe this would make things worse since the region being locked is small. Suggestions are very welcome.

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  • asp.net mvc ajax helper/post additional data w/o jquery.

    - by Jopache
    I would like to use the ajax helper to create ajax requests that send additional, dynamic data with the post (for example, get the last element with class = blogCommentDateTime and send the value of that last one to the controller which will return only blog comments after it). I have successfully done so with the help of jQuery Form plugin like so: $(document).ready(function () { $("#addCommentForm").submit(function () { var lastCommentDate = $(".CommentDateHidden:last").val(); var lastCommentData = { lastCommentDateTicks: lastCommentDate }; var formSubmitParams = { data: lastCommentData, success: AddCommentResponseHandler } $("#addCommentForm").ajaxSubmit(formSubmitParams); return false; }); This form was created with html.beginform() method. I am wondering if there is an easy way to do this using the ajax.beginform() helper? When I try to use the same code but replace html.beginform() with ajax.beginform(), when i try to submit the form, I am issuing 2 posts (which is understandable, one being taken care of by the helper, the other one by me with the JS above. I can't create 2 requests, so this option is out) I tried getting rid of the return false and changing ajaxSubmit() to ajaxForm() so that it would only "prepare" the form, and this leads in only one post, but it does not include the extra parameter that I defined, so this is worthless as well. I then tried keeping the ajaxForm() but calling that whenever the submit button on the form gets clicked rather than when the form gets submitted (I guess this is almost the same thing) and that results in 2 posts also. The biggest reason I am asking this question is that I have run in to some issues with the javascript above and using mvc validation provided by the mvc framework (which i will set up another question for) and would like to know this so I can dive further in to my validation issue.

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  • C# delegate or Func for 'all methods'?

    - by Michel
    Hi, i've read something about Func's and delegates and that they can help you to pass a method as a parameter. Now i have a cachingservice, and it has this declaration: public static void AddToCache<T>(T model, double millisecs, string cacheId) where T : class public static T GetFromCache<T>(string cacheId) where T : class So in a place where i want to cache some data, i check if it exists in the cache (with GetFromCache) and if not, get the data from somewhere, and the add it to the cache (with AddToCache) Now i want to extend the AddToCache method with a parameter, which is the class+method to call to get the data Then the declaration would be like this public static void AddToCache<T>(T model, double millisecs, string cacheId, Func/Delegate methode) where T : class Then this method could check wether the cache has data or not, and if not, get the data itself via the method it got provided. Then in the calling code i could say: AddToCache<Person>(p, 10000, "Person", new PersonService().GetPersonById(1)); AddToCache<Advert>(a, 100000, "Advert", new AdvertService().GetAdverts(3)); What i want to achieve is that the 'if cache is empty get data and add to cache' logic is placed on only one place. I hope this makes sense :) Oh, by the way, the question is: is this possible?

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  • Using Tcl DSL in Python

    - by Sridhar Ratnakumar
    I have a bunch of Python functions. Let's call them foo, bar and baz. They accept variable number of string arguments and does other sophisticated things (like accessing the network). I want the "user" (let's assume he is only familiar with Tcl) to write scripts in Tcl using those functions. Here's an example (taken from Macports) that user can come up with: post-configure { if {[variant_isset universal]} { set conflags "" foreach arch ${configure.universal_archs} { if {${arch} == "i386"} {append conflags "x86 "} else { if {${arch} == "ppc64"} {append conflags "ppc_64 "} else { append conflags ${arch} " " } } } set profiles [exec find ${worksrcpath} -name "*.pro"] foreach profile ${profiles} { reinplace -E "s|^(CONFIG\[ \\t].*)|\\1 ${conflags}|" ${profile} # Cures an isolated case system "cd ${worksrcpath}/designer && \ ${qt_dir}/bin/qmake -spec ${qt_dir}/mkspecs/macx-g++ -macx \ -o Makefile python.pro" } } } Here, variant_issset, reinplace are so on (other than Tcl builtins) are implemented as Python functions. if, foreach, set, etc.. are normal Tcl constructs. post-configure is a Python function that accepts, well, a Tcl code block that can later be executed (which in turns would obviously end up calling the above mentioned Python "functions"). Is this possible to do in Python? If so, how? from Tkinter import *; root= Tk(); root.tk.eval('puts [array get tcl_platform]') is the only integration I know of, which is obviously very limited (not to mention the fact that it starts up X11 server on mac).

