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• How to reconcile my support of open-source software and need to feed and house myself?

  - by Guzba

  I have a bit of a dilemma and wanted to get some other developers' opinions on it and maybe some guidance. So I have created a 2D game for Android from the ground up, learning and re factoring as I went along. I did it for the experience, and have been proud of the results. I released it for free as ad supported with AdMob not really expecting much out of it, but curious to see what would happen. Its been a few of months now since release, and it has become very popular (250k downloads!). Additionally, the ad revenue is great and is driving me to make more good games and even allowing me to work less so that I can focus on my own works. When I originally began working on the game, I was pretty new to concurrency and completely new to Android (had Java experience though). The standard advice I got for starting an Android game was to look at the sample games from Google (Snake, Lunar Lander, ...) so I did. In my opinion, these Android sample games from Google are decent to see in general what your code should look like, but not actually all that great to follow. This is because some of their features don't work (saving game state), the concurrency is both unexplained and cumbersome (there is no real separation between the game thread and the UI thread since they sync lock each other out all the time and the UI thread runs game thread code). This made it difficult for me as a newbie to concurrency to understand how it was organized and what was really running what code. Here is my dilemma: After spending this past few months slowly improving my code, I feel that it could be very beneficial to developers who are in the same position that I was in when I started. (Since it is not a complex game, but clearly coded in my opinion.) I want to open up the source so that others can learn from it but don't want to lose my ad revenue stream, which, if I did open the source, I fear I would when people released versions with the ad stripped, or minor tweaks that would fragment my audience, etc. I am a CS undergrad major in college and this money is giving me the freedom to work less at summer job, thus giving me the time and will to work on more of my own projects and improving my own skills while still paying the bills. So what do I do? Open the source at personal sacrifice for the greater good, or keep it closed and be a sort of hypocritical supporter of open source?

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• ODBC: when is the best time to create my database?

  - by mawg

  I have a windows program which generates PGP forms which will be filled in later. Those PHP forms will populate a database. It looks very much like MySql, but I can't be certain, so let's call it ODBC. And, yes, it does have to be a windows program. There will also be PHP forms which query the database - examine which tables and fields it contains and then generates forms which can be used to search the database (e.g, it finds a table with fields "employee_name", etc and generates a form which lets you search based on employee name. Let's call that design time and run time. At design time, some manager or IT guy or similar gets to define the nature of the database and at runtime 1) a worker fills in the form daily and 2) management can extract reports. Here's my question: given that the database is defined at "design time" (and populated at run time), where and how is best to do so? 1 I could use an ODBC interface from the windows program, but I am having difficulty finding something good to work with Delphi. Things like ADO and firebird tend to expect you to already have a database and allow you to manipulate it, but I can find no code example of how to create a database and some tables, so ... 2 I could used DOS commands from Delphi in my windows program. I just tried and got a response to MySql --version, but am not sure if MySql etc are more interactive. That is, can I use a script file or a very long stacked command with semicolons and returns separating? e.g 'CREATE DATABASE db; CREATE TABLE t1;' 3) Since the best way to work with databases seems to be PHP, perhaps my windows program could spit out a PHP page which would, when run in a browser, create the database. I have tried to make this as uncomplicated as I can, but please feel free to ask questions. It may be that there are several valid ways, but there is probably one 'better' solution in terms of ease of implementation or maintenance. Better scratch option 3. What if the user later wants to come back and have the windows program change the input form? It needs to update the database too.

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• Planning to create PDF files in Ruby on Rails

  - by deau

  Hi there, A Ruby on Rails app will have access to a number of images and fonts. The images are components of a visual layout which will be stored separately as a set of rules. The rules specify document dimensions along with which images are used and where. The app needs to take these rules, fetch the images, and generate a PDF that is ready for local printing or emailing. The fonts will also be important. The user needs to customize the layout by inputting text which will be included in the PDF. The PDF must therefore also contain the desired font so that the document renders identically across different machines. Each PDF may have many pages. Each page may have different dimensions but this is not essential. Either way, the ability to manipulate the dimensions and margins given by the PDF is essential. The only thing that needs to be regularly changed is the text. If this is takes too much development then the app can store the layouts in 3rd party PDFs and edit the textual content directly. Eventually though, this will prove too restrictive on the apps intended functionality so I would prefer the app to generate the PDF's itself. I have never worked with PDFs before and, for the most part, I've never had to output anything to the user outside their monitor. A printed medium could require a very different approach to get the best results. If anyone has any advice on how to model the PDF format this it would be really appreciated. The technical aspects of printing such as bleed, resolution and colour have already been factored in to the layouts and images. I am aware that PDF is a proprietary file format and I want to use free or open source software. I have seen a number of Ruby libraries for generating PDF files but because I am new on this scene I have no way to reliably compare them and too little time to implement and test them all. I also have the option of using C to handle this feature and if this is process intensive then that might be preferred. What should I be thinking about and how should I be planning to implement this?

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• MySQL Query to find consecutive available times of variable lenth

  - by Armaconn

  I have an events table that has user_id, date ('2013-10-01'), time ('04:15:00'), and status_id; What I am looking to find is a solution similar to http://stackoverflow.com/questions/2665574/find-consecutive-rows-calculate-duration but I need I need two additional components: 1) Take date into consideration, so 10/1/2013 at 11:00 PM - 10/2/2013 at 3:00AM. Feel free to just put in a fake date range (like '2013-10-01' to '2013-10-31') 2) Limit output to only include when there are 4+ consecutive times (each event is 15 minutes and I want it to display minimum blocks of an hour, but would also like to be able to switch this restriction to 1.5 hours or some other duration if possible). SUMMARY - Looking for a query that provides the start and end times for a set of events that have the same user_id, status_id, and are in a continuous series based on date and time. For which I can restrict results based on date range and minimum series duration. So the output should have: user_id, date_start, time_start, date_end, time_end, status_id, duration CREATE TABLE `events` ( `event_id` int(11) NOT NULL auto_increment COMMENT 'ID', `user_id` int(11) NOT NULL, `date` date NOT NULL, `time` time NOT NULL, `status_id` int(11) default NULL, PRIMARY KEY (`event_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=1568 ; INSERT INTO `events` VALUES(1, 101, '2013-08-14', '23:00:00', 2); INSERT INTO `events` VALUES(2, 101, '2013-08-14', '23:15:00', 2); INSERT INTO `events` VALUES(3, 101, '2013-08-14', '23:30:00', 2); INSERT INTO `events` VALUES(4, 101, '2013-08-14', '23:45:00', 2); INSERT INTO `events` VALUES(5, 101, '2013-08-15', '00:00:00', 2); INSERT INTO `events` VALUES(6, 101, '2013-08-15', '00:15:00', 1); INSERT INTO `events` VALUES(7, 500, '2013-08-14', '23:45:00', 1); INSERT INTO `events` VALUES(8, 500, '2013-08-15', '00:00:00', 1); INSERT INTO `events` VALUES(9, 500, '2013-08-15', '00:15:00', 2); INSERT INTO `events` VALUES(10, 500, '2013-08-15', '00:30:00', 2); INSERT INTO `events` VALUES(11, 500, '2013-08-15', '00:45:00', 1); Desired output row |user_id | date_start | time_start | date_end | time_end | status_id | duration 1 |101 |'2013-08-14'| '23:00:00' |'2013-08-15'|'00:15:00'| 2 | 5 2 |101 |'2013-08-15'| '00:00:15' |'2013-08-15'|'00:30:00'| 1 | 1 3 |500 |'2013-08-14'| '00:23:45' |'2013-08-15'|'00:15:00'| 1 | 2 4 |500 |'2013-08-15'| '00:00:15' |'2013-08-15'|'00:45:00'| 2 | 2 5 |500 |'2013-08-15'| '00:00:45' |'2013-08-15'|'01:00:00'| 2 | 1 *except that rows 2 and 5 wouldn't appear if duration had to be greater than 30 minutes Thanks for any help that you can provide! And please let me know if there is anything I can further clarify!!

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• No more memory available in Mathematica, Fit the parameters of system of differential equation

  - by user1058051

  I encountered a memory problem in Mathematica, when I tried to process my experimental data. It's a system of two differential equations and I need to find most suitable parameters. Unfortunately I am not a Pro in Mathematica, so the program used a lot of memory, when the parameter epsilon is more than 0.4. When it less than 0.4, the program work properly. The command 'historylength = 0' and attempts to reduce the Accuracy Goal and WorkingPrecision didn`t help. I can't use ' clear Cache ', because there isnt a circle. I'm trying to understand what mistakes I made, and how I may limit the memory usage. I have already bought extra-RAM, now its 4GB, and now I haven't free memory-slots in motherboard Remove["Global`*"]; T=13200; L = 0.085; e = 0.41; v = 0.000557197; q = 0.1618; C0 = 0.0256; R = 0.00075; data = {{L,600,0.141124587},{L,1200,0.254134509},{L,1800,0.342888644}, {L,2400,0.424476295},{L,3600,0.562844542},{L,4800,0.657111356}, {L,6000,0.75137817},{L,7200,0.815876516},{L,8430,0.879823594}, {L,9000,0.900771775},{L,13200,1}}; model[(De_)?NumberQ, (Kf_)?NumberQ, (Y_)?NumberQ] := model[De, Kf, Y] = yeld /.Last[Last[ NDSolve[{ v (Ci^(1,0))[z,t]+(Ci^(0,1))[z,t]== -((3 (1-e) Kf (Ci[z,t]-C0))/ (R e (1-(R Kf (1-R/r[z,t]))/De))), (r^(0,1))[z,t]== (R^2 Kf (Ci[z,t]-C0))/ (q r[z,t]^2 (1-(R Kf (1-R/r[z,t]))/De)), (yeld^(0,1))[z,t]== Y*(v e Ci[z,t])/(L q (1-e)), r[z,0]==R, Ci[z,0]==0, Ci[0,t]==0, yeld[z,0]==0}, {r[z,t],Ci[z,t],yeld},{z,0,L},{t,0,T}]]] fit = FindFit[data, {model[De, Kf, Y][z, t], {Y > 0.97, Y < 1.03, Kf > 10^-6, Kf < 10^-4, De > 10^-13, De < 10^-9}}, {{De,7*10^-13}, {Kf, 10^-5}, {Y, 1}}, {z, t}, Method -> NMinimize] data = {{600,0.141124587},{1200,0.254134509},{1800,0.342888644}, {2400,0.424476295},{3600,0.562844542},{4800,0.657111356}, {6000,0.75137817},{7200,0.815876516},{8430,0.879823594}, {9000,0.900771775},{13200,1}}; YYY = model[ De /. fit[[1]], Kf /. fit[[2]], Y /. fit[[3]]]; Show[Plot[Evaluate[YYY[L,t]],{t,0,T},PlotRange->All], ListPlot[data,PlotStyle->Directive[PointSize[Medium],Red]]] the link on the .nb file http://www.4shared.com/folder/249TSjlz/_online.html

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• Undefined template methods trick ?

