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• getting CS1502 compiler error on dev environment but not production.

  - by nw

  When I try to run my ASP.NET app from my development environment I get the following error message: Compiler Error Message: CS1502: The best overloaded method match for 'mmars.Printing.printFunctions.SetPrintSummaryProperties(mmars.contextInfo, ref mmars.Printing.printObjSummary)' has some invalid arguments. When I publish and run on our production server I don't get this error. It seems to compile fine when I build from the build menu (in fact if I change the second argument of the bolded function call below, i get a compiler error in visual studio), but now i've suddenly started getting this error message at runtime. So another question I have in addition to getting rid of the error is why is the .NET development server even trying to do JIT compilation on my project if it is already compiled into a DLL? Printing.printObjSummary myPrintObj = new Printing.printObjSummary(); Printing.printFunctions.SetPrintSummaryProperties(ci, ref myPrintObj); printObjects.Add(myPrintObj); This seems to have just suddenly appeared from nowhere today and it's extremely frustrating. Also, though there are no warnings at compile-time, when I get redirected to the page with that first compilation error there are many warnings like the following: Warning: CS0436: The type 'mmars.MMARSSummaryDataItem' in 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3dad423c\40569048\App_Code.b0rgpkzr.4.cs' conflicts with the imported type 'mmars.MMARSSummaryDataItem' in 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3dad423c\40569048\assembly\dl3\7179c19a\345f948c_ece7ca01\mmars.DLL'. Using the type defined in 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3dad423c\40569048\App_Code.b0rgpkzr.4.cs'. What's the deal with that? Is the webserver complaining about name conflicts in the source file and dll resulting from the source file?

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• Function with parameter type that has a copy-constructor with non-const ref chosen?

  - by Johannes Schaub - litb

  Some time ago I was confused by the following behavior of some code when I wanted to write a is_callable<F, Args...> trait. Overload resolution won't call functions accepting arguments by non-const ref, right? Why doesn't it reject in the following because the constructor wants a Test&? I expected it to take f(int)! struct Test { Test() { } // I want Test not be copyable from rvalues! Test(Test&) { } // But it's convertible to int operator int() { return 0; } }; void f(int) { } void f(Test) { } struct WorksFine { }; struct Slurper { Slurper(WorksFine&) { } }; struct Eater { Eater(WorksFine) { } }; void g(Slurper) { } void g(Eater) { } // chooses this, as expected int main() { // Error, why? f(Test()); // But this works, why? g(WorksFine()); } Error message is m.cpp: In function 'int main()': m.cpp:33:11: error: no matching function for call to 'Test::Test(Test)' m.cpp:5:3: note: candidates are: Test::Test(Test&) m.cpp:2:3: note: Test::Test() m.cpp:33:11: error: initializing argument 1 of 'void f(Test)' Can you please explain why one works but the other doesn't?

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• Using Mergesort to calculate number of inversions in C++

  - by Brown

  void MergeSort(int A[], int n, int B[], int C[]) { if(n > 1) { Copy(A,0,floor(n/2),B,0,floor(n/2)); Copy(A,floor(n/2),n-1,C,0,floor(n/2)-1); MergeSort(B,floor(n/2),B,C); MergeSort(C,floor(n/2),B,C); Merge(A,B,0,floor(n/2),C,0,floor(n/2)-1); } }; void Copy(int A[], int startIndexA, int endIndexA, int B[], int startIndexB, int endIndexB) { while(startIndexA < endIndexA && startIndexB < endIndexB) { B[startIndexB]=A[startIndexA]; startIndexA++; startIndexB++; } }; void Merge(int A[], int B[],int leftp, int rightp, int C[], int leftq, int rightq) //Here each sub array (B and C) have both left and right indices variables (B is an array with p elements and C is an element with q elements) { int i=0; int j=0; int k=0; while(i < rightp && j < rightq) { if(B[i] <=C[j]) { A[k]=B[i]; i++; } else { A[k]=C[j]; j++; inversions+=(rightp-leftp); //when placing an element from the right array, the number of inversions is the number of elements still in the left sub array. } k++; } if(i=rightp) Copy(A,k,rightp+rightq,C,j,rightq); else Copy(A,k,rightp+rightq,B,i,rightp); } I am specifically confused on the effect of the second 'B' and 'C' arguments in the MergeSort calls. I need them in there so I have access to them for Copy and and Merge, but

