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• Generate A Simple Read-Only DAL?

  - by David

  I've been looking around for a simple solution to this, trying my best to lean towards something like NHibernate, but so far everything I've found seems to be trying to solve a slightly different problem. Here's what I'm looking at in my current project: We have an IBM iSeries database as a primary repository for a third party software suite used for our core business (a financial institution). Part of what my team does is write applications that report on or key off of a lot of this data in some way. In the past, we've been manually creating ADO .NET connections (we're using .NET 3.5 and Visual Studio 2008, by the way) and manually writing queries, etc. Moving forward, I'd like to simplify the process of getting data from there for the development team. Rather than creating connections and queries and all that each time, I'd much rather a developer be able to simply do something like this: var something = (from t in TableName select t); And, ideally, they'd just get some IQueryable or IEnumerable of generated entities. This would be done inside a new domain core that I'm building where these entities would live and the applications would interface with it through a request/response service layer. A few things to note are: The entities that correspond to the database tables should be generated once and we'd prefer to manually keep them updated over time. That is, if columns/tables are added to the database then we shouldn't have to do anything. (If some are deleted, of course, it will break, but that's fine.) But if we need to use a new column, we should be able to just add it to the necessary class(es) without having to re-gen the whole thing. The whole thing should be SELECT-only. We're not doing a full DAL here because we don't want to be able to break anything in the database (even accidentally). We don't need any kind of mapping between our domain objects and the generated entity types. The domain barely covers a fraction of the data that's in there, most of it we'll never need, and we would rather just create re-usable maps manually over time. I already have a logical separation for the DAL where my "repository" classes return domain objects, I'm just looking for a better alternative to manual ADO to be used inside the repository classes. Any suggestions? It seems like what I'm doing is just enough outside the normal demand for DAL/ORM tools/tutorials online that I haven't been able to find anything. Or maybe I'm just overlooking something obvious?

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• NSNotifications vs delegate for multiple instances of same protocol

  - by Brent Traut

  I could use some architectural advice. I've run into the following problem a few times now and I've never found a truly elegant way to solve it. The issue, described at the highest level possible:I have a parent class that would like to act as the delegate for multiple children (all using the same protocol), but when the children call methods on the parent, the parent no longer knows which child is making the call. I would like to use loose coupling (delegates/protocols or notifications) rather than direct calls. I don't need multiple handlers, so notifications seem like they might be overkill. To illustrate the problem, let me try a super-simplified example: I start with a parent view controller (and corresponding view). I create three child views and insert each of them into the parent view. I would like the parent view controller to be notified whenever the user touches one of the children. There are a few options to notify the parent: Define a protocol. The parent implements the protocol and sets itself as the delegate to each of the children. When the user touches a child view, its view controller calls its delegate (the parent). In this case, the parent is notified that a view is touched, but it doesn't know which one. Not good enough. Same as #1, but define the methods in the protocol to also pass some sort of identifier. When the child tells its delegate that it was touched, it also passes a pointer to itself. This way, the parent know exactly which view was touched. It just seems really strange for an object to pass a reference to itself. Use NSNotifications. The parent defines a separate method for each of the three children and then subscribes to the "viewWasTouched" notification for each of the three children as the notification sender. The children don't need to attach themselves to the user dictionary, but they do need to send the notification with a pointer to themselves as the scope. Same as #4, but rather than using separate methods, the parent could just use one with a switch case or other branching along with the notification's sender to determine which path to take. Create multiple man-in-the-middle classes that act as the delegates to the child views and then call methods on the parent either with a pointer to the child or with some other differentiating factor. This approach doesn't seem scalable. Are any of these approaches considered best practice? I can't say for sure, but it feels like I'm missing something more obvious/elegant.

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• JPA Database strcture for internationalisation

  - by IrishDubGuy

  I am trying to get a JPA implementation of a simple approach to internationalisation. I want to have a table of translated strings that I can reference in multiple fields in multiple tables. So all text occurrences in all tables will be replaced by a reference to the translated strings table. In combination with a language id, this would give a unique row in the translated strings table for that particular field. For example, consider a schema that has entities Course and Module as follows :- Course int course_id, int name, int description Module int module_id, int name The course.name, course.description and module.name are all referencing the id field of the translated strings table :- TranslatedString int id, String lang, String content That all seems simple enough. I get one table for all strings that could be internationalised and that table is used across all the other tables. How might I do this in JPA, using eclipselink 2.4? I've looked at embedded ElementCollection, ala this... JPA 2.0: Mapping a Map - it isn't exactly what i'm after cos it looks like it is relating the translated strings table to the pk of the owning table. This means I can only have one translatable string field per entity (unless I add new join columns into the translatable strings table, which defeats the point, its the opposite of what I am trying to do). I'm also not clear on how this would work across entites, presumably the id of each entity would have to use a database wide sequence to ensure uniqueness of the translatable strings table. BTW, I tried the example as laid out in that link and it didn't work for me - as soon as the entity had a localizedString map added, persisting it caused the client side to bomb but no obvious error on the server side and nothing persisted in the DB :S I been around the houses on this about 9 hours so far, I've looked at this Internationalization with Hibernate which appears to be trying to do the same thing as the link above (without the table definitions it hard to see what he achieved). Any help would be gratefully achieved at this point... Edit 1 - re AMS anwser below, I'm not sure that really addresses the issue. In his example it leaves the storing of the description text to some other process. The idea of this type of approach is that the entity object takes the text and locale and this (somehow!) ends up in the translatable strings table. In the first link I gave, the guy is attempting to do this by using an embedded map, which I feel is the right approach. His way though has two issues - one it doesn't seem to work! and two if it did work, it is storing the FK in the embedded table instead of the other way round (I think, I can't get it to run so I can't see exactly how it persists). I suspect the correct approach ends up with a map reference in place of each text that needs translating (the map being locale-content), but I can't see how to do this in a way that allows for multiple maps in one entity (without having corresponding multiple columns in the translatable strings table)...

