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  • C++ templates error: instantiated from 'void TestClass::testMethod(T, std::map) [with T = SomeClass]

    - by pureconsciousness
    Hello there, I've some problem in my code I cannot deal with: #ifndef TESTCLASS_H_ #define TESTCLASS_H_' #include <map> using namespace std; template <typename T> class TestClass { public: TestClass(){}; virtual ~TestClass(){}; void testMethod(T b,std::map<T,int> m); }; template <typename T> void TestClass`<T`>::testMethod(T b,std::map<T,int> m){ m[b]=0; } #endif /*TESTCLASS_H_*/ int main(int argc, char* argv[]) { SomeClass s; TestClass<SomeClass> t; map<SomeClass,int> m; t.testMethod(s,m); } Compiler gives me following error in line m[b]=0; : instantiated from 'void TestClass::testMethod(T, std::map) [with T = SomeClass] Could you help find the problem?? Thanks in advance

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  • Implementing a Version check between an Abstract class and it's implementation

    - by Michael Stum
    I have this abstract class and concrete implementation (they are in different assemblies): public abstract class MyAbstractClass { private static readonly int MyAbstractClassVersion = 1; public abstract int ImplementedVersion { get; } protected MyAbstractClass() { CheckVersion(); } private void CheckVersion() { var message = string.Format( "MyAbstractClass implements Version {0}, concrete is Version {1}", RepositoryVersion, ImplementedVersion); if (!MyAbstractClassVersion.Equals(ImplementedVersion)) throw new InvalidOperationException(message); } } public class ConcreteClass : MyAbstractClass { public ConcreteClass() : base() { // ConcreteClass is guaranteed to have // a constructor that calls the base constructor // I just simplified the example } public override int ImplementedVersion { get { return 2; } } } As you see, I call CheckVersion() from the abstract constructor, to get rid of the "virtual member call in base constructor" message, but I am not sure if that's really the way to do it. Sure, it works, but that doesn't mean it will always work, will it? Also, I wonder if I can get the name of the Concrete Type from the CheckVersion() function? I know that adding new abstract members will force an error anyway (System.TypeLoadException) and I'm not sure if I want this type of strict Versioning, but I'm just curious how it would be done properly given only the abstract class and an implementation (I know I could do it by using interfaces and/or a Factory pattern).

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  • Events + Adapter Pattern

    - by Stretto
    I have an adapter pattern on a generic class that essentially adapts between types: class A<T> { event EventHandler e; } class Aadapter<T1, T2> : A<T1> { A<T2> a; Aadapter(A<T2> _a) { a = _a; } } The problem is that A contains an event. I effectively want all event handlers assigned to Adapter to fall through to a. It would be awesome if I could assign the a's event handler to adapter's event handler but this is impossible? The idea here is that A is almost really just A but we need a way to adapt the them. Because of the way event's work I can't how to efficiently do it except manually add two event handlers and when they are called they "relay" the to the other event. This isn't pretty though and it would seem much nicer if I could have something like class A<T> { event EventHandler e; } class Aadapter<T1, T2> : A<T1> { event *e; A<T2> a; Aadapter(A<T2> _a) { a = _a; e = a.e; } } in a sense we have a pointer to the event that we can assign a2's event to. I doubt there is any simple way but maybe someone has some idea to make it work. (BTW, I realize this is possible with virtual events but I'd like to avoid this if at all possible)

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  • Windows: Does something temporarily grab the com ports on startup?

    - by Tim
    I have a WPF/C# app that is launched as part of the "Startup" group on a Windows Embedded Standard machine. One of the first things the app does (in its static App() method) is create a new SerialPort object for COM1. COM1 is a hardwired serial port, not a USB virtual port or anything like that. My problem is that every so often (maybe 1 out of 12) on startup, I get an exception: System.UnauthorizedAccessException: Access to the port 'COM1' is denied. There are no other applications using this port. Also, when I relaunch the app following this error, it grabs the port just fine. It's as if the com port isn't ready/set up for my app sometimes. I'm clueless on this one! Any insight is appreciated! UPDATE: I added a call to SerialPort.GetPortNames() and printout all available ports before attempting to open the port. In the failure case COM1 is indeed THERE! So, it's not that the port isn't ready. It looks like something in Windows is actually grabbing the port temporarily and blocking me.