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• Drupal module permissions

  - by Trevor Newhook

  When I run the code with an admin user, the module returns what it should. However, when I run it with a normal user, I get a 403 error. The module returns data from an AJAX call. I've already tried adding a 'access callback' = 'user_access'); line to the exoticlang_chat_logger_menu() function. I'd appreciate any pointers you might have. Thanks for the help The AJAX call: jQuery.ajax({ type: 'POST', url: '/chatlog', success: exoticlangAjaxCompleted, data:'messageLog=' + privateMessageLogJson, dataType: 'json' }); The module code: function exoticlang_chat_logger_init(){ drupal_add_js('misc/jquery.form.js'); drupal_add_library('system', 'drupal.ajax'); } function exoticlang_chat_logger_permission() { return array( 'Save chat data' => array( 'title' => t('Save ExoticLang Chat Data'), 'description' => t('Send private message on chat close') ), ); } /** * Implementation of hook_menu(). */ function exoticlang_chat_logger_menu() { $items = array(); $items['chatlog'] = array( 'type' => MENU_CALLBACK, 'page callback' => 'exoticlang_chat_log_ajax', 'access arguments' => 'Save chat data'); //'access callback' => 'user_access'); return $items; } function exoticlang_chat_logger_ajax(){ $messageLog=stripslashes($_POST['messageLog']); $chatLog= 'Drupal has processed this. Message log is: '.$messageLog; $chatLog=str_replace('":"{[{','":[{',$chatLog); $chatLog=str_replace(',,',',',$chatLog); $chatLog=str_replace('"}"','"}',$chatLog); $chatLog=str_replace('"}]}"','"}]',$chatLog); echo json_encode(array('messageLog' => $chatLog)); // echo $chatLog; echo print_r(privatemsg_new_thread(array(user_load(1)), 'The subject', 'The body text')); drupal_exit(); }

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• Enum "copy" problem

  - by f0b0s

  Hi all! I have a class, let's call it A. It has a enum (E) and a method Foo(E e), with gets E in the arguments. I want to write a wrapper (decorator) W for A. So it'll have its own method Foo(A::E). But I want to have some kind of encapsulation, so this method should defined as Foo(F f), where F is another enum defined in W, that can be converted to A::E. For example: class A { public: enum E { ONE, TWO, THREE }; void Foo(E e); }; class B { //enum F; // ??? void Foo(F f) { a_.Foo(f); } private: A a_; }; How F should be defined? I don't want to copy value like this: enum F { ONE = A::ONE, TWO = A::TWO, THREE = A::THREE }; because its a potential error in the near feature. Is the typedef definition: typedef A::E F; is the best decision? Is it legal?

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• problm with MANIFEST.MF in jar

  - by Atul

  hi I have created jar in the following folder: /usr/local/bin/niidle.jar. And my MANIFEST.MF file is as follows: Manifest-Version: 1.0 Main-Class: com.ensarm.niidle.web.scraper.NiidleScrapeManager Class-Path: hector-0.6.0-17.jar And I verified that,this 'hector-0.6.0-17.jar' file is also present in the folder: /Projects/EnwelibDatedOct13/Niidle/lib/hector-0.6.0-17.jar I don't want to give full class-path name in MANIFEST.MF file,because I have to run this jar on other's machine,so I gave only jar file name 'Class-Path=hector-0.6.0-17.jar' in MANIFEST.MF file. Inspite of mentioning the Class-Path in MANIFEST.MF file, when I run this using command: java -jar /usr/local/bin/niidle.jar arguments... It is showing error massage: --Exception in thread "main" java.lang.NoClassDefFoundError: me/prettyprint/hector/api/Serializer at com.ensarm.niidle.web.scraper.NiidleScrapeManager.main(NiidleScrapeManager.java:21) Caused by: java.lang.ClassNotFoundException: me.prettyprint.hector.api.Serializer at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) ... 1 more Please give me solution for this error message..

