Search Results

Search found 44965 results on 1799 pages for 'presenter first'.

Page 432/1799 | < Previous Page | 428 429 430 431 432 433 434 435 436 437 438 439  | Next Page >

• MVC for a desktop application, connection a view/controller pair with another one

  - by lcf

  Hello. I've had mostly experience with "server-side" mvc frameworks very popular in different languages like ASP.NET MVC or Zend Framework for php, Spring for Java etc. Some of them are also possible to use for desktop applications development but I never tried that. I fully understand that design patterns should not limit implementation, they should generally provide ideas and common rules that can be differently implemented. Now I'm playing with one of those mvc frameworks for usual Desktop Applications development (it does not have many tutorials or a decent quickstart) and I have some questions regarding to the mvc paradigm. Here is one of them: What are common ways to link different views / controllers? If I click a button, special controller for that button dispatches the event that is generated, does something with the model, changes view state. But what if I need to interact with another view? Like, when I click on a button, it changes a model, but also I need to open another window or change state of another window (hiding a button on another window let's say...), without changing actually the model. What are common ways here to address this? Should my first controller generate an event for the second controller (or second view)? Or should the second controller be handling events from first view? Some links or examples for any languages/frameworks would be really helpful, thanks!

  Read the article

• Android game logic problem

  - by semajhan

  I'm currently creating a game and have a problem which I think I know why it is occurring but not entirely sure and even if I knew, don't know how to solve. I have a 2D array 10 x 10 and have a "player" class that takes up a tile. Now, I have created 2 instances of the player and move them around via swiping. Around the edges I have put "walls" that the player cannot walk through and everything works fine, until I remove a wall. Once I remove a wall and move the character/player to the edge of the screen, the player cannot go any further. The problem occurs here, where the second instance of the player is not at the edge of the screen but say 2 tiles from the first instance of "player" who is at the edge. If I try moving them further into the direction of the edge, I understand that the first instance of player wouldn't move or do anything but the second instance of player should still move, but it won't. This is the code that executed when the user swipes: if (player.getArrayX() - 1 != player2.getArrayX()) { player.moveLeft(); } else if (player.getArrayX() - 1 == player2.getArrayX() && player.getArrayY() != player2.getArrayY()) { player.moveLeft(); } if (player2.getArrayX() - 1 != player.getArrayX()) { player2.moveLeft(); } else if (player2.getArrayX() - 1 == player.getArrayX() && player2.getArrayY() != player.getArrayY()) { player2.moveLeft(); } In the player class I have: public void moveLeft() { if (alive) { switch (levelMaster.getLevel1(getArrayX() - 1, getArrayY())) { case 0: break; case 1: subX(); // basically moves player left setArrayX(getArrayX() - 1); // shifts x coord of player 1 within tilemap Log.d("semajhan", "x: " + getArrayX()); break; case 9: subX(); setArrayX(getArrayX() - 1); setAlive(false); break; } } } Any help on the matter or further insight would be greatly appreciated, thanks.

  Read the article

• Advice on Linq to SQL mapping object design

  - by fearofawhackplanet

  I hope the title and following text are clear, I'm not very familiar with the correct terms so please correct me if I get anything wrong. I'm using Linq ORM for the first time and am wondering how to address the following. Say I have two DB tables: User ---- Id Name Phone ----- Id UserId Model The Linq code generator produces a bunch of entity classes. I then write my own classes and interfaces which wrap these Linq classes: class DatabaseUser : IUser { public DatabaseUser(User user) { _user = user; } public Guid Id { get { return _user.Id; } } ... etc } so far so good. Now it's easy enough to find a users phones from Phones.Where(p => p.User = user) but surely comsumers of the API shouldn't need to be writing their own Linq queries to get at data, so I should wrap this query in a function or property somewhere. So the question is, in this example, would you add a Phones property to IUser or not? In other words, should my interface specifically be modelling my database objects (in which case Phones doesn't belong in IUser), or are they actually simply providing a set of functions and properties which are conceptually associated with a User (in which case it does)? There seems drawbacks to both views, but I'm wondering if there is a standard approach to the problem. Or just any general words of wisdom you could share. My first thought was to use extension methods but in fact that doesn't work in this case.