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  • [PHP] Local/Dev/Live deployment - best workflow

    - by Adam Kiss
    Hello, situation We our little company with 3 people, each has a localhost webserver and most projects (previous and current) are on one PC network shared disk. We have virtual server, where some of our clients' sites and our site. Our standard workflow is: Coder PC ? Programmer localhost ? dev domain (client.company.com) ? live version (client.com) It often happens, that there are two or three guys working on same projects at the same time - one is on dev version, two are on localhost. When finished, we try to synchronize the files on dev version and ideally not to mess up any files, which *knock knock * doesn't happen often. And then one of us deploys dev version on live webserver. question we are looking for a way to simplify this workflow while updating websites - ideally some sort of diff uploader or VCS probably (Git/SVN/VCS/...), but we are not completely sure where to begin or what way would be ideal, therefore I ask you, fellow stackoverflowers for your experience with website / application deployment and recommended workflow. We probably will also need to use Mac in process, so if it won't be a problem, that would be even better. Thank you

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  • How to secure connection strings in VS?

    - by salvationishere
    I see several others have posted this question, however, none of the solutions I've tried have fixed this yet. I have a 32-bit XP running VS 2008 and I am trying to encrypt my connection string in my web.config file. But I am getting the error: The configuration section '...' was not found. Failed! The command I give it: C:\Program Files\Microsoft Visual Studio 9.0\VCAspnet_regiis.exe -pe "system.we b/AdventureWorksConnectionString2" -app "/Documents and Settings/Admin/My Docume nts/Visual Studio 2008/Projects/AddFileToSQL2" Also, how does -app map virtual directory? In other words the path above is the directory right below c:. Is this the correct path to use? And AddFileToSQL2 is the name of my project, although it is part of the AddFileToSQL solution. I have this folder web shared with all of the permissions. And the relevant part of my web.config file: <add name="AdventureWorksConnectionString2" connectionString="Data Source=SIDEKICK;Initial Catalog=AdventureWorks;Persist Security Info=true; User ID=AdventureWorks;Password=sqlMagic" providerName="System.Data.SqlClient" />

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  • One-to-many Associations Empty Columns Issue (Ext on Rails)

    - by Joe
    I'm playing with rewriting part of a web application in Rails + Ext. However, I'm having trouble getting an associated models' name to display in the grid view. I've been able to successfully convert several models and arrange the views nicely using tabs and Ext's layout helpers. However, I'm in the middle of setting up an association -- I've followed along with Jon Barket's tutorial on how to do this using Ext -- and I've made all the Rails and JS changes suggested (with appropriate name changes for my models,) the result being that the combo box is now being correctly populated with the names of the associated models, and changes are actually written correctly to database, BUT the data doesn't show up in the column, it's just empty. However, the correct data is there in the 'detail' view. Really just wondering if anyone else ran into this, or had any thoughts on what could be happening. Definitely willing to post code if requested; just note that (AFAIK) my changes follow the tutorial pretty closely. Thanks in advance! UPDATE: Alright, slight progress - kind of. I can get the associated model id # displaying properly -- just by modifying the column model slightly. But I can't get the virtual attribute displayed in the main table (in Jon's example it's country_name.) It still goes blank when I change the data source for that column from dataIndex: 'model[associated_model_id]' to dataIndex: 'virtual_attributes[associated_model_name]' ANOTHER UPDATE: Bump. Has NOBODY here tried integrating Ext with Rails?

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  • LINQ to SQL Queries odd Materialization