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  • jQuery rotator not rotating properly - too much recursion

    - by Matt Nathanson
    I've built a custom jQuery rotator using just basic animation to rotate the 3 Divs (images). I've built the function and then reinitiate the function using it as a call back. Here's the code: function ImageRotate() { var CurrentFeature = "#container" + featureNumber; $(CurrentFeature).stop(false, true).delay(4500).animate({'top' : '330px'}, 3000); var featureNumber2 = featureNumber-1; if ( featureNumber == 1) {featureNumber2=3} var CurrentFeature2 = "#container" + featureNumber2; $(CurrentFeature2).stop(false, true).delay(4500).animate({'top' : '0px'}, 3000); $('#container2').stop(false, true).delay(4500).animate({'top' : '-330px'}, 25); var featureNumber3 = featureNumber+1; if ( featureNumber == 3){featureNumber3=1} var CurrentFeature3 = "#container" + featureNumber3; $(CurrentFeature3).stop(false, true).delay(7500).animate({'top' : '0px'}, 3000); $(CurrentFeature2).stop(false, true).delay(4500).animate({'top' : '330px'}, 3000); $(CurrentFeature).stop(false, true).delay(4500).animate({'top' : '-330px'}, 25); if (featureNumber ==1) {featureNumber=3} else{featureNumber--}; $(CurrentFeature).stop(false, true).delay(7500).animate({'top' : '0px'}, 3000); $(CurrentFeature3).stop(false, true).delay(4500).animate({'top' : '330px'}, 3000); $(CurrentFeature2).stop(false, false).delay(4500).animate({'top' : '-330px'}, 25,ImageRotate()); }; It's worth noting that when calling the function again I also tried making another function called ImageRotate2(); and it did the same thing. It loops, but i get all sorts of funkiness. Edit: I've also tried some answers in the replies and they both leave me with recursion errors each second.

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  • How do I convert an AMD module from a singleton to an instance?

    - by Jamie Ide
    I'm trying to convert a working Durandal view model module from a singleton to an instance. The original working version followed this pattern: define(['knockout'], function(ko) { var vm = { activate: activate, companyId: null; company: ko.observable({}) }; return vm; function activate(companyId) { vm.companyId = companyId; //get company data then vm.company(data); } } The new version exports a function so that I get a new instance on every request... define(['knockout'], function(ko) { var vm = function() { activate = activate; companyId = null; company = ko.observable({}); }; return vm; function activate(companyId) { vm.companyId = companyId; //get company data then vm.company(data); } } The error I'm getting is "object function () [...function signature...] has no method company on the line vm.company(data);. What am I doing wrong? Why can I set the property but can't access the knockout observable? How should I refactor the original code so that I get a new instance on every request? My efforts to simplify the code for this question hid the actual problem. My real code was using Q promises and calling two methods with Q.All. Since Q is in the global namespace, it couldn't resolve my viewmodel after converting to a function. Passing the view model to the methods called by Q resolved the problem.

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  • How do I return an array from a method?

    - by dwwilson66
    I'm trying to create a deck of cards for my homework. Code is posted below. I need to create four sets of cards (the four suits) and am create a multidimensional array. When I print the results instead of trying to pass the array, I can see that the data in the array is as expected. However, when I try to pass the array card, I get an error cannot find symbol. I've got this modeled after texbook and Java tutorial examples, and I need some help figuring out what I'm missing. I've over-documented to give an idea of how I'm thinking this SHOULD work...please let me know where I've gone horribly wrong in my understanding. import java.util.*; import java.lang.*; // public class CardGame { public static int[][] main(String[] args) { int[][] startDeck = deckOfCards(); /* cast new deck as int[][], calling method deckOfCards System.out.println(" /// from array: " + Arrays.deepToString(startDeck)); } public static int[][] deckOfCards() /* method to return a multi-dimensional array */ { int rank; int suit; for(rank=1;rank<14;rank++) /* cards 1 - 13 .... */ { for(suit=1;suit<5;suit++) /* suits 1 - 4 .... */ { int[][] card = new int[][] /* define a new card... */ { {rank,suit} /* with rank/suit from for... loops */ }; System.out.println(" /// from array: " + Arrays.deepToString(card)); } } return card; /* Error: cannot find symbol } }