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• Visual Studio 2010 and Test Driven Development

  - by devoured elysium

  I'm making my first steps in Test Driven Development with Visual Studio. I have some questions regarding how to implement generic classes with VS 2010. First, let's say I want to implement my own version of an ArrayList. I start by creating the following test (I'm using in this case MSTest): [TestMethod] public void Add_10_Items_Remove_10_Items_Check_Size_Is_Zero() { var myArrayList = new MyArrayList<int>(); for (int i = 0; i < 10; ++i) { myArrayList.Add(i); } for (int i = 0; i < 10; ++i) { myArrayList.RemoveAt(0); } int expected = 0; int actual = myArrayList.Size; Assert.AreEqual(expected, actual); } I'm using VS 2010 ability to hit ctrl + . and have it implement classes/methods on the go. I have been getting some trouble when implementing generic classes. For example, when I define an .Add(10) method, VS doesn't know if I intend a generic method(as the class is generic) or an Add(int number) method. Is there any way to differentiate this? The same can happen with return types. Let's assume I'm implementing a MyStack stack and I want to test if after I push and element and pop it, the stack is still empty. We all know pop should return something, but usually, the code of this test shouldn't care for it. Visual Studio would then think that pop is a void method, which in fact is not what one would want. How to deal with this? For each method, should I start by making tests that are "very specific" such as is obvious the method should return something so I don't get this kind of ambiguity? Even if not using the result, should I have something like int popValue = myStack.Pop() ? How should I do tests to generic classes? Only test with one generic kind of type? I have been using ints, as they are easy to use, but should I also test with different kinds of objects? How do you usually approach this? I see there is a popular tool called TestDriven for .NET. With VS 2010 release, is it still useful, or a lot of its features are now part of VS 2010, rendering it kinda useless? Thanks

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• Simplifying const Overloading?

  - by templatetypedef

  Hello all- I've been teaching a C++ programming class for many years now and one of the trickiest things to explain to students is const overloading. I commonly use the example of a vector-like class and its operator[] function: template <typename T> class Vector { public: T& operator[] (size_t index); const T& operator[] (size_t index) const; }; I have little to no trouble explaining why it is that two versions of the operator[] function are needed, but in trying to explain how to unify the two implementations together I often find myself wasting a lot of time with language arcana. The problem is that the only good, reliable way that I know how to implement one of these functions in terms of the other is with the const_cast/static_cast trick: template <typename T> const T& Vector<T>::operator[] (size_t index) const { /* ... your implementation here ... */ } template <typename T> T& Vector<T>::operator[] (size_t index) { return const_cast<T&>(static_cast<const Vector&>(*this)[index]); } The problem with this setup is that it's extremely tricky to explain and not at all intuitively obvious. When you explain it as "cast to const, then call the const version, then strip off constness" it's a little easier to understand, but the actual syntax is frightening,. Explaining what const_cast is, why it's appropriate here, and why it's almost universally inappropriate elsewhere usually takes me five to ten minutes of lecture time, and making sense of this whole expression often requires more effort than the difference between const T* and T* const. I feel that students need to know about const-overloading and how to do it without needlessly duplicating the code in the two functions, but this trick seems a bit excessive in an introductory C++ programming course. My question is this - is there a simpler way to implement const-overloaded functions in terms of one another? Or is there a simpler way of explaining this existing trick to students? Thanks so much!

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• 'Scanner' does not name a type error in g++

  - by Max

  Hi. I'm trying to compile code in g++ and I get the following errors: In file included from scanner.hpp:8, from scanner.cpp:5: parser.hpp:14: error: ‘Scanner’ does not name a type parser.hpp:15: error: ‘Token’ does not name a type Here's my g++ command: g++ parser.cpp scanner.cpp -Wall Here's parser.hpp: #ifndef PARSER_HPP #define PARSER_HPP #include <string> #include <map> #include "scanner.hpp" using std::string; class Parser { // Member Variables private: Scanner lex; // Lexical analyzer Token look; // tracks the current lookahead token // Member Functions <some function declarations> }; #endif and here's scanner.hpp: #ifndef SCANNER_HPP #define SCANNER_HPP #include <iostream> #include <cctype> #include <string> #include <map> #include "parser.hpp" using std::string; using std::map; enum { // reserved words BOOL, ELSE, IF, TRUE, WHILE, DO, FALSE, INT, VOID, // punctuation and operators LPAREN, RPAREN, LBRACK, RBRACK, LBRACE, RBRACE, SEMI, COMMA, PLUS, MINUS, TIMES, DIV, MOD, AND, OR, NOT, IS, ADDR, EQ, NE, LT, GT, LE, GE, // symbolic constants NUM, ID, ENDFILE, ERROR }; class Token { public: int tag; int value; string lexeme; Token() {tag = 0;} Token(int t) {tag = t;} }; class Num : public Token { public: Num(int v) {tag = NUM; value = v;} }; class Word : public Token { public: Word() {tag = 0; lexeme = "default";} Word(int t, string l) {tag = t; lexeme = l;} }; class Scanner { private: int line; // which line the compiler is currently on int depth; // how deep in the parse tree the compiler is map<string,Word> words; // list of reserved words and used identifiers // Member Functions public: Scanner(); Token scan(); string printTag(int); friend class Parser; }; #endif anyone see the problem? I feel like I'm missing something incredibly obvious.