    - by ptoinson
    I ran across an interesting Linq to SQL, uh, feature, the other day. Perhaps someone can give me a logical explanation for the reasoning behind the results. Take the code below as my example which utilizes the AdventureWorks database setup in a Linq to SQL DataContext. This is a clip from my unit test. The resulting customer returned from a call to both CustomerQuery_Test_01() and CustomerQuery_Test_02() is the same. However, the query executed on the SQLServer are different is a major way. The method CustomerQuery_Test_01 us causing the entire Customer table to be materialized, which the call to CustomerQuery_Test_02 is only causing the single customer to be materialized. The resulting SQL Queries are at the bottom of this post. Anyone have a good reason for this? To me, it was highly non-intuitive. protected virtual Customer GetByPrimaryKey(Func<Customer, bool> keySelection) { AdventureWorksDataContext context = new AdventureWorksDataContext(); return (from r in context.Customers select r).SingleOrDefault(keySelection); } [TestMethod] public void CustomerQuery_Test_01() { Customer customer = GetByPrimaryKey(c => c.CustomerID == 2); } [TestMethod] public void CustomerQuery_Test_02() { AdventureWorksDataContext context = new AdventureWorksDataContext(); Customer customer = (from r in context.Customers select r).SingleOrDefault(c => c.CustomerID == 2); } Query for CustomerQuery_Test_01 (notice the lack of a where clause) SELECT [t0].[CustomerID], [t0].[NameStyle], [t0].[Title], [t0].[FirstName], [t0].[MiddleName], [t0].[LastName], [t0].[Suffix], [t0].[CompanyName], [t0].[SalesPerson], [t0].[EmailAddress], [t0].[Phone], [t0].[PasswordHash], [t0].[PasswordSalt], [t0].[rowguid], [t0].[ModifiedDate] FROM [SalesLT].[Customer] AS [t0] Query for CustomerQuery_Test_02 (notice the where clause) SELECT [t0].[CustomerID], [t0].[NameStyle], [t0].[Title], [t0].[FirstName], [t0].[MiddleName], [t0].[LastName], [t0].[Suffix], [t0].[CompanyName], [t0].[SalesPerson], [t0].[EmailAddress], [t0].[Phone], [t0].[PasswordHash], [t0].[PasswordSalt], [t0].[rowguid], [t0].[ModifiedDate] FROM [SalesLT].[Customer] AS [t0] WHERE [t0].[CustomerID] = @p0

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  • Context.Items.Add on an XML return type?

    - by Scott Schluer
    So I have the following code contained within an HttpModule in an application I've been asked to support: app.Context.Response.ContentType = "text/xml"; app.Context.Items.Add("IpixRoomId", ipixRoomId); app.Context.Items.Add("IpixId", ipixId); app.Context.Response.Cache.SetCacheability(HttpCacheability.NoCache); app.Context.RewritePath(rewriteUrl, true); What's the purpose of adding data to Context.Items when the content type is XML? EDIT: For clarification, I'm calling up this URL: http://website.com/virtualtour/1971/6284/panorama2flash.swf I assume the SWF file (I know very little about Flash) makes another call to http://website.com/virtualtour/config.xml. The code I pasted above only executes on calls to config.xml. So since it's only the SWF file and config.xml being requested from the server, I'm a little confused. Can the .SWF file have access to HttpContext.Current.Items? Other than the HttpModule, there is no .NET involved in the code, it's a straight request to the SWF file which triggers a call to config.xml but it seems that those Context.Items contain the data needed to make the SWF file display the right virtual tour. I'm just missing where that link happens. It can't happen in the XML, so maybe in Flash?

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  • ref and out parameters in C# and cannot be marked as variant.

    - by Water Cooler v2
    What does the statement mean? From here ref and out parameters in C# and cannot be marked as variant. 1) Does it mean that the following can not be done. public class SomeClass<R, A>: IVariant<R, A> { public virtual R DoSomething( ref A args ) { return null; } } 2) Or does it mean I cannot have the following. public delegate R Reader<out R, in A>(A arg, string s); public static void AssignReadFromPeonMethodToDelegate(ref Reader<object, Peon> pReader) { pReader = ReadFromPeon; } static object ReadFromPeon(Peon p, string propertyName) { return p.GetType().GetField(propertyName).GetValue(p); } static Reader<object, Peon> pReader; static void Main(string[] args) { AssignReadFromPeonMethodToDelegate(ref pReader); bCanReadWrite = (bool)pReader(peon, "CanReadWrite"); Console.WriteLine("Press any key to quit..."); Console.ReadKey(); } I tried (2) and it worked.

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  • Why does the VS2005 debugger not report "base." values properly? (was "Why is this if statement fail

    - by Rawling
    I'm working on an existing class that is two steps derived from System.Windows.Forms.Combo box. The class overrides the Text property thus: public override string Text { get { return this.AccessibilityObject.Value; } set { if (base.Text != value) { base.Text = value; } } } The reason given for that "get" is this MS bug: http://support.microsoft.com/kb/814346 However, I'm more interested in the fact that the "if" doesn't work. There are times where "base.Text != value" is true and yet pressing F10 steps straight to the closing } of the "set" and the Text property is not changed. I've seen this both by just checking values in the debugger, and putting a conditional breakpoint on that only breaks when the "if" statement's predicate is true. How on earth can "if" go wrong? The class between this and ComboBox doesn't touch the Text property. The bug above shouldn't really be affecting anything - it says it's fixed in VS2005. Is the debugger showing different values than the program itself sees? Update I think I've found what is happening here. The debugger is reporting value incorrectly (including evaluating conditional breakpoints incorrectly). To see this, try the following pair of classes: class MyBase { virtual public string Text { get { return "BaseText"; } } } class MyDerived : MyBase { public override string Text { get { string test = base.Text; return "DerivedText"; } } } Put a breakpoint on the last return statement, then run the code and access that property. In my VS2005, hovering over base.Text gives the value "DerivedText", but the variable test has been correctly set to "BaseText". So, new question: why does the debugger not handle base properly, and how can I get it to?