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  • Use Django ORM as standalone [closed]

    - by KeyboardInterrupt
    Possible Duplicates: Use only some parts of Django? Using only the DB part of Django I want to use the Django ORM as standalone. Despite an hour of searching Google, I'm still left with several questions: Does it require me to set up my Python project with a setting.py, /myApp/ directory, and modules.py file? Can I create a new models.py and run syncdb to have it automatically setup the tables and relationships or can I only use models from existing Django projects? There seems to be a lot of questions regarding PYTHONPATH. If you're not calling existing models is this needed? I guess the easiest thing would be for someone to just post a basic template or walkthrough of the process, clarifying the organization of the files e.g.: db/ __init__.py settings.py myScript.py orm/ __init__.py models.py And the basic essentials: # settings.py from django.conf import settings settings.configure( DATABASE_ENGINE = "postgresql_psycopg2", DATABASE_HOST = "localhost", DATABASE_NAME = "dbName", DATABASE_USER = "user", DATABASE_PASSWORD = "pass", DATABASE_PORT = "5432" ) # orm/models.py # ... # myScript.py # import models.. And whether you need to run something like: django-admin.py inspectdb ... (Oh, I'm running Windows if that changes anything regarding command-line arguments.).

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  • .NET consumer of ActiveX throwing TargetParameterCountException

    - by DevSolo
    I have a .NET (3.5 w/ Dev Studio 2008) app that hosts a visual Active X (written in C++ w/ Dev Studio 2003). Have access to all sources, but can't easily move the Active X control up to 2008. This as worked fine in the past. Made some changes to the Active X control and now, when calling one method on the Active X, I'm getting a TargetParameterCountException 100% of the time. The signature of the Active X method is: LONG CMyActive::License(LPCTSTR string1, LPCTSTR string2, LONG long1, LPCTSTR string3, LPCTSTR string4); When viewing the method in object browser of reflector, .NET sees it as: public virtual int License(string string1, string string2, int long1, string string3, string string4) I renamed the parameters for demonstration purpose (boss gets twitchy about any code). I left the method name, as it could be relevant. There are method calls prior that work. I just can't seen to figure out why I'm all of a sudden getting this exception. The HRESULT is 0x8002000e and a quick search seems to indicate that's a general one. Thanks to all for reading.

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  • What VC++ compiler/linker does when building a C++ project with Managed Extension

    - by ???
    The initial problem is that I tried to rebuild a C++ project with debug symbols and copied it to test machine, The output of the project is external COM server(.exe file). When calling the COM interface function, there's a RPC call failre: COMException(0x800706BE): The remote procedure call failed. According to the COM HRESULT design, if the FACILITY code is 7, it's actually a WIN32 error, and the win32 error code is 0x6BE, which is the above mentioned "remote procedure call failed". All I do is replace the COM server .exe file, the origin file works well. When I checked into the project, I found it's a C++ project with Managed Extension. When I checking the DLL with reflector, it shows there's 2 additional .NET assembly reference. Then I checked the project setting and found nothing about the extra 2 assembly reference. I turned on the show includes option of compiler and verbose library of linker, and try to analyze whether the assembly is indirectly referenced via .h file. I've collect all the .h file and grep all the files with '#using' '#import' and the assembly file itself. There really is a '#using ' in one of the .h file but not-relevant to the referenced assembly. And about the linked .lib library files, only one of the .lib file is a side-product of another managed-extension-enabled C++ project, all others are produced by a pure, traditional C++ project. For the managed-extension-enabled C++ project, I checked the output DLL assembly, it did NOT reference to the 2 assembly. I even try to capture the access of the additional assembly file via sysinternal's filemon and procmon, but the rebuild process does NOT access these file. I'm very confused about the compile and linking process model of a VC++/CLI project, where the additional assembly reference slipped into the final assembly? Thanks in advance for any of your help.