  - by Matthieu M.

  A colleague of mine told me about a little piece of design he has used with his team that sent my mind boiling. It's a kind of traits class that they can specialize in an extremely decoupled way. I've had a hard time understanding how it could possibly work, and I am still unsure of the idea I have, so I thought I would ask for help here. We are talking g++ here, specifically the versions 3.4.2 and 4.3.2 (it seems to work with both). The idea is quite simple: 1- Define the interface // interface.h template <class T> struct Interface { void foo(); // the method is not implemented, it could not work if it was }; // // I do not think it is necessary // but they prefer free-standing methods with templates // because of the automatic argument deduction // template <class T> void foo(Interface<T>& interface) { interface.foo(); } 2- Define a class, and in the source file specialize the interface for this class (defining its methods) // special.h class Special {}; // special.cpp #include "interface.h" #include "special.h" // // Note that this specialization is not visible outside of this translation unit // template <> struct Interface<Special> { void foo() { std::cout << "Special" << std::endl; } }; 3- To use, it's simple too: // main.cpp #include "interface.h" class Special; // yes, it only costs a forward declaration // which helps much in term of dependencies int main(int argc, char* argv[]) { Interface<Special> special; foo(special); return 0; }; It's an undefined symbol if no translation unit defined a specialization of Interface for Special. Now, I would have thought this would require the export keyword, which to my knowledge has never been implemented in g++ (and only implemented once in a C++ compiler, with its authors advising anyone not to, given the time and effort it took them). I suspect it's got something to do with the linker resolving the templates methods... Do you have ever met anything like this before ? Does it conform to the standard or do you think it's a fortunate coincidence it works ? I must admit I am quite puzzled by the construct...

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• Realtime MySQL search results on an advanced search page

  - by Andrew Heath

  I'm a hobbyist, and started learning PHP last September solely to build a hobby website that I had always wished and dreamed another more competent person might make. I enjoy programming, but I have little free time and enjoy a wide range of other interests and activities. I feel learning PHP alone can probably allow me to create 98% of the desired features for my site, but that last 2% is awfully appealing: The most powerful tool of the site is an advanced search page that picks through a 1000+ record game scenario database. Users can data-mine to tremendous depths - this advanced page has upwards of 50 different potential variables. It's designed to allow the hardcore user to search on almost any possible combination of data in our database and it works well. Those who aren't interested in wading through the sea of options may use the Basic Search, which is comprised of the most popular parts of the Advanced search. Because the advanced search is so comprehensive, and because the database is rather small (less than 1,200 potential hits maximum), with each variable you choose to include the likelihood of getting any qualifying results at all drops dramatically. In my fantasy land where I can wield AJAX as if it were Excalibur, my users would have a realtime Total Results counter in the corner of their screen as they used this page, which would automatically update its query structure and report how many results will be displayed with the addition of each variable. In this way it would be effortless to know just how many variables are enough, and when you've gone and added one that zeroes out the results set. A somewhat similar implementation, at least visually, would be the Subtotal sidebar when building a new custom computer on IBuyPower.com For those of you actually still reading this, my question is really rather simple: Given the time & ability constraints outlined above, would I be able to learn just enough AJAX (or whatever) needed to pull this one feature off without too much trouble? would I be able to more or less drop-in a pre-written code snippet and tweak to fit? or should I consider opening my code up to a trusted & capable individual in the future for this implementation? (assuming I can find one...) Thank you.

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• Finding good heuristic for A* search

  - by Martin

  I'm trying to find the optimal solution for a little puzzle game called Twiddle (an applet with the game can be found here). The game has a 3x3 matrix with the number from 1 to 9. The goal is to bring the numbers in the correct order using the minimum amount of moves. In each move you can rotate a 2x2 square either clockwise or counterclockwise. I.e. if you have this state 6 3 9 8 7 5 1 2 4 and you rotate the upper left 2x2 square clockwise you get 8 6 9 7 3 5 1 2 4 I'm using a A* search to find the optimal solution. My f() is simply the number of rotations need. My heuristic function already leads to the optimal solution but I don't think it's the best one you can find. My current heuristic takes each corner, looks at the number at the corner and calculates the manhatten distance to the position this number will have in the solved state (which gives me the number of rotation needed to bring the number to this postion) and sums all these values. I.e. You take the above example: 6 3 9 8 7 5 1 2 4 and this end state 1 2 3 4 5 6 7 8 9 then the heuristic does the following 6 is currently at index 0 and should by at index 5: 3 rotations needed 9 is currently at index 2 and should by at index 8: 2 rotations needed 1 is currently at index 6 and should by at index 0: 2 rotations needed 4 is currently at index 8 and should by at index 3: 3 rotations needed h = 3 + 2 + 2 + 3 = 10 But there is the problem, that you rotate 4 elements at once. So there a rare cases where you can do two (ore more) of theses estimated rotations in one move. This means theses heuristic overestimates the distance to the solution. My current workaround is, to simply excluded one of the corners from the calculation which solves this problem at least for my test-cases. I've done no research if really solves the problem or if this heuristic still overestimates in same edge-cases. So my question is: What is the best heuristic you can come up with? (Disclaimer: This is for a university project, so this is a bit of homework. But I'm free to use any resource if can come up with, so it's okay to ask you guys. Also I will credit Stackoverflow for helping me ;) )

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• Threadpool with pasistant worker instances

  - by Matt Smokey-waters Holmes

  So basically what im trying to do is queue up tasks in a thread pool to be executed as soon as a worker becomes free, i have found various examples of this but in all cases the examples have been setup to use a new Worker instance for each job, i want persistent workers. Im trying to make a ftp backup tool, i have it working but because of the limitations of a single connection it is slow. What i ideally want to do is have a single connection for scanning directories and building up a file list then four workers to download said files. Here is an example of my worker /** * FTP Worker */ public class Worker implements Runnable { protected FTPClient _ftp; // Connection details protected String _host = ""; protected String _user = ""; protected String _pass = ""; // worker status protected boolean _working = false; public Worker(String host, String user, String pass) { this._host = host; this._user = user; this._pass = pass; } // Check if the worker is in use public boolean inUse() { return this._working; } @Override public void run() { this._ftp = new FTPClient(); this._connect(); } // Download a file from the ftp server public boolean download(String base, String path, String file) { this._working = true; boolean outcome = true; //create directory if not exists File pathDir = new File(base + path); if (!pathDir.exists()) { pathDir.mkdirs(); } //download file try { OutputStream output = new FileOutputStream(base + path + file); this._ftp.retrieveFile(file, output); output.close(); } catch (Exception e) { outcome = false; } finally { this._working = false; return outcome; } } // Connect to the server protected boolean _connect() { try { this._ftp.connect(this._host); this._ftp.login(this._user, this._pass); } catch (Exception e) { return false; } return this._ftp.isConnected(); } // Disconnect from the server protected void _disconnect() { try { this._ftp.disconnect(); } catch (Exception e) { /* do nothing */ } } } and basically i want to be able to call Worker.download(...) for each task in a queue whenever a worker becomes available without having to create a new connection to the ftp server for each download Any help would be appreciated as iv'e never used threads before and I'm going round in circles at the moment

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• Learning C, would appreciate input on why this solution works.

  - by Keifer

  This is literally the first thing I've ever written in C, so please feel free to point out all it's flaws. :) My issue, however is this: if I write the program the way I feel is cleanest, I get a broken program: #include <sys/queue.h> #include <stdlib.h> #include <stdio.h> #include <string.h> /* Removed prototypes and non related code for brevity */ int main() { char *cmd = NULL; unsigned int acct = 0; int amount = 0; int done = 0; while (done==0) { scanf ("%s %u %i", cmd, &acct, &amount); if (strcmp (cmd, "exit") == 0) done = 1; else if ((strcmp (cmd, "dep") == 0) || (strcmp (cmd, "deb") == 0)) debit (acct, amount); else if ((strcmp (cmd, "wd") == 0) || (strcmp (cmd, "cred") == 0)) credit (acct, amount); else if (strcmp (cmd, "fee") == 0) service_fee(acct, amount); else printf("Invalid input!\n"); } return(0); } void credit(unsigned int acct, int amount) { } void debit(unsigned int acct, int amount) { } void service_fee(unsigned int acct, int amount) { } As it stands, the above generates no errors at compile, but gives me a segfault when ran. I can fix this by changing the program to pass cmd by reference when calling scanf and strcmp. The segfault goes away and is replaced by warnings for each use of strcmp at compile time. Despite the warnings, the affected code works. warning: passing arg 1 of 'strcmp' from incompatible pointer type As an added bonus, modifying the scanf and strcmp calls allows the program to progress far enough to execute return(0), at which point the thing crashes with an Abort trap. If I swap out return(0) for exit(0) then everything works as expected. This leaves me with two questions: why was the original program wrong? How can I fix it better than I have? The bit about needing to use exit instead of return has me especially baffled.

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• Why is .NET Post different from CURL? broken?