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  • which sql consumes less memory

    - by prmatta
    Yesterday I asked a question on how to re-write sql to do selects and inserts in batches. I needed to do this to try and consume less virtual memory, since I need to move millions of rows here. The object is to move rows from Table B into Table A. Here are the ways I can think of doing this: SQL #1) INSERT INTO A (x, y, z) SELECT x, y, z FROM B b WHERE ... SQL #2) FOREACH SELECT x,y,z FROM B b WHERE ... INSERT INTO A(x,y,z); END FOREACH; SQL #3) FOREACH SELECT FIRST 2000 x,y,z FROM B b WHERE ... INSERT INTO A(x,y,z); END FOREACH; SQL #4) FOREACH SELECT FIRST 2000 x,y,z FROM B b WHERE ... AND NOT EXISTS IN (SELECT * FROM A) INSERT INTO A(x,y,z); END FOREACH; Are any of the above incorrect? The database is informix 11.5.

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  • How can I make PHP scripts timeout gracefully while waiting for long-running MySQL queries?

    - by Mark B
    I have a PHP site which runs quite a lot of database queries. With certain combinations of parameters, these queries can end up running for a long time, triggering an ugly timeout message. I want to replace this with a nice timeout message themed according to the rest of my site style. Anticipating the usual answers to this kind of question: "Optimise your queries so they don't run for so long" - I am logging long-running queries and optimising them, but I only know about these after a user has been affected. "Increase your PHP timeout setting (e.g. set_time_limit, max_execution_time) so that the long-running query can finish" - Sometimes the query can run for several minutes. I want to tell the user there's a problem before that (e.g. after 30 seconds). "Use register_tick_function to monitor how long scripts have been running" - This only gets executed between lines of code in my script. While the script is waiting for a response from the database, the tick function doesn't get called. In case it helps, the site is built using Drupal (with lots of customisation), and is running on a virtual dedicated Linux server on PHP 5.2 with MySQL 5.

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  • BackgroundWorker acting bizarrely...

    - by vdh_ant
    Hi guys I'm working on some code that calls a service. This service call could fail and if it does I want the system to try again until it works or too much time has passed. I am wondering where I am going wrong as the following code doesn't seem to be working correctly... It randomly only does one to four loops... protected virtual void ProcessAsync(object data, int count) { var worker = new BackgroundWorker(); worker.DoWork += (sender, e) => { throw new InvalidOperationException("oh shiznit!"); }; worker.RunWorkerCompleted += (sender, e) => { //If an error occurs we need to tell the data about it if (e.Error != null) { count++; System.Threading.Thread.Sleep(count * 5000); if (count <= 10) { if (count % 5 == 0) this.Logger.Fatal("LOAD ERROR - The system can't load any data", e.Error); else this.Logger.Error("LOAD ERROR - The system can't load any data", e.Error); this.ProcessAsync(data, count); } } }; worker.RunWorkerAsync(); } Cheers Anthony

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  • Is method reference caching a good idea in Java 8?

    - by gexicide
    Consider I have code like the following: class Foo { Y func(X x) {...} void doSomethingWithAFunc(Function<X,Y> f){...} void hotFunction(){ doSomethingWithAFunc(this::func); } } Consider that hotFunction is called very often. Would it then be advisable to cache this::func, maybe like this: class Foo { Function<X,Y> f = this::func; ... void hotFunction(){ doSomethingWithAFunc(f); } } As far as my understanding of java method references goes, the Virtual Machine creates an object of an anonymous class when a method reference is used. Thus, caching the reference would create that object only once while the first approach creates it on each function call. Is this correct? Should method references that appear at hot positions in the code be cached or is the VM able to optimize this and make the caching superfluous? Is there a general best practice about this or is this highly VM-implemenation specific whether such caching is of any use?

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  • How to ensure nginx serves a request from an external IP?