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  • Is it possible to defer member initialization to the constructor body?

    - by Kjir
    I have a class with an object as a member which doesn't have a default constructor. I'd like to initialize this member in the constructor, but it seems that in C++ I can't do that. Here is the class: #include <boost/asio.hpp> #include <boost/array.hpp> using boost::asio::ip::udp; template<class T> class udp_sock { public: udp_sock(std::string host, unsigned short port); private: boost::asio::io_service _io_service; udp::socket _sock; boost::array<T,256> _buf; }; template<class T> udp_sock<T>::udp_sock(std::string host = "localhost", unsigned short port = 50000) { udp::resolver res(_io_service); udp::resolver::query query(udp::v4(), host, "spec"); udp::endpoint ep = *res.resolve(query); ep.port(port); _sock(_io_service, ep); } The compiler tells me basically that it can't find a default constructor for udp::socket and by my research I understood that C++ implicitly initializes every member before calling the constructor. Is there any way to do it the way I wanted to do it, or is it too "Java-oriented" and not feasible in C++? I worked around the problem by defining my constructor like this: template<class T> udp_sock<T>::udp_sock(std::string host = "localhost", unsigned short port = 50000) : _sock(_io_service) { udp::resolver res(_io_service); udp::resolver::query query(udp::v4(), host, "spec"); udp::endpoint ep = *res.resolve(query); ep.port(port); _sock.bind(ep); } So my question is more out of curiosity and to better understand OOP in C++

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  • Android, phone call audio stream via wlan

    - by moppel
    I am planning on developing my specific voip app for android. Here's the scenario: when a phone call occurs I want to hear the person who's calling on my local pc speakers and I want to speak to him via my own pc microphone / headset. So I need to send the audio stream of both me and the person I am talking to via the wlan network. Something like this: ... onCallStateChanged(int state, String phoneNumber){ while(state == PhoneListener.CALL_STATE_OFFHOOK){ //while phone call is happaning //send incoming speech via wlan to pc //receive audiostream from pc microphone and direct it to the phone call } } ... Is this possible with the current Android API? (Actually it should be since voip apps are available in the market) I did some research in the Android API and all I found was the AudioManager which has constant named public static final int STREAM_VOICE_CALL; //The audio stream for phone calls But I don't know how to use it our how it should give me access to the actual audiostreams which I can send via network. How do I manage to do this? The connection would be realised by TCP sockets.

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  • PHP 5.2 Function needed for GENERIC sorting FOLLOWUP

    - by donbriggs
    OK, you guys gave me a great solution for sorting a recordset array last Friday. (http://stackoverflow.com/questions/2884325/php-5-2-function-needed-for-generic-sorting-of-a-recordset-array) But now when I implement it, I end up with an extra element in the recordset array. I won't wast space reposting the same info, as the link is above. But the bottom line is that when I sort an array of 5 records, the resulting array has 6 records. The last element in the array is not a record array, but rather just a element containing an integer value of 1. I presume that it is somehow getting the output value of the "strnatcasecmp" function, but I have no idea how it is happening. Here is the function that you fine folks provided last week: function getSortCommand($field, $sortfunc) { return create_function('$var1, $var2', 'return '.$sortfunc.'($var1["'.$field.'"], $var2["' .$field .'"]);'); } And here is the line I am calling to sort the array: $trek[] = usort($trek, getSortCommand('name', 'strnatcasecmp')); This produces the following output, with an extra element tacked on to the end. Array ( [0] = Array ( [name] = Kirk [shirt] = Gold [assign] = Bridge ) [1] => Array ( [name] => McCoy [shirt] => Blue [assign] => Sick Bay ) [2] => Array ( [name] => Scotty [shirt] => Red [assign] => Engineering ) [3] => Array ( [name] => Spock [shirt] => Blue [assign] => Bridge ) [4] => Array ( [name] => Uhura [shirt] => Red [assign] => Bridge ) [5] => 1 )