  - by ironnailpiercethesky

  I dont understand this. I ran this code below and the result json string was the link is expired (meaning invalid). However the curl code does the exact same thing and works. I either get the expected string with the url or it says i need to wait (for a few seconds to 1 minute). Why? whats the difference between the two? It looks very F%^&*ed up that it is behaving differently (its been causing me HOURS of problems). NOTE: the only cookie required by the site is SID (tested). It holds your session id. The first post activates it and the 2nd command checks the status with the returning json string. Feel free to set the CookieContainer to only use SID if you like. WARNING: you may want to change SID to a different value so other people arent activating it. Your may want to run the 2nd url to ensure the session id is not used and says expired/invalid before you start. additional note: with curl or in your browser if you do the POST command you can stick the sid in .NET cookie container and the 2nd command will work. But doing the first command (the POST data) will not work. This post function i have used for many other sites that require post and so far it has worked. Obviously checking the Method is a big deal and i see it is indeed POST when doing the first command. static void Main(string[] args) { var cookie = new CookieContainer(); PostData("http://uploading.com/files/get/37e36ed8/", "action=second_page&file_id=9134949&code=37e36ed8", cookie); Thread.Sleep(4000); var res = PostData("http://uploading.com/files/get/?JsHttpRequest=12719362769080-xml&action=get_link&file_id=9134949&code=37e36ed8&pass=undefined", null/*this makes it GET*/, cookie); Console.WriteLine(res); /* curl -b "SID=37468830" -A "DUMMY_User_Aggent" -d "action=second_page&file_id=9134949&code=37e36ed8" "http://uploading.com/files/get/37e36ed8/" curl -b "SID=37468830" -A "DUMMY_User_Aggent" "http://uploading.com/files/get/?JsHttpRequest=12719362769080-xml&action=get_link&file_id=9134949&code=37e36ed8&pass=undefined" */ }

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• Confusion over C++ new operator and classes

  - by Nils

  Hi all I created a simple class in C++ which has a private dynamic array. In the constructor I initialize the array using new and in the destructor I free it using delete. When I instantiate the class using Class a = Class(..); it works as expected, however it seems I cannot instantiate it using the new operator (Like Class *a = new Class(..);), I always get a segmentation fault. What I don't understand is when I should use new to instantiate a class and when just call the constructor or should it be possible to instantiate a class either with new or by just calling the constructor. float** A = new float*[3]; for (int i=0; i<3; i++) { A[i] = new float[3]; } A[0][0] = 3; A[0][1] = 3; A[0][2] = 4; A[1][0] = 5; A[1][1] = 6; A[1][2] = 7; A[2][0] = 1; A[2][1] = 2; A[2][2] = 3; Matrix *M = new Matrix(A, 3, 3); delete[] A; delete M; Below the class definition.. class Matrix { private: int width; int height; int stride; float* elements; public: Matrix(float** a, int n, int m); ~Matrix(); }; Matrix::Matrix(float** a, int n, int m) { // n: num rows // m: elem per rows elements = new float[n*m]; for (int i=0; i<n; i++) { for (int j=0; j<m; j++) { elements[i*n + j] = a[n][m]; } } } Matrix::~Matrix() { delete[] elements; }

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• Browsers (IE and Firefox) freeze when copying large amount of text

  - by Matt

  I have a web application - a Java servlet - that delivers data to users in the form of a text printout in a browser (text marked up with HTML in order to display in the browser as we want it to). The text does display in different colors, though most of it is black. One typical mode of operation is this: 1. User submits a form to request data. 2. Servlet delivers HTML file to browser. 3. User does CTRL+A to select all the text. 4. User does CTRL+C to copy all the text. 5. User goes to a text editor and does CTRL+V to paste the text. In the testing where I'm having this problem, step #2 successfully loads all the data - we wait for that to complete. We can scroll down to the end of what the browser loaded and see the end of the data. However, the browser freezes on step #3 (Firefox) or on step #4 (IE). Because step #2 finishes, I think it is a browser/memory issue, and not an issue with the web application. If I run queries to deliver smaller amounts of data (but after several queries we get the same data we would have above in one query) and copy/paste this text, the file I save it into ends up being about 8 MB. If I save the browser's displayed HTML to a file on my computer via File-Save As from the browser menu, it works fine and the file is about 22 MB. We've tried this on 2 different computers at work (both running Windows XP, with at least 2 GB of RAM and many GB of free disk space), using Firefox and IE. We also tried it on a home computer from a home network outside of work (thinking it might be our IT security software causing the problem), running Windows 7 using IE, and still had the problem. When I've done this, I can see whatever browser I'm using utilizing the CPU at 50%. Firefox's memory usage grows to about 1 GB; IE's stays in the several hundred MBs. We once let this run for half an hour, and it did not complete. I'm most likely going to modify the web app to have an option of delivering a plain text file for download, and I imagine that will get the users what they need. But for the mean time, and because I'm curious - and I don't like my application freezing people's browsers, does anyone have any ideas about the browser freezing? I understand that sometimes you just reach your memory limit, but 22 MB sounds to me like an amount I should be able to copy to the clipboard.

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• Best way to ask confirmation from user before leaving the page

  - by JohnathanKong

  Hey Everyone, I am currently building a registration page where if the user leaves, I want to pop up a CSS box asking him if he is sure or not. I can accomplish this feat using confirm boxes, but the client says that they are too ugly. I've tried using unload and beforeunload, but both cannot stop the page from being redirected. Using those to events, I return false, so maybe there's a way to cancel other than returning false? Another solution that I've had was redirecting them to another page that has my popup, but the problem with that is that if they do want to leave the page, and it wasn't a mistake, they lose the page they were originally trying to go to. If I was a user, that would irritate me. The last solution was real popup window. The only thing I don't like about that is that the main winow will have their destination page while the pop will have my page. In my opinion it looks disjoint. On top of that, I'd be worried about popup blockers. Just to add to everyones comments. I understand that it is irritating to prevent users from exiting the page, and in my opinion it should not be done. Right now I am using a confirm box at this point. What happens is that it's not actually "preventing" the user from leaving, what the client actually wants to do is make a suggestion if the user is having doubts about registering. If the user is halfway through the registraiton process and leaves for some reason, the client wants to offer the user a free coupon to a seminar (this client is selling seminars) to hopefully persuade the user to register. The client is under the impression that since the user is already on the form, he is thinking of registering, and therefore maybe a seminar of what he is registering for would be the final push to get the user to register. Ideally I don't have to prevent the user from leaving, what would be just as good, and in my opinion better is if I can pause the unload process. Maybe a sleep command? I don't really have to keep the user on the page because either way they will be leaving to go to a different page. Also, as people have stated, this is a terriable title, so if someone knows a better one, I'd really appreciate it if they could change the title to something no so spammer inviting.

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• C#: Object having two constructors: how to limit which properties are set together?

  - by Dr. Zim

  Say you have a Price object that accepts either an (int quantity, decimal price) or a string containing "4/$3.99". Is there a way to limit which properties can be set together? Feel free to correct me in my logic below. The Test: A and B are equal to each other, but the C example should not be allowed. Thus the question How to enforce that all three parameters are not invoked as in the C example? AdPrice A = new AdPrice { priceText = "4/$3.99"}; // Valid AdPrice B = new AdPrice { qty = 4, price = 3.99m}; // Valid AdPrice C = new AdPrice { qty = 4, priceText = "2/$1.99", price = 3.99m};// Not The class: public class AdPrice { private int _qty; private decimal _price; private string _priceText; The constructors: public AdPrice () : this( qty: 0, price: 0.0m) {} // Default Constructor public AdPrice (int qty = 0, decimal price = 0.0m) { // Numbers only this.qty = qty; this.price = price; } public AdPrice (string priceText = "0/$0.00") { // String only this.priceText = priceText; } The Methods: private void SetPriceValues() { var matches = Regex.Match(_priceText, @"^\s?((?<qty>\d+)\s?/)?\s?[$]?\s?(?<price>[0-9]?\.?[0-9]?[0-9]?)"); if( matches.Success) { if (!Decimal.TryParse(matches.Groups["price"].Value, out this._price)) this._price = 0.0m; if (!Int32.TryParse(matches.Groups["qty"].Value, out this._qty)) this._qty = (this._price > 0 ? 1 : 0); else if (this._price > 0 && this._qty == 0) this._qty = 1; } } private void SetPriceString() { this._priceText = (this._qty > 1 ? this._qty.ToString() + '/' : "") + String.Format("{0:C}",this.price); } The Accessors: public int qty { get { return this._qty; } set { this._qty = value; this.SetPriceString(); } } public decimal price { get { return this._price; } set { this._price = value; this.SetPriceString(); } } public string priceText { get { return this._priceText; } set { this._priceText = value; this.SetPriceValues(); } } }

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• How to ensure structures are completly initialized (by name) in GCC?

  - by Steven Spark

  How do I ensure each and every field of my structures are initialized in GCC when using designated initializers? (I'm especially interested in function pointers.) (I'm using C not C++.) Here is an example: typedef struct { int a; int b; } foo_t; typedef struct { void (*Start)(void); void (*Stop)(void); } bar_t; foo_t fooo = { 5 }; foo_t food = { .b=4 }; bar_t baro = { NULL }; bar_t bard = { .Start = NULL }; -Wmissing-field-initializers does not help at all. It works for fooo only in GCC (mingw 4.7.3, 4.8.1), and clang does only marginally better (no warnings for food and bard). I'm sure there is a reason for not producing warnings for designated initializer (even when I explicitly ask for them) but I want/need them. I do not want to initialize structures based on order/position because that is more error prone (for example swapping Start and Stop won't even give any warning). And neither gcc nor clang will give any warning that I failed to explicitly initialize a field (when initializing by name). I also don't want to litter my code with if(x.y==NULL) lines for multiple reasons, one of which is I want compile time warnings and not runtime errors. At least splint will give me warnings on all 4 cases, but unfortunately I cannot use splint all the time (it chokes on some of the code (fails to parse some C99, GCC extensions)). Note: If I'm using a real function instead of NULL GCC will also show a warning for baro (but not bard). I searched google and stack overflow but only found related questions and have not found answer for this specific problem. The best match I have found is 'Ensure that all elements in a structure are initialized' Ensure that all elements in a structure are initialized Which asks pretty much the same question, but has no satisfying answer. Is there a better way dealing with this that I have not mentioned? (Maybe other code analysis tool? Preferably something (free) that can be integrated into Eclipse or Visual Studio...)

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• Fastest way to copy a set (100+) of related SQLAlchemy objects and change attribute on each one

  - by rebus

  I am developing an app that keeps track of items going in and out of factory. For example, lets say you have 3 kinds of plastic coming in, they are mixed in various ratios and then sent out as a new product. So to keep track of this I've created following database structure: This is very simplified overview of my SQLAlchemy models: IN <- RATIO <- OUT <- REPORT ITEMS -> REPORT IN are products coming in, RATIO is various information on measurements, and OUT is a final product. REPORT is basically a header model which has a lot of REPORT ITEMS attached to it, which in turn relate it to OUT products. This would all work perfectly, but IN and RATION values can change. These changes ultimately change the OUT product which would mean the REPORT values would change. So in order to change an attribute on IN object for example I should copy that object with that attribute changed. I would think this is basically a question about database normalization, because i didn't want to duplicate all the IN, RATIO and OUT information by writing it in REPORT ITEMS table for example, but I've came across this problem (well not really a problem but rather a feature I'd like for a user to have). When the attribute on IN object is changed I want related objects (RATIO and OUT) automatically copied and related to a new IN object. So I was thinking something like: Take an existing instance of model IN that needs to change (call it old_in) Create a new one out of it with some attributes changed (call it new_in) Collect all the RATIO objects that are related to old_in Copy each RATIO and relate them to a new_in Collect all the OUT objects that are related to old RATIO Copy each OUT and relate them to a new RATIO Few questions pop to mind when i look at this problem: Should i just duplicate the data, does all this copying even make sense? If it does, should i rather do it in plain SQL? If no what would be the best approach to do it with Python and SQLAlchemy? Any general answer would suffice really, at least a pointer in right direction. I really want to free then end user for hassle of having create new ratios and out products.