  Read the article

• Simple POSIX threads question

  - by Andy

  Hi, I have this POSIX thread: void subthread(void) { while(!quit_thread) { // do something ... // don't waste cpu cycles if(!quit_thread) usleep(500); } // free resources ... // tell main thread we're done quit_thread = FALSE; } Now I want to terminate subthread() from my main thread. I've tried the following: quit_thread = TRUE; // wait until subthread() has cleaned its resources while(quit_thread); But it does not work! The while() clause does never exit although my subthread clearly sets quit_thread to FALSE after having freed its resources! If I modify my shutdown code like this: quit_thread = TRUE; // wait until subthread() has cleaned its resources while(quit_thread) usleep(10); Then everything is working fine! Could someone explain to me why the first solution does not work and why the version with usleep(10) suddenly works? I know that this is not a pretty solution. I could use semaphores/signals for this but I'd like to learn something about multithreading, so I'd like to know why my first solution doesn't work. Thanks!

  Read the article

• lapply slower than for-loop when used for a BiomaRt query. Is that expected?

  - by ptocquin

  I would like to query a database using BiomaRt package. I have loci and want to retrieve some related information, let say description. I first try to use lapply but was surprise by the time needed for the task to be performed. I thus tried a more basic for-loop and get a faster result. Is that expected or is something wrong with my code or with my understanding of apply ? I read other posts dealing with *apply vs for-loop performance (Here, for example) and I was aware that improved performance should not be expected but I don't understand why performance here is actually lower. Here is a reproducible example. 1) Loading the library and selecting the database : library("biomaRt") athaliana <- useMart("plants_mart_14") athaliana <- useDataset("athaliana_eg_gene",mart=athaliana) 2) Querying the database : loci <- c("at1g01300", "at1g01800", "at1g01900", "at1g02335", "at1g02790", "at1g03220", "at1g03230", "at1g04040", "at1g04110", "at1g05240" ) I create a function for the use in lapply : foo <- function(loci) { getBM("description","tair_locus",loci,athaliana) } When I use this function on the first element : > system.time(foo(cwp_loci[1])) utilisateur système écoulé 0.020 0.004 1.599 When I use lapply to retrieve the data for all values : > system.time(lapply(loci, foo)) utilisateur système écoulé 0.220 0.000 16.376 I then created a new function, adding a for-loop : foo2 <- function(loci) { for (i in loci) { getBM("description","tair_locus",loci[i],athaliana) } } Here is the result : > system.time(foo2(loci)) utilisateur système écoulé 0.204 0.004 10.919 Of course, this will be applied to a big list of loci, so the best performing option is needed. I thank you for assistance. EDIT Following recommendation of @MartinMorgan Simply passing the vector loci to getBM greatly improves the query efficiency. Simpler is better. > system.time(lapply(loci, foo)) utilisateur système écoulé 0.236 0.024 110.512 > system.time(foo2(loci)) utilisateur système écoulé 0.208 0.040 116.099 > system.time(foo(loci)) utilisateur système écoulé 0.028 0.000 6.193

  Read the article

• Is something along the lines of nested memoization needed here?