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• Python CGI Premature end of script error depending on script parameters.

  - by nickengland

  I have a python script which should parse a file and produce some output to disk, as well as returning a webpage linking to the outputted files. When run with a file posted from the HTML form I get no HTML output back, just a 500 error page and the error_log contains the line: [Mon Apr 19 15:03:23 2010] [error] [client xxx.xxx.121.79] Premature end of script headers: uploadcml.py, referer: http://xxx.ch.cam.ac.uk:9000/ However, the files which the script should be saving are indeed saved to disk. If I run it without any arguments, the script returns the correct HTML indicating no file was parsed. All the information I have found on the web about Premature end of script headers implies it is due to either a missing header, or lack of permissions on the python script but neither can apply to me. The first lines of the script are: #!/home/nwe23/bin/bin/python import cgitb; cgitb.enable() import cgi import pybel,openbabel import random print "Content-Type: text/html" print so when run, I can see no way for it to fail to output the header, and it DOES output the header when run without a file to parse, but when given a file produces the error(but still parsed the file and saves the output to disk!). Does anyone know how this is happening and what can be done to fix it? I have tried adding wrongly-indented gibberish (such as foobar) at various points in the file, and this results in adding an indent error to the error_log wherever it is, even if its the very last line in the script. The Premature script headers error remains though. Does this mean the script is executing all the way through?

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• What are the skills a Drupal Developer needs?

  - by hfidgen

  I'm trying to write out a list of key Drupal competencies, mainly so I can confirm what I know, don't know and don't know I don't know. (Thanks D. Rumsfeld for that quote!) I think some of these are really broad, for instance there's quite a difference between making a functional theme and creating a theme with good SEO, load times and so on, but I'm hoping you could assume that a half decent web developer would look after that anyway. Just interested to see what people here feel is also important. Able to install Drupal on a server (pretty obvious). Able to research and install modules to meet project requirements Able to configure all the basic modules and core settings to get a site running Able to create a custom Theme from scratch which validates with good HTML/CSS and also pays attention to usability and accessibility. (Whilst still looking kick-ass). Able to use Hooks in the theme template.php to alter forms, page layout and other core functionality Can make forms from scratch using the API - with validation and posting back to the DB/email Can use Views to create blocks or pages, use php snippets as arguments, etc. Can create custom modules from scratch utilising core hooks and other hooks.

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• Any merit to a lazy-ish juxt function?

  - by NielsK

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

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• How do I run NUnit in debug mode from Visual Studio?

  - by Jon Cage

  I've recently been building a test framework for a bit of C# I've been working on. I have NUnit set up and a new project within my workspace to test the component. All works well if I load up my unit tests from Nunit (v2.4), but I've got to the point where it would be really useful to run in debug mode and set some break points. I've tried the suggestions from several guides which all suggest changing the 'Debug' properties of the test project: Start external program: C:\Program Files\NUnit 2.4.8\bin\nunit-console.exe Command line arguments: /assembly: <full-path-to-solution>\TestDSP\bin\Debug\TestDSP.dll I'm using the console version there, but have tried the calling the GUI as well. Both give me the same error when I try and start debugging: Cannot start test project 'TestDSP' because the project does not contain any tests. Is this because I normally load \DSP.nunit into the Nunit GUI and that's where the tests are held? I'm beginning to think the problem may be that VS wants to run it's own test framework and that's why it's failing to find the NUnit tests? [Edit] To those asking about test fixtures, one of my .cs files in the TestDSP project looks roughly like this: namespace Some.TestNamespace { // Testing framework includes using NUnit.Framework; [TestFixture] public class FirFilterTest { /// <summary> /// Tests that a FirFilter can be created /// </summary> [Test] public void Test01_ConstructorTest() { ...some tests... } } } ...I'm pretty new to C# and the Nunit test framework so it's entirely possible I've missed some crucial bit of information ;-) [FINAL SOLUTION] The big problem was the project I'd used. If you pick: Other Languages->Visual C#->Test->Test Project ...when you're choosing the project type, Visual Studio will try and use it's own testing framework as far as I can tell. You should pick a normal c# class library project instead and then the instructions in my selected answer will work.

