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  • Why user control with code behind file doesn't want to compile under MVC2?

    - by kyrisu
    I have user control in my MVC2 app placed in the Content folder (it's not supposed to be a view, just reusable part of the app). UserControl1.ascx looks like: <@ Control AutoEventWireup="true" Language="C#" CodeFile="~/Content/UserControl1.ascx.cs" Inherits="MVCDrill.Content.UserControl1" %> <div runat="server" id="mydiv"> <asp:LinkButton id="lb_text" runat="server"></asp:LinkButton> </div> UserControl1.ascx.cs looks like: using System; using System.Web; using System.Web.UI; namespace MVCDrill.Content { public class UserControl1 : UserControl { public string Text { get { return this.lb_text.Text; } set { this.lb_text.Text = value; } } } } I'm pretty sure this kind of stuff compiled under webforms but I'm getting compilation error: 'MVCDrill.Content.UserControl1' does not contain a definition for 'lb_text' and no extension method 'lb_text' accepting a first argument of type 'MVCDrill.Content.UserControl1' could be found (are you missing a using directive or an assembly reference?) Am I missing something? How to change it (what is the alternative) in MVC2 ? p.s. Intellisense sees lb_text with no problem. I've tried with different controls with the same outcome.

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  • Dilemma of Sending a Byte Array from JavaScript to COM.

    - by Voulnet
    Hello there, I'm having a bit of a problem because neither Javascript nor ActiveX (written in C++) are behaving like good little children. All I'm asking them to do is for Javascript to send a byte array and for the ActiveX to receive the byte array correctly in order to do more computation. This is how I declared my byte array in JS, and I verified it inside JS: var arr = new Array(0x00, 0xA4, 0x04, 0x00, 0x10,0xA0, 0x00, 00, 00, 0x18, 0x30, 0x03, 0x01, 00, 00, 00, 00, 00, 00, 00, 00); Javascript sends this array as an argument to an ActiveX method. Here is the tricky part; I want the ActiveX method to receive the byte array as a SAFEARRAY or VARIANT, but I can't get it to work for the life of me. I tried debugging and seeing the contents received inside the ActiveX as both SAFEARRAY or VARIANT, but to no avail. Here is the IDL segment: [id(7), helpstring("NEW Sends APDU to Card and Reads the Response")] HRESULT NewSendAPDU( [in] VARIANT pAPDU, [out, retval]VARIANT* pAPDUResponse); Any help is greatly appreciated. Thanks in advance!

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  • Why do the overloads of String.Format exist?

    - by GiddyUpHorsey
    I was using Reflector to look at the implementation of String.Format and had always been under the impression that the overloads of String.Format that took 1, 2 & 3 arguments were optimized versions of the method that takes an object array. However, what I found was that internally they create an object array and then call a method that takes an object array. 1 arg public static string Format(string format, object arg0) { if (format == null) { throw new ArgumentNullException("format"); } return Format(null, format, new object[] { arg0 }); } 2 args public static string Format(string format, object arg0, object arg1) { if (format == null) { throw new ArgumentNullException("format"); } return Format(null, format, new object[] { arg0, arg1 }); } 3 args public static string Format(string format, object arg0, object arg1, object arg2) { if (format == null) { throw new ArgumentNullException("format"); } return Format(null, format, new object[] { arg0, arg1, arg2 }); } Object array public static string Format(string format, params object[] args) { if ((format == null) || (args == null)) { throw new ArgumentNullException((format == null) ? "format" : "args"); } return Format(null, format, args); } Internally they all end up using the same code and so using the 1, 2 & 3 argument versions are no faster than the object array version. So my question is - why do they exist? When you use the object array version with a comma separated list of values, the compiler automatically converts the arguments into an object array because of the params/ParamArray keyword which is essentially what the 1, 2 & 3 versions do, so they seem redundant. Why did the BCL designers add these overloads?