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• cellForRowAtIndexPath not being called, but rowsInSections is and it's delegate is set

  - by Jhorra

  I searched around prior to posting this and made sure I hadn't missed anything obvious, though I have a feeling I am missing something basic. I'm using this as a sidebar navigation view. I tried making them static cells and pre-populating them, but they were blank that way as well. When I do it this way I can see everything gets called except that. I've tried deleting it and re-adding it. #import "acxSideBarController.h" @interface acxSideBarController () @end @implementation acxSideBarController @synthesize sidebarDelegate = _sidebarDelegate; - (id)initWithStyle:(UITableViewStyle)style { self = [super initWithStyle:style]; if (self) { // Custom initialization } return self; } - (void)viewDidLoad { [super viewDidLoad]; if ([self.sidebarDelegate respondsToSelector:@selector(lastSelectedIndexPathForSidebarViewController:)]) { NSIndexPath *indexPath = 0; [self.tableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionNone]; } self.tableView.backgroundColor = [UIColor underPageBackgroundColor]; self.tableView.dataSource = self; self.tableView.delegate = self; } - (void)viewDidUnload { [super viewDidUnload]; } - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return (interfaceOrientation == UIInterfaceOrientationPortrait); } #pragma mark - Table view data source - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 3; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { if(section == 0) return 2; else if(section == 1) return 1; else return 1; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"linkCell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; } NSString *name = @""; if(indexPath.section == 1) name = @"Inbox"; else if(indexPath.section == 2) name = @"Logout"; else { if(indexPath.row == 0) name = @"Roster"; else if(indexPath.row == 1) name = @"Environmental Variables"; } cell.textLabel.text = name; cell.textLabel.textColor = [UIColor darkTextColor]; return cell; } - (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section { if(section == 0) return @"Students"; else if(section == 1) return @"Communication"; else return @" "; } #pragma mark - Table view delegate - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { if (self.sidebarDelegate) { [self.sidebarDelegate acxSideBarController:self atIndexPath:indexPath]; } } @end If it's helpful here's the header file #import <UIKit/UIKit.h> @protocol acxSideBarControllerDelegate; @interface acxSideBarController : UITableViewController @property (nonatomic, assign) id <acxSideBarControllerDelegate> sidebarDelegate; @end @protocol acxSideBarControllerDelegate <NSObject> - (void)acxSideBarController:(acxSideBarController *)acxSideBarController atIndexPath:(NSIndexPath *)indexPath; @optional - (NSIndexPath *)lastSelectedIndexPathForacxSideBarController:(acxSideBarController *)acxSideBarController; @end

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• Authlogic Help! Registering a new user when currently logged-in as a user not working.

  - by looloobs

  Hi Just as a disclaimer I am new to rails and programming in general so apologize for misunderstanding something obvious. I have Authlogic with activation up and running. So for my site I would like my users who are logged in to be able to register other users. The new user would pick their login and password through the activation email, but the existing user needs to put them in by email, position and a couple other attributes. I want that to be done by the existing user. The problem I am running into, if I am logged in and then try and create a new user it just tries to update the existing user and doesn't create a new one. I am not sure if there is some way to fix this by having another session start??? If that is even right/possible I wouldn't know how to go about implementing it. I realize without knowing fully about my application it may be difficult to answer this, but does this even sound like the right way to go about this? Am I missing something here? Users Controller: class UsersController < ApplicationController before_filter :require_no_user, :only => [:new, :create] before_filter :require_user, :only => [:show, :edit, :update] def new @user = User.new end def create @user = User.new if @user.signup!(params) @user.deliver_activation_instructions! flash[:notice] = "Your account has been created. Please check your e-mail for your account activation instructions!" redirect_to profile_url else render :action => :new end end def show @user = @current_user end def edit @user = @current_user end def update @user = @current_user # makes our views "cleaner" and more consistent if @user.update_attributes(params[:user]) flash[:notice] = "Account updated!" redirect_to profile_url else render :action => :edit end end end My User_Session Controller: class UserSessionsController < ApplicationController before_filter :require_no_user, :only => [:new, :create] before_filter :require_user, :only => :destroy def new @user_session = UserSession.new end def create @user_session = UserSession.new(params[:user_session]) if @user_session.save flash[:notice] = "Login successful!" if @user_session.user.position == 'Battalion Commander' : redirect_to battalion_path(@user_session.user.battalion_id) else end else render :action => :new end end def destroy current_user_session.destroy flash[:notice] = "Logout successful!" redirect_back_or_default new_user_session_url end end

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• Android Progress Dialog not showing