  - by Daniel

  System.Transactions notoriously escalates transactions involving multiple connections to the same database to the DTC. The module and helper class, ConnectionContext, below are meant to prevent this by ensuring multiple connection requests for the same database return the same connection object. This is, in some sense, memoization, although there are multiple things being memoized and the second is dependent on the first. Is there some way to hide the synchronization and/or mutable state (perhaps using memoization) in this module, or perhaps rewrite it in a more functional style? (It may be worth nothing that there's no locking when getting the connection by connection string because Transaction.Current is ThreadStatic.) type ConnectionContext(connection:IDbConnection, ownsConnection) = member x.Connection = connection member x.OwnsConnection = ownsConnection interface IDisposable with member x.Dispose() = if ownsConnection then connection.Dispose() module ConnectionManager = let private _connections = new Dictionary<string, Dictionary<string, IDbConnection>>() let private getTid (t:Transaction) = t.TransactionInformation.LocalIdentifier let private removeConnection tid = let cl = _connections.[tid] for (KeyValue(_, con)) in cl do con.Close() lock _connections (fun () -> _connections.Remove(tid) |> ignore) let getConnection connectionString (openConnection:(unit -> IDbConnection)) = match Transaction.Current with | null -> new ConnectionContext(openConnection(), true) | current -> let tid = getTid current // get connections for the current transaction let connections = match _connections.TryGetValue(tid) with | true, cl -> cl | false, _ -> let cl = Dictionary<_,_>() lock _connections (fun () -> _connections.Add(tid, cl)) cl // find connection for this connection string let connection = match connections.TryGetValue(connectionString) with | true, con -> con | false, _ -> let initial = (connections.Count = 0) let con = openConnection() connections.Add(connectionString, con) // if this is the first connection for this transaction, register connections for cleanup if initial then current.TransactionCompleted.Add (fun args -> let id = getTid args.Transaction removeConnection id) con new ConnectionContext(connection, false)

  Read the article

• [FIXED] Scan file contents into an array of a structure.

  - by ZaZu

  Hello, I have a structure in my program that contains a particular array. I want to scan a random file with numbers and put the contents into that array. This is my code : ( NOTE : This is a sample from a bigger program, so I need the structure and arrays as declared ) The contents of the file are basically : 5 4 3 2 5 3 4 2 #include<stdio.h> #define first 500 #define sec 500 struct trial{ int f; int r; float what[first][sec]; }; int trialtest(trial *test); main(){ trial test; trialtest(&test); } int trialtest(trial *test){ int z,x,i; FILE *fin; fin=fopen("randomfile.txt","r"); for(i=0;i<5;i++){ fscanf(fin,"%5.2f\t",(*test).what[z][x]); } fclose(fin); return 0; } But the problem is, whenever this I run this code, I get this error : (25) : warning 508 - Data of type 'double' supplied where a pointer is required I tried adding do{ for(i=0;i<5;i++){ q=fscanf(fin,"%5.2f\t",(*test).what[z][x]); } }while(q!=EOF); But that didnt work either, it gives the same error. Does anyone have a solution to this problem ?

  Read the article

• optimize output value using a class and public member

  - by wiso

  Suppose you have a function, and you call it a lot of times, every time the function return a big object. I've optimized the problem using a functor that return void, and store the returning value in a public member: #include <vector> const int N = 100; std::vector<double> fun(const std::vector<double> & v, const int n) { std::vector<double> output = v; output[n] *= output[n]; return output; } class F { public: F() : output(N) {}; std::vector<double> output; void operator()(const std::vector<double> & v, const int n) { output = v; output[n] *= n; } }; int main() { std::vector<double> start(N,10.); std::vector<double> end(N); double a; // first solution for (unsigned long int i = 0; i != 10000000; ++i) a = fun(start, 2)[3]; // second solution F f; for (unsigned long int i = 0; i != 10000000; ++i) { f(start, 2); a = f.output[3]; } } Yes, I can use inline or optimize in an other way this problem, but here I want to stress on this problem: with the functor I declare and construct the output variable output only one time, using the function I do that every time it is called. The second solution is two time faster than the first with g++ -O1 or g++ -O2. What do you think about it, is it an ugly optimization?

  Read the article

• Approach for caching data from data logger

  - by filip-fku

  Greetings, I've been working on a C#.NET app that interacts with a data logger. The user can query and obtain logs for a specified time period, and view plots of the data. Typically a new data log is created every minute and stores a measurement for a few parameters. To get meaningful information out of the logger, a reasonable number of logs need to be acquired - data for at least a few days. The hardware interface is a UART to USB module on the device, which restricts transfers to a maximum of about 30 logs/second. This becomes quite slow when reading in the data acquired over a number of days/weeks. What I would like to do is improve the perceived performance for the user. I realize that with the hardware speed limitation the user will have to wait for the full download cycle at least the first time they acquire a larger set of data. My goal is to cache all data seen by the app, so that it can be obtained faster if ever requested again. The approach I have been considering is to use a light database, like SqlServerCe, that can store the data logs as they are received. I am then hoping to first search the cache prior to querying a device for logs. The cache would be updated with any logs obtained by the request that were not already cached. Finally my question - would you consider this to be a good approach? Are there any better alternatives you can think of? I've tried to search SO and Google for reinforcement of the idea, but I mostly run into discussions of web request/content caching. Thanks for any feedback!

