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  • How do I debug JavaScript .onlick event?

    - by user3700824
    I'm learning JavaScript but seem to be having a problem. I have a piece of code that is executed when the page is fully loaded. The function then gathers all the button elements on my HTML page. From here I loop through getting each button's title attribute and then assign an onclick event to the button that is equal to a function that writes to the console.log with the title. I have tried various ways of doing this but it is not working. Here is the JavaScript code that I'm working with. Currently all it does is loop through calling the function and logging the tile to the console.log, but this is not supposed to happen. Each time I click the button it should call the function with its title and log that. window.onload = myPageIsReady; function myPageIsReady(){ var myList = document.getElementsByTagName("button"); var myTitle = []; for(var i = 0; i < myList.length; i++){ myTitle[i] = myList[i].getAttribute("title"); myList[i].onclick = getMyTitle(myTitle[i]); }; function getMyTitle(myTitle){ console.log(myTitle); }; };

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  • The use of getters and setters for different programming languages [closed]

    - by leonhart88
    So I know there are a lot of questions on getters and setters in general, but I couldn't find something exactly like my question. I was wondering if people change the use of get/set depending on different languages. I started learning with C++ and was taught to use getters and setters. This is what I understand: In C++ (and Java?), a variable can either be public or private, but we cannot have a mix. For example, I can't have a read-only variable that can still be changed inside the class. It's either all public (can read and change it), or all private (can't read and can only change inside the class). Because of this (and possibly other reasons), we use getters and setters. In MATLAB, I can control the "setaccess" and "getaccess" properties of variables, so that I can make things read-only (can directly access the property, but can't overwrite it). In this case, I don't feel like I need a getter because I can just do class.property. Also, in Python it is considered "Pythonic" to not use getters/setters and to only put things into properties if needed. I don't really understand why its OK to have all public variables in Python, because that's opposite of what I learned when I started with C++. I'm just curious what other people's thoughts are on this. Would you use getters and setters for all languages? Would you only use it for C++/Java and do direct access in MATLAB and Python (which is what I am currently doing)? Is the second option considered bad? For my purposes, I am only referring to simple getters and setters (just return/set the value and do not do anything else). Thanks!

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  • wrap from last screen to first screen in android Launcher2

    - by poboy975
    hi, I'm learning java and android. and I've been looking at trying to wrap the last screen to the first screen in the android Launcher2. I've tried googleing, and searching here, but there really isnt much information about the launcher2 source...I've been modifying the workspace.java file, but there has been minimal effect. no wrap around so far...I have not been able to find a .xml file that also might control the hard stop when you reach the end of the screens. I'll give a small example of the code that i have been modifying. original code: public void scrollRight() { clearVacantCache(); if (mNextScreen == INVALID_SCREEN && mCurrentScreen < getChildCount() -1 && mScroller.isFinished()) { snapToScreen(mCurrentScreen + 1); } modified code: public void scrollRight() { clearVacantCache(); if (mNextScreen == INVALID_SCREEN && mCurrentScreen < getChildCount() -1 && mScroller.isFinished()) { snapToScreen(mCurrentScreen + 1); }if (mCurrentScreen == getChildCount() -1 && mScroller.isFinished()) { snapToScreen(0); I would appreciate any tips or pointers if anyone has an idea where i'm going wrong, or someplace i can search to get the answers. the code looks to me like it should work, but I'm probably missing something obvious.

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  • URL routing in an MVC framework - PHP

    - by Walderman
    I'm developing an MVC framework in PHP from scratch; mostly for the learning experience but this could easily end up in a live project. I went through this tutorial as a base and I've expanded from there. Requests are made like this: examplesite.com/controller/action/param1/param2/ and so on... And this is my .htaccess file: RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$ index.php?rt=$1 [L,QSA] So all requests go to index.php and they are routed to the correct controller and action from there. If no controller or action is given, then the default 'index' is assumed for both. I have an index controller with an index action, which is supposed to be the home page of my site. I can access it by going to examplesite.com (since the index part is assumed). It has some images, a link to a stylesheet, and some scripts. They are linked with paths relative to index.php. I thought this would be fine since all request go to index.php and all content is simply included in this page using php. This works if I go to examplesite.com. I will see all of the images and styles, and scripts will run. However, if I go to examplesite.com/index, I am routed to the correct part of the site, but all of the links don't work. Does the browser think I am in a different folder? I would like to be able to use relative paths for all of the content in my site, because otherwise I need to use absolute paths everywhere to make sure things will show up. Is this possible?

