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  • STLifying C++ classes

    - by shambulator
    I'm trying to write a class which contains several std::vectors as data members, and provides a subset of vector's interface to access them: class Mesh { public: private: std::vector<Vector3> positions; std::vector<Vector3> normals; // Several other members along the same lines }; The main thing you can do with a mesh is add positions, normals and other stuff to it. In order to allow an STL-like way of accessing a Mesh (add from arrays, other containers, etc.), I'm toying with the idea of adding methods like this: public: template<class InIter> void AddNormals(InIter first, InIter last); Problem is, from what I understand of templates, these methods will have to be defined in the header file (seems to make sense; without a concrete iterator type, the compiler doesn't know how to generate object code for the obvious implementation of this method). Is this actually a problem? My gut reaction is not to go around sticking huge chunks of code in header files, but my C++ is a little rusty with not much STL experience outside toy examples, and I'm not sure what "acceptable" C++ coding practice is on this. Is there a better way to expose this functionality while retaining an STL-like generic programming flavour? One way would be something like this: (end list) class RestrictedVector<T> { public: RestrictedVector(std::vector<T> wrapped) : wrapped(wrapped) {} template <class InIter> void Add(InIter first, InIter last) { std::copy(first, last, std::back_insert_iterator(wrapped)); } private: std::vector<T> wrapped; }; and then expose instances of these on Mesh instead, but that's starting to reek a little of overengineering :P Any advice is greatly appreciated!

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  • How to organize database access code in Android project?

    - by Mladen Jablanovic
    I have created a ContentProvider for my main Sqlite table, pretty much following NotePad example from SDK (although I am not sure whether I will ever be exposing my data to other apps). However, I need to create lots of other, non-trivial queries on that and other tables and views. A good example would be queries to extract some statistics from the base data, averages, totals etc. So what's the best place for this code in an Android project? How it should be related and connected to the Uri-based data access exposed by a Provider? Any good examples out there?

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  • Guidance on using drop in DLLs

    - by Scott Chamberlain
    I have been giving the task to rewrite a internal utility in .net for my work. One of program requirements the new system has is have a dll that implements a set of interfaces and have the program call the DLL. Now this dll will be changed out a lot per deployment. My question is what is the best way to do it from a development standpoint? Do I add a template DLL (one that only has the interfaces but no implementation) to the project references like I would do any other dll that I would use. Or do I need to use somthing like this every time I want to use code from the dll? var DropIn = System.Reflection.Assembly.LoadFrom("DropInDll.dll"); var getActions = DropIn.GetType("Main").GetMethod("GetActions"); List<IAction> ActionList = (List<IAction>)getActions.Invoke(null, null);

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  • Parsing timestamps - do it in MySQL or in PHP?

    - by Andrew Heath
    Let's say you've got a table with a timestamp column, and you want to parse that column into two arrays - $date and $time. Do you, personally: a) query like this DATE(timestamp), TIME(timestamp) , or perhaps even going as far as HOUR(timestamp), MINUTE(timestamp b) grab the timestamp column and parse it out as needed with a loop in PHP I feel like (a) is easier... but I know that I don't know anything. And it feels a little naughty to make my query hit the same column 2 or 3 times for output... Is there a best-practice for this?

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  • Handling missing data

    - by soppotare
    Say I have a simple helpdesk application which logs calls made by users. I would typically have such fields in a table relating to the call e.g. CallID, Description, CustomerID etc. I Would also have a table of customers including CustomerID, Username, Password, FullName etc. Now when a user is deleted from the customers table then the inner join between the calls table and the users table to find out historically which user logged a call would produce no results. How do people usually deal with this? Have seperate customer and useraccount tables Just disable the accounts so the data is still available Record the customers name in the calls table as a seperate field. or any other methods / suggestions?

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  • Creating and Compiling a C++ project on Windows

    - by sc_ray
    I need to work on C++ project on my windows machine. My project will consist of various classes(.h and .cpp) as well as the startup file to start the application. The preliminary design is simple but the application has the potential to gain complexity as time goes by. What I need here is ideas to set up the C++ project compiler/IDE/Makefile etc..etc. as well as some standard tools besides Visual C++ to compile/build/link projects such as these on a Windows OS. Thanks

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  • Imposing email limits on web page

    - by Martin
    To avoid spammers, what's a good strategy for imposing limits on users when sending email from our site? A count limit per day on individual IPs? Sender emails? Domains? In general terms, but recommended figures will also be helpful. Our users can send emails through our web page. They can register and log in but are also allowed to do this without logging in, but with a captcha and with a field for the senders email. Certainly, there is a header, "The user has sent you the following message.", limiting the use for spammers, so perhaps it's not a big problem. Any comments on what I'm doing will be greatly appreciated.