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  • Instantiating class with custom allocator in shared memory

    - by recipriversexclusion
    I'm pulling my hair due to the following problem: I am following the example given in boost.interprocess documentation to instantiate a fixed-size ring buffer buffer class that I wrote in shared memory. The skeleton constructor for my class is: template<typename ItemType, class Allocator > SharedMemoryBuffer<ItemType, Allocator>::SharedMemoryBuffer( unsigned long capacity ){ m_capacity = capacity; // Create the buffer nodes. m_start_ptr = this->allocator->allocate(); // allocate first buffer node BufferNode* ptr = m_start_ptr; for( int i = 0 ; i < this->capacity()-1; i++ ) { BufferNode* p = this->allocator->allocate(); // allocate a buffer node } } My first question: Does this sort of allocation guarantee that the buffer nodes are allocated in contiguous memory locations, i.e. when I try to access the n'th node from address m_start_ptr + n*sizeof(BufferNode) in my Read() method would it work? If not, what's a better way to keep the nodes, creating a linked list? My test harness is the following: // Define an STL compatible allocator of ints that allocates from the managed_shared_memory. // This allocator will allow placing containers in the segment typedef allocator<int, managed_shared_memory::segment_manager> ShmemAllocator; //Alias a vector that uses the previous STL-like allocator so that allocates //its values from the segment typedef SharedMemoryBuffer<int, ShmemAllocator> MyBuf; int main(int argc, char *argv[]) { shared_memory_object::remove("MySharedMemory"); //Create a new segment with given name and size managed_shared_memory segment(create_only, "MySharedMemory", 65536); //Initialize shared memory STL-compatible allocator const ShmemAllocator alloc_inst (segment.get_segment_manager()); //Construct a buffer named "MyBuffer" in shared memory with argument alloc_inst MyBuf *pBuf = segment.construct<MyBuf>("MyBuffer")(100, alloc_inst); } This gives me all kinds of compilation errors related to templates for the last statement. What am I doing wrong?

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  • Java design: too many getters

    - by dege
    After writing a few lesser programs when learning Java the way I've designed the programs is with Model-View-Control. With using MVC I have a plethora of getter methods in the model for the view to use. It feels that while I gain on using MVC, for every new value added I have to add two new methods in the model which quickly get all cluttered with getter & setters. So I was thinking, maybe I should use the notifyObserver method that takes an argument. But wouldn't feel very smart to send every value by itself either so I figured, maybe if I send a kind of container with all the values, preferably only those that actually changed. What this would accomplish would be that instead of having a whole lot of getter methods I could just have one method in the model which put all relevant values in the container. Then in the view I would have a method called from the update which extracted the values from the container and assigning them to the correct fields. I have two questions concerning this. First: is this actually a viable way to do this. Would you recommend me doing something along these lines? Secondly: if I do use this plan and I don't want to keep sending fields that didn't actually change. How would I handle that without having to have if statements to check if the value is not null for every single value?

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  • Reference-type conversion operators: asking for trouble?

    - by Ben
    When I compile the following code using g++ class A {}; void foo(A&) {} int main() { foo(A()); return 0; } I get the following error messages: > g++ test.cpp -o test test.cpp: In function ‘int main()’: test.cpp:10: error: invalid initialization of non-const reference of type ‘A&’ from a temporary of type ‘A’ test.cpp:6: error: in passing argument 1 of ‘void foo(A&)’ After some reflection, these errors make plenty of sense to me. A() is just a temporary value, not an assignable location on the stack, so it wouldn't seem to have an address. If it doesn't have an address, then I can't hold a reference to it. Okay, fine. But wait! If I add the following conversion operator to the class A class A { public: operator A&() { return *this; } }; then all is well! My question is whether this even remotely safe. What exactly does this point to when A() is constructed as a temporary value? I am given some confidence by the fact that void foo(const A&) {} can accept temporary values according to g++ and all other compilers I've used. The const keyword can always be cast away, so it would surprise me if there were any actual semantic differences between a const A& parameter and an A& parameter. So I guess that's another way of asking my question: why is a const reference to a temporary value considered safe by the compiler whereas a non-const reference is not?