  Read the article

• Creating a new object destroys an older object with different name in C++

  - by Mikael

  First question here! So, I am having some problems with pointers in Visual C++ 2008. I'm writing a program which will control six cameras and do some processing on them so to clean things up I have created a Camera Manager class. This class handles all operations which will be carried out on all the cameras. Below this is a Camera class which interacts with each individual camera driver and does some basic image processing. Now, the idea is that when the manager is initialised it creates two cameras and adds them to a vector so that I can access them later. The catch here is that when I create the second camera (camera2) the first camera's destructor is called for some reason, which then disconnects the camera. Normally I'd assume that the problem is somewhere in the Camera class, but in this case everything works perfectly as long as I don't create the camera2 object. What's gone wrong? CameraManager.h: #include "stdafx.h" #include <vector> #include "Camera.h" class CameraManager{ std::vector<Camera> cameras; public: CameraManager(); ~CameraManager(); void CaptureAll(); void ShowAll(); }; CameraManager.cpp: #include "stdafx.h" #include "CameraManager.h" CameraManager::CameraManager() { printf("Camera Manager: Initializing\n"); [...] Camera *camera1 = new Camera(NodeInfo,1, -44,0,0); cameras.push_back(*camera1); // Adding the following two lines causes camera1's destructor to be called. Why? Camera *camera2 = new Camera(NodeInfo,0, 44,0,0); cameras.push_back(*camera2); printf("Camera Manager: Ready\n"); }

  Read the article

• Viewing recently edited etherpads (note new 'etherpad' tag for open sourced etherpad code!)

  - by dreeves

  Prescript: The amazing etherpad was recently open sourced. Get it here: http://code.google.com/p/etherpad. This is the first question that I know of on StackOverflow about the etherpad code. If you're part of the etherpad open source community, you might want to subscribe to the RSS feed for questions tagged 'etherpad' just in case this catches on! My actual question, which assumes you have etherpad installed on your own server: First, here's a query to view recently edited pads: SELECT id,lastWriteTime,creationTime,headRev FROM PAD_SQLMETA ORDER BY lastWriteTime, headRev; Or, if you want to run it from a unix prompt: mysql -u root -pPASSWD etherpad -e "select id,lastWriteTime,creationTime,headRev from PAD_SQLMETA order by lastWriteTime, headRev" That's handy, however lastWriteTime actually gets updated every time someone so much as views a pad in their browser. I'd rather sort the pads by when they were actually last edited. There's probably a fancy SQL query involving a join with another table that would show actual last edit time. Does anyone know what that is? Alternatively, you could have a script that notices when headRev changes but that doesn't seem like the cleanest way to do it.

  Read the article

• Can somebody explain this remark in the MSDN CreateMutex() documentation about the bInitialOwner fla

  - by Tom Williams

  The MSDN CreatMutex() documentation (http://msdn.microsoft.com/en-us/library/ms682411%28VS.85%29.aspx) contains the following remark near the end: Two or more processes can call CreateMutex to create the same named mutex. The first process actually creates the mutex, and subsequent processes with sufficient access rights simply open a handle to the existing mutex. This enables multiple processes to get handles of the same mutex, while relieving the user of the responsibility of ensuring that the creating process is started first. When using this technique, you should set the bInitialOwner flag to FALSE; otherwise, it can be difficult to be certain which process has initial ownership. Can somebody explain the problem with using bInitialOwner = TRUE? Earlier in the same documentation it suggests a call to GetLastError() will allow you to determine whether a call to CreateMutext() created the mutex or just returned a new handle to an existing mutex: Return Value If the function succeeds, the return value is a handle to the newly created mutex object. If the function fails, the return value is NULL. To get extended error information, call GetLastError. If the mutex is a named mutex and the object existed before this function call, the return value is a handle to the existing object, GetLastError returns ERROR_ALREADY_EXISTS, bInitialOwner is ignored, and the calling thread is not granted ownership. However, if the caller has limited access rights, the function will fail with ERROR_ACCESS_DENIED and the caller should use the OpenMutex function.