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• Advice needed: stay with Java team or move to C++ team?

  - by user68759

  Some background - I have been programming in Java as a professional for the last few years. This is mainly using Java SE. I have also touched bits and pieces of other various Java technologies and have some basic knowledge about them. I consider my self as an intermediate Java programmer. I like Java very much. I think it is only going to get bigger. Recently, my manager asked my opinion on whether I would like to be transferred to another team within the company that is developing a product in C++. This is mainly because my current Java team simply didn't make enough money due to poor sales and the economic downturn. Now, I have never had any experience with C++ nor have I ever coded a single line of code in C++. I have always wanted to learn it and now is my chance. But I really want to make sure I get benefit out of it in the future, in the sense that I will have the skills that will still be on-demand in the future. So, what do you experts think? Is C++ still the language to learn these days to secure yourself for the future? What will I learn more in C++ but not in Java? And are they worthy to learn considering the current and possible future demands in IT industry? (Apart from the obvious more control over memory management and something along that line.) What is a good excuse to refuse the offer in order to stay with the Java team? I don't want to blatantly refuse it because you can never predict the future and I could possibly come back to my manager in the future and ask him to transfer me to the C++ team. How do I say it nicely that I am taking the offer but I would like to still be involved with Java one way or another, such as when there is a new Java project I would like to be considered. I have to admit that I am kind of 50-50 at the moment. I want to learn C++ for the sake of improving my skills and also helping my company to reduce the fund required for the Java team. But it is also hard for me to leave Java because I know Java is going to get bigger, so I am afraid of getting behind when I start concentrating on C++. I could, of course, decide to just join the C++ team, and then spend my free time reading about Java to keep in touch with it, but I thought I would ask anyway in case some people can point out the strong points of either over the other given the current and possibly future circumstances.

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• What kind of string is this? What can I do in php to read it?