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  • Autodetect Presence of CSV Headers in a File

    - by banzaimonkey
    Short question: How do I automatically detect whether a CSV file has headers in the first row? Details: I've written a small CSV parsing engine that places the data into an object that I can access as (approximately) an in-memory database. The original code was written to parse third-party CSV with a predictable format, but I'd like to be able to use this code more generally. I'm trying to figure out a reliable way to automatically detect the presence of CSV headers, so the script can decide whether to use the first row of the CSV file as keys / column names or start parsing data immediately. Since all I need is a boolean test, I could easily specify an argument after inspecting the CSV file myself, but I'd rather not have to (go go automation). I imagine I'd have to parse the first 3 to ? rows of the CSV file and look for a pattern of some sort to compare against the headers. I'm having nightmares of three particularly bad cases in which: The headers include numeric data for some reason The first few rows (or large portions of the CSV) are null There headers and data look too similar to tell them apart If I can get a "best guess" and have the parser fail with an error or spit out a warning if it can't decide, that's OK. If this is something that's going to be tremendously expensive in terms of time or computation (and take more time than it's supposed to save me) I'll happily scrap the idea and go back to working on "important things". I'm working with PHP, but this strikes me as more of an algorithmic / computational question than something that's implementation-specific. If there's a simple algorithm I can use, great. If you can point me to some relevant theory / discussion, that'd be great, too. If there's a giant library that does natural language processing or 300 different kinds of parsing, I'm not interested.

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  • bash - how to filter java exception info

    - by Michael Mao
    Hi all: We've got a multi-agent Java environment where different agent would most likely produce all sorts of exceptions thrown to stderr. Here is a sample taken from the huge exception log **java.security.AccessControlException: access denied (java.io.FilePermission ..\tournament\Driver\HotelRoomAnalyser.class read)** at java.security.AccessControlContext.checkPermission(Unknown Source) at java.security.AccessController.checkPermission(Unknown Source) at java.lang.SecurityManager.checkPermission(Unknown Source) at java.lang.SecurityManager.checkRead(Unknown Source) at java.io.File.length(Unknown Source) at emarket.client.EmarketSandbox$SandboxFileLoader.loadClassData(EmarketSandbox.java:218) at emarket.client.EmarketSandbox$SandboxFileLoader.loadClass(EmarketSandbox.java:199) at java.lang.ClassLoader.loadClass(Unknown Source) **java.security.AccessControlException: access denied (java.io.FilePermission ..\tournament\Driver\HotelRoomAnalyser.class read)** at java.security.AccessControlContext.checkPermission(Unknown Source) at java.security.AccessController.checkPermission(Unknown Source) at java.lang.SecurityManager.checkPermission(Unknown Source) at java.lang.SecurityManager.checkRead(Unknown Source) at java.io.File.length(Unknown Source) at emarket.client.EmarketSandbox$SandboxFileLoader.loadClassData(EmarketSandbox.java:218) at emarket.client.EmarketSandbox$SandboxFileLoader.loadClass(EmarketSandbox.java:199) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) at MySmarterAgent.hotelRoomBookings(MySmarterAgent.java:108) fortunately all top-tier exceptions are denoted by no leading spaces, as wrapped by ** above. My concern is to get all of the top-tier exception name (delimited by colon :), together with the first line below which contains something like at emarket.client.EmarketSandbox$SandboxFileLoader.loadClassData(EmarketSandbox.java:218) Basically, something with padded style, starts with "at" and ends with ".java:108" So this info can be forwarded to the owner of that error-prone agent and let him/her fix it. My code in ~/.bashrc is incompleted now : alias startmatch='java -jar "emarket.jar" ../tournament 100'; function geterrors() { startmatch 2>"$1"; a=0; while read line do if true; then a=$(($a+1)); echo $a; fi; done } What it does now is to redirect all stderr to a text file specified by the first argument passed in, and after that, parse that text file line by line, if certain conditions returns true, echo only that line. And I am stuck with what to do inside the loop. Any suggestion is much appreciates, any hint is welcomed.