  Read the article

• jquery tabbed interface breaks when using images

  - by Steve

  hello all, using jquery to create a tabbed interface. coding is quite typical: html: <div id="tabbed-interface"> <ul> <li><a href="#option1">Option1</a></li> <li><a href="#option2">Option2</a></li> <li><a href="#option3">Option3</a></li> </ul> </div> jquery: $(document).ready(function(){ $('#tabbed-interface li:first').addClass('active'); $('#tabbed-interface div').not(':first').hide(); $('#tabbed-interface>ul>li>a').click(function(event){ $('#tabbed-interface>ul>li').removeClass('active'); $(event.target).parent().addClass('active'); $('#tabbed-interface>div').fadeOut().filter(this.hash).fadeIn(250); return false;});}); css: ul li {background: #232323; list-style: none; border: 1px solid #616161; } ul li.active {background: none; list-style: none; border: 1px solid: #616161; border-bottom: 1px solid #121212; z-index: 1; } as you can see, all this does is add the class 'active' to the li that is clicked, and this corresponds to whether a background is shown or not. this works perfectly with text, but i am required to use non standard fonts. when i try to side step the issue using transparent .png images, it is unreliable. For instance, changing the HTML to: <div id="tabbed-interface"> <ul> <li><a href="#option1"><img src="option1.png" /></a></li>

  Read the article

• How to prevent multiple definitions in C?

  - by Jordi

  I'm a C newbie and I was just trying to write a console application with Code::Blocks. Here's the (simplified) code: main.c: #include <stdio.h> #include <stdlib.h> #include "test.c" // include not necessary for error in Code::Blocks int main() { //t = test(); // calling of method also not necessary return 0; } test.c: void test() {} When I try to build this program, it gives the following errors: *path*\test.c|1|multiple definition of `_ test'| obj\Debug\main.o:*path*\test.c|1|first defined here| There is no way that I'm multiply defining test (although I don't know where the underscore is coming from) and it seems highly unlikely that the definition is somehow included twice. This is all the code there is. I've ruled out that this error is due to some naming conflict with other functions or files being called test or test.c. Note that the multiple and the first definition are on the same line in the same file. Does anyone know what is causing this and what I can do about it? Thanks!

  Read the article

• Question regarding parent/child relationships with dynamically generated checkboxes using jquery

  - by Jeff

  I have a form of checkboxes, that is dynamically generated based on the users content. Sections of checkboxes are broken up by categories, and each category has projects within. For database purposes, the category values have checkboxes, that are hidden. IF a category has sub items that have checkboxes that are checked, THEN the category checkbox is checked as well. I have gotten this working ok using the JQuery .click(), but I can't figure out how to do it when the page loads. Here is my code for when a checkbox is actually clicked: $(".project").click(function() { if($(this).is(":checked") && $(this).hasClass("project")) { $(this).parent().parent().children(':first').attr('checked', true); }else if(!$(this).parent().children('.project').is(":checked")){ $(this).parent().parent().children(':first').attr('checked', false); } }); Now when I am editing the status of these boxes (meaning after they have been saved to the db) the category boxes are not showing up as checked even though their children projects are checked. What can I do to make it so that my category box will be checked at load time if that category's child is checked? Part of the problem I think is with the dynamically changing parent child setup, how can I find the parent box in order to have it checked? Thanks!

  Read the article

• Can anyone explain this strange behaviour?

  - by partizan

  Hi, guys. Here is the example with comments: class Program { // first version of structure public struct D1 { public double d; public int f; } // during some changes in code then we got D2 from D1 // Field f type became double while it was int before public struct D2 { public double d; public double f; } static void Main(string[] args) { // Scenario with the first version D1 a = new D1(); D1 b = new D1(); a.f = b.f = 1; a.d = 0.0; b.d = -0.0; bool r1 = a.Equals(b); // gives true, all is ok // The same scenario with the new one D2 c = new D2(); D2 d = new D2(); c.f = d.f = 1; c.d = 0.0; d.d = -0.0; bool r2 = c.Equals(d); // false! this is not the expected result } } So, what do you think about this?