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• javamail api isertion of main class help

  - by bobby

  import javax.servlet.*; import javax.servlet.http.*; import java.io.*; import javax.mail.*; import javax.mail.internet.*; import javax.mail.event.*; import javax.mail.Authenticator; import java.net.*; import java.util.*; public class servletmail extends HttpServlet { public void doPost(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException { PrintWriter out=response.getWriter(); response.setContentType("text/html"); try { Properties props=new Properties(); props.put("mail.transport.protocol", "smtp"); props.put("mail.smtp.host","smtp.googlemail.com"); props.put("mail.smtp.port", "995"); props.put("mail.smtp.auth", "true"); javax.mail.Authenticator authenticator = new javax.mail.Authenticator() { protected javax.mail.PasswordAuthentication getPasswordAuthentication() { return new javax.mail.PasswordAuthentication("[email protected]", "password"); } }; Session sess=Session.getDefaultInstance(props,authenticator); sess.setDebug (true); Transport transport =sess.getTransport ("smtp"); Message msg=new MimeMessage(sess); msg.setFrom(new InternetAddress("[email protected]")); msg.addRecipient(Message.RecipientType.TO, new InternetAddress("[email protected]")); msg.setSubject("Hello JavaMail"); msg.setText("Welcome to JavaMail"); transport.connect(); transport.send(msg); out.println("mail has been sent"); } catch(Exception e) { System.out.println("err"+e); } } } how to insert main class in above java code and how to pass arguments of "from" and "to"

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• handle large Parcelable ArrayList in Android

  - by Gal Ben-Haim

  I'm developing an Android app that is a client to a JSON webservice API. I have classes of resource objects (some are nested) and I pass results from an IntentService that access the webserive using the Parcelable interface for all the resource classes. the webservice returns arrays or results that can be potentially large (because of the nesting, for example, a post object also contains comments array, each comment also contains a user object). currently I'm either inserting the results into a SQlite database or displaying them in a ListView. (my relevant methods are accepting ArrayList<resourceClass> as arguments). (some data need to be persistent stored and some should not). since I don't know what size of lists I can handle this way without reaching the memory limits, is this a good practice ? is it a better idea to save the parsed JSON to a local file immediately and pass the file path to the ResultReceiver, then either insert to database from that file or display the data ? is there a better way to handle this ? btw - I'm parsing the JSON as a stream with Gson's Reader so there shouldn't be memory issues at that stage.

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• How to do buffered intersection checks on an IPoint?

  - by Quigrim

  How would I buffer an IPoint to do an intersection check using IRelationalOperator? I have, for arguments sake: IPoint p1 = xxx; IPoint p2 = yyy; IRelationalOperator rel1 = (IRelationalOperator)p1; if (rel.Intersects (p2)) // Do something But now I want to add a tolerance to my check, so I assume the right way to do that is by either buffering p1 or p2. Right? How do I add such a buffer? Note: the Intersects method I am using is an extension method I wrote to simplify my code. Here it is: /// <summary> /// Returns true if the IGeometry is intersected. /// This method negates the Disjoint method. /// </summary> /// <param name="relOp">The rel op.</param> /// <param name="other">The other.</param> /// <returns></returns> public static bool Intersects ( this IRelationalOperator relOp, IGeometry other) { return (!relOp.Disjoint (other)); }