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  • Applying a function to a custom type in F#

    - by Frederik Wordenskjold
    On my journey to learning F#, I've run into a problem I cant solve. I have defined a custom type: type BinTree = | Node of int * BinTree * BinTree | Empty I have made a function which takes a tree, traverses it, and adds the elements it visits to a list, and returns it: let rec inOrder tree = seq{ match tree with | Node (data, left, right) -> yield! inOrder left yield data; yield! inOrder right | Empty -> () } |> Seq.to_list; Now I want to create a function, similar to this, which takes a tree and a function, traverses it and applies a function to each node, then returns the tree: mapInOrder : ('a -> 'b) -> 'a BinTree -> 'b BinTree This seems easy, and it probably is! But I'm not sure how to return the tree. I've tried this: let rec mapInOrder f tree = match tree with | Node(data, left, right) -> mapInOrder f left Node(f(data), left, right) mapInOrder f right | Empty -> () but this returns a unit. I havent worked with custom types before, so I'm probably missing something there!

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  • What are salesforce.com and Apex like as an application development platform?

    - by mhollers
    I have recently discovered that salesforce.com is much more than an online CRM after coming across a Morrison's Case Study in which they develop a works management application. I've been trying it out with a view to recreating our own Works Management system on the platform. My background is in Microsoft and .Net, and the obvious 1st choice would be asp.net. However, there's only really myself with .net experience and my manager with a more legacy Synergy programming background, and I am self taught and am looking at evaluating other RAD options (eg Ironspeed). the nature of the business is in the main 2-5 concurrent construction type contracts that run for 3-5 yrs each, each requiring 15-50 system users. Traditionally we have used our character based Works Mangement system for everything and tweaked it for each contract. The Salesforce licensing model on the face of it suits this sort of flexibilty, but I'm worried about the development flexibilty/learning curve and all the issues that surround lock-in. There doesn't seem to be much neutral sober analysis of the platform on the web that isn't salesforce's own material/blogs Has anyone any experience of developing an application on salesforce as compared to the more 'traditional' .Net route?

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  • Handling Apache Thrift list/map Return Types in C++

    - by initzero
    First off, I'll say I'm not the most competent C++ programmer, but I'm learning, and enjoying the power of Thrift. I've implemented a Thrift Service with some basic functions that return void, i32, and list. I'm using a Python client controlled by a Django web app to make RPC calls and it works pretty well. The generated code is pretty straight forward, except for list returns: namespace cpp Remote enum N_PROTO { N_TCP, N_UDP, N_ANY } service Rcon { i32 ping() i32 KillFlows() i32 RestartDispatch() i32 PrintActiveFlows() i32 PrintActiveListeners(1:i32 proto) list<string> ListAllFlows() } The generated signatures from Rcon.h: int32_t ping(); int32_t KillFlows(); int32_t RestartDispatch(); int32_t PrintActiveFlows(); int32_t PrintActiveListeners(const int32_t proto); int64_t ListenerBytesReceived(const int32_t id); void ListAllFlows(std::vector<std::string> & _return); As you see, the ListAllFlows() function generated takes a reference to a vector of strings. I guess I expect it to return a vector of strings as laid out in the .thrift description. I'm wondering if I am meant to provide the function a vector of strings to modify and then Thrift will handle returning it to my client despite the function returning void. I can find absolutely no resources or example usages of Thrift list< types in C++. Any guidance would be appreciated.

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  • Is there a better way to change user password in cakephp using Auth?