  - by ilomambo

  This is the handler, in the main Thread, which shows and dismisses a progress dialog. public static final int SHOW = 0; public static final int DISMISS = 1; public Handler pdHandler = new Handler() { @Override public void handleMessage(Message msg) { Log.i(TAG, "+ handleMessage(msg:" + msg + ")"); switch(msg.what) { case SHOW: pd = ProgressDialog.show(LogViewer.this, "", getText(R.string.loading_msg), true); break; case DISMISS: if(pd != null) { pd.dismiss(); pd = null; } break; } } }; The message to show the progress is: pdHandler.sendMessage(pdHandler.obtainMessage(SHOW)); The message to dismiss it is: pdHandler.sendMessage(pdHandler.obtainMessage(DISMISS)); It works well when I call it before I start an AsyncTask, the AsyncTask onPostExecute() dismisses it. But when it runs within a runnable (runOnUiThread), the dialog does not show. Examining the pd variable on the debugger, it shows that is is created, it is running and it is visible, but in practice it is not visible. Any suggestion? UPDATE: I did the obvious test I should have done in the first place. I commented the DISMISS message. And the progress dialog did show up. It appeared too late, after the runnable was finished. I undestand now that the DISMISS message did dismiss the not-yet-visible ProgressDialog, that's why I did not see it. The question becomes now: I need the ProgressDialog to show BEFORE the runnable code is executed. And it is not so straight forward. My call hierarchy is like this: onScrollEventChanged --> runOnUiThread ( --> checkScrollLimits --> if need to scroll show ProgressDialog "Loading" get new data into table dismiss ProgressDIalog ) I tried something like this: onScrollEventChanged --> checkScrollLimits --> if need to scroll show ProgressDialog "Loading" --> runOnUiThread ( get new data into table dismiss ProgressDIalog ) But still the dismiss message got there before the ProgressDialog could show. According to Logcat there is a five second interval between the arrival of the SHOW message and the arrival of the DISMISS message. UPDATE II: I though I will use the isShowing() method of ProgressDIalog pd = ProgressDialog.show(...) while(!pd.isShowing()); But it does not help at all, it returns true even if the dialog is not showing yet.

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• Tokenizing a string with variable whitespace

  - by Ron Holcomb

  I've read through a few threads detailing how to tokenize strings, but I'm apparently too thick to adapt their suggestions and solutions into my program. What I'm attempting to do is tokenize each line from a large (5k+) line file into two strings. Here's a sample of the lines: 0 -0.11639404 9.0702948e-05 0.00012207031 0.0001814059 0.051849365 0.00027210884 0.062103271 0.00036281179 0.034423828 0.00045351474 0.035125732 The difference I'm finding between my lines and the other sample input from other threads is that I have a variable amount of whitespace between the parts that I want to tokenize. Anyways, here's my attempt at tokenizing: #include <iostream> #include <iomanip> #include <fstream> #include <string> using namespace std; int main(int argc, char *argv[]) { ifstream input; ofstream output; string temp2; string temp3; input.open(argv[1]); output.open(argv[2]); if (input.is_open()) { while (!input.eof()) { getline(input, temp2, ' '); while (!isspace(temp2[0])) getline(input, temp2, ' '); getline (input, temp3, '\n'); } input.close(); cout << temp2 << endl; cout << temp3 << endl; return 0; } I've clipped it some, since the troublesome bits are here. The issue that I'm having is that temp2 never seems to catch a value. Ideally, it should get populated with the first column of numbers, but it doesn't. Instead, it is blank, and temp3 is populated with the entire line. Unfortunately, in my course we haven't learned about vectors, so I'm not quite sure how to implement them in the other solutions for this I've seen, and I'd like to not just copy-paste code for assignments to get things work without actually understanding it. So, what's the extremely obvious/already been answered/simple solution I'm missing? I'd like to stick to standard libraries that g++ uses if at all possible.

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• actionscript 2.0 input text box

  - by user1769760

  So, here's what I'm trying to do, and I, frankly, believe it should be obvious, but I can't figure it out. I am creating a very simple Artificial Intelligence simulation. And in this simulation there's an input box at the bottom of the screen (called "input" exactly). "input" has a variable in its properties that is called "inbox" (exactly). Using a key listener the script calls up a function when the enter button is pressed. This function has 2 if statements and an else statement which dictate the responses of the AI (named "nistra"). The problem is this, When I type in what I want to say, and hit enter, it always uses the second response ("lockpick" in the code below). I have tried variations on the code but I still don't see the solution. I believe the problem is that the "typein" variable holds all the format information from the text box as well as the variable, but I could be wrong, that information is in here as well, underneath the code itself. Any help I can get would be greatly appreciated. var typein = ""; //copies the text from inbox into here, this is what nistra responds to var inbox = ""; //this is where the text from the input text box goes var respond = ""; //nistra's responses go here my_listener = new Object(); // key listener my_listener.onKeyDown = function() { if(Key.isDown(13)) //enter button pressed { typein = inbox; // moves inbox into typein nistraresponse(); // calles nistra's responses } //code = Key.getCode(); //trace ("Key pressed = " + code); } Key.addListener(my_listener); // key listener ends here nistraresponse = function() // nistra's responses { trace(typein); // trace out what "typein" holds if(typein = "Hello") // if you type in "Hello" { respond = "Hello, How are you?"; } if(typein = "lockpick") // if you type in "lockpick" { respond = "Affirmative"; } else // anything else { respond = "I do not understand the command, please rephrase"; } cntxtID = setInterval(clearnistra, 5000); // calls the function that clears out nistra's response box so that her responses don't just sit there } clearnistra = function() // clears her respond box { respond = ""; clearInterval(cntxtID); } // "typein" traces out the following <TEXTFORMAT LEADING="2"><P ALIGN="CENTER"><FONT FACE="Times New Roman" SIZE="20" COLOR="#FF0000" LETTERSPACING="0" KERNING="0">test</FONT></P></TEXTFORMAT>

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• Authenticating users in iPhone app