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  • PHP - CodeIgniter

    - by nXqd
    I try to write a site with CodeIgniter but I've a problem with PHP. I'm sure that it's so simple and can't be wrong. But I don't know bugs from , just a newbie of CodeIgniter :) <html> <head> <title><?=$page_title?></title> </head> <body> <?php foreach($result as $row):?> <h3><? echo $row->title; ?></h3> <p><? echo $row->text; ?></p> <?php endforeach;?> </body> </html> I've a bug from this file : A PHP Error was encountered Severity: Warning Message: Invalid argument supplied for foreach() Filename: views/helloworld_view.php Line Number: 6 thanks in advance for reading this :)

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  • Are CMake GLOB and source_group compatible?

    - by jwfearn
    I'm using CMake 2.8.0 (on Windows) with the "Visual Studio 10 Win64" generator. GLOB and source_group don't seem to work together. Is there a way to get this to work? I use file( GLOB ... ) to create a list of .cpp files and then use source_group to create a filter in the generated Visual Studio project: # C:\Users\My Name\hello\CMakeLists.txt cmake_minimum_required( VERSION 2.8 ) project( hello_proj ) file( GLOB HELLO_SRCS *.cpp ) message( "HELLO_SRCS="${HELLO_SRCS} ) #source_group( hello_group ${HELLO_SRCS} ) #line 6: uncomment to get error add_executable( hello_exec ${HELLO_SRCS} ) with line 6 commented out, the project is generated fine: HELLO_SRCS=C:/Users/My Name/hello/hello.cppC:/Users/My Name/hello/print_line.cpp -- Configuring done -- Generating done -- Build files have been written to: C:/Users/My Name/hello with line 6 un-commented, I get an error: HELLO_SRCS=C:/Users/My Name/hello/hello.cppC:/Users/My Name/hello/print_line.cpp CMake Error at CMakeLists.txt:6 (source_group): source_group Unknown argument "C:/Users/My Name/hello/hello.cpp". Perhaps the FILES keyword is missing. -- Configuring incomplete, errors occurred! I notice that output value of ${HELLO_SRCS} does not seem to contain any delimiters between the file names, nor does it have quotes or other delimiters wrapping the file names which contain spaces. Does that have anything to do with my problem? Renaming all directories to avoid spaces is not really an option.

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  • What are the most interesting equivalences arising from the Curry-Howard Isomorphism?

    - by Tom
    I came upon the Curry-Howard Isomorphism relatively late in my programming life, and perhaps this contributes to my being utterly fascinated by it. It implies that for every programming concept there exists a precise analogue in formal logic, and vice versa. Here's an "obvious" list of such analogies, off the top of my head: program/definition | proof type/declaration | proposition inhabited type | theorem function | implication function argument | hypothesis/antecedent function result | conclusion/consequent function application | modus ponens recursion | induction identity function | tautology non-terminating function | absurdity tuple | conjunction (and) disjoint union | exclusive disjunction (xor) parametric polymorphism | universal quantification So, to my question: what are some of the more interesting/obscure implications of this isomorphism? I'm no logician so I'm sure I've only scratched the surface with this list. For example, here are some programming notions for which I'm unaware of pithy names in logic: currying | "((a & b) => c) iff (a => (b => c))" scope | "known theory + hypotheses" And here are some logical concepts which I haven't quite pinned down in programming terms: primitive type? | axiom set of valid programs? | theory ? | disjunction (or)

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  • BitmapFrame in another thread

    - by Lasse Lindström
    Hi I am using a WPF BackgroundWorker to create thumbnails. My worker function looks like: private void work(object sender, DoWorkEventArgs e) { try { var paths = e.Argument as string[]; var boxList = new List(); foreach (string path in paths) { if (!string.IsNullOrEmpty(path)) { FileInfo info = new FileInfo(path); if (info.Exists && info.Length 0) { BitmapImage bi = new BitmapImage(); bi.BeginInit(); bi.DecodePixelWidth = 200; bi.CacheOption = BitmapCacheOption.OnLoad; bi.UriSource = new Uri(info.FullName); bi.EndInit(); var item = new BoxItem(); item.FilePath = path; MemoryStream ms = new MemoryStream(); PngBitmapEncoder encoder = new PngBitmapEncoder(); encoder.Frames.Add(BitmapFrame.Create(bi)); encoder.Save(ms); item.ThumbNail = ms.ToArray(); ms.Close(); boxList.Add(item); } } } e.Result = boxList; } catch (Exception ex) { //nerver comes here } } When this fuction is finnished and before the BackgroundWorker "Completed" function is started, I can see on the output window on Vs2008, that a exception is generated. It looks like: A first chance exception of type 'System.NotSupportedException' occurred in PresentationCore.dll The number of exceptions generates equals the number of thumbnails to be generated. Using "trial and error" I have isolated the problem to: BitmapFrame.Create(bi) Removing that line (makes my function useless) also removes the exception. I have not found any explanation to this,,, or a better method to create thumbnails i a background thread. Can anyone help me? //lasse