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  • EXC_BAD_ACCESS iPhone Development

    - by gkres121
    Sorry, this could be a simple fix, as I am new to iPhone Development. In my Delegate, after pressing the create profile button, the create profile view is pushed: -(void) createProfile_clicked:(id)sender { AddNewProfile *create = [[AddNewProfile alloc] init]; [self.window addSubview:create.view]; [self invisibleCreateProfileBar]; AddNewProfile *controller = [[AddNewProfile alloc] initWithNibName:@"AddNewProfile" bundle:[NSBundle mainBundle]]; [ self.navigationController pushViewController:controller animated:YES ]; currentController=controller; } Then in the AddNewProfile.m: - (IBAction)backgroundTap:(id)sender { if([nameField isFirstResponder]){ [nameField resignFirstResponder]; } if([ageField isFirstResponder]){ [ageField resignFirstResponder]; } if([doctorNameField isFirstResponder]){ [doctorNameField isFirstResponder]; } if([doctorNumberField isFirstResponder]){ [doctorNumberField resignFirstResponder]; } } This leads to a exc_bad_access error every time the FirstResponder is ever messed with, with any of my controls. I can select a control(text box), but once I click out of one, it crashes. Any help would be greatly appreciated.

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  • Preferred way of filling up a C++ vector of structs

    - by henle
    Alternative 1, reusing a temporary variable: Sticker sticker; sticker.x = x + foreground.x; sticker.y = foreground.y; sticker.width = foreground.width; sticker.height = foreground.height; board.push_back(sticker); sticker.x = x + outline.x; sticker.y = outline.y; sticker.width = outline.width; sticker.height = outline.height; board.push_back(sticker); Alternative 2, scoping the temporary variable: { Sticker sticker; sticker.x = x + foreground.x; sticker.y = foreground.y; sticker.width = foreground.width; sticker.height = foreground.height; board.push_back(sticker); } { Sticker sticker; sticker.x = x + outline.x; sticker.y = outline.y; sticker.width = outline.width; sticker.height = outline.height; board.push_back(sticker); } Alternative 3, writing straight to the vector memory: { board.push_back(Sticker()); Sticker &sticker = board.back(); sticker.x = x + foreground.x; sticker.y = foreground.y; sticker.width = foreground.width; sticker.height = foreground.height; } { board.push_back(Sticker()); Sticker &sticker = board.back(); sticker.x = x + outline.x; sticker.y = outline.y; sticker.width = outline.width; sticker.height = outline.height; } Which approach do you prefer?

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  • Is object clearing/array deallocation really necessary in VB6/VBA (Pros/Cons?)

    - by Oorang
    Hello, A lot of what I have learned about VB I learned from using Static Code Analysis (Particularly Aivosto's Project Analyzer). And one one of things it checks for is whether or not you cleared all objects and arrays. I used to just do this blindly because PA said so. But now that I know a little bit more about the way VB releases resources, it seems to me that these things should be happening automatically. Is this a legacy feature from pre VB6, or is there a reason why you should explicitly set objects back to nothing and use Erase on arrays?

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  • Clarifying... So Background Jobs don't Tie Up Application Resources (in Rails)?

    - by viatropos
    I'm trying to get a better grasp of the inner workings of background jobs and how they improve performance. I understand that the goal is to have the application return a response to the user as fast as it can, so you don't want to, say, parse a huge feed that would take 10 seconds because it would prevent the application from being able to process any other requests. So it's recommended to put any operations that take more than say 500ms to execute, into a queued background job. What I don't understand is, doesn't that just delay the same problem? I know the user who invoked that background job will get an immediate response, but what if another user comes right when that background job starts (and it takes 10 seconds to finish), wont that user have to wait? Or is the main issue that, requests are the only thing that can happen one-at-a-time, while on the other hand a request can start while one+ background jobs are in the middle of running? Is that correct?