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• URL protocol handler shell execute problem

  - by Chuck

  Hi, I'm working on a small hobby web site where I'm able to launch a local app with certain arguments based on links. Setting up a protocol wasn't difficult, as described in http://msdn.microsoft.com/en-us/library/aa767914(VS.85).aspx, but I have one dilemma: Let's say the protocol is: foo:127.0.0.1:1111, so a link like href="foo:127.0.0.1:1111" would launch an app like: bar.exe "%1". Since I don't have any control over bar.exe (if I had, then it would be no problem to just parse it, obviously), I need some help parsing %1. bar.exe will launch correctly if it's run as bar.exe 127.0.0.1:1111, but not if it's run as bar.exe foo:127.0.0.1:1111. So I guess my question is... is there ANY way to tell the registry to pass on not %1, but a trimmed %1? (Thinking in terms of regexp where you have match[0] = all of the matched, match[1] = first capture in the matched text). I can solve it by having a .bat instead of .exe, but as I would like to make it as easy as possible for the user to use, I would LOVE it if I could handle it all stricly in registry. Any help is greatly appreciated! Chuck

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• Python and the self parameter

  - by Svend

  I'm having some issues with the self parameter, and some seemingly inconsistent behavior in Python is annoying me, so I figure I better ask some people in the know. I have a class, Foo. This class will have a bunch of methods, m1, through mN. For some of these, I will use a standard definition, like in the case of m1 below. But for others, it's more convinient to just assign the method name directly, like I've done with m2 and m3. import os def myfun(x, y): return x + y class Foo(): def m1(self, y, z): return y + z + 42 m2 = os.access m3 = myfun f = Foo() print f.m1(1, 2) print f.m2("/", os.R_OK) print f.m3(3, 4) Now, I know that os.access does not take a self parameter (seemingly). And it still has no issues with this type of assignment. However, I cannot do the same for my own modules (imagine myfun defined off in mymodule.myfun). Running the above code yields the following output: 3 True Traceback (most recent call last): File "foo.py", line 16, in <module> print f.m3(3, 4) TypeError: myfun() takes exactly 2 arguments (3 given) The problem is that, due to the framework I work in, I cannot avoid having a class Foo at least. But I'd like to avoid having my mymodule stuff in a dummy class. In order to do this, I need to do something ala def m3(self,a1, a2): return mymodule.myfun(a1,a2) Which is hugely redundant when you have like 20 of them. So, the question is, either how do I do this in a totally different and obviously much smarter way, or how can I make my own modules behave like the built-in ones, so it does not complain about receiving 1 argument too many.

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• Usage Rails 3.0 beta 3 without ActiveRecord ORM

  - by Anton

  Hi everybody! Just installed Rails 3.0 beta 3 in Windows 7. And started playing with some easy examples class SignupController < ApplicationController def index @user = User.new(params[:user]) if method.post? and @user.save redirect_to :root end end end class User def initialize(params = {}) @email = params[:email] @passw = params[:password] end def save end end <div align="center"> <% form_for :user do |form| %> <%= form.label :email %> <%= form.text_field :email %><br /> <%= form.label :password %> <%= form.text_field :password %><br /> <%= form.submit :Register! %> <% end %> </div> When I go to /signup I'm getting this error ArgumentError in SignupController#index wrong number of arguments(0 for 1) Is there a problem with constructor or what's wrong?Please, need your help!