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  • Please explain JSONP

    - by Cheeso
    I don't understand jsonp. I understand JSON. I don't understand JSONP. Wikipedia is the top search result for JSONP. It says JSONP or "JSON with padding" is a JSON extension wherein a prefix is specified as an input argument of the call itself. Huh? What call? That doesn't make any sense to me. JSON is a data format. There's no call. The 2nd search result is from some guy named Remy, who writes JSONP is script tag injection, passing the response from the server in to a user specified function. I can sort of understand that, but it's still not making any sense. What is JSONP, why was it created (what problem does it solve), and why would I use it? Addendum: I've updated Wikipedia with a clearer and more thorough description of JSONP, based on jvenema's answer. Thanks, all.

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  • Error Log states that I have MySQL connect error, yet script runs fine

    - by rob - not a robber
    Hello All, First, thanks for all the help I've received so far from StackOverflow. I've learned much. Once again, I'm posing a rudimentary question that I've searched on, but cannot find the exact answer to. Here or on PHP.net. It's sort of like what this guy asked, but not exactly: http://stackoverflow.com/questions/288603/mysql-throwing-query-error-yet-finishing-query-just-fine-why So, I saw my errorlog ballooning up when I checked my site directory and opened to notice that a bunch of errors have been recorded since I wrote this new Admin area. I know something is obviously awry with my scripting for the error to be thrown, but the weird thing is, the script actually runs through and pulls all the data I need without breaking. The log contains: PHP Warning: mysql_query() [function.mysql-query]: Access denied for user 'someuser'@'localhost' (using password: NO) in /home/mysite/adminconsole.php on line 15 I don't get that because that very line is where I setup my connection... the exact same way I do it everywhere else on the site with no problem. After that error, I have these thrown at the same time [09-Apr-2010 08:44:18] PHP Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /home/mysite/adminconsole.php on line 15 [09-Apr-2010 08:44:18] PHP Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/mysite/adminconsole.php on line 16 From what I read in the other guys thread, the problem is the contents of the query maybe? Maybe my query is malformed? Thanks so much for any guidance you can provide. -Rob

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  • COM: How to handle a specific exception?

    - by Ian Boyd
    i'm talking to a COM object (Microsoft ADO Recordset object). In a certain case the recordset will return a failed (i.e. negative) HRESULT, with the message: Item cannot be found in the collection corresponding to the requested name or ordinal i know what this error message means, know why it happened, and i how to fix it. But i know these things because i read the message, which fortunately was in a language i understand. Now i would like to handle this exception specially. The COM object threw an HRESULT of 0x800A0CC1 In an ideal world Microsoft would have documented what errors can be returned when i try to access: records.Fields.Items( index ) with an invalid index. But they do not; they most they say is that an error can occur, i.e.: If Item cannot find an object in the collection corresponding to the Index argument, an error occurs. Given that the returned error code is not documented, is it correct to handle a specific return code of `0x800A0CC1' when i'm trying to trap the exception: Item cannot be found in the collection corresponding to the requested name or ordinal ? Since Microsoft didn't document the error code, they technically change it in the future.