    - by Matt
    I have a strange situation, where my nginx setup stopped handling external requests. I'm pretty stuck. If I hit the domain without a subdomain, I properly get redirected, however, if I request the full url, that fails and doesn't log anything, anywhere. I am able to curl localhost on the server itself, however when I attempt to curl from an external machine, it fails with: curl: (7) couldn't connect to host I've also noticed that bots can get through, I've seen Google hit the log every now and then. My nginx.conf file: upstream mongrels { server 127.0.0.1:5000; } server { listen 80; server_name culini.com; rewrite ^/(.*) http://www.culini.com/$1 permanent; } # the server directive is nginx's virtual host directive. server { # port to listen on. Can also be set to an IP:PORT listen 80; # Set the max size for file uploads to 50Mb client_max_body_size 50M; # sets the domain[s] that this vhost server requests for server_name www.culini.com; # doc root root /var/www/culini/current/public; log_format app '$remote_addr - $remote_user [$time_local] ' '"$request" $status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for" [$upstream_addr $upstream_response_time $upstream_status]'; # vhost specific access log access_log /var/www/culini/current/log/nginx.access.log app; error_log /var/www/culini/current/log/nginx.error.log debug; location / { proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect false; proxy_max_temp_file_size 0; proxy_intercept_errors on; proxy_ignore_client_abort on; if (-f $request_filename) { break; } if (!-f $request_filename) { proxy_pass http://mongrels; break; } } } Please, please, any help would be greatly appreciated.

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  • In Castle Windsor, can I register a Interface component and get a proxy of the implementation?

    - by Thiado de Arruda
    Lets consider some cases: _windsor.Register(Component.For<IProductServices>().ImplementedBy<ProductServices>().Interceptors(typeof(SomeInterceptorType)); In this case, when I ask for a IProductServices windsor will proxy the interface to intercept the interface method calls. If instead I do this : _windsor.Register(Component.For<ProductServices>().Interceptors(typeof(SomeInterceptorType)); then I cant ask for windsor to resolve IProductServices, instead I ask for ProductServices and it will return a dynamic subclass that will intercept virtual method calls. Of course the dynamic subclass still implements 'IProductServices' My question is : Can I register the Interface component like the first case, and get the subclass proxy like in the second case?. There are two reasons for me wanting this: 1 - Because the code that is going to resolve cannot know about the ProductServices class, only about the IProductServices interface. 2 - Because some event invocations that pass the sender as a parameter, will pass the ProductServices object, and in the first case this object is a field on the dynamic proxy, not the real object returned by windsor. Let me give an example of how this can complicate things : Lets say I have a custom collection that does something when their items notify a property change: private void ItemChanged(object sender, PropertyChangedEventArgs e) { int senderIndex = IndexOf(sender); SomeActionOnItemIndex(senderIndex); } This code will fail if I added an interface proxy, because the sender will be the field in the interface proxy and the IndexOf(sender) will return -1.

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  • Doubt on pointer conversion

    - by Simone
    Suppose we have the following code: #include <iostream> struct A { virtual void f() { std::cout << "A::f()" << std::endl; } }; struct B: A { void f() { std::cout << "B::f()" << std::endl; } }; void to_A(void* voidp) { A* aptr = static_cast<A*>(voidp); aptr->f(); } void to_B(void* voidp) { B* bptr2 = static_cast<B*>(voidp); bptr2->f(); } int main() { B* bptr = new B; void* voidp = bptr; to_A(voidp); // prints B::f() to_B(voidp); // prints B::f() } is this code guaranteed to always work as in the code comments or is it UB? AFAIK it should be ok, but I'd like to be reassured.

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  • Quantifying the Performance of Garbage Collection vs. Explicit Memory Management

    - by EmbeddedProg
    I found this article here: Quantifying the Performance of Garbage Collection vs. Explicit Memory Management http://www.cs.umass.edu/~emery/pubs/gcvsmalloc.pdf In the conclusion section, it reads: Comparing runtime, space consumption, and virtual memory footprints over a range of benchmarks, we show that the runtime performance of the best-performing garbage collector is competitive with explicit memory management when given enough memory. In particular, when garbage collection has five times as much memory as required, its runtime performance matches or slightly exceeds that of explicit memory management. However, garbage collection’s performance degrades substantially when it must use smaller heaps. With three times as much memory, it runs 17% slower on average, and with twice as much memory, it runs 70% slower. Garbage collection also is more susceptible to paging when physical memory is scarce. In such conditions, all of the garbage collectors we examine here suffer order-of-magnitude performance penalties relative to explicit memory management. So, if my understanding is correct: if I have an app written in native C++ requiring 100 MB of memory, to achieve the same performance with a "managed" (i.e. garbage collector based) language (e.g. Java, C#), the app should require 5*100 MB = 500 MB? (And with 2*100 MB = 200 MB, the managed app would run 70% slower than the native app?) Do you know if current (i.e. latest Java VM's and .NET 4.0's) garbage collectors suffer the same problems described in the aforementioned article? Has the performance of modern garbage collectors improved? Thanks.