    - by sipiatti
    Hi, I am learning cakephp by myself. I tried to create a user controller with a changepassword function. It works, but I am not sure if this is the best way, and I could not googled up useful tutorials on this. Here is my code: class UsersController extends AppController { var $name = 'Users'; function login() { } function logout() { $this->redirect($this->Auth->logout()); } function changepassword() { $session=$this->Session->read(); $id=$session['Auth']['User']['id']; $user=$this->User->find('first',array('conditions' => array('id' => $id))); $this->set('user',$user); if (!empty($this->data)) { if ($this->Auth->password($this->data['User']['password'])==$user['User']['password']) { if ($this->data['User']['passwordn']==$this->data['User']['password2']) { // Passwords match, continue processing $data=$this->data; $this->data=$user; $this->data['User']['password']=$this->Auth->password($data['User']['passwordn']); $this->User->id=$id; $this->User->save($this->data); $this->Session->setFlash('Password changed.'); $this->redirect(array('controller'=>'Toners','action' => 'index')); } else { $this->Session->setFlash('New passwords differ.'); } } else { $this->Session->setFlash('Typed passwords did not match.'); } } } } password is the old password, passwordn is the new one, password2 is the new one retyped. Is there any other, more coomon way to do it in cake?

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  • Should frontend and backend be handled by different controllers?

    - by DR
    In my previous learning projects I always used a single controller, but now I wonder if that is good practice or even always possible. In all RESTful Rails tutorials the controllers have a show, an edit and an index view. If an authorized user is logged on, the edit view becomes available and the index view shows additional data manipulation controls, like a delete button or a link to the edit view. Now I have a Rails application which falls exactly into this pattern, but the index view is not reusable: The normal user sees a flashy index page with lots of pictures, complex layout, no Javascript requirement, ... The Admin user index has a completly different minimalistic design, jQuery table and lots of additional data, ... Now I'm not sure how to handle this case. I can think of the following: Single controller, single view: The view is split into two large blocks/partials using an if statement. Single controller, two views: index and index_admin. Two different controllers: BookController and BookAdminController None of these solutions seems perfect, but for now I'm inclined to use the 3rd option. What's the preferred way to do this?

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  • Cross Platform C library for GUI Apps?

    - by Moshe
    Free of charge, simple to learn/use, Cross Platform C library for GUI Apps? Am I looking for Qt? Bonus question: Can I develop with the said library/toolkit on Mac then recompile on PC/Linux? Super Bonus Question: Link to tutorial and/or download of said library. (RE)EDIT: The truth is that I'm in the process of catching up on the C family (coming from web development - XHTML/PHP/MySQL) to learn iPhone development. I do understand that C is not C++ or ObjectiveC but I want to keep the learning curve as simple as possible. Not to get too off topic, but I am also on the lookout for good starter books and websites. I've found this so far. I'm trying to kill many birds with one stone here. I don understand that there are platform specific extensions, but I will try to avoid those for porting purposes The idea is that I want to write the code on one machine and just compile thrice. (Mac/Win/Linux) If Objective C will compile on Windows and Linux as well as OS X then that's good. If I must use C++, that's also fine. EDIT: Link to QT Please...

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  • Decimal To Octal Converter, last digit issue

    - by Srishan Supertramp
    I tried making a C program to convert a user entered decimal number to octal. I wrote the C code with my own logic without any research of how other users try to do it. It works fine for the number 601 and some other numbers but for most numbers it returns the octal equivalent with the last digit being 1 less than it should be. For 75 it returns 112 instead of 113. I realize using printf with %o gets the job done but it's kind of defeating the purpose of learning to program. Here's my code: #include <stdio.h> #include <math.h> /* converting decimal to octal */ int main() { int n,x,y,p,s; printf("Enter a decimal number "); scanf("%d",&x); s=0;p=0; while (x!=0) { y=x%8; s=s+y*pow(10,p); x=(x-y)/8; p=p+1; } printf("the octal equivalent is: %d\n",s); getch(); return 0; }

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  • How do I capture keystrokes on the web?