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  • CIL and JVM Little endian to big endian in c# and java

    - by Haythem
    Hello, I am using on the client C# where I am converting double values to byte array. I am using java on the server and I am using writeDouble and readDouble to convert double values to byte arrays. The problem is the double values from java at the end are not the double values at the begin giving to c# writeDouble in Java Converts the double argument to a long using the doubleToLongBits method , and then writes that long value to the underlying output stream as an 8-byte quantity, high byte first. DoubleToLongBits Returns a representation of the specified floating-point value according to the IEEE 754 floating-point "double format" bit layout. The Program on the server is waiting of 64-102-112-0-0-0-0-0 from C# to convert it to 1700.0 but he si becoming 0000014415464 from c# after c# converted 1700.0 this is my code in c#: class User { double workingStatus; public void persist() { byte[] dataByte; using (MemoryStream ms = new MemoryStream()) { using (BinaryWriter bw = new BinaryWriter(ms)) { bw.Write(workingStatus); bw.Flush(); bw.Close(); } dataByte = ms.ToArray(); for (int j = 0; j < dataByte.Length; j++) { Console.Write(dataByte[j]); } } public double WorkingStatus { get { return workingStatus; } set { workingStatus = value; } } } class Test { static void Main() { User user = new User(); user.WorkingStatus = 1700.0; user.persist(); } thank you for the help.

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  • Lua task scheduling

    - by Martin
    I've been writing some scripts for a game, the scripts are written in Lua. One of the requirements the game has is that the Update method in your lua script (which is called every frame) may take no longer than about 2-3 milliseconds to run, if it does the game just hangs. I solved this problem with coroutines, all I have to do is call Multitasking.RunTask(SomeFunction) and then the task runs as a coroutine, I then have to scatter Multitasking.Yield() throughout my code, which checks how long the task has been running for, and if it's over 2 ms it pauses the task and resumes it next frame. This is ok, except that I have to scatter Multitasking.Yield() everywhere throughout my code, and it's a real mess. Ideally, my code would automatically yield when it's been running too long. So, Is it possible to take a Lua function as an argument, and then execute it line by line (maybe interpreting Lua inside Lua, which I know is possible, but I doubt it's possible if all you have is a function pointer)? In this way I could automatically check the runtime and yield if necessary between every single line.

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  • Efficient way to handle multiple HTMLPurifier configs.

    - by anomareh
    I'm using HTMLPurifier in a current project and I'm not sure about the most efficient way to go about handling multiple configs. For the most part the only major thing changing is the allowed tags. Currently I have a private method, in each class using HTMLPurifier, that gets called when a config is needed and it creates one from the default. I'm not really happy with this as if 2 classes are using the same config, that's duplicating code, and what if a class needs 2 configs? It just feels messy. The one upside to it, is it's lazy in the sense that it's not creating anything until it's needed. The various classes could be used and never have to purify anything. So I don't want to be creating a bunch of config objects that might not even be used. I just recently found out that you can create a new instance of HTMLPurifier and directly set config options like so: $purifier = new HTMLPurifier(); $purifier->config->set('HTML.Allowed', ''); I'm not sure if that's bad form at all or not, and if it isn't I'm not really sure of a good way to put it to use. My latest idea was to create a config handler class that would just return an HTMLPurifier config for use in subsequent purify calls. At some point it could probably be expanded to allow the setting of configs, but just from the start I figured they'd just be hardcoded and run a method parameter through a switch to grab the requested config. Perhaps I could just send the stored purifier instance as an argument and have the method directly set the config on it like shown above? This to me seems the best of the few ways I thought of, though I'm not sure if such a task warrants me creating a class to handle it, and if so, if I'm handling it in the best way. I'm not too familiar with the inner workings of HTMLPurifier so I'm not sure if there are any better mechanisms in place for handling multiple configs. Thanks for any insight anyone can offer.

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  • Generic function pointers in C

    - by Lucas
    I have a function which takes a block of data and the size of the block and a function pointer as argument. Then it iterates over the data and performes a calculation on each element of the data block. The following is the essential outline of what I am doing: int myfunction(int* data, int size, int (*functionAsPointer)(int)){ //walking through the data and calculating something for (int n = 0; n < size; n++){ data[n] = (*function)(data[n]); } } The functions I am passing as arguments look something like this: int mycalculation(int input){ //doing some math with input //... return input; } This is working well, but now I need to pass an additional variable to my functionpointer. Something along the lines int mynewcalculation(int input, int someVariable){ //e.g. input = input * someVariable; //... return input; } Is there an elegant way to achieve this and at the same time keeping my overall design idea?