  Read the article

• what exactly is this.id ?

  - by kwokwai

  Hi all, I was doing some dynamic effect on DIV using JQuery when I found that the returned value of this.id varied from function to function. I got two sets of simple parent-child DIV tags like this: <DIV ID="row"> <DIV ID="c1"> <Input type="radio" name="testing" id="testing" VALUE="1">testing1 </DIV> </DIV> <DIV ID="row"> <DIV ID="c2"> <Input type="radio" name="testing" id="testing" VALUE="2">testing2 </DIV> </DIV> Code 1. $('#row DIV').mouseover(function(){ radio_btns.each(function() { $('#row DIV).addClass('testing'); // worked }); }); Code 2. $('#row DIV').mouseover(function(){ var childDivID = this.id; radio_btns.each(function() { $('#'+childDivID).parent('DIV').addClass('testing'); // didn't work }); }); I don't understand why only the first code couldn work and highlighted all the "row" DIV, but the first code failed to do so?

  Read the article

• AngularJS: Using Shared Service(with $resource) to share data between controllers, but how to define callback functions?

  - by shaunlim

  Note: I also posted this question on the AngularJS mailing list here: https://groups.google.com/forum/#!topic/angular/UC8_pZsdn2U Hi All, I'm building my first AngularJS app and am not very familiar with Javascript to begin with so any guidance will be much appreciated :) My App has two controllers, ClientController and CountryController. In CountryController, I'm retrieving a list of countries from a CountryService that uses the $resource object. This works fine, but I want to be able to share the list of countries with the ClientController. After some research, I read that I should use the CountryService to store the data and inject that service into both controllers. This was the code I had before: CountryService: services.factory('CountryService', function($resource) { return $resource('http://localhost:port/restwrapper/client.json', {port: ':8080'}); }); CountryController: //Get list of countries //inherently async query using deferred promise $scope.countries = CountryService.query(function(result){ //preselected first entry as default $scope.selected.country = $scope.countries[0]; }); And after my changes, they look like this: CountryService: services.factory('CountryService', function($resource) { var countryService = {}; var data; var resource = $resource('http://localhost:port/restwrapper/country.json', {port: ':8080'}); var countries = function() { data = resource.query(); return data; } return { getCountries: function() { if(data) { console.log("returning cached data"); return data; } else { console.log("getting countries from server"); return countries(); } } }; }); CountryController: $scope.countries = CountryService.getCountries(function(result){ console.log("i need a callback function here..."); }); The problem is that I used to be able to use the callback function in $resource.query() to preselect a default selection, but now that I've moved the query() call to within my CountryService, I seemed to have lost what. What's the best way to go about solving this problem? Thanks for your help, Shaun

  Read the article

• Adding date to multiple fields via datepicker

  - by Andy

  i have a form in drupal with jquery based date module. there are multiple fields with date picker enabled. i want to set the value of all of them (they all have class .date-popup-init) to the value of the first field (#edit-field, the 'from' date) when that field is set. my code so far: <script type="text/javascript"> var DatePicked = function() { var firstdate = $("#edit-field"); var updater = firstdate.datepicker("getDate"); $(".date-popup-init").each(function(){ $(this).datepicker("setDate", updater); }); } $(function() { $("#edit-field").datepicker({ onSelect: DatePicked }); }); </script> this seems to randomly work; it sets the date of some fields to the value of #edit-field, seemingly different fields each time. also, the form adds more datepicker-enabled fields via ajax. is there any way to ensure that all these new fields, when they load, pick up the value of #edit-field as well? disclaimer: last night was my first attempt at javascript of any kind. i have a basic idea now. the above was cobbled through countless google examples.