    - by Sean
    Using PHP, JS, or HTML (or something similar) how would I capture keystokes? Such as if the user presses ctrl+f or maybe even just f, a certain function will happen. ++++++++++++++++++++++++EDIT+++++++++++++++++++ Ok, so is this correct, because I can't get it to work. And I apologize for my n00bness is this is an easy question, new to jQuery and still learning more and more about JS. <script> var element = document.getElementById('capture'); element.onkeypress = function(e) { var ev = e || event; if(ev.keyCode == 70) { alert("hello"); } } </script> <div id="capture"> Hello, Testing 123 </div> ++++++++++++++++EDIT++++++++++++++++++ Here is everything, but I can't get it to work: <link rel="icon" href="favicon.ico" type="image/x-icon"> <style> * { margin: 0px } div { height: 250px; width: 630px; overflow: hidden; vertical-align: top; position: relative; background-color: #999; } iframe { position: absolute; left: -50px; top: -130px; } </style> <script> document.getElementsByTagName('body')[0].onkeyup = function(e) { var ev = e || event; if(ev.keyCode == 70 && ev.ctrlKey) { //control+f alert("hello"); } } </script> <div id="capture"> Hello, Testing 123<!--<iframe src="http://www.pandora.com/" scrolling="no" width="1000" height="515"frameborder="0"></iframe>--> </div>

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  • Scanning, Checking, Converting, Copying values ... How to ? -- C --

    - by ZaZu
    Hi there, Its been a while now and im still trying to get a certain code to work. I asked some question about different commands etc. before, but now I hope this is the final one (combining all questions in one code). I basically want to : *Scan an input (should be character ? ) *Check if its a number *If not, return error *Convert that character into a float number *Copy the value to another variable ( I called it imp here) Here is what I came up with : #include<stdio.h> #include<stdlib.h> #include<ctype.h> main(){ int digits; float imp=0; int alpha; do{ printf("Enter input\n\n"); scanf("\n%c",&alpha); digits=isdigit(alpha); if(digits==0){ printf("error\n\n"); } imp=atof(alpha); }while(digits==0); } The problem is this code does not work at all ... It gives me that atof must be of a const char and whenever I try changing it around, it just keeps failing. I am frustrated and forced to ask here, because I believe I have tried alot and I keep failing, but I wont be relieved until I get it to work xD So I really need your help guys. Please tell me why isnt this code working, what am I doing wrong ? I am still learning C and really appreciate your help :)

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  • Magento products will not show in category

    - by Aaron
    I've recently been tasked with the build and deployment of a large Ecommerce site. In the past we've had to use the clients legacy X-cart installation for redevelopment (too far integrated with their existing work flow). We'd heard good things about Magento, so I've set up a test install to get to grips with it. After a couple of initial issues, there is a live development site which displays categories on the default theme. The problem we've hit now is that products don't display..! After a lot more in-depth research into this, all I've been able to discover is that quite a number of developers endorse using other solutions entirely, with the other 50% saying after the steep learning curve the platform is as wonderful as we'd initially been led to believe. Now, my test category is showing, so I know this is configured properly. I've set up three test products and associated them with this (all done following the Magento user guide), checked double checked and thrice checked the products are enabled and visible individually, yet still the front end says the category has no products in it. I've cleared the cache repeatedly, reset everything possible many times in index management - no products show up. I have to make a call tomorrow morning on whether we're going ahead with Magento. If I can't even get it to show products I'm going to have to go with something with a more established track record and more community support available. Can anybody advise what could possibly be wrong here?

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  • objective-c having issues with an NSDictioary object

    - by Mark
    I have a simple iPhone app that Im learning and I want to have an instance variable called urlLists which is an NSDictionary I have declared it like so: @interface MyViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>{ IBOutlet UIPickerView *pickerView; NSMutableArray *categories; NSDictionary *urlLists; } @property(retain) NSDictionary *urlLists; @end and in the implementation: @implementation MyViewController @synthesize urlLists; ... - (void)viewDidLoad { [super viewDidLoad]; categories = [[NSMutableArray alloc] init]; [categories addObject:@"Sport"]; [categories addObject:@"Entertainment"]; [categories addObject:@"Technology"]; [categories addObject:@"Political"]; NSArray *objects = [NSArray arrayWithObjects:@"value1", @"value2", @"value3", @"value4", nil]; urlLists = [NSDictionary dictionaryWithObjects:objects forKeys:categories]; for (id key in urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } ... @end And, this all works up to here. I have added a UIPicker to my app, and when I select one of the items, I want to Log the one picked and its related entry in my dictionary. -(void) pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger) component { for (id key in self.urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } but I get the old EXC_BAD_ACCESS error... I know Im missing something small, but what? Thanks