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  • I need an abstract field !

    - by Jules Olléon
    I know abstract fields do not exist in java. I also read this question but the solutions proposed won't solve my problem. Maybe there is no solution, but it's worth asking :) Problem I have an abstract class that does an operation in the constructor depending on the value of one of its fields. The problem is that the value of this field will change depending on the subclass. How can I do so that the operation is done on the value of the field redefined by the subclass ? If I just "override" the field in the subclass the operation is done on the value of the field in the abstract class. I'm open to any solution that would ensure that the operation will be done during the instantiation of the subclass (ie putting the operation in a method called by each subclass in the constructor is not a valid solution, because someone might extend the abstract class and forget to call the method). Also, I don't want to give the value of the field as an argument of the constructor. Is there any solution to do that, or should I just change my design ?

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  • Understanding OOP Principles in passing around objects/values

    - by Hans
    I'm not quite grokking a couple of things in OOP and I'm going to use a fictional understanding of SO to see if I can get help understand. So, on this page we have a question. You can comment on the question. There are also answers. You can comment on the answers. Question - comment - comment - comment Answer -comment Answer -comment -comment -comment Answer -comment -comment So, I'm imagining a very high level understanding of this type of system (in PHP, not .Net as I am not yet familiar with .Net) would be like: $question = new Question; $question->load($this_question_id); // from the URL probably echo $question->getTitle(); To load the answers, I imagine it's something like this ("A"): $answers = new Answers; $answers->loadFromQuestion($question->getID()); // or $answers->loadFromQuestion($this_question_id); while($answer = $answers->getAnswer()) { echo $answer->showFormatted(); } Or, would you do ("B"): $answers->setQuestion($question); // inject the whole obj, so we have access to all the data and public methods in $question $answers->loadFromQuestion(); // the ID would be found via $this->question->getID() instead of from the argument passed in while($answer = $answers->getAnswer()) { echo $answer->showFormatted(); } I guess my problem is, I don't know when or if I should be passing in an entire object, and when I should just be passing in a value. Passing in the entire object gives me a lot of flexibility, but it's more memory and subject to change, I'd guess (like a property or method rename). If "A" style is better, why not just use a function? OOP seems pointless here. Thanks, Hans

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  • From VB6 to .net via COM and Remoting...What a mess!

    - by Robert
    I have some legacy vb6 applications that need to talk to my .Net engine application. The engine provides an interface that can be connected to via .net Remoting. Now I have a stub class library that wraps all of the types that the interface exposes. The purpose of this stub is to translate my .net types into COM-friendly types. When I run this class library as a console application, it is able to connect to the engine, call various methods, and successfully return the wrapped types. The next step in the chain is to allow my VB6 application to call this COM enabled stub. This works fine for my main engine-entry type (IModelFetcher which is wrapped as COM_ModelFetcher). However, when I try and get any of the model fetcher's model types (IClientModel, wrapped as COM_IClientModel, IUserModel, wrapped as COM_IUserModel, e.t.c.), I get the following exception: [Exception - type: System.InvalidCastException 'Return argument has an invalid type.'] in mscorlib at System.Runtime.Remoting.Proxies.RealProxy.ValidateReturnArg(Object arg, Type paramType) at System.Runtime.Remoting.Proxies.RealProxy.PropagateOutParameters(IMessage msg, Object[] outArgs, Object returnValue) at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) at AWT.Common.AWTEngineInterface.IModelFetcher.get_ClientModel() at AWT.Common.AWTEngineCOMInterface.COM_ModelFetcher.GetClientModel() The first thing I did when I saw this was to handle the 'AppDomain.CurrentDomain.AssemblyResolve' event, and this allowed me to load the required assemblies. However, I'm still getting this exception now. My AssemblyResolve event handler is loading three assemblies correctly, and I can confirm that it does not get called prior to this exception. Can someone help me untie myself from this mess of interprocess communication?!