  - by Myron

  I'm developing an HTTP api for our web application. Initially, the primary consumer of the API will be an iPhone app we're developing, but I'm designing this with future uses in mind (such as mobile apps for other platforms). I'm trying to decide on the best way to authenticate users so they can access their accounts from the iPhone. I've got a design that I think works well, but I'm no security expert, so I figured it would be good to ask for feedback here. The design of the user authentication has 3 primary goals: Good user experience: We want to allow users to enter their credentials once, and remain logged in indefinitely, until they explicitly log out. I would have considered OAuth if not for the fact that the experience from an iPhone app is pretty awful, from what I've heard (i.e. it launches the login form in Safari, then tells the user to return to the app when authentication succeeds). No need to store the user creds with the app: I always hate the idea of having the user's password stored in either plain text or symmetrically encrypted anywhere, so I don't want the app to have to store the password to pass it to the API for future API requests. Security: We definitely don't need the intense security of a banking app, but I'd obviously like this to be secure. Overall, the API is REST-inspired (i.e. treating URLs as resources, and using the HTTP methods and status codes semantically). Each request to the API must include two custom HTTP headers: an API Key (unique to each client app) and a unique device ID. The API requires all requests to be made using HTTPS, so that the headers and body are encrypted. My plan is to have an api_sessions table in my database. It has a unique constraint on the API key and unique device ID (so that a device may only be logged into a single user account through a given app) as well as a foreign key to the users table. The API will have a login endpoint, which receives the username/password and, if they match an account, logs the user in, creating an api_sessions record for the given API key and device id. Future API requests will look up the api_session using the API key and device id, and, if a record is found, treat the request as being logged in under the user account referenced by the api_session record. There will also be a logout API endpoint, which deletes the record from the api_sessions table. Does anyone see any obvious security holes in this?

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• How to reference a particular JSON in a function call.

  - by Jane Wilkie

  Hi guys! I have two javascript routines.. the first one declares some JSON and it contains a function that takes two arguments, the first argument being the json object that needs traversing and the second argument is the tab that the rendering is done in. The second routine merely passes the name of the JSON that needs traversing and tab to render in. The code is below.... <script language="JavaScript1.2" type="text/javascript"> var arr = [ {"id":"10", "class":"child-of-9", "useless":"donotneed"}, {"id":"11", "class":"child-of-10", "useless":"donotneed"}]; var arrtwo = [ {"id":"12", "class":"child-of-12", "useless":"donotneed"}, {"id":"13", "class":"child-of-13", "useless":"donotneed"}]; function render_help(json,tab){ var html=''; for(var i=0;i<json.length;i++){ var obj = json[i]; for(var key in obj){ var attrName = key; var attrValue = obj[key]; if (attrName == "id"){ html = html +'<B>'+attrValue+'</B>'+'<BR><BR>'; }else if (attrName == "class"){ html = html + attrValue + '<BR><BR>'; } } } document.getElementById(tab).innerHTML=(html); } </script> <script language="JavaScript1.2" type="text/javascript"> render_help(arr,"helptab"); </script> Various testing and strategically placed alert boxes indicate that the tab parameter is being passed and interpreted correctly. I know this because when I change .... document.getElementById(tab).innerHTML=(html); to document.getElementById(tab).innerHTML=("Howdy"); and it renders "Howdy" just fine. Putting an alert box (alert(json)) in to check the value of json yields.... [object.Object],[object.Object] The JSON object remains elusive. For the purposes of this scripting I need the JSON "arr" to be iterated over. I feel like the answer is fairly obvious so far no luck. Admittedly I am new with Javascript and I am apparently missing something. Does anyone have a clue as to what I'm overlooking here? Happy New Year to you all! Janie

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• avoiding enums as interface identifiers c++ OOP

  - by AlasdairC

  Hi I'm working on a plugin framework using dynamic loaded shared libraries which is based on Eclipse's (and probally other's) extension-point model. All plugins share similar properties (name, id, version etc) and each plugin could in theory satisfy any extension-point. The actual plugin (ie Dll) handling is managed by another library, all I am doing really is managing collections of interfaces for the application. I started by using an enum PluginType to distinguish the different interfaces, but I have quickly realised that using template functions made the code far cleaner and would leave the grunt work up to the compiler, rather than forcing me to use lots of switch {...} statements. The only issue is where I need to specify like functionality for class members - most obvious example is the default plugin which provides a particular interface. A Settings class handles all settings, including the default plugin for an interface. ie Skin newSkin = settings.GetDefault<ISkin>(); How do I store the default ISkin in a container without resorting to some other means of identifying the interface? As I mentioned above, I currently use a std::map<PluginType, IPlugin> Settings::defaults member to achieve this (where IPlugin is an abstract base class which all plugins derive from. I can then dynamic_cast to the desired interface when required, but this really smells of bad design to me and introduces more harm than good I think. would welcome any tips edit: here's an example of the current use of default plugins typedef boost::shared_ptr<ISkin> Skin; typedef boost::shared_ptr<IPlugin> Plugin; enum PluginType { skin, ..., ... } class Settings { public: void SetDefault(const PluginType type, boost::shared_ptr<IPlugin> plugin) { m_default[type] = plugin; } boost::shared_ptr<IPlugin> GetDefault(const PluginType type) { return m_default[type]; } private: std::map<PluginType, boost::shared_ptr<IPlugin> m_default; }; SkinManager::Initialize() { Plugin thedefault = g_settings.GetDefault(skinplugin); Skin defaultskin = boost::dynamic_pointer_cast<ISkin>(theskin); defaultskin->Initialize(); } I would much rather call the getdefault as the following, with automatic casting to the derived class. However I need to specialize for every class type. template<> Skin Settings::GetDefault<ISkin>() { return boost::dynamic_pointer_cast<ISkin>(m_default(skin)); }

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• Is throwing an exception a healthy way to exit?