  - by kevin

  This is a string (see below, after the dashed line) in a database.inf file for a free program I downloaded that lists some websites. The file is plain text as you can see , but there is a string after it that looks base64 encoded (due to the end chars of ==). But b64_decoding it gives giberish. I wanted to decode it so I could add to the list of sites it had (the program lists a bunch of sites and data about them which I can read in the GUI) and to do that I need to decode this, add to it, and re-encode it. I think the program uses .net since I think the .net library was required on install, but I know nothing of the original source language. I am using php to figure out if there is a simple way to read this. I have tried using unpack, binhex, base_convert, etc as I suspect the file is binary at some level, but I am lost. Nothing illegal, just wanting to know what it is and if I can add a few things to it to make it more useful for me. here is the file - any ideas how to decode and recode this for playing with? Site List file size: 62139 db version: 13 generated: 2010-04-27 11:53:40 eJztPWmT27iVnze/gjVVk56pXXXz1BW3XW2PPXaNr/iIa69SUSIkMaZIhaQstys/fgHwEIiDBEjQk6Q2lUraeuAD8PDwbgAPtkl6eBoZsX8At1enDKRXRvGfL350gj/9uEmBn4MVAqFGP14Z+f0R3FoP//CA+Rb9ddXj26OfZYJ+EeicpEHrt/5V/2/XA75FDTjzlf7WvlL/NgWXnlW/BQc/jPjzxaAfMUzU7+Xr7m+pj7cVZ/C63pa8Iewa/e+299fbMM3yuv8+fa8wCs5Cy/W9EmwLztfU51Eb2SKZoUe9v458gmq9+l4hFDyiS/W9Ei0Z52tO5/W8+VQ3aGwipvcjIRGUMPmnfN8XE40qCFKABSaFpgQg2ggGARtwB9D55SbM77lfIkCxGIIvsxw2460jBrRxwbfwyJdVEFB2eSERTaTstP4r2OQsG+RhHoEfL7+XOGy6d9yObKaKwE/zJo4eCFYNDD0QhJsIXHD0RHAZRV8EzF6WRQCXkU/ECnDBIUSwB37A8oEsgg3kuF2S3rOCtASwCNq1H4ECCYVCuTT4mRlDUwH2QNDUgT1HcFGDfUewIobQjaBVGdIYkMqoV0I8h2gIgqZK7DmCi1bsOYKVcB25CFp1I38djAY6wXqeokg8Enk8qEWSXg0eT4GHGFFPPMk5BmkHn8rgaVoOA+ZVStCaTgPoo2U8eBzD6bNdHUHci38Ycwi14Xk2F0C7aCpZh3Vv1BAQQ1BFUDDdAATk9PsjuBiW/WjQGIUqglPamACBAJpBH9+9JIwFsbkE27GaXhoBXkZiHKoIzmCdhTnH9VBEsKrHoIoAfd0gZB8i8pexAnQpGMhBySndsIKmAnDsJc6GXocJX1RBQJfJViwkgaEfAmIMqgjI0fcbwTo55cINLYOg0BsXPL1GQGrnnkQMQA65hvRWxQgoDAHINlxbBQHS8JiHSUz6nswQiHZXvRCUVGzi4SNpV98NDCoIstPh4BPeR8scWkdA4FFEkOVJo38JBBSGz+AehSWzKwZDBekwe8s5EHj6IVhdMHQioN3AJM5BnHPWocQtsSFXTSTqCPAc1klAhWLUEAyaAmpGzKIfghx87UuDQqYMQFBFNGoMiggu1JcmImP5VpGD8BKW4AcV2udQtV2FZCqAiwCOIQeHYwSBxotfbq/uChTGL362Xyd+GhhRsgtjOzutD2EOO7g+7o9XD//wbw+yI9iEfrRCmB5KffbgpvENxLGN/F328O/P/axo//e7U54U3/z9wU0Bhc0wDNk+D2+4aC/wS+MMpA+DZHM6QIa83oH8aQTQn9nj+9eQVj9BYtd5qZ//2/zfa0ymGhX6usaFsicduOrMC4sLf13j2oZxmO0f3tQzwCKYnEbZAlEYt0HzsvkfkA1g+xTswiyH/gKmVBbu4tOxaNiAXDAXQrpjanW08jI149b4oQzU/fCn/4H/6cRQKRkKB6knJDHhbUahqTaYJApob9IYahNUEgVUDjSKWl/88Kd6ZUoCXygeJDEoludwX466sZQ1nPokSpLPcKtb9UZ7f9psoEeGgi33xtsELm7QRFJ/ATGVDnXRcfmPolsSQjQkMTx8C2IDTb3Z510QoC65X5C8KMVjDSeTomsjlSizPGU+Uhc6ztYmEdWpVbmh6cS2paQXiahIHMlgiVqwRNJYSmpbAkRVGkkGVZHd4eNBCR4ZHDgrxUeB81IyOIr8FB9JkaJCO51mdCTpUSx2s/fjHXhom+Z8YjoT2zKsxdKyl5YHBT3R4A8PbioF/JBWxjdhHICvaKc+Ovo7cIsVBKt8uc10KFs+Xo62rTb+R6g3jZdkM0IkSCpm1GBV8qQ1TC8Tm43GxNfK9YRZZUz+u54VnKrx5pQ3W5NzbqhwipwNjc4o88s/rRrhc5AC4z45GRs/NooGRgzORmUVkEgsrjTmLWsFHGImNPOBPS0FKqJNK3l++FcebRaHxyPIh9kgNTK+QXOxRGRsAGohDlBCwv+XNwb+E9os1eIbe7iv1wBUjNFqEHB+t5vYwqwDj82RdLOJucCSbrq05kvPVJB0aGdf413EdzCoBkLpdhdFydl4/uHVS0LQ8aUbjbGPF1FERAc7EBLuA7Gzy6FDnXpN2JCPHjW2PyN9ur/hOBH4o+Kn1EdbBH8FZc4BHNYgvX0Nzv/+Cv85RHoMkhp15EZsj3du6ktUlyd0UERSWjIUGMpIyCe4w5Pzdf0Zcl6uwzgGKeJQUmKgf0t0IuVHcUSPijlOKuAhpuUlJT3MuMTjoTdaH1ten+2t046vckOsJsF5me/FvRQSWQa+BO0xB19JWcRYT1gLw7KgObw05wp6ohhndiMyhRtwCRuYrxooLH00w8dLdGmgFfu224ptCPpq8NU63ARJp5ynvxkizT8MkebvdQSKnoXsACrDbRuKzDMVGfmRjR2S27+ua+8e61ttgqTC9CSJoZl8GI7wGTK2Xw9XBC/9VjSyeuCpBhXwOEx2qX/cs4b7RVRKSjBvYi8M21ma9tK25SXYVRs2c2nPl46CPCzDgR9SP4CG2iY5CEPzlya9pSL+86afOMQHSLTYydIh9uZwOzx56PxAD+oLgF4PEeSETXcgMKCHIOPiW1WU/qbdEuc04ojkWnxr8Mt1uOVaQvhknq93EL9RwTDYYJfwHzQY1MMVhS4L+G64YkBNH8uhURGmlr10vKXlKpiD5+OkLWhAgnWEDJr4+shB2EyDGDzLRQpsPGI/OEA5eEyyfAIdd4nMITnLR/4Gbe2WIGH970omvit/MJ4lqfFhH2bGe+jfEB+ywlNiE6HxDwsvHjZwowRhDt0cc5iXrsPBLhyYwVJByTlW3IzmdOk6CpuxULjGT2s/MPb5IfqZsyOZNv+61ohena9f4Uhzg2UhT92ZLW1LnhtevH/6y+vrJN2xTFCDdIjkgp6TykjhMwSRrwlj44/G+yJ3clfnTYYkq/TUkGC9KS3W6VkX/nsp6itgPOGVGAiqRZoI+WUjjAR/gpnKuIuNu80mOcU5j7bD5H5lXw6zO1uqRiQjr63WJoFjoG4gTkMNc7oPYRBEYAXdlRxuMArZ9wveQn/z6Mc07SXI3Vq9IV9OMLwQ4JgmX8J401UJ0IkG2i/MOqiVNRz3SUwPQ6KQwf/KlFN8h6i0DneFI117mkn6wvUbNVRKSnaG0qa2Sji8zfnR5flUYptE2Fdf+hqrLv0VZYAV9O7Umit5rVj9a2gVpZ8OrYxYZVC/5/i0wMAITL6KwvgzOgvUP+OUrvApT95oWK0qwPb4/kXw01WIwtXICUueQtfMuvp5UOp0oPLlcmdPiVNwp6geTkHgFIhsHYh0yGR/aKIRSo0NLiUYppb9lZSKUgrmm0vbWbrTVvkbhKkB0d9enc/na0j5z0kcQoZNY5DX8XckH/jgBzel7EBc9PCVn34GeRjvDD8OjAxEEfo7ieH/AeMc5nvDN7KDH0VGkhr75ACM9SmDsAxa1RgBRLRLkl0EHk6ga1b+CX/0I/DVx78Vf1Fh6n2eH5c3N/wh3hQG/Ko04K+Rl94azx6EzVYTpNXlHT3laHFiqVVicUQIyy7uxLQxu7hLh/WJIYswnOIf/G9o5RgeIQFN7rgrIcxau+xSW3PPnBGrrexHE4tIjuimqPMpolXXm+1hQJkUa9KPVy3VyPmozq0jVbRPwfb2Bzib2pCA3z7CLFjWdK7uk1NaQTO51JFokFQ/sjtRFgdr9IiQ1LYQxvD7pqSInI1Ffq9S80WWaykIA2VnXlMllQZfXOOxCP1VCxIGjqQu7yGci0Vfh99Y8dwAUQK6rJV9HH5jZPSUldGeNTOtVhlNSGaRaGgMh3Jo2tPOvbCoq2fUUhzEIoq4ZYodMTZhKEqlCLzExbWAiYsopBENEl8ljuFByQpRq0U+kkWTAT+FLaqAMbT3GhuHBTc3z3sMv0SJqf3jcWwcZ+bNZ90mLdszFd1W0aPKyBR3DK8uqvdJB26FlBJ3D6rdu2tVqTLFf+Eu9vNTyqfIqNxcWSXNQipKC+REDRVPERQ1VlK87E3nU132Oj24MjX6KABZfnvJPP7DJkqFxrrSxIYVeMkd4WodnFSKtxVDnf6lZ6jrYBZzrFL1aFaADoKE6xOK36zIm9V0H9ZqdKTjiAcPr86SturiiGFJxuoEXHk5T3e6UX3REOrVMfLZ6pN2Kfv/FW/aPBRvYs9wScV8abGH5HjqqQyKTzZJmvoRo59YcK2gdFzTgfVZGac3nuA+GCXnsErOtheeaxNaToeiBpUtVoRJGVJw4PppUZmtxhvciUyEbu5NvXkHLSxMCw+Ro5MWMUhqC5QgQfNn/TN/DZK76sSyRFjSsuYzT+OsCb2Zhpu9yFCrYKOtvPEO9iBDAddzGk6/RgJ8gYLGF1GgBo5Ggr+gHmTEgOWac1RHqJUGh/tS5q1PYcQz2XkN9NPi1b1RycXHRT9SFHHMhauTK2r/FP4CNijJsUuioEETcRP9VPml6uJX2IVRY6p+ldk39tS1zREo5KbgmIZxzqUNCRxRabjGu6IfhhAmJ2o4s217JBG69UOhr1vBxhOhz2APDAVsDis4c9ObjkOBLAY5SlqKqEDCR+SI10UvUrLDMq2FTkMCzTZOcnD0g+vySG1FhMvPIxgSBW6ZKU89+B9X85RPx9M6gq4+nNw2acy6AdE/8Y/G2wI/USLbLQ8905nqXvUqDRAleS4OehHg8WTB46ITGW6YzSxzoZkS2xSAKqA7CcAxYWs5+E30U+QZ7OeiMlE/MkRxp/OF9i2Shrt9dT8RQw8aqJ8S71APFSmkbG3L9izdiuLo536cQ1syO0VFRUulGr748JcGTTra6ifRW9whMkFRj/DPzHiBi29wgRXHS+eEomeOO7VnI6lXHG0SKtcaOp5qvUNdyFgZlu0ubO2CxY8i6BsgsxLE4JQijcJSg99mBJpE0VOioxdYvUlQZr5wF7oZBHyrHRJGAVMw/YR4+l+17m3xSni6Z+o4C61uCcrAX2++3dSapRrOxTkRNhlPHSu5apY7s2Y6iUKIiA2I2GgnBRuPDE9gDzI+GnRVLVMnBa7a+xN3ZZmoK9vDZ6ndpSMXXa62G9bpcXIWCmyywXgyGyv+18mZIT2nxtW25wvt7lCtn04b1vChgeOx33vUhYwKt73ZwtYdYSvn+dlPD8IoYw0cjQi/oR6kAkbuwprqjpOgaxn/dgIZMlKuT58pY68BG8O4KzuQmf5s6lnaI+1lOGxSRlJZH4CFj+AGFJ1UcVYZYixmnjOSResHX+AgTqlQLjQajCcb7qpuZMwW6BU5nnYNbU2SYx4ewm/FxZCku9MkTEvDEQhkTd4QvUlEnzuPTggLOFom1nr9Pldnu4YJdba5NNkLolv48VAdIamP2lP82GgwHj/WR1nkMkLWCOGKKvcHcpSXF6YGL+ARs4NFJ1J7E7rf2oMWdRKQVyxAA8cjw19C2UoBbzGf6SZCqZW2JxCBgKECAx2tYuIZ7kKKDObMm+q244LT4RCCbHcKA5Cz0QcWrJ8QH/bwu6If41fUkQwxFtO5N9ettML4S5iFaygW16xRSwP1E+JF1cOrx3cyNHBm5szVLSfzvZ9nh/s43OxZK4YGjsEMsAfj1b3xGvUhRQUbunj6qVBVCp2TNGLlAwc+zsaovv+EupGSElNvrt3TgdMtJeImSWNONojXYByCEIVmsWw9heNYuhkEneGr8htMiJIG6qcEvo2/23jl88fMHKligCkr4cBGsyd+ffPyF5mAtePazlglEwdo2SXHJAo5J3l5LUa0uOt+pIooZtPFQmuMskqKnsG6FAwsSTjwETKm754+NT6BdSU4pOgxm831kwO/5wGCyy1arIXBNhjDysC9iOsLeEkec6rf9IS+FhRcqJA6Cr9A37Ccdp3A4ASUuj8YI8JU9Wq8xN1KyF2e2IF62TV10/Ds7w9ihmKg+qnz6e75q4kSK808z/S66r77yl8/Pol92gt0zEgH6kMmLWTPp+58rMx6GGcoTSJMTxDwEQvXXhS9tGwUHl2mtjt3RmKQjTj0sxk57POEE/HhZSqcETRxHd3yo4M49FUC+RSQfEaOCnRBlHJli97CstpnPZ2YHn4TxFracolLZF9wdASdqhE3G06JZr2WyjaYtO8AdWocQbqF3QuVBQc+fP5vC6RiY4PHDPbcnC/aC+DVpr+FIyZWuTF1DkzDssO2Brn2UpUSpgudM93LTs6NTgJQMD3srjBjG/rl3rRdB6rN+LN/hhPa+2WRLkpskIvNBw+f928l3qp4l5fp4B6AWkxnHcEa9RWvHG6opUAsdMdrqJLCk7CAfsWYZQoTPHPecYpDffKHe7E5TMF0TfzVvUy9GO/Qn23PdS7+8Logc7F00Du0UqT+GzR0w/yeECIsyQVtdJH+zwX6hqiV8kJcqGQcnSqG2Fq1ESEMAjVbfIdCPZYm3GIpx5yJhfGFSWboIkSLvYiWR5Mo8FEEND0USXD6HhgWrJ8aL3+5I/ooeKVinH6uvOWZC7GeJgllzXg3RnLzkX6aRGHsC7cSr8EIWcmyF6XjJ9bUk6LHdOnA/y7kNtN60xkQErQZYUM9ftLvoKJltVXPk5RBkkaOU8opx+DrSShhauB4wuU16kLGk7Es1xbXYJI0gBvGk9M9+LwNMt3F2p7fRJfmwVIEm/nCjcIlxXwxd3UavGQAIzkcw6guNuLGOJpNRqyNvnQk5/qYltgSarCIs/TkBMgO1dhUS4/Ef3JgmUTUSBeb/IrwX8xD2IPxCnYhQ5Pp3LQX7fHi/iZKNQGhhUI2GNFAqb6VqmOeOmJyXHjEW3rO0mZfJuKGz4tLoi8SgrZPeA108canArdSbMRFx5BGchiz2M/Fl2ZcoKOxw3vchSEZM+Pdm7bwxDZ9g0MgbeSkyD5Zr+87DRFhK1288hx10C/hb9mLxdTSHVYqJzspbkAE8Y53246okeaQw+Q9gf93ia0GAByFhggNHOFGDdiDkvvrebOZ3E5xob6Vk6U130+S7UVeMrUx4mYj3jRivNkq2WmOYzVvYGwhkLc0lZIwAeaGA+/EBLeFrs1SvryFK4deg7MwMv099osfJPgCvWr9W1y8tpYjaKKyu74RvelUcl85ztLp3lenz9fr1IcuzBpOoUEbBqKLTR4jrOjGhZ1avmpmubO5tSCPSHPuxmSGfUOvSvN2TJbZqucnoQqXOL9YC5jsGAYg3VCnF/lgQT4A3U143bnLMKInyScleWPPLdsy20vc1XdZvgenzxIJ0JZ2Q0iBqjU//tYv++k4ZmuMrR9BCmue5x83IIJJFxeaZjdtiaBPFR6pU3nzmWe77RuGGRxxhqjaOYUYl9s5tolOEXEekW/XWAnvjCML5l98zL+nhHfZhNes6Zd765W9NJcYEfssWXXK6nd5wrP9XZL2y4TJWcXgXCVuO98pa8fU/oiZyrWuJZks4VMWRq8nKQQof4dXAs9aHgjUgaX7kS2ll60slNCRiLxW70t9jpMz5KIdyKAxSR2Cb2nTlA6Py4a/VQ3f44ZydQPedDZvF5wt42hKzqGPTpVojIFP+BVIylro/pfko3umfchPrzks71Nvn0lcle9NzJlhLZauJVtqhp4P3KWodoI9JULBmvzwEgJ/LYBy94pMZ2YHD3D6pF955L3P0EoGp3ubVLgBfv01TU4x97JNGt4kB6qdM57iFv1MKNtcLOwOc1wwEuFl9TzKWCaijDNbmtLmODSjwm+UFcaC+MbE86KBlH01c8xGgYWSPcEO6FIR1PqM+IfE8IPA8GOj2tX3yck4nLIc9Uq8JqD+QCpu9l2fppcgxiP8rvhtYZJImSIcbMVra1mBb5PfHtNkGyKztvOV8WdhFBnQhTG2IYiCzFgD9EpGnhhVS8M34NgMRKP/QE8lwj8MqAv4T4+rGDz0avS0KzTdY6/nGnuogLZymNTeL8ZCwptDZ03eZ4c0PO8TvsN+gTXFxEe4uJ/27M1lPB9zbi08zjMrtXiwZeQDOZSbR2Fwe2f9k7yCKN7m7JwclX3Nfm7L7uMwRsIyNQKQQ2rUm3kPYmMThZvPxnv0SAu6p+6ev3+5zGfhwjZXJnO82QP/CB3ufZKh+you0WoMKH9NwZcQnOGCfAk3IMNPwAdIeJGcOhRRk62foI/wMbbnxZeqtoDpTht3vHAWf+iI6+W/3EFHvYZVx/snuDgDA7MsTGJJSwOvI8pIdIcvAHqa8pJfICufWVCT1k8x/BIA9nN/7cfs9cs8kYKumeqwudjui5+ouI4KSTx76XbfC4NyLMckiVA86QtcwKbfxoU2CfOphBjobsi3sK2Ur2YvPIvz+KycEcYdVfnQ0z/wm1WcZefPROVVKD6G+lWoYcEbuTd55PW9ZVjmEp1R6t6qB7gF/CrBgxK5IcWaogbUc9m4Ve0r3RXtpG4GXszdRUccVjSGm80unKwhNxbfXB/ZUIKYPlAloepACa86gUvHPj9a/yqIWJ+Pk64gPYFCppoRDn/Bf2Sx4XTXWNEQsHtwc4T6QylW2cAhGaWsDIF3lemPCq7yfQgNCUgIeYsBBcWK67bkEgto2ML8Pw1ssi2CKpUAefa0+W6SYA3obrtixmI29dylK0cHaz6fC+lAA5t0QFAxHXinR1zT7q1XeOMpUwVFOLCPasm/5vrSBRBZ/4wBMzXqVVJuyFO0ERlk9WYs0PR/fjD/WgVhBwQ8v+aDIq9oDDix1x1T70Cj5b1AiKd8t7DjOcOBb/DBflqyIj3zNfwN0DMswt8APUMbENkmidXwyXBO63PpJVRyrvskBtSTjlIfbv2vVz0+Qwqxz3eohNyP7zlrLPW5jlcbEZulNBLZwR/Y9IqiXWstzfnSlCuKq+RmmEV+LKy2JsACS67weIyf1n5gIKn7c+fVCxij1LGvKXTQzPZLsvtUeE0Ofp6GX5mS6gZk6HSDySuMS+qiuOl0Pm2/B6zH8eow9uMNmFTpxknksxekixo1LaBnRSujSowad3FgvPTPxrsydymXFlvYjt0W1ey0i0Sj/ad0u1snVHrfjx5J20JCVC1uuHIqWUcmWefjxZIPLEtiwy8h63gHuXgGufsRZDG6D/6uwBhu07p4pUzBfwrjIDlf1x+uk+D+OoxjkCLUSqNmu7GVumlO6V/q8WVfT9ZqLYdG6QFmdNBsaUkeVi1PXYYb4YHMAqRHvUNkMlX+C2vutFSx91Ts8b3Qw6dgVAI/vlc6VOzC0VtOd5yD6vQGWt3tfq6CfyoWVTKlXoWxSYtNpeqbwt5Ex+3V7M3yeWvBre8EmFtkofJytTdz3Mapq9LeuItQ5g7JLNLgaK9wJMZF1+nwIlbKirVd7SgsibN0F7LnUMEXkN4HvnjX8BpQGSmqhdx9g1OnsS4C0vN6V01BFbLSlKNHtkmSY/U0SpMSTVCTBu8R7M+yD55YrjdrXvAhmH6zy5tqAyhTwF3ai6Ut9zgDCj5P3JCdPwmgiuPevPlt4r74IBcgXkwtTtmT0o4kh0JHDwfuRa7Jtg3TLP/RKP6BaChjhHAxyZofG5+R7fAnsEvSe5kYRF/7nAk+qZnkjKWjZjpvWkKcCvIPcru3tLtLefAVQGeQsamr+tcmn/8Z/Sz18LU7h//t3t91P9+jOgHSxYHaWu4Ki3wPinOxRSEdTSAW3KQUOl1TnHs18I2+UifoZ47tSKSO2L6pkmmV/JGLLn2xJF/USsEhBOnlEBJtwPAaNOnytmiheHDc9UyZvCave/pATrvx2UKluaxF4Uw9oTFBwZq0gUCVU2kLy5pyMmyEHpEPKlHjujkkwQn9jeo90Uhu0bnU1d1mk5zQK16/71Ed1HzVP/vWOdfiKO6qPoErGXxSouEfkyMqycVTHxKTyvBzo6qGs0pEAl08qz8XpS8RhblBR8BDxFY9Ax8NdLbmCAiSSTN8SlnpPohjmgjvpKpgXJfzLQTKnbA2p5wjgn28zWo8OGKQnOOBdi2bkqIO3LTustO6Mj5XvVJrKG6ozb2doVsNJC9IIa929ONA9BikuBmVBFG9yXEOdZQpcYhWPIBKga+qEq5BbLD1/Q1vCfu7ORgjV/4o+TsYzaDUQoFhUEwMo1hHp5T1Y+jziyrcOlc80ZztEyg9henYGsqPjj1HYKnaV3QxokQQgukXiaQoxAXX1352fARlw61m0SRf2kI4qPRZ3MvCK62XN1tacqGSKs+2D3f7CL9YQHsE3Bb8k6bG86qNzOKhBzssicXjDgDfkDBpOgRDAtFf83LrGkbPzYtQ7IEfQJYaXKG0Gn5MFSJZ36NgbwdjyiDCQrVL5sqNCbOkEJOkwEaICnnNrJaSxEZ4tJZA1c3RAkKyHPRgxYZoU0ooV+asypv2VqLKHgUBM8e3RIoiDv8H/FOXyg==