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  • Simple perl program failing to execute

    - by yves Baumes
    Here is a sample that fails: #!/usr/bin/perl -w # client.pl #---------------- use strict; use Socket; # initialize host and port my $host = shift || 'localhost'; my $port = shift || 55555; my $server = "10.126.142.22"; # create the socket, connect to the port socket(SOCKET,PF_INET,SOCK_STREAM,(getprotobyname('tcp'))[2]) or die "Can't create a socket $!\n"; connect( SOCKET, pack( 'Sn4x8', AF_INET, $port, $server )) or die "Can't connect to port $port! \n"; my $line; while ($line = <SOCKET>) { print "$line\n"; } close SOCKET or die "close: $!"; with the error: Argument "10.126.142.22" isn't numeric in pack at D:\send.pl line 16. Can't connect to port 55555! I am using this version of Perl: This is perl, v5.10.1 built for MSWin32-x86-multi-thread (with 2 registered patches, see perl -V for more detail) Copyright 1987-2009, Larry Wall Binary build 1006 [291086] provided by ActiveState http://www.ActiveState.com Built Aug 24 2009 13:48:26 Perl may be copied only under the terms of either the Artistic License or the GNU General Public License, which may be found in the Perl 5 source kit. Complete documentation for Perl, including FAQ lists, should be found on this system using "man perl" or "perldoc perl". If you have access to the Internet, point your browser at http://www.perl.org/, the Perl Home Page. While I am running the netcat command on the server side. Telnet does work.

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  • Rest WebService error handling.

    - by Pratik
    Hi there, I am using RestWebservice for few basic operations , like creating/searching. The request xml looks something like this <customer> <name/> ..... </customer> For a successful operation I return the same customer XML with extra fields populated in it(eg. systemId etc which we blank in the request) . with Response.Status=2000 For an unsuccessful operation i return something like this with different error codes . e.g Response.Status = 422(Unprocessable entity) Response.Status= 500(Internal Server Error) and few others.. <errors> <error> An exception occurred while creating the customer</error> <error> blah argument is not valid.</error> </errors> Now i am not sure , whether this is the correct way of sending the errors to the client. Maybe it should be present in the header of the response. I will really appreciate any help. Thanks!

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  • PythonMagickWand Shepards Distortion (ctypes LP_c_double problem)

    - by betamax
    I am trying to use PythonMagickWand to use a Shepards distortion on an image. You can also see the source of distort.c that is used by ImageMagick. I have the following code (snippet): from PythonMagickWand import * arrayType = c_double * 8 pointsNew = arrayType() pointsNew[0] = c_double(eyeLeft[0]) pointsNew[1] = c_double(eyeLeft[1]) pointsNew[2] = c_double(eyeLeftDest[0]) pointsNew[3] = c_double(eyeLeftDest[1]) pointsNew[4] = c_double(eyeRight[0]) pointsNew[5] = c_double(eyeRight[1]) pointsNew[6] = c_double(eyeRightDest[0]) pointsNew[7] = c_double(eyeRightDest[1]) MagickWandGenesis() wand = NewMagickWand() MagickReadImage(wand,path_to_image+'image_mod.jpg') MagickDistortImage(wand,ShepardsDistortion, 8, pointsNew, False) MagickWriteImage(wand,path_to_image+'image_mod22.jpg') I get the following error: MagickDistortImage(wand,ShepardsDistortion, 8, pointsNew, False) ctypes.ArgumentError: argument 4: <type 'exceptions.TypeError'>: expected LP_c_double instance instead of list I am aware that pointsNew is the wrong way of providing the arguments.. But I just don't know what is the right format. This is an example distort command that works when run in Terminal: convert image.jpg -virtual-pixel Black -distort Shepards 121.523809524,317.79638009 141,275 346.158730159,312.628959276 319,275 239.365079365,421.14479638 232,376 158.349206349,483.153846154 165,455 313.015873016,483.153846154 300,455 0,0 0,0 0,571.0 0,571.0 464.0,571.0 464.0,571.0 0,571.0 0,571.0 image_out.jpg So I guess the question is: How do I create a list of c_doubles that will be accepted by PythonMagickWand? I basically need to re-create the terminal command. I have got it working by using subprocess to run the command from Python but that is not how I want to do it.

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