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  • ecommerce - use server side code for hidden values in an html form

    - by bsarmi
    I'm trying to learn how to implement a donation form on a website using virtual merchant. The html code from their developer manual goes like this: <form action="https://www.myvirtualmerchant.com/VirtualMerchant/process.do" method="POST"> Your Total: $5.00 <br/> <input type="hidden" name="ssl_amount" value="5.00"> <br/> <input type="hidden" name="ssl_merchant_id" value="my_virtualmerchant_ID"> <input type="hidden" name="ssl_pin" value="my_PIN"> <input type="hidden" name="ssl_transaction_type" value="ccsale"> <input type="hidden" name="ssl_show_form" value="false"> Credit Card Number: <input type="text" name="ssl_card_number"> <br/> Expiration Date (MMYY): <input type="text" name="ssl_exp_date" size="4"> <br/> <br/> <input type="submit" value="Continue"> </form> I have that in an html file and it works fine, but they suggest that the merchant data (the input type="hidden" values) should be in a Server Side Code. I was looking at cURL but it'a all very new to me and I spent a couple of hours trying to find some guide or some sample code on how to accomplish that. Any suggestions or help is greatly appreciated. Thanks!

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  • What happens to exinsting workspaces after upgrading to TFS 2010

    - by user351671
    Hi, I was looking for some insight about what happens to existing workspaces and files that are already checked-out on people, after an upgrade to TFS2010. Surprisingly enough I can not find any satisfactory information on this. (I am talking about upgrading on new hardware by the way. Fresh TFS instance, upgraded databases) I've checked TFS Installation guide, I searched through the web, all I could find is upgrade scenarios for the server side. Nobody even mentions what happens to source control clients. I've created a virtual machine to test the upgrade process, The upgrade was successful and all my files and workspaces exist in the new server too. The problem is: The new TFS installation has a new instanceID. When I redirected on the clients to the new server, the client seemed unable to match files and file states in the workspace with the ones on the new server. This makes me wonder if it will be possible to keep working after the production upgrade. As I mentioned above I can not find anything on this, it would be great if anyone could point me to some paper or blog post about this. Thanks in advance...

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  • C# Function Inheritance--Use Child Class Vars with Base Class Function

    - by Sean O'Connor
    Good day, I have a fairly simple question to experienced C# programmers. Basically, I would like to have an abstract base class that contains a function that relies on the values of child classes. I have tried code similar to the following, but the compiler complains that SomeVariable is null when SomeFunction() attempts to use it. Base class: public abstract class BaseClass { protected virtual SomeType SomeVariable; public BaseClass() { this.SomeFunction(); } protected void SomeFunction() { //DO SOMETHING WITH SomeVariable } } A child class: public class ChildClass:BaseClass { protected override SomeType SomeVariable=SomeValue; } Now I would expect that when I do: ChildClass CC=new ChildClass(); A new instance of ChildClass should be made and CC would run its inherited SomeFunction using SomeValue. However, this is not what happens. The compiler complains that SomeVariable is null in BaseClass. Is what I want to do even possible in C#? I have used other managed languages that allow me to do such things, so I certain I am just making a simple mistake here. Any help is greatly appreciated, thank you.