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• Second query to SQLite (on iPhone) errors.

  - by Luke

  Hi all, On the iPhone, I am developing a class for a cart that connects directly to a database. To view the cart, all items can be pulled from the database, however, it seems that removing them doesn't work. It is surprising to me because the error occurs during connection to the database, except not the second time I connect even after the DB has been closed. #import "CartDB.h" #import "CartItem.h" @implementation CartDB @synthesize database, databasePath; - (NSMutableArray *) getAllItems { NSMutableArray *items = [[NSMutableArray alloc] init]; if([self openDatabase]) { const char *sqlStatement = "SELECT * FROM items;"; sqlite3_stmt *compiledStatement; if(sqlite3_prepare_v2(cartDatabase, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) { while(sqlite3_step(compiledStatement) == SQLITE_ROW) { int rowId = sqlite3_column_int(compiledStatement, 0); int productId = sqlite3_column_int(compiledStatement, 1); NSString *features = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)]; int quantity = sqlite3_column_int(compiledStatement, 3); CartItem *cartItem = [[CartItem alloc] initWithRowId:rowId productId:productId features:features quantity:quantity]; [items addObject:cartItem]; [cartItem release]; } } sqlite3_finalize(compiledStatement); } [self closeDatabase]; return items; } - (BOOL) removeCartItem:(CartItem *)item { sqlite3_stmt *deleteStatement; [self openDatabase]; const char *sql = "DELETE FROM items WHERE id = ?"; if(sqlite3_prepare_v2(cartDatabase, sql, -1, &deleteStatement, NULL) != SQLITE_OK) { return NO; } sqlite3_bind_int(deleteStatement, 1, item.rowId); if(SQLITE_DONE != sqlite3_step(deleteStatement)) { sqlite3_reset(deleteStatement); [self closeDatabase]; return NO; } else { sqlite3_reset(deleteStatement); [self closeDatabase]; return YES; } } - (BOOL) openDatabase { if(sqlite3_open([databasePath UTF8String], &cartDatabase) == SQLITE_OK) { return YES; } else { return NO; } } - (void) closeDatabase { sqlite3_close(cartDatabase); } The error occurs on the line where the connection is opened in openDatabase. Any ideas? Need to flush something? Something gets autoreleased? I really can't figure it out. --Edit-- The error that I receive is GDB: Program received signal "EXC_BAD_ACCESS". --Edit-- I ended up just connecting in the init and closing in the free methods, which might not be the proper way, but that's another question altogether so it's effectively persistent instead of connecting multiple times. Still would be nice to know what was up with this for future reference.

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• Command prompt in debug mode for Eclipse? (OpenCV + Eclipse + Win7)

  - by Tony

  I am a beginner for Eclipse. I now have Eclipse C/C++ IDE with OpenCV library running on Windows 7. So far it works after spending hours trying to get it running. But then I realize that Eclipse does not pop up a command prompt as VS2010 does while debugging. And moreover Eclipse's debug mode is just stuck in there and refuse to output anything. But if the code doesn't involve the OpenCV things it works again. Below is the code I use for testing. It captures images from webcam and output it to the screen. The infinite loop (until you press 'q') makes sure it constantly grabs new inputs from the camera. I browsed through the workspace and run the exe just compiled and it worked flawlessly. So I don't think there's anything wrong in the code (it's an example code anyway In brief, can I just pop up a command prompt window in debug mode? And why is Eclipse console stuck when the code involves some OpenCV functions? #include <stdio.h> #include <stdlib.h> #include <tchar.h> #include <cv.h> #include <cxcore.h> #include <highgui.h> #include <iostream> int _tmain(int argc, _TCHAR* argv[]) { CvCapture *capture = 0; IplImage *frame = 0; int key = 0; /* initialize camera */ capture = cvCaptureFromCAM( 0 ); /* always check */ if ( !capture ) { printf("Cannot open initialize webcam!\n"); return 1; } /* create a window for the video */ cvNamedWindow( "result", CV_WINDOW_AUTOSIZE ); while( key != 'q' ) { /* get a frame */ frame = cvQueryFrame( capture ); /* always check */ if( !frame ) break; /* display current frame */ cvShowImage( "result", frame ); /* exit if user press 'q' */ key = cvWaitKey( 1 ); } /* free memory */ cvDestroyWindow( "result" ); cvReleaseCapture( &capture ); return 0; }

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• progress at work

  - by noopize

  I work in a small department in a very large company. Our department operates largely as a independent unit within the company. Each member of the team has a different role. My role within the team is a operations/admin and no one knew of my skills in programing as I never said anything before about it. I just did my work and in the free time read up on things for my own development Our developer who used to look after our websites has left a few months ago. Now when we require edits to our websites even basic HTML changes we outsource the work. We are getting shafted big time. I could of so said something sooner to highlight my skills in this area but I guess I was just happy to do my own development projects. And one reason was they are using asp.net and I have mainly done things in php. I only hinted before that I have done things but I did not want to reveal them before I had completed anything. I was working on something for myself that the company was also trying to implement something similar(e commerce site). I used open source and they decided to go for a propriety solution. Now I have finished my project and showed it to my boss, their project is still not completed and is quite expensive. He was impressed with what I showed him and suggested I should go for courses to learn asp.net. that I may be able to do the development work for them and there are some big upcoming projects in the future. He said this would be a benefit for me that I should look to be doing a better then role then admin. My employer does have a policy if relevent to the role they may support the costs of courses. Now how do I play this what should I say to my boss. I want to get advise on which MS certified courses would be good for asp.net and how to best approach my boss to see if they will pay all the amount for the course. And how much different will asp.net be from php.