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  • OCaml delimiters and scopes

    - by Jack
    Hello! I'm learning OCaml and although I have years of experience with imperative programming languages (C, C++, Java) I'm getting some problems with delimiters between declarations or expressions in OCaml syntax. Basically I understood that I have to use ; to concatenate expressions and the value returned by the sequence will be the one of last expression used, so for example if I have exp1; exp2; exp3 it will be considered as an expression that returns the value of exp3. Starting from this I could use let t = something in exp1; exp2; exp3 and it should be ok, right? When am I supposed to use the double semicol ;;? What does it exactly mean? Are there other delimiters that I must use to avoid syntax errors? I'll give you an example: let rec satisfy dtmc state pformula = match (state, pformula) with (state, `Next sformula) -> let s = satisfy_each dtmc sformula and adder a state = let p = 0.; for i = 0 to dtmc.matrix.rows do p <- p +. get dtmc.matrix i state.index done; a +. p in List.fold_left adder 0. s | _ -> [] It gives me syntax error on | but I don't get why.. what am I missing? This is a problem that occurs often and I have to try many different solutions until it suddently works :/ A side question: declaring with let instead that let .. in will define a var binding that lasts whenever after it has been defined? What I basically ask is: what are the delimiters I have to use and when I have to use them. In addition are there differences I should consider while using the interpreter ocaml instead that the compiler ocamlc? Thanks in advance!

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  • 3D and AI basics. The foundation before the coding.

    - by Allan
    Hi, everyone. (If you have the time and patience:) I've recently made the decision to study programming seriously and I'm about to order TAOCP and Concrete Mathematics to begin my studies (please don't get caught up on this). I'm very much interested in learning and understanding how 3D works but I'm aware that if I plan to do it right there's still a long walk before I get to actually play with 3D coding. Now to the question.. (tl;dr) Excluding programming itself, what disciplines do I have to be familiar with to code 3D? What kinds of mathematics? Physics? What else? What books do you recommend on such subjects? Now read it all again but replacing "3D" with "AI". Please don't recommend computer-specific books. The question is about the foundation to be learned before using the machine. Also, if possible, please keep the list brief; I plan to order one book on each subject but no more than that for now. Excuse me for any English mistakes, it's not my first language. Thank you.

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  • Beginner PHP: I can't insert data into MYSQL database

    - by Victor
    I'm learning PHP right now and I'm trying to insert data into a MySQL database called "pumpl2" The table is set up like this. create table product ( productid int unsigned not null auto_increment primary key, price int(9) not null, value int(9) not null, description text ); I have a form and want to insert the fields from the form in the database. Here is what the php file looks like. <?php // create short variable names $price = $_POST['price']; $value = $_POST['value']; $description = $_POST['description']; if (!$price || !$value || !$description) { echo "You have not entered all the required details.<br />" ."Please go back and try again."; exit; } @ $db = new mysqli('localhost', 'pumpl', '********', 'pumpl2'); if (mysqli_connect_errno()) { echo "Error: Could not connect to database. Please try again later."; exit; } $query = "insert into pumpl2 values ('".$price."', '".$value."', '".$description."')"; $result = $db->query($query); if ($result) { echo $db->affected_rows." product inserted into database."; } else { echo "An error has occurred. The item was not added."; } $db->close(); ?> When I submit the form, I get an error message "An error has occurred. The item was not added." Does anyone know what the problem is? Thank you!

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  • How might a C# programmer approach writing a solution in javascript?