  Read the article

• hasAndBelongsToMany only working one way

  - by Cameron

  In my application I have users that are able to be friends with other users. This is controlled with a users table and a friends_users table. The friends_users table has the following columns: id, user_id, friend_id, status And the model User looks like: public $hasAndBelongsToMany = array( 'Friend'=>array( 'className' => 'User', 'joinTable' => 'friends_users', 'foreignKey' => 'user_id', 'associationForeignKey' => 'friend_id' ) ); This seems to work fine when viewing the Users for a user who is in the user_id column, but doesn't work the other way around, i.e. in reverse... Any ideas why? Here is the method I use to list the friends for a user: $user = $this->User->find('first', array( 'conditions' => array('User.id' => $this->Auth->user('id')), 'contain'=>'Profile' )); $friends = $this->User->find('first', array( 'conditions'=>array( 'User.id'=>$user['User']['id'] ), 'contain'=>array( 'Profile', 'Friend'=>array( 'Profile', 'conditions'=>array( 'FriendsUser.status'=>1 ) ) ) ) ); $this->set('friends', $friends);

  Read the article

• Who deletes the copied instance in + operator ? (c++)

  - by Dima

  Hello, I searched how to implement + operator properly all over the internet and all the results i found do the following steps : const MyClass MyClass::operator+(const MyClass &other) const { MyClass result = *this; // Make a copy of myself. Same as MyClass result(*this); result += other; // Use += to add other to the copy. return result; // All done! } I have few questions about this "process" : Isn't that stupid to implement + operator this way, it calls the assignment operator(which copies the class) in the first line and then the copy constructor in the return (which also copies the class , due to the fact that the return is by value, so it destroys the first copy and creates a new one.. which is frankly not really smart ... ) When i write a=b+c, the b+c part creates a new copy of the class, then the 'a=' part copies the copy to himself. who deletes the copy that b+c created ? Is there a better way to implement + operator without coping the class twice, and also without any memory issues ? thanks in advance

  Read the article

• There is a Default instance of form in VB.Net but not in C#, WHY?

  - by Shekhar_Pro

  I'm just curious to know that there is The (Name) property, which represents the name of the Form class.This property is used within the namespace to uniquely identify the class that the Form is an instance of and, in the case of Visual Basic, is used to access the default instance of the form. Now where this Default Instance come from, why can't C# have a equivalent method to this. Also for example to show a form in C# we do something like this: //Only method Form1 frm = new Form1(); frm.Show(); But in VB.Net we have both ways to do it: //'First common method (used slash because editor wouldn't format it properly) Form1.Show(); //'Second method Dim frm as New Form1(); frm.Show(); My question comes from this first method. What is this Form1, is it an instance of Form1 or the Form1 class itself. Now as i mentioned above the Form name is the Default instance in VB.Net. But we also know that Form1 is a class defined in Designer so how can the names be same for both the Instance and class name. If Form1 is Class then there is no (Static\Shared) method named Show(). So where does this method come from. And finally why C# can't have an equivalent of this. If there some mistake in my question Please let me know *I've checked this on stackoverflow, but couldn't find an answer to this.If you do find then please give a link to it.*