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• Restrict sprite movement to vertical and horizontal

  - by Daniel Granger

  I have been battling with this for some time and my noob brain can't quite work it out. I have a standard tile map and currently use the following code to move my enemy sprite around the map -(void) movePlayer:(ccTime)deltaTime { if (CGPointEqualToPoint(self.position, requestedPosition)) return; float step = kPlayerSpeed * deltaTime; float dist = ccpDistance(self.position, requestedPosition); CGPoint vectorBetweenAB = ccpSub(self.position, requestedPosition); if (dist <= step) { self.position = requestedPosition; [self popPosition]; } else { CGPoint normVectorBetweenAB = ccpNormalize(vectorBetweenAB); CGPoint movementVectorForThisFrame = ccpMult(normVectorBetweenAB, step); if (abs(vectorBetweenAB.x) > abs(vectorBetweenAB.y)) { if (vectorBetweenAB.x > 0) { [self runAnimation:walkLeft]; } else { [self runAnimation:walkRight]; } } else { if (vectorBetweenAB.y > 0) { [self runAnimation:walkDown]; } else { [self runAnimation:walkUp]; } } if (self.position.x > movementVectorForThisFrame.x) { movementVectorForThisFrame.x = -movementVectorForThisFrame.x; } if (self.position.y > movementVectorForThisFrame.y) { movementVectorForThisFrame.y = -movementVectorForThisFrame.y; } self.position = ccpAdd(self.position, movementVectorForThisFrame); } } movePlayer: is called by the classes updateWithDeltaTime: method. the ivar requestedPosition is set in the updateWithDeltaTime method as well, it basically gets the next point out of a queue to move to. These points can be anywhere on the map, so if they are in a diagonal direction from the enemy the enemy sprite will move directly to that point. But how do I change the above code to restrict the movement to vertical and horizontal movement only so that the enemies movement 'staircases' its way along a diagonal path, taking the manhattan distance (I think its called). As shown by my crude drawing below... S being the start point F being the finish and the numbers being each intermediate point along its path to create a staircase type diagonal movement. Finally I intend to be able to toggle this behaviour on and off, so that I can choose whether or not I want the enemy to move free around the map or be restricted to this horizontal / vertical movement only. | | | | | | | | | | | | | | | | | | | | | |F| | | | | | | | | |5|4| | | | | | | | | |3|2| | | | | | | | | |1|S| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

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• safe dereferencing and deletion

  - by serejko

  Hi, I'm relatively new to C++ and OOP in general and currently trying to make such a class that allows to dereference and delete a dead or invalid pointer without any care of having undefined behavior or program fault in result, and I want to ask you is it a good idea and is there something similar which is already implemented by someone else? or maybe I'm doing something completely wrong? I've just started making it and here is the code I currently have: template<class T> class SafeDeref { public: T& operator *() { hash_set<T*>::iterator it = theStore.find(reinterpret_cast<T*>(ptr)); if (it != theStore.end()) return *this; return theDefaultObject; } T* operator ->() { hash_set<T*>::iterator it = theStore.find(reinterpret_cast<T*>(ptr)); if (it != theStore.end()) return this; return &theDefaultObject; } void* operator new(size_t size) { void* ptr = malloc(size * sizeof(T)); if (ptr != 0) theStore.insert(reinterpret_cast<T*>(ptr)); return ptr; } void operator delete(void* ptr) { hash_set<T*>::iterator it = theStore.find(reinterpret_cast<T*>(ptr)); if (it != theStore.end()) { theStore.erase(it); free(ptr); } } protected: static bool isInStore(T* ptr) { return theStore.find(ptr) != theStore.end(); } private: static T theDefaultObject; static hash_set<T*> theStore; }; The idea is that each class with the safe dereference should be inherited from it like this: class Foo : public SafeDeref<Foo> { void doSomething(); }; So... Any advices? Thanks in advance. P.S. If you're wondering why I need this... well, I'm creating a set of native functions for some scripting environment, and all of them use pointers to internally allocated objects as handles to them and they're able to delete them as well (input data can be wrong), so this is kinda protection from damaging host application's memory And I really sorry for my bad English

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• Integrating JavaScript Unit Tests with Visual Studio