    - by Ben McCormack
    UPDATE: Perhaps this wasn't clear from my original post, but I'm mainly interested in knowing a best practice for how to structure javascript code while building a solution, not simply learning how to use APIs (though that is certainly important). I need to add functionality to a web site and our team has decided to approach the solution using a web service that receives a call from a JSON-formatted AJAX request from within the web site. The web service has been created and works great. Now I have been tasked with writing the javascript/html side of the solution. If I were solving this problem in C#, I would create separate classes for formatting the request, handling the AJAX request/response, parsing the response, and finally inserting the response somehow into the DOM. I would build properties and methods appropriately into each class, doing my best to separate functionality and structure where appropriate. However, I have to solve this problem in javascript. Firstly, how could I approach my solution in javascript in the way I would approach it from C# as described above? Or more importantly, what's a better way to approach structuring code in javascript? Any advice or links to helpful material on the web would be greatly appreciated. NOTE: Though perhaps not immediately relevant to this question, it may be worth noting that we will be using jQuery in our solution.

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  • What's the best approach for getting into VS2010, C# 4, and WPF if my background is in C++/MFC

    - by Canacourse
    All my past programming experience has been in C++ on VS2003/8, Mostly service based and completely self taught. 2 Years ago I had to create my first real GUI app and (Foolishly) choose MFC. I got the app working but it took a long time & was a bit of a nightmare to learn MCF (and its many shortcomings) but I ended up with a reliable workable app which was difficult to change or extend. Again I have to create another GUI app more complex than the first and again this will be created from scratch and will only ever be used on windows. I had put off learning C# for a long time but not wishing to re-visit MFC have decided that the new application with be birthed in VS2010 and WPF 4 will be the midwife. Trying to avoid the several expensive (Time wise) mistakes I made previously. Im looking for for good books/tutorials on the current versions of C# 4 & WPF 4 and also general advice on the best approach. The application will do several things one of them would persisting info in a SQL DB. So Im thinking LINQ for that? Please chip in...

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  • Applying MVVM to ASP.NET

    - by Moussa
    Hi everyone, I am learning MVVM and i want to use it with ASP.NET. Some of the examples that i found on the internet uses XAML for the view. Is there a way to use a regular ASP.NET page instead of XAML for the view? Here is a XAML example: <UserControl x:Class="MVVMExample.DetailView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> <Grid x:Name="LayoutRoot" Background="White" DataContext="{Binding CurrentContact}"> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition/> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <TextBlock Text="Name:" HorizontalAlignment="Right" Margin="5"/> <TextBlock Text="{Binding FullName}" HorizontalAlignment="Left" Margin="5" Grid.Column="1"/> <TextBlock Text="Phone:" HorizontalAlignment="Right" Margin="5" Grid.Row="1"/> <TextBlock Text="{Binding PhoneNumber}" HorizontalAlignment="Left" Margin="5" Grid.Row="1" Grid.Column="1"/> </Grid> </UserControl> Thank you for your time.

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  • Concrete examples of state sharing between multiple viewmodels (WPF MVVM)

    - by JohnMetta
    I have a WPF/Entity Framework (4.0) project with many objects. I'd like to build the application so that that I can have object selection state shared across viewmodels. For Example: We have Cars, Drivers, Passengers, and Cargo classes. We also have UserControls for CarList, DriverList, etc. and editor windows for CarEditor, DriverEditor, etc. Furthermore, we have viewmodels for all of these (CarListViewModel, DriverListViewModel, CargoEditorViewModel, etc). This all composes a dockable interface where the user can have multiple object lists, editors, and viewers open. What I want is a concrete code example of how to wireup multiple viewmodels so that selecting a car in the CarList will cause that car to go live in the CarEditorView, but also be selected in any other view for which the context is valid (such as a DriverByCarView- or just DriverList if there is a filter predicate). There are a number of suggestions and discussions based on this question. The two methods that seem to dominate are: 3018307: Discusses state sharing by mentioning a messaging subsystem 1159035: Discusses state sharing by using an enclosing viewmodel Is one of these approaches better than the other? Does anyone have a concrete example of either/both of these methods in the form of a write-up or small code project? I'm still learning WPF, so pointers to entry points for reading API fundamentals are appreciated, but looking at code examples is where I usually go. Thanks In case anyone is interested, here are some other similar discussions: 3816961: Discusses returning multiple viewmodels depending on object type (i.e. a collection of arbitrary types adhering to a specific interface) 1928130: Discusses whether it is a good idea to aggregate viewmodels as properties of other viewmodels (e.g. a MainWindow viewmodel composed of panel viewmodels) 1120061: Essentially discusses whether to have use a viewmodel-per-model strategy or a viewmodel-per-view-element strategy. 4244222: Discusses whether or not to nest the viewmodels when using a nested object hierarchy. 4429708: Discusses sharing collections between viewmodels directly, but doesn't go into detail. List item: Discusses managing multiple selections within a single viewmodel.