  Read the article

• Get Browser to send both If-None-Match and If-Modified-Since

  - by Glen

  My Browser isn't sending back an If-Modified-Since Header for PHP generated Content on the first request my script sends: (Status-Line) HTTP/1.1 200 OK Date Thu, 21 Jan 2010 08:55:25 GMT Server Apache/2.2.11 (Win32) PHP/5.2.9-1 X-Powered-By PHP/5.2.9-1 Pragma no-cache x-ua-compatible IE=8;FF=3;OtherUA=4 Last-Modfied Sat, 02 Jan 2010 02:02:20 GMT Content-Length 28453 Etag b98e0795b509be20146f58e06fbb624f Keep-Alive timeout=5, max=90 Connection Keep-Alive Content-Type image/png it on the second request it sends: (Request-Line) GET /kincumberunitingchurch/banner_image.php?id=1 HTTP/1.1 Host localhost User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.0.17) Gecko/2009122116 Firefox/3.0.17 Accept image/png,image/*;q=0.8,*/*;q=0.5 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 300 Connection keep-alive Referer http://localhost/kincumberunitingchurch/index.php?sid=tgl9jq3f71nau3cj9vps6pna03 Cookie sid=tgl9jq3f71nau3cj9vps6pna03; PHPSESSID=m0jvven6d7l65pl6odm9ecfnt4 If-None-Match b98e0795b509be20146f58e06fbb624f Cache-Control max-age=0 for other files the sever sends first: (Status-Line) HTTP/1.1 200 OK Date Thu, 21 Jan 2010 08:55:25 GMT Server Apache/2.2.11 (Win32) PHP/5.2.9-1 Last-Modified Wed, 30 Dec 2009 02:40:58 GMT Etag "1000000013d35-40d9-47be9117f6280" Accept-Ranges bytes Content-Length 16601 Keep-Alive timeout=5, max=84 Connection Keep-Alive Content-Type image/png and my browser send the following on the next request: (Request-Line) GET /kincumberunitingchurch/img/cbuttons.png HTTP/1.1 Host localhost User-Agent Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.0.17) Gecko/2009122116 Firefox/3.0.17 Accept image/png,image/*;q=0.8,*/*;q=0.5 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 300 Connection keep-alive Referer http://localhost/kincumberunitingchurch/mystyle.css Cookie sid=tgl9jq3f71nau3cj9vps6pna03; PHPSESSID=m0jvven6d7l65pl6odm9ecfnt4 If-Modified-Since Wed, 30 Dec 2009 02:40:58 GMT If-None-Match "1000000013d35-40d9-47be9117f6280" Cache-Control max-age=0 why would it send the If-Modified-Since header

  Read the article

• My treeview Data is Not changing.

  - by Vibin Jith

  Hai , I am trying to display the user permission in a treeview.For each user permissions are stored in the database as xml file. In the page, a Combo box used to list the users and a treeView used to bind the Permission xml. When the user get selected in the combo box , i took the xml from the database and connect with xmlDatasource and bind with the treeView. What happening is , First time the TreeView fill with the xml nodes and another time it will not work. For the first selection it's ok. Anothers selections are not effected by the treeview. The code is debugging. No problem. Can you just tell ,why the treeview datasource is not updating. I used this code .. Dim permissionRoot = From permissionNode In MyUser.UserPermissionXml.Root.Elements("menuNode") XmlTreeViewSource.Data = permissionRoot(0).ToString trvPermission.DataSource = XmlTreeViewSource trvPermission.DataBind() SetPermission(trvPermission.Nodes(0)) The markups <asp:TreeView ID="trvPermission" runat="server" ExpandDepth="2" ShowCheckBoxes="All" ShowLines="True" ForeColor="#005782" > <DataBindings> <asp:TreeNodeBinding DataMember="menuNode" TextField="title" ValueField="value" /> </DataBindings> </asp:TreeView>

  Read the article

• Pythagoras tree with g2d

  - by owca

  I'm trying to build my first fractal (Pythagoras Tree): in Java using Graphics2D. Here's what I have now : import java.awt.*; import java.awt.geom.*; import javax.swing.*; import java.util.Scanner; public class Main { public static void main(String[] args) { int i=0; Scanner scanner = new Scanner(System.in); System.out.println("Give amount of steps: "); i = scanner.nextInt(); new Pitagoras(i); } } class Pitagoras extends JFrame { private int powt, counter; public Pitagoras(int i) { super("Pythagoras Tree."); setSize(1000, 1000); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setVisible(true); powt = i; } private void paintIt(Graphics2D g) { double p1=450, p2=800, size=200; for (int i = 0; i < powt; i++) { if (i == 0) { g.drawRect((int)p1, (int)p2, (int)size, (int)size); counter++; } else{ if( i%2 == 0){ //here I must draw two squares } else{ //here I must draw right triangle } } } } @Override public void paint(Graphics graph) { Graphics2D g = (Graphics2D)graph; paintIt(g); } So basically I set number of steps, and then draw first square (p1, p2 and size). Then if step is odd I need to build right triangle on the top of square. If step is even I need to build two squares on free sides of the triangle. What method should I choose now for drawing both triangle and squares ? I was thinking about drawing triangle with simple lines transforming them with AffineTransform but I'm not sure if it's doable and it doesn't solve drawing squares.

  Read the article

< Previous Page | 428 429 430 431 432 433 434 435 436 437 438 439  | Next Page >