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  • Implementing prompts in text-input

    - by AntonAL
    Hi, I have a form with some text-inputs: login, password. If user sees this form the first time, input-texts should "contain" prompts, like "enter login", "enter password". If user clicks text-input, it's prompt should disappear to allow typing. I have seen various examples, that uses background image with prerendered text on it. Those images are appearing with following jQuery: $("form > :text").focus(function(){ // hide image }).blur(function(){ // show image, if text-input is still empty if ( $(this).val() == "" ) // show image with prompt }); This approach has following problems: localization is impossible need to pre-render images for various textual prompts overhead with loading images How do you overcomes such a problems ?

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  • Where does one get data like Country:(list) State:(list)

    - by rlb.usa
    As a programmer of data-entry forms of all kinds, I often find myself making fields for things like Country: <choose from list>, State: <choose from list>, Race/Ethnicity: <choose from list>. Consider: Perhaps a list the 50 United States names is an easy thing to find (does one include DC?) , but the countries are not. Nearly every site you find has a differing list with all of the political goings on over the years, and they become outdated quickly. What's the best/common practice regarding population of these kinds of lists? Where does this data come from if it's not given in the specs?

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  • What's the best practice in case something goes wrong in Perl code?

    - by Geo
    I saw code which works like this: do_something($param) || warn "something went wrong\n"; and I also saw code like this: eval { do_something_else($param); }; if($@) { warn "something went wrong\n"; } Should I use eval/die in all my subroutines? Should I write all my code based on stuff returned from subroutines? Isn't eval'ing the code ( over and over ) gonna slow me down?

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  • What goes into the "Controller" in "MVC"?

    - by P72endragon
    I think I understand the basic concepts of MVC - the Model contains the data and behaviour of the application, the View is responsible for displaying it to the user and the Controller deals with user input. What I'm uncertain about is exactly what goes in the Controller. Lets say for example I have a fairly simple application (I'm specifically thinking Java, but I suppose the same principles apply elsewhere). I organise my code into 3 packages called app.model, app.view and app.controller. Within the app.model package, I have a few classes that reflect the actual behaviour of the application. These extends Observable and use setChanged() and notifyObservers() to trigger the views to update when appropriate. The app.view package has a class (or several classes for different types of display) that uses javax.swing components to handle the display. Some of these components need to feed back into the Model. If I understand correctly, the View shouldn't have anything to do with the feedback - that should be dealt with by the Controller. So what do I actually put in the Controller? Do I put the public void actionPerformed(ActionEvent e) in the View with just a call to a method in the Controller? If so, should any validation etc be done in the Controller? If so, how do I feedback error messages back to the View - should that go through the Model again, or should the Controller just send it straight back to View? If the validation is done in the View, what do I put in the Controller? Sorry for the long question, I just wanted to document my understanding of the process and hopefully someone can clarify this issue for me!

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  • Should the function or the caller be resonsible for input validation?

    - by haudenschilt
    I'm doing a security audit on a fairly large php application and was wondering where I should include my user-input validation. Should I validate the data, then send the clean data off to the back-end functions or should I rely on each function to do it's own validation? Or even both? Is there any standard or best-practice for this sort of thing? Currently the app does both inconsistently and I'll like to make things more consistent.

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  • Is it the best practice to extract an interface for every class?

    - by the_drow
    I have seen code where every class has an interface that it implements. Sometimes there is no common interface for them all. They are just there and they are used instead of concreate objects. They do not offer a generic interface for two classes and are specific to the domain of the problem that the class solves. Is there any reason to do that?

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  • Fastest way to convert a binary file to SQLite database

    - by chown
    I've some binary files and I'm looking for a way to convert each of those files to a SQLite database. I've already tried C# but the performance is too slow. I'm seeking an advice on how and what programming language should be the best to perform this kind of conversion. Though I prefer any Object Oriented Language more (like C#, Java etc), I'm open for any programming language that boosts up the conversion. I don't need a GUI frontend for the conversion, running the script/program from console is okay. Thanks in advance