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• std::conditional compile-time branch evaluation

  - by cmannett85

  Compiling this: template < class T, class Y, class ...Args > struct isSame { static constexpr bool value = std::conditional< sizeof...( Args ), typename std::conditional< std::is_same< T, Y >::value, isSame< Y, Args... >, // Error! std::false_type >::type, std::is_same< T, Y > >::type::value; }; int main() { qDebug() << isSame< double, int >::value; return EXIT_SUCCESS; } Gives me this compiler error: error: wrong number of template arguments (1, should be 2 or more) The issue is that isSame< double, int > has an empty Args parameter pack, so isSame< Y, Args... > effectively becomes isSame< Y > which does not match the signature. But my question is: Why is that branch being evaluated at all? sizeof...( Args ) is false, so the inner std:conditional should not be evaluated. This isn't a runtime piece of code, the compiler knows that sizeof..( Args ) will never be true with the given template types. If you're curious, it's supposed to be a variadic version of std::is_same, not that it works...

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• How to get SimpleRpcClient.Call() to be a blocking call to achieve synchronous communication with RabbitMQ?

  - by Nick Josevski

  In the .NET version (2.4.1) of RabbitMQ the RabbitMQ.Client.MessagePatterns.SimpleRpcClient has a Call() method with these signatures: public virtual object[] Call(params object[] args); public virtual byte[] Call(byte[] body); public virtual byte[] Call(IBasicProperties requestProperties, byte[] body, out IBasicProperties replyProperties); The problem: With various attempts, the method still continues to not block where I expect it to, so it's unable ever handle the response. The Question: Am I missing something obvious in the setup of the SimpleRpcClient, or earlier with the IModel, IConnection, or even PublicationAddress? More Info: I've also tried various paramater configurations of the QueueDeclare() method too with no luck. string QueueDeclare(string queue, bool durable, bool exclusive, bool autoDelete, IDictionary arguments); Some more reference code of my setup of these: IConnection conn = new ConnectionFactory{Address = "127.0.0.1"}.CreateConnection()); using (IModel ch = conn.CreateModel()) { var client = new SimpleRpcClient(ch, queueName); var queueName = ch.QueueDeclare("t.qid", true, true, true, null); ch.QueueBind(queueName, "exch", "", null); //HERE: does not block? var replyMessageBytes = client.Call(prop, msgToSend, out replyProp); } Looking elsewhere: Or is it likely there's an issue in my "server side" code? With and without the use of BasicAck() it appears the client has already continued execution.

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• Is C++ (one of) the best language to learn at first

  - by AlexV

  C++ is one of the most used programming language in the world since like 25+ years. My first job as programmer was in C++ and I coded in C++ everyday for nearly 4 years. Now I do mostly PHP, but I will forever cherish this C++ background. C++ has helped me understand many "under the hood" features/behaviors/restrictions of many other (and different) programming languages like PHP and Delphi. I'm a full time programmer for 6+ years now and since I have a quite varied programming background I often get questions by "newbies" as where to start to become a "good" programmer. I think C++ is one of the best language to start with because it gives you a real usefull experience that will last and will teach you how things work under the hood. It's not the easier one to learn for a newbie, but in my opinion it's one that will reward in the long term. I would like to know your opinion on this matter to add to my arguments when I guide "newbies". After this introduction, here's my question : Is C++ (one of) the best language to learn at first for you. Since it's subjective, I've marked this question as community wiki. EDIT: This question is not about why Java (or C# or any other language) is better than C++ to start with, it's about what's make C++ a good choice or not a good choice to learn as one of your firsts languages. For example, for me C++ made me understand how the memory works. Now today in many languages everything is managed by the garbadge collector and some people don't even know that. I'm glad I know how it works underneath and I think it can help you to write better code.

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• How to write a flexible modular program with good interaction possibilities between modules?