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  • Why would an image (the Mandelbrot) be skewed and wrap around?

    - by Sean D
    So I just wrote a little snippet to generate the Mandelbrot fractal and imagine my surprise when it came out all ugly and skewed (as you can see at the bottom). I'd appreciate a point in the direction of why this would even happen. It's a learning experience and I'm not looking for anyone to do it for me, but I'm kinda at a dead end debugging it. The offending generation code is: module Mandelbrot where import Complex import Image main = writeFile "mb.ppm" $ imageMB 1000 mandelbrotPixel x y = mb (x:+y) (0:+0) 0 mb c x iter | magnitude x > 2 = iter | iter >= 255 = 255 | otherwise = mb c (c+q^2) (iter+1) where q = x --Mandelbrot --q = (abs.realPart $ x) :+ (abs.imagPart $ x) --Burning Ship argandPlane x0 x1 y0 y1 width height = [(x,y)| y<-[y1,(y1-dy)..y0], --traverse from x<-[x0,(x0+dx)..x1]] --top-left to bottom-right where dx = (x1 - x0)/width dy = (y1 - y0)/height drawPicture :: (a->b->c)->(c->Colour)->[(a,b)]->Image drawPicture function colourFunction plane = map (colourFunction.uncurry function) plane imageMB s = createPPM s s $ drawPicture mandelbrotPixel (\x->[x,x,x]) $ argandPlane (-1.8) (-1.7) (0.02) 0.055 s' s' where s' = fromIntegral s And the image code (which I'm fairly confident in) is: module Image where type Colour = [Int] type Image = [Colour] createPPM :: Int -> Int -> Image -> String createPPM w h i = concat ["P3 ", show w, " ", show h, " 255\n", unlines.map (unwords.map show) $ i]

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  • Thread mutex behaviour

    - by Alberteddu
    Hi there, I'm learning C. I'm writing an application with multiple threads; I know that when a variable is shared between two or more threads, it is better to lock/unlock using a mutex to avoid deadlock and inconsistency of variables. This is very clear when I want to change or view one variable. int i = 0; /** Global */ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; /** Thread 1. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); /** Thread 2. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); This is correct, I think. The variable i, at the end of the executions, contains the integer 2. Anyway, there are some situations in which I don't know exactly where to put the two function calls. For example, suppose you have a function obtain(), which returns a global variable. I need to call that function from within the two threads. I have also two other threads that call the function set(), defined with a few arguments; this function will set the same global variable. The two functions are necessary when you need to do something before getting/setting the var. /** (0) */ /** Thread 1, or 2, or 3... */ if(obtain() == something) { if(obtain() == somethingElse) { // Do this, sometimes obtain() and sometimes set(random number) (1) } else { // Do that, just obtain(). (2) } } else { // Do this and do that (3) // If # of thread * 3 > 10, then set(3*10) For example. (4) } /** (5) */ Where I have to lock, and where I have to unlock? The situation can be, I think, even more complex. I will appreciate an exhaustive answer. Thank you in advance. —Alberto

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  • Tired of Exploring

    - by Abhi
    Dear All I am tired of my work. I am exploring all day and at the end of the day i feel that i have not gain anything. Its been 1 year & 3 month working in Wince 6.0 r3 but i feel that i have gained nothing. I feel like that i have wasted these month without doing anything. At fast i worked in GUI application in which i was gaining confidence but then i was shifted from that domain to something for which lot of knowledge is required i.e writing or adjusting BSP. Now at present i have shifted to work on silverlight which is again a new domain for me. My day starts from 10am and ends at 7pm @ office by doing nothing. I am tired completely. Can anyone help me what shall i do in this situation? How shall i start to achieve the target? Where should i stick "deadline" or "learning the target first" as deadline is also important? I am completely depressed.

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