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  • Dynamic Method Creation

    - by TJMonk15
    So, I have been trying to research this all morning, and have had no luck. I am trying to find a way to dynamically create a method/delegate/lambda that returns a new instance of a certain class (not known until runtime) that inherits from a certain base class. I can guarantee the following about the unknown/dynamic class It will always inherit from one known Class (Row) It will have atleast 2 constructors (one accepting a long, and one accepting an IDataRecord) I plan on doign the following: Finding all classes that have a certain attribute on them Creating a delegate/method/lambda/whatever that creates a new instance of the class Storing the delegate/whatever along with some properties in a struct/class Insert the struct into a hashtable When needed, pull the info out of the hashtable and calling the delegate/whatever to get a new instance of the class and returning it/adding it to a list/etc. I need help only with #2 above!!! I have no idea where to start. I really just need some reference material to get me started, or some keywords to throw into google. This is for a compact/simple to use ORM for our office here. I understand the above is not simple, but once working, should make maintaining the code incredibly simple. Please let me know if you need any more info! And thanks in advance! :)

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  • extension methods with generics - when does caller need to include type parameters?

    - by Greg
    Hi, Is there a rule for knowing when one has to pass the generic type parameters in the client code when calling an extension method? So for example in the Program class why can I (a) not pass type parameters for top.AddNode(node), but where as later for the (b) top.AddRelationship line I have to pass them? class Program { static void Main(string[] args) { // Create Graph var top = new TopologyImp<string>(); // Add Node var node = new StringNode(); node.Name = "asdf"; var node2 = new StringNode(); node2.Name = "test child"; top.AddNode(node); top.AddNode(node2); top.AddRelationship<string, RelationshipsImp>(node,node2); // *** HERE *** } } public static class TopologyExtns { public static void AddNode<T>(this ITopology<T> topIf, INode<T> node) { topIf.Nodes.Add(node.Key, node); } public static INode<T> FindNode<T>(this ITopology<T> topIf, T searchKey) { return topIf.Nodes[searchKey]; } public static void AddRelationship<T,R>(this ITopology<T> topIf, INode<T> parentNode, INode<T> childNode) where R : IRelationship<T>, new() { var rel = new R(); rel.Child = childNode; rel.Parent = parentNode; } } public class TopologyImp<T> : ITopology<T> { public Dictionary<T, INode<T>> Nodes { get; set; } public TopologyImp() { Nodes = new Dictionary<T, INode<T>>(); } }

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  • In Ruby, why is a method invocation not be able to be treated as a unit when "do" and "end" is used?

    - by Jian Lin
    The following question is related to the question "Ruby Print Inject Do Syntax". My question is, can we insist on using do and end and make it work with puts or p? This works: a = [1,2,3,4] b = a.inject do |sum, x| sum + x end puts b # prints out 10 so, is it correct to say, inject is a class method of the Array class, which takes a block of code, and then returns a number. If so, then it should be no different from calling a function and getting back a return value: b = foo(3) puts b or b = circle.getRadius() puts b In the above two cases, we can directly say puts foo(3) puts circle.getRadius() so, there is no way to make it work directly by using the following 2 ways: a = [1,2,3,4] puts a.inject do |sum, x| sum + x end but it gives ch01q2.rb:7:in `inject': no block given (LocalJumpError) from ch01q2.rb:4:in `each' from ch01q2.rb:4:in `inject' from ch01q2.rb:4 grouping the method call using ( ) doesn't work either: a = [1,2,3,4] puts (a.inject do |sum, x| sum + x end) and this gives: ch01q3.rb:4: syntax error, unexpected kDO_BLOCK, expecting ')' puts (a.inject do |sum, x| ^ ch01q3.rb:4: syntax error, unexpected '|', expecting '=' puts (a.inject do |sum, x| ^ ch01q3.rb:6: syntax error, unexpected kEND, expecting $end end) ^ finally, the following version works: a = [1,2,3,4] puts a.inject { |sum, x| sum + x } but why doesn't the grouping of the method invocation using ( ) work in the earlier example? What if a programmer insist that he uses do and end, can it be made to work?