  - by ramaseshan

  I have a setup that looks like this. class Checker { // member data Results m_results; // see below public: bool Check(); private: bool Check1(); bool Check2(); // .. so on }; Checker is a class that performs lengthy check computations for engineering analysis. Each type of check has a resultant double that the checker stores. (see below) bool Checker::Check() { // initilisations etc. Check1(); Check2(); // ... so on } A typical Check function would look like this: bool Checker::Check1() { double result; // lots of code m_results.SetCheck1Result(result); } And the results class looks something like this: class Results { double m_check1Result; double m_check2Result; // ... public: void SetCheck1Result(double d); double GetOverallResult() { return max(m_check1Result, m_check2Result, ...); } }; Note: all code is oversimplified. The Checker and Result classes were initially written to perform all checks and return an overall double result. There is now a new requirement where I only need to know if any of the results exceeds 1. If it does, subsequent checks need not be carried out(it's an optimisation). To achieve this, I could either: Modify every CheckN function to keep check for result and return. The parent Check function would keep checking m_results. OR In the Results::SetCheckNResults(), throw an exception if the value exceeds 1 and catch it at the end of Checker::Check(). The first is tedious, error prone and sub-optimal because every CheckN function further branches out into sub-checks etc. The second is non-intrusive and quick. One disadvantage is I can think of is that the Checker code may not necessarily be exception-safe(although there is no other exception being thrown anywhere else). Is there anything else that's obvious that I'm overlooking? What about the cost of throwing exceptions and stack unwinding? Is there a better 3rd option?

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• Using KnockoutJS 2.2.0 & jQuery 1.8.2 remove all bindings from all children of #someDiv

  - by Nukeface

  I'm wanting to delete All bindings (ko.cleanNode) from all child elements of a certain div. Must be a noobie question but I can't figure out how to use jQuery to loop through all childre, grand-children, great-grand-children, etc. whilst having KnockoutJS remove the bindings of all the DOM elements. I do NOT want to remove the elements from the DOM. This is a single page application, therefore the elements are pre-loaded as embedded resources and don't get resend to a client if they were to visit the page again. If a client revisits that part of the application I'll have a function rebind the necessary elements, which currently works fine. Current setup: <html> <head> //loading all resources </head> <body> //load first element using some obscure setup <div id="firsPage" data-role="page"> <div data-role="header">@Global.header</div> <div data-role="fieldcontain"> <label for="firstInput" /> <input id="firstInput some other stuff /> </div> <div data-role="datebox <!-- some settings --> > //creates table using jQuery mobile (lots of (great-)(grand-)children) </div> <div data-role="fieldcontain"> <div id="secondInput"> <div class="checklist"> <ul> <li /> <li /> </ul> </div> </div> </div> </div> //Here the whole thing starts again <div id="secondPage" data-role="page"> <!-- repeat above innerHTML in your mind ;) --> </div> //And here again! and again... </body> The problem I'm having is that bindings of the children don't seem to get "cleaned up" when i use ko.cleanNode($('#firstPage')[0]); Or when I get the Element into a variable and then format it to ko.cleanNode($element). Is there a way to do this? Been staring at it for a good few hours now, so probably overlooking a way too obvious way of doing it... Thanks!

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• Several C# Language Questions

  - by Water Cooler v2

  1) What is int? Is it any different from the struct System.Int32? I understand that the former is a C# alias (typedef or #define equivalant) for the CLR type System.Int32. Is this understanding correct? 2) When we say: IComparable x = 10; Is that like saying: IComparable x = new System.Int32(); But we can't new a struct, right? or in C like syntax: struct System.In32 *x; x=>someThing = 10; 3) What is String with a capitalized S? I see in Reflector that it is the sealed String class, which, of course, is a reference type, unlike the System.Int32 above, which is a value type. What is string, with an uncapitalized s, though? Is that also the C# alias for this class? Why can I not see the alias definitions in Reflector? 4) Try to follow me down this subtle train of thought, if you please. We know that a storage location of a particular type can only access properties and members on its interface. That means: Person p = new Customer(); p.Name = "Water Cooler v2"; // legal because as Name is defined on Person. but // illegal without an explicit cast even though the backing // store is a Customer, the storage location is of type // Person, which doesn't support the member/method being // accessed/called. p.GetTotalValueOfOrdersMade(); Now, with that inference, consider this scenario: int i = 10; // obvious System.object defines no member to // store an integer value or any other value in. // So, my question really is, when the integer is // boxed, what is the *type* it is actually boxed to. // In other words, what is the type that forms the // backing store on the heap, for this operation? object x = i; Update Thank you for your answers, Eric Gunnerson and Aaronought. I'm afraid I haven't been able to articulate my questions well enough to attract very satisfying answers. The trouble is, I do know the answers to my questions on the surface, and I am, by no means, a newbie programmer. But I have to admit, a deeper understanding to the intricacies of how a language and its underlying platform/runtime handle storage of types has eluded me for as long as I've been a programmer, even though I write correct code.

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• What's the fastest lookup algorithm for a key, pair data structure (i.e, a map)?

  - by truncheon

  In the following example a std::map structure is filled with 26 values from A - Z (for key) and 0 – 26 for value. The time taken (on my system) to lookup the last entry (10000000 times) is roughly 250 ms for the vector, and 125 ms for the map. (I compiled using release mode, with O3 option turned on for g++ 4.4) But if for some odd reason I wanted better performance than the std::map, what data structures and functions would I need to consider using? I apologize if the answer seems obvious to you, but I haven't had much experience in the performance critical aspects of C++ programming. #include <ctime> #include <map> #include <vector> #include <iostream> struct mystruct { char key; int value; mystruct(char k = 0, int v = 0) : key(k), value(v) { } }; int find(const std::vector<mystruct>& ref, char key) { for (std::vector<mystruct>::const_iterator i = ref.begin(); i != ref.end(); ++i) if (i->key == key) return i->value; return -1; } int main() { std::map<char, int> mymap; std::vector<mystruct> myvec; for (int i = 'a'; i < 'a' + 26; ++i) { mymap[i] = i - 'a'; myvec.push_back(mystruct(i, i - 'a')); } int pre = clock(); for (int i = 0; i < 10000000; ++i) { find(myvec, 'z'); } std::cout << "linear scan: milli " << clock() - pre << "\n"; pre = clock(); for (int i = 0; i < 10000000; ++i) { mymap['z']; } std::cout << "map scan: milli " << clock() - pre << "\n"; return 0; }

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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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• Unity JS - simple if statements not behaving as expected?