  - by PeterK

  I went through answers on similar topics here on SO but could't find a satisfying answer. Since i know this is a rather large topic, i will try to be more specific. I want to write a program which processes files. The processing is nontrivial, so the best way is to split different phases into standalone modules which then would be used as necessary (since sometimes i will be only interested in the output of module A, sometimes i would need output of five other modules, etc). The thing is, that i need the modules to cooperate, because the output of one might be the input of another. And i need it to be FAST. Moreover i want to avoid doing certain processing more than once (if module A creates some data which then need to be processed by module B and C, i don't want to run module A twice to create the input for modules B,C ). The information the modules need to share would mostly be blocks of binary data and/or offsets into the processed files. The task of the main program would be quite simple - just parse arguments, run required modules (and perhaps give some output, or should this be the task of the modules?). I don't need the modules to be loaded at runtime. It's perfectly fine to have libs with a .h file and recompile the program every time there is a new module or some module is updated. The idea of modules is here mainly because of code readability, maintaining and to be able to have more people working on different modules without the need to have some predefined interface or whatever (on the other hand, some "guidelines" on how to write the modules would be probably required, i know that). We can assume that the file processing is a read-only operation, the original file is not changed. Could someone point me in a good direction on how to do this in C++ ? Any advice is wellcome (links, tutorials, pdf books...).

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• Does "epsilon" really guarantees anything in floating-point computations?!

  - by Michal Czardybon

  To make the problem short let's say I want to compute expression: a / (b - c) on float's. To make sure the result is meaningful, I can check if 'b' and 'c' are inequal: float eps = std::numeric_limits<float>::epsilon(); if ((b - c) > EPS || (c - b) > EPS) { return a / (b - c); } but my tests show it is not enough to guarantee either meaningful results nor not failing to provide a result if it is possible. Case 1: a = 1.0f; b = 0.00000003f; c = 0.00000002f; Result: The if condition is NOT met, but the expression would produce a correct result 100000008 (as for the floats' precision). Case 2: a = 1e33f; b = 0.000003; c = 0.000002; Result: The if condition is met, but the expression produces not a meaningful result +1.#INF00. I found it much more reliable to check the result, not the arguments: const float INF = numeric_limits<float>::infinity(); float x = a / (b - c); if (-INF < x && x < INF) { return x; } But what for is the epsilon then and why is everyone saying epsilon is good to use?

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• Boost's "cstdint" Usage

  - by patt0h

  Boost's C99 stdint implementation is awfully handy. One thing bugs me, though. They dump all of their typedefs into the boost namespace. This leaves me with three choices when using this facility: Use "using namespace boost" Use "using boost::[u]<type><width>_t" Explicitly refer to the target type with the boost:: prefix; e.g., boost::uint32_t foo = 0; Option ? 1 kind of defeats the point of namespaces. Even if used within local scope (e.g., within a function), things like function arguments still have to be prefixed like option ? 3. Option ? 2 is better, but there are a bunch of these types, so it can get noisy. Option ? 3 adds an extreme level of noise; the boost:: prefix is often = to the length of the type in question. My question is: What would be the most elegant way to bring all of these types into the global namespace? Should I just write a wrapper around boost/cstdint.hpp that utilizes option ? 2 and be done with it? Also, wrapping the header like so didn't work on VC++ 10 (problems with standard library headers): namespace Foo { #include <boost/cstdint.hpp> using namespace boost; } using namespace Foo; Even if it did work, I guess it would cause ambiguity problems with the ::boost namespace.

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• How to run OpenGL code with out compiling?