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  • Values are not returning from MY SQL database to my java class

    - by sam
    Hi, This is my Query DELIMITER $$ DROP PROCEDURE IF EXISTSdiscoverdb.getuser_info$$ # MySQL returned an empty result set (i.e. zero rows). `CREATE PROCEDURE discoverdb.getuser_info ( IN name VARCHAR(100), IN pass VARCHAR(100) ) BEGIN SELECT * FROM ad_user WHERE sLogin = name AND sPassHash=password(pass); END $$ # MySQL returned an empty result set (i.e. zero rows). DELIMITER ; This is my calling method public Authentication getAuthentication (String username,String password) { //TODO write your implementation code here: Authentication ack = new Authentication(); try{ String simpleProc = "{ call getuser_infosam(?,?)}"; java.sql.CallableStatement cs = con.prepareCall(simpleProc); cs.setString(1, username); cs.setString(2, password); java.sql.ResultSet rs = cs.executeQuery(); while (rs.next()) { System.out.println(rs.getString("sLogin")); System.out.println(rs.getString("sPassHash")); System.out.println(rs.getString("sForename")); System.out.println(rs.getString("sName")); System.out.println(rs.getString("company")); System.out.println(rs.getString("sEmail")); rs.close();} }catch ( Exception e) { e.printStackTrace(); System.out.print(e); } return ack; }

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  • Objective-C subclass and base class casting

    - by ryanjm.mp
    I'm going to create a base class that implements very similar functions for all of the subclasses. This was answered in a different question. But what I need to know now is if/how I can cast various functions (in the base class) to return the subclass object. This is both for a given function but also a function call in it. (I'm working with CoreData by the way) As a function within the base class (this is from a class that is going to become my subclass) +(Structure *)fetchStructureByID:(NSNumber *)structureID inContext:(NSManagedObjectContext *)managedObjectContext {...} And as a function call within a given function: Structure *newStructure = [Structure fetchStructureByID:[currentDictionary objectForKey:@"myId"]]; inContext:managedObjectContext]; Structure is one of my subclasses, so I need to rewrite both of these so that they are "generic" and can be applied to other subclasses (whoever is calling the function). How do I do that? Update: I just realized that in the second part there are actually two issues. You can't change [Structure fetch...] to [self fetch...] because it is a class method, not an instance method. How do I get around that too?

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  • datareader.close is called in if - else branching. How to validate datareader is actually closed usi

    - by tanmay
    Hi, I have written couple of custom rules in for fxcop 1.36. I have written a code to find weather opened datareader is closed or not. But it does not check which datareader object is calling the close() method so I can't be sure if all opened datareader objs are closed!! 2nd: if I am using data reader in IF else like if 1=2 dr = cmd.executeReader(); else dr = cmd2.execureReader(); end if in this case it will search for 2 datareader objects to be closed.. I am putting my code for more clarity. public override ProblemCollection Check(Member member) { Method method = member as Method; int countCatch =0; int countErrLog = 0; Instruction objInstr = null; if (method != null) { for (int i = 0; i < method.Instructions.Count; i++) { objInstr = method.Instructions[i]; if (objInstr.Value != null) { if (objInstr.Value.ToString().Contains("System.Data.SqlClient.SqlDataReader")) { countCatch += 1; } if (countCatch>0) { if (objInstr.Value.ToString().Contains("System.Data.SqlClient.SqlDataReader.Close")) { countErrLog += 1; } } } } } if (countErrLog!=countCatch) { Resolution resolu = GetResolution(new string[] { method.ToString() }); Problems.Add(new Problem(resolu)); } return Problems; Thanks and regards, Tanmay.

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