  - by IHazABone

  I have a simple script (please no remarks on the fact that I'm not using a switch statement or better code, this is the earliest version and written this way by a peer, I am improving it) that takes an object and moves it back and forth. For some reason, the variable time gets stuck at 249. It is probably an obvious bug with this inefficient logic, but I cannot seem to find it. var speed = 1; private var time = 0; function Start() { } function Update() { if(condition == true)moveStuff(); } function moveStuff() { var timeSwitch = false; if(time == 0)timeSwitch = false; if(time == timeSet)timeSwitch = true; if(direction == 1) { if(timeSwitch == false) { transform.Translate(Vector3.up * (Time.deltaTime * speed)); time += 1; Debug.Log(time); }else if(timeSwitch == true) { transform.Translate(Vector3.up * ((Time.deltaTime * speed) * -1)); time -= 1; Debug.Log(time); } } else if(direction == 2) { if(timeSwitch == false) { transform.Translate(Vector3.down * (Time.deltaTime * speed)); time += 1; Debug.Log("Moved down. "); }else if(timeSwitch == true){ transform.Translate(Vector3.down * ((Time.deltaTime * speed) * -1)); time -= 1; } } else if(direction == 3) { if(timeSwitch == false) { transform.Translate(Vector3.forward * (Time.deltaTime * speed)); time += 1; Debug.Log("Moved forward. "); }else if(timeSwitch == true){ transform.Translate(Vector3.forward * ((Time.deltaTime * speed) * -1)); time -= 1; } } else if(direction == 4) { if(timeSwitch == false) { transform.Translate(Vector3.back * (Time.deltaTime * speed)); time += 1; Debug.Log("Moved back. "); }else if(timeSwitch == true){ transform.Translate(Vector3.back * ((Time.deltaTime * speed) * -1)); time -= 1; } } else if(direction == 5) { if(timeSwitch == false) { transform.Translate(Vector3.right * (Time.deltaTime * speed)); time += 1; Debug.Log("Moved right. "); }else if(timeSwitch == true){ transform.Translate(Vector3.right * ((Time.deltaTime * speed) * -1)); time -= 1; } } else if(direction == 6) { if(timeSwitch == false) { transform.Translate(Vector3.left * (Time.deltaTime * speed)); time += 1; Debug.Log("Moved left. "); }else if(timeSwitch == true){ transform.Translate(Vector3.left * ((Time.deltaTime * speed) * -1)); time -= 1; } } }

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• C++ beginner question regarding chars

  - by Samwhoo

  I'm just messing around with some C++ at the moment trying to make a simple tic-tac-toe game and I'm running into a bit of a problem. This is my code: #include <iostream> using namespace std; class Square { public: char getState() const; void setState(char); Square(); ~Square(); private: char * pState; }; class Board { public: Board(); ~Board(); void printBoard() const; Square getSquare(short x, short y) const; private: Square board[3][3]; }; int main() { Board board; board.getSquare(1,2).setState('1'); board.printBoard(); return 0; } Square::Square() { pState = new char; *pState = ' '; } Square::~Square() { delete pState; } char Square::getState() const { return *pState; } void Square::setState(char set) { *pState = set; } Board::~Board() { } Board::Board() { } void Board::printBoard() const { for (int x = 0; x < 3; x++) { cout << "|"; for (int y = 0; y < 3; y++) { cout << board[x][y].getState(); } cout << "|" << endl; } } Square Board::getSquare(short x, short y) const { return board[x][y]; } Forgive me if there are blatantly obvious problems with it or it's stupidly written, this is my first program in C++ :p However, the problem is that when I try and set the square 1,2 to the char '1', it doesn't print out as a 1, it prints out as some strange character I didn't recognise. Can anyone tell me why? :) Thanks in advance.

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• jQuery validation plugin addMethod firing incorrectly

  - by LoganEtherton

  I must be missing something obvious, but everything that I've tried for this is leaving me empty handed, so I'm a bit puzzled. I'm attempting to use the jQuery validation plugin with custom validation methods, but it seems to be hit or miss. It seems that I am able to successfully add rules to a certain extent, but some of the methods are not applied. Or the specified method is not applied, and the incorrect method is instead applied. So, for example, this works without a hitch: $.validator.addMethod("emailValidation", function(value, element) { return /^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/.test(value); }, "Please enter a valid email address." ); $.validator.addMethod("password", function(value, element) { return /[^\s]{6,25}/.test(value); }, "Please enter a password between 6 and 25 characters long." ); ... $(function(){ $("#registrationForm").validate({ rules: { email: { required: true, emailValidation: true }, password: { required: true, password: true }, } }); }); Both the password validation and email validation work. But then I add, in the same exact manner, a validation test for names. So, right below where the password method ends, I add: $.validator.addMethod("name", function(value, element) { return /[^\s]{6,25}/.test(value); }, "Please enter a valid name." ); Which turns the validate call into: $(function(){ $("#registrationForm").validate({ rules: { email: { required: true, emailValidation: true }, password: { required: true, password: true }, studentFirstName: { name: true } } }); }); And suddenly, everything is only validating for names. Both the email and password fields now validate using the name method, as does the name field. This is confusing! I've added console.log calls to all methods, and indeed, it's not that one is being called after the other - the only one being called is name. I've checked and double checked that the element selection is good. I've checked that everything is groovy with the methods themselves. Any ideas?