  - by Stephen Walther

  Modern ASP.NET web applications take full advantage of client-side JavaScript to provide better interactivity and responsiveness. If you are building an ASP.NET application in the right way, you quickly end up with lots and lots of JavaScript code. When writing server code, you should be writing unit tests. One big advantage of unit tests is that they provide you with a safety net that enable you to safely modify your existing code – for example, fix bugs, add new features, and make performance enhancements -- without breaking your existing code. Every time you modify your code, you can execute your unit tests to verify that you have not broken anything. For the same reason that you should write unit tests for your server code, you should write unit tests for your client code. JavaScript is just as susceptible to bugs as C#. There is no shortage of unit testing frameworks for JavaScript. Each of the major JavaScript libraries has its own unit testing framework. For example, jQuery has QUnit, Prototype has UnitTestJS, YUI has YUI Test, and Dojo has Dojo Objective Harness (DOH). The challenge is integrating a JavaScript unit testing framework with Visual Studio. Visual Studio and Visual Studio ALM provide fantastic support for server-side unit tests. You can easily view the results of running your unit tests in the Visual Studio Test Results window. You can set up a check-in policy which requires that all unit tests pass before your source code can be committed to the source code repository. In addition, you can set up Team Build to execute your unit tests automatically. Unfortunately, Visual Studio does not provide “out-of-the-box” support for JavaScript unit tests. MS Test, the unit testing framework included in Visual Studio, does not support JavaScript unit tests. As soon as you leave the server world, you are left on your own. The goal of this blog entry is to describe one approach to integrating JavaScript unit tests with MS Test so that you can execute your JavaScript unit tests side-by-side with your C# unit tests. The goal is to enable you to execute JavaScript unit tests in exactly the same way as server-side unit tests. You can download the source code described by this project by scrolling to the end of this blog entry. Rejected Approach: Browser Launchers One popular approach to executing JavaScript unit tests is to use a browser as a test-driver. When you use a browser as a test-driver, you open up a browser window to execute and view the results of executing your JavaScript unit tests. For example, QUnit – the unit testing framework for jQuery – takes this approach. The following HTML page illustrates how you can use QUnit to create a unit test for a function named addNumbers(). <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>Using QUnit</title> <link rel="stylesheet" href="http://github.com/jquery/qunit/raw/master/qunit/qunit.css" type="text/css" /> </head> <body> <h1 id="qunit-header">QUnit example</h1> <h2 id="qunit-banner"></h2> <div id="qunit-testrunner-toolbar"></div> <h2 id="qunit-userAgent"></h2> <ol id="qunit-tests"></ol> <div id="qunit-fixture">test markup, will be hidden</div> <script type="text/javascript" src="http://code.jquery.com/jquery-latest.js"></script> <script type="text/javascript" src="http://github.com/jquery/qunit/raw/master/qunit/qunit.js"></script> <script type="text/javascript"> // The function to test function addNumbers(a, b) { return a+b; } // The unit test test("Test of addNumbers", function () { equals(4, addNumbers(1,3), "1+3 should be 4"); }); </script> </body> </html> This test verifies that calling addNumbers(1,3) returns the expected value 4. When you open this page in a browser, you can see that this test does, in fact, pass. The idea is that you can quickly refresh this QUnit HTML JavaScript test driver page in your browser whenever you modify your JavaScript code. In other words, you can keep a browser window open and keep refreshing it over and over while you are developing your application. That way, you can know very quickly whenever you have broken your JavaScript code. While easy to setup, there are several big disadvantages to this approach to executing JavaScript unit tests: You must view your JavaScript unit test results in a different location than your server unit test results. The JavaScript unit test results appear in the browser and the server unit test results appear in the Visual Studio Test Results window. Because all of your unit test results don’t appear in a single location, you are more likely to introduce bugs into your code without noticing it. Because your unit tests are not integrated with Visual Studio – in particular, MS Test -- you cannot easily include your JavaScript unit tests when setting up check-in policies or when performing automated builds with Team Build. A more sophisticated approach to using a browser as a test-driver is to automate the web browser. Instead of launching the browser and loading the test code yourself, you use a framework to automate this process. There are several different testing frameworks that support this approach: · Selenium – Selenium is a very powerful framework for automating browser tests. You can create your tests by recording a Firefox session or by writing the test driver code in server code such as C#. You can learn more about Selenium at http://seleniumhq.org/. LTAF – The ASP.NET team uses the Lightweight Test Automation Framework to test JavaScript code in the ASP.NET framework. You can learn more about LTAF by visiting the project home at CodePlex: http://aspnet.codeplex.com/releases/view/35501 jsTestDriver – This framework uses Java to automate the browser. jsTestDriver creates a server which can be used to automate multiple browsers simultaneously. This project is located at http://code.google.com/p/js-test-driver/ TestSwam – This framework, created by John Resig, uses PHP to automate the browser. Like jsTestDriver, the framework creates a test server. You can open multiple browsers that are automated by the test server. Learn more about TestSwarm by visiting the following address: https://github.com/jeresig/testswarm/wiki Yeti – This is the framework introduced by Yahoo for automating browser tests. Yeti uses server-side JavaScript and depends on Node.js. Learn more about Yeti at http://www.yuiblog.com/blog/2010/08/25/introducing-yeti-the-yui-easy-testing-interface/ All of these frameworks are great for integration tests – however, they are not the best frameworks to use for unit tests. In one way or another, all of these frameworks depend on executing tests within the context of a “living and breathing” browser. If you create an ASP.NET Unit Test then Visual Studio will launch a web server before executing the unit test. Why is launching a web server so bad? It is not the worst thing in the world. However, it does introduce dependencies that prevent your code from being tested in isolation. One of the defining features of a unit test -- versus an integration test – is that a unit test tests code in isolation. Another problem with launching a web server when performing unit tests is that launching a web server can be slow. If you cannot execute your unit tests quickly, you are less likely to execute your unit tests each and every time you make a code change. You are much more likely to fall into the pit of failure. Launching a browser when performing a JavaScript unit test has all of the same disadvantages as launching a web server when performing an ASP.NET unit test. Instead of testing a unit of JavaScript code in isolation, you are testing JavaScript code within the context of a particular browser. Using the frameworks listed above for integration tests makes perfect sense. However, I want to consider a different approach for creating unit tests for JavaScript code. Using Server-Side JavaScript for JavaScript Unit Tests A completely different approach to executing JavaScript unit tests is to perform the tests outside of any browser. If you really want to test JavaScript then you should test JavaScript and leave the browser out of the testing process. There are several ways that you can execute JavaScript on the server outside the context of any browser: Rhino – Rhino is an implementation of JavaScript written in Java. The Rhino project is maintained by the Mozilla project. Learn more about Rhino at http://www.mozilla.org/rhino/ V8 – V8 is the open-source Google JavaScript engine written in C++. This is the JavaScript engine used by the Chrome web browser. You can download V8 and embed it in your project by visiting http://code.google.com/p/v8/ JScript – JScript is the JavaScript Script Engine used by Internet Explorer (up to but not including Internet Explorer 9), Windows Script Host, and Active Server Pages. Internet Explorer is still the most popular web browser. Therefore, I decided to focus on using the JScript Script Engine to execute JavaScript unit tests. Using the Microsoft Script Control There are two basic ways that you can pass JavaScript to the JScript Script Engine and execute the code: use the Microsoft Windows Script Interfaces or use the Microsoft Script Control. The difficult and proper way to execute JavaScript using the JScript Script Engine is to use the Microsoft Windows Script Interfaces. You can learn more about the Script Interfaces by visiting http://msdn.microsoft.com/en-us/library/t9d4xf28(VS.85).aspx The main disadvantage of using the Script Interfaces is that they are difficult to use from .NET. There is a great series of articles on using the Script Interfaces from C# located at http://www.drdobbs.com/184406028. I picked the easier alternative and used the Microsoft Script Control. The Microsoft Script Control is an ActiveX control that provides a higher level abstraction over the Window Script Interfaces. You can download the Microsoft Script Control from here: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=d7e31492-2595-49e6-8c02-1426fec693ac After you download the Microsoft Script Control, you need to add a reference to it to your project. Select the Visual Studio menu option Project, Add Reference to open the Add Reference dialog. Select the COM tab and add the Microsoft Script Control 1.0. Using the Script Control is easy. You call the Script Control AddCode() method to add JavaScript code to the Script Engine. Next, you call the Script Control Run() method to run a particular JavaScript function. The reference documentation for the Microsoft Script Control is located at the MSDN website: http://msdn.microsoft.com/en-us/library/aa227633%28v=vs.60%29.aspx Creating the JavaScript Code to Test To keep things simple, let’s imagine that you want to test the following JavaScript function named addNumbers() which simply adds two numbers together: MvcApplication1\Scripts\Math.js function addNumbers(a, b) { return 5; } Notice that the addNumbers() method always returns the value 5. Right-now, it will not pass a good unit test. Create this file and save it in your project with the name Math.js in your MVC project’s Scripts folder (Save the file in your actual MVC application and not your MVC test application). Creating the JavaScript Test Helper Class To make it easier to use the Microsoft Script Control in unit tests, we can create a helper class. This class contains two methods: LoadFile() – Loads a JavaScript file. Use this method to load the JavaScript file being tested or the JavaScript file containing the unit tests. ExecuteTest() – Executes the JavaScript code. Use this method to execute a JavaScript unit test. Here’s the code for the JavaScriptTestHelper class: JavaScriptTestHelper.cs   using System; using System.IO; using Microsoft.VisualStudio.TestTools.UnitTesting; using MSScriptControl; namespace MvcApplication1.Tests { public class JavaScriptTestHelper : IDisposable { private ScriptControl _sc; private TestContext _context; /// <summary> /// You need to use this helper with Unit Tests and not /// Basic Unit Tests because you need a Test Context /// </summary> /// <param name="testContext">Unit Test Test Context</param> public JavaScriptTestHelper(TestContext testContext) { if (testContext == null) { throw new ArgumentNullException("TestContext"); } _context = testContext; _sc = new ScriptControl(); _sc.Language = "JScript"; _sc.AllowUI = false; } /// <summary> /// Load the contents of a JavaScript file into the /// Script Engine. /// </summary> /// <param name="path">Path to JavaScript file</param> public void LoadFile(string path) { var fileContents = File.ReadAllText(path); _sc.AddCode(fileContents); } /// <summary> /// Pass the path of the test that you want to execute. /// </summary> /// <param name="testMethodName">JavaScript function name</param> public void ExecuteTest(string testMethodName) { dynamic result = null; try { result = _sc.Run(testMethodName, new object[] { }); } catch { var error = ((IScriptControl)_sc).Error; if (error != null) { var description = error.Description; var line = error.Line; var column = error.Column; var text = error.Text; var source = error.Source; if (_context != null) { var details = String.Format("{0} \r\nLine: {1} Column: {2}", source, line, column); _context.WriteLine(details); } } throw new AssertFailedException(error.Description); } } public void Dispose() { _sc = null; } } }     Notice that the JavaScriptTestHelper class requires a Test Context to be instantiated. For this reason, you can use the JavaScriptTestHelper only with a Visual Studio Unit Test and not a Basic Unit Test (These are two different types of Visual Studio project items). Add the JavaScriptTestHelper file to your MVC test application (for example, MvcApplication1.Tests). Creating the JavaScript Unit Test Next, we need to create the JavaScript unit test function that we will use to test the addNumbers() function. Create a folder in your MVC test project named JavaScriptTests and add the following JavaScript file to this folder: MvcApplication1.Tests\JavaScriptTests\MathTest.js /// <reference path="JavaScriptUnitTestFramework.js"/> function testAddNumbers() { // Act var result = addNumbers(1, 3); // Assert assert.areEqual(4, result, "addNumbers did not return right value!"); }   The testAddNumbers() function takes advantage of another JavaScript library named JavaScriptUnitTestFramework.js. This library contains all of the code necessary to make assertions. Add the following JavaScriptnitTestFramework.js to the same folder as the MathTest.js file: MvcApplication1.Tests\JavaScriptTests\JavaScriptUnitTestFramework.js var assert = { areEqual: function (expected, actual, message) { if (expected !== actual) { throw new Error("Expected value " + expected + " is not equal to " + actual + ". " + message); } } }; There is only one type of assertion supported by this file: the areEqual() assertion. Most likely, you would want to add additional types of assertions to this file to make it easier to write your JavaScript unit tests. Deploying the JavaScript Test Files This step is non-intuitive. When you use Visual Studio to run unit tests, Visual Studio creates a new folder and executes a copy of the files in your project. After you run your unit tests, your Visual Studio Solution will contain a new folder named TestResults that includes a subfolder for each test run. You need to configure Visual Studio to deploy your JavaScript files to the test run folder or Visual Studio won’t be able to find your JavaScript files when you execute your unit tests. You will get an error that looks something like this when you attempt to execute your unit tests: You can configure Visual Studio to deploy your JavaScript files by adding a Test Settings file to your Visual Studio Solution. It is important to understand that you need to add this file to your Visual Studio Solution and not a particular Visual Studio project. Right-click your Solution in the Solution Explorer window and select the menu option Add, New Item. Select the Test Settings item and click the Add button. After you create a Test Settings file for your solution, you can indicate that you want a particular folder to be deployed whenever you perform a test run. Select the menu option Test, Edit Test Settings to edit your test configuration file. Select the Deployment tab and select your MVC test project’s JavaScriptTest folder to deploy. Click the Apply button and the Close button to save the changes and close the dialog. Creating the Visual Studio Unit Test The very last step is to create the Visual Studio unit test (the MS Test unit test). Add a new unit test to your MVC test project by selecting the menu option Add New Item and selecting the Unit Test project item (Do not select the Basic Unit Test project item): The difference between a Basic Unit Test and a Unit Test is that a Unit Test includes a Test Context. We need this Test Context to use the JavaScriptTestHelper class that we created earlier. Enter the following test method for the new unit test: [TestMethod] public void TestAddNumbers() { var jsHelper = new JavaScriptTestHelper(this.TestContext); // Load JavaScript files jsHelper.LoadFile("JavaScriptUnitTestFramework.js"); jsHelper.LoadFile(@"..\..\..\MvcApplication1\Scripts\Math.js"); jsHelper.LoadFile("MathTest.js"); // Execute JavaScript Test jsHelper.ExecuteTest("testAddNumbers"); } This code uses the JavaScriptTestHelper to load three files: JavaScripUnitTestFramework.js – Contains the assert functions. Math.js – Contains the addNumbers() function from your MVC application which is being tested. MathTest.js – Contains the JavaScript unit test function. Next, the test method calls the JavaScriptTestHelper ExecuteTest() method to execute the testAddNumbers() JavaScript function. Running the Visual Studio JavaScript Unit Test After you complete all of the steps described above, you can execute the JavaScript unit test just like any other unit test. You can use the keyboard combination CTRL-R, CTRL-A to run all of the tests in the current Visual Studio Solution. Alternatively, you can use the buttons in the Visual Studio toolbar to run the tests: (Unfortunately, the Run All Impacted Tests button won’t work correctly because Visual Studio won’t detect that your JavaScript code has changed. Therefore, you should use either the Run Tests in Current Context or Run All Tests in Solution options instead.) The results of running the JavaScript tests appear side-by-side with the results of running the server tests in the Test Results window. For example, if you Run All Tests in Solution then you will get the following results: Notice that the TestAddNumbers() JavaScript test has failed. That is good because our addNumbers() function is hard-coded to always return the value 5. If you double-click the failing JavaScript test, you can view additional details such as the JavaScript error message and the line number of the JavaScript code that failed: Summary The goal of this blog entry was to explain an approach to creating JavaScript unit tests that can be easily integrated with Visual Studio and Visual Studio ALM. I described how you can use the Microsoft Script Control to execute JavaScript on the server. By taking advantage of the Microsoft Script Control, we were able to execute our JavaScript unit tests side-by-side with all of our other unit tests and view the results in the standard Visual Studio Test Results window. You can download the code discussed in this blog entry from here: http://StephenWalther.com/downloads/Blog/JavaScriptUnitTesting/JavaScriptUnitTests.zip Before running this code, you need to first install the Microsoft Script Control which you can download from here: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=d7e31492-2595-49e6-8c02-1426fec693ac

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