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  • Implementing inotifycollectionchanged interface

    - by George
    Hello, I need to implement a collection with special capabilities. In addition, I want to bind this collection to a ListView, Therefore I ended up with the next code (I omitted some methods to make it shorter here in the forum): public class myCollection<T> : INotifyCollectionChanged { private Collection<T> collection = new Collection<T>(); public event NotifyCollectionChangedEventHandler CollectionChanged; public void Add(T item) { collection.Insert(collection.Count, item); OnCollectionChange(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, item)); } protected virtual void OnCollectionChange(NotifyCollectionChangedEventArgs e) { if (CollectionChanged != null) CollectionChanged(this, e); } } I wanted to test it with a simple data class: public class Person { public string GivenName { get; set; } public string SurName { get; set; } } So I created an instance of myCollection class as follows: myCollection<Person> _PersonCollection = new myCollection<Person>(); public myCollection<Person> PersonCollection { get { return _PersonCollection; } } The problem is that the ListView does not update when the collection updates although I implemented the INotifyCollectionChanged interface. I know that my binding is fine (in XAML) because when I use the ObservableCollecion class instead of myCollecion class like this: ObservableCollection<Person> _PersonCollection = new ObservableCollection<Person>(); public ObservableCollection<Person> PersonCollection { get { return _PersonCollection; } } the ListView updates What is the problem?

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  • Which design pattern fits - strategy makes sense ?

    - by user554833
    --Bump *One desperate try to get someone's attention I have a simple database table that stores list of users who have subscribed to folders either by email OR to show up on the site (only on the web UI). In the storage table this is controlled by a number(1 - show on site 2- by email). When I am showing in UI I need to show a checkbox next to each of folders for which the user has subscribed (both email & on site). There is a separate table which stores a set of default subscriptions which would apply to each user if user has not expressed his subscription. This is basically a folder ID and a virtual group name. But, Email subscriptions do not count for applying these default groups. So if no "on site" subscription apply default group. Thats the rule. How about a strategy pattern here (Pseudo code) Interface ISubscription public ArrayList GetSubscriptionData(Pass query object) Public class SubscriptionWithDefaultGroup Implement ArrayList GetSubscriptionData(Pass query object) Public class SubscriptionWithoutDefaultGroup Implement ArrayList GetSubscriptionData(Pass query object) Public class SubscriptionOnlyDefaultGroup Implement ArrayList GetSubscriptionData(Pass query object) does this even make sense? I would be more than glad for receive any criticism / help / notes. I am learning. Cheers

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  • Resource allocation and automatic deallocation

    - by nabulke
    In my application I got many instances of class CDbaOciNotifier. They all share a pointer to only one instance of class OCIEnv. What I like to achieve is that allocation and deallocation of the resource class OCIEnv will be handled automatically inside class CDbaOciNotifier. The desired behaviour is, with the first instance of class CDbaOciNotifier the environment will be created, after that all following notifiers use that same environment. With the destruction of the last notifier, the environment will be destroyed too (call to custom deleter). What I've got so far (using a static factory method to create notifiers): #pragma once #include <string> #include <memory> #include "boost\noncopyable.hpp" class CDbaOciNotifier : private boost::noncopyable { public: virtual ~CDbaOciNotifier(void); static std::auto_ptr<CDbaOciNotifier> createNotifier(const std::string &tnsName, const std::string &user, const std::string &password); private: CDbaOciNotifier(OCIEnv* envhp); // All notifiers share one environment static OCIEnv* m_ENVHP; // Custom deleter static void freeEnvironment(OCIEnv *env); OCIEnv* m_envhp; }; CPP: #include "DbaOciNotifier.h" using namespace std; OCIEnv* CDbaOciNotifier::m_ENVHP = 0; CDbaOciNotifier::~CDbaOciNotifier(void) { } CDbaOciNotifier::CDbaOciNotifier(OCIEnv* envhp) :m_envhp(envhp) { } void CDbaOciNotifier::freeEnvironment(OCIEnv *env) { OCIHandleFree((dvoid *) env, (ub4) OCI_HTYPE_ENV); *env = null; } auto_ptr<CDbaOciNotifier> CDbaOciNotifier::createNotifier(const string &tnsName, const string &user, const string &password) { if(!m_ENVHP) { OCIEnvCreate( (OCIEnv **) &m_ENVHP, OCI_EVENTS|OCI_OBJECT, (dvoid *)0, (dvoid * (*)(dvoid *, size_t)) 0, (dvoid * (*)(dvoid *, dvoid *, size_t))0, (void (*)(dvoid *, dvoid *)) 0, (size_t) 0, (dvoid **) 0 ); } //shared_ptr<OCIEnv> spEnvhp(m_ENVHP, freeEnvironment); ...got so far... return auto_ptr<CDbaOciNotifier>(new CDbaOciNotifier(m_ENVHP)); } I'd like to avoid counting references (notifiers) myself, and use something like shared_ptr. Do you see an easy solution to my problem?

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