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• Type casting int into double C++

  - by user1705380

  I am new to programming and this might be an obvious question, though i cannot for life of me figure out why my program is not returning as a double. I am suppose to write a stocks program that takes in shares of stock, whole dollar portion of price and the fraction portion. And the fraction portion is to be inputted as two int values, and include a function definition with 3 int values.The function returns the price as a double. #include <iostream> using namespace std; int price(int, int, int); int main() { int dollars, numerator, denominator, price1, shares; char ans; do { cout<<"Enter the stock price and the number of shares.\n"; cout<<"Enter the price and integers: Dollars, numerator, denominator\n"; cin>>dollars>>numerator>>denominator; cout<<"Enter the number of shares held\n"; cin>>shares; cout<<shares; price1 = price(dollars,numerator,denominator); cout<<" shares of stock with market price of "; cout<< dollars << " " << numerator<<'/'<<denominator<<endl; cout<<"have a value of " << shares * price1<<endl; cout<<"Enter either Y/y to continue"; cin>>ans; }while (ans == 'Y' || ans == 'y'); system("pause"); return 0; } int price(int dollars, int numerator, int denominator) { return dollars + numerator/static_cast<double>(denominator); }

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• curl problems in c++ class

  - by Danilo

  I read a few articles on c++ / curl here on stackoverflow and assembled the following. The main goal is to handle the whole request in an instance of a class -- and maybe later in a secondary thread. My problem is: "content_" seems to stay empty though its the same addr and HttpFetch.h: class HttpFetch { private: CURL *curl; static size_t handle(char * data, size_t size, size_t nmemb, void * p); size_t handle_impl(char * data, size_t size, size_t nmemb); public: std::string content_; static std::string url_; HttpFetch(std::string url); void start(); std::string data(); }; HttpFetch.cpp: HttpFetch::HttpFetch(std::string url) { curl_global_init(CURL_GLOBAL_ALL); //pretty obvious curl = curl_easy_init(); content_.append("Test"); std::cout << &content_ << "\n"; curl_easy_setopt(curl, CURLOPT_URL, &url); curl_easy_setopt(curl, CURLOPT_WRITEDATA, &content_); curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &HttpFetch::handle); //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); //tell curl to output its progress curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); //std::cout << &content_ << "\n"; } void HttpFetch::start() { curl_easy_perform(curl); curl_easy_cleanup(curl); } size_t HttpFetch::handle(char * data, size_t size, size_t nmemb, void * p) { std::string *stuff = reinterpret_cast<std::string*>(p); stuff->append(data, size * nmemb); std::cout << stuff << "\n"; // has content from data in it! return size * nmemb; } main.cpp: #include "HttpFetch.h" int main(int argc, const char * argv[]) { HttpFetch call = *new HttpFetch("http://www.example.com"); call.start(); ::std::cout << call.content_ << "\n" } Thanks in advance

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• Chrome is creating duplicate sessions with the same id

  - by dlwiest

  I encountered an issue while I was revising my session library today, and this might be the first time I've ever seen a browser-specific problem on a back end script. I hope somebody can shed some light. Basically how the session library works is: when instantiated, it checks for a cookie called 'id' (in the form of a uniqid result) on the client machine. If a cookie is found, the script checks that and a hashed copy of the user agent string against entries in a session table. If a matching entry is found, the script resumes the session. If no cookie named 'id' is found, or if no matching entry exists in the sessions table, the script creates both. Fairly standard, I think. Now here's the weird part: in Firefox, everything works as predicted. The user gets one session, which he'll always resume upon connection, as long as 24 hours of inactivity has not elapsed. But when I visit the page in Chrome, even though it looks the same and appears to be executing queries in the same order, I see two entries in the session table. The sessions share an agent string, but the ids are different, and timestamp logs indicate that the ghost session is being created shortly (within a second) after the one created for the user. For debugging purposes, I've been printing queries to the screen as they're executed, and this is an example of what I'm seeing when Chrome should be opening one session and is somehow opening two instead: // Attempting to resume a session SELECT id FROM sessions WHERE id = '4fd24a5cd8df12.62439982' AND agent = '9bcd5c6aac911f8bcd938a9563bc4eca' // No result, so it creates a new one INSERT INTO sessions (id, agent, start, last) VALUES ('4fd24ef0347f26.72354606', '9bcd5c6aac911f8bcd938a9563bc4eca', '1339182832', '1339182832') // Clear old sessions DELETE FROM sessions WHERE last < 1339096432 And here's what I'm seeing in the database afterward: id, agent, start, last 4fd24ef0347f26.72354606, 9bcd5c6aac911f8bcd938a9563bc4eca, 1339182832, 1339182832 4fd24ef0857f94.72251285, 9bcd5c6aac911f8bcd938a9563bc4eca, 1339182833, 1339182833 Am I missing something obvious? The only thing I can think of is that Chrome might be creating a hidden session in the background, possibly to crawl the page. If that's the case though, it could become a problem later, when I begin associating active sessions with entries in the users table. I've been looking for possible bugs in my script, but I haven't found anything so far, and everything works as expected in Firefox.

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