  - by Ole Jak

  So I have some openGL code (such code for example) /* FUNCTION: YCamera :: CalculateWorldCoordinates ARGUMENTS: x mouse x coordinate y mouse y coordinate vec where to store coordinates RETURN: n/a DESCRIPTION: Convert mouse coordinates into world coordinates */ void YCamera :: CalculateWorldCoordinates(float x, float y, YVector3 *vec) { // START GLint viewport[4]; GLdouble mvmatrix[16], projmatrix[16]; GLint real_y; GLdouble mx, my, mz; glGetIntegerv(GL_VIEWPORT, viewport); glGetDoublev(GL_MODELVIEW_MATRIX, mvmatrix); glGetDoublev(GL_PROJECTION_MATRIX, projmatrix); real_y = viewport[3] - (GLint) y - 1; // viewport[3] is height of window in pixels gluUnProject((GLdouble) x, (GLdouble) real_y, 1.0, mvmatrix, projmatrix, viewport, &mx, &my, &mz); /* 'mouse' is the point where mouse projection reaches FAR_PLANE. World coordinates is intersection of line(camera->mouse) with plane(z=0) (see LaMothe 306) Equation of line in 3D: (x-x0)/a = (y-y0)/b = (z-z0)/c Intersection of line with plane: z = 0 x-x0 = a(z-z0)/c <=> x = x0+a(0-z0)/c <=> x = x0 -a*z0/c y = y0 - b*z0/c */ double lx = fPosition.x - mx; double ly = fPosition.y - my; double lz = fPosition.z - mz; double sum = lx*lx + ly*ly + lz*lz; double normal = sqrt(sum); double z0_c = fPosition.z / (lz/normal); vec->x = (float) (fPosition.x - (lx/normal)*z0_c); vec->y = (float) (fPosition.y - (ly/normal)*z0_c); vec->z = 0.0f; } I want to run It but with out precompiling. Is there any way to do such thing

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• ASP.NET MVC Viewmodel trouble...

  - by ile

  I've already started similar topic, but still didn't find final solution... So here I am with new one :) ... I'm developing NerdDinner from scratch and now I came to point where I define DinnerViewModel. Following these instructions (starting from Listing 5) I came to this: namespace Nerd.Controllers { // View Model Classes public class DinnerViewModel { public DinnerViewModel(List<Dinner> dinners) { this.Dinners = dinners; } public List<Dinner> Dinners { get; private set; } } public class DinnerController : Controller { private DinnerRepository dinnerRepository = new DinnerRepository(); .... public ActionResult NewDinners() { // Create list of products var dinners = new List<Dinner>(); dinners.Add(new Dinner(/*Something to add*/)); // Return view return View(new DinnerViewModel(dinners)); } } } Also, the Dinner table in this new version of NerdDinner is a bit shortened (it contains of DinnerID, Title, EventDate and Description fields). No matter what I try to add here dinners.Add(new Dinner(/*Something to add*/)); I always get following error Error 1 'Nerd.Model.Dinner' does not contain a constructor that takes '1' arguments C:\Documents and Settings\ilija\My Documents\Visual Studio 2008\Projects\Nerd\Nerd\Controllers\DinnerController.cs 150 25 Nerd Because I'm total beginner in C# and generally OOP, I have no idea what to do here... I suppose I need to declare a constructor, but how and where exactly? Thanks, Ile

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• Does C# allow method overloading, PHP style (__call)?

  - by mr.b

  In PHP, there is a special method named __call($calledMethodName, $arguments), which allows class to catch calls to non-existing methods, and do something about it. Since most of classic languages are strongly typed, compiler won't allow calling a method that does not exist, I'm clear with that part. What I want to accomplish (and I figured this is how I would do it in PHP, but C# is something else) is to proxy calls to a class methods and log each of these calls. Right now, I have code similar to this: class ProxyClass { static logger; public AnotherClass inner { get; private set; } public ProxyClass() { inner = new AnotherClass(); } } class AnotherClass { public void A() {} public void B() {} public void C() {} // ... } // meanwhile, in happyCodeLandia... ProxyClass pc = new ProxyClass(); pc.inner.A(); pc.inner.B(); // ... So, how can I proxy calls to an object instance in extensible way? Extensible, meaning that I don't have to modify ProxyClass whenever AnotherClass changes. In my case, AnotherClass can have any number of methods, so it wouldn't be appropriate to overload or wrap all methods to add logging. I am aware that this might not be the best approach for this kind of problem, so if anyone has idea what approach to use, shoot. Thanks!

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