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  • Feedback + Bad output

    - by user1770094
    So I've got an assignment I think I'm more or less done with, but there is something which is messing up the output badly somewhere down the line, or even the calculation, and I don't see where the problem is. The assignment is to make a game in which a certain ammount of players run up through a tunnel towards a spot,where they will stop and spin around it,and then their dizziness is supposed to make them randomly either progress towards goal or regress back towards start.And each time they get another spot closer to goal,they get another "marking",and it goes on like this until one of them reaches goal. The program includes three files: one main.cpp,one header file and another cpp file. The header file: #ifndef COMPETITOR_H #define COMPETITOR_H #include <string> using namespace std; class Competitor { public: void setName(); string getName(); void spin(); void move(); int checkScore(); void printResult(); private: string name; int direction; int markedSpots; }; #endif // COMPETITOR_H The second cpp file: #include <iostream> #include <string> #include <cstdlib> #include <ctime> #include "Competitor.h" using namespace std; void Competitor::setName() { cin>>name; } string Competitor::getName() { return name; } void Competitor::spin() { srand(time(NULL)); direction = rand()%1+0; } void Competitor::move() { if(direction == 1) { markedSpots++; } else if(direction == 0 && markedSpots != 0) { markedSpots--; } } int Competitor::checkScore() { return markedSpots; } void Competitor::printResult() { if(direction == 1) { cout<<" is heading towards goal and has currently "<<markedSpots<<" markings."; } else if(direction == 0) { cout<<"\n"<<getName()<<" is heading towards start and has currently "<<markedSpots<<" markings."; } } The main cpp file: #include <iostream> #include <string> #include <cstdlib> #include <ctime> #include "Competitor.h" using namespace std; void inputAndSetNames(Competitor comps[],int nrOfComps); void makeTwist(Competitor comps[],int nrOfComps); void makeMove(Competitor comps[],int nrOfComps); void showAll(Competitor comps[],int nrOfComps); int winner(Competitor comps[],int nrOfComps, int nrOfTwistPlaces); int main() { int nrOfTwistPlaces; int nrOfComps; int noWinner = -1; int laps = 0; cout<<"How many spinning places should there be? "; cin>>nrOfTwistPlaces; cout<<"How many competitors should there be? "; cin>>nrOfComps; Competitor * comps = new Competitor[nrOfComps]; inputAndSetNames(comps, nrOfComps); do { laps++; cout<<"\nSpin "<<laps<<":"; makeTwist(comps, nrOfComps); makeMove(comps, nrOfComps); showAll(comps, nrOfComps); }while(noWinner == -1); delete [] comps; return 0; } void inputAndSetNames(Competitor comps[],int nrOfComps) { cout<<"Type in the names of the "<<nrOfComps<<" competitors:\n"; for(int i=0;i<nrOfComps;i++) { comps[i].setName(); } cout<<"\n"; } void makeTwist(Competitor comps[],int nrOfComps) { for(int i=0;i<nrOfComps;i++) { comps[i].spin(); } } void makeMove(Competitor comps[],int nrOfComps) { for(int i=0;i<nrOfComps;i++) { comps[i].move(); } } void showAll(Competitor comps[],int nrOfComps) { for(int i=0;i<nrOfComps;i++) { comps[i].printResult(); } cout<<"\n\n"; system("pause"); } int winner(Competitor comps[],int nrOfComps, int nrOfTwistPlaces) { int end = 0; int score = 0; for(int i=0;i<nrOfComps;i++) { score = comps[i].checkScore(); if(score == nrOfTwistPlaces) { end = 1; } else end = -1; } return end; } I'd be grateful if you would point out other mistakes if you see any.Thanks in advance.

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  • jQuery Animation and Classes

    - by ehdv
    Assume you have a list item, <li id="foo"> which you want to fade from one color to another when moused over, and that you are using jQuery. This is fairly easy: $('li#foo').bind('mouseenter' , function(e) { $(this).animate({backgroundColor: '#F00'} , 300); }); However, what if you wanted to get the resulting color or other style rules from a class defined in CSS without also declaring them in JavaScript? It seems there's no way to learn style information from CSS rules without having an example of the rule already in the document, which would require you to animate the <li> to the target appearance, then in the animation-finished callback, set the class which leads to redundant style declarations and can foul up your CSS at "runtime". Sorry if this question's unclear: It doesn't occur in the context of any specific project, I'm just curious how you'd go about this. Also, I know CSS3 hypothetically includes support for such transitions but using CSS for dynamic behavior like this seems such an ugly hack.

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