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Articles indexed in November 2012

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  • can we connect more than two devices with bluetooth

    - by menuka devinda
    can we connect more than two devices with blue-tooth to play a game. I am totally new to Android. I was thinking to write application for card game that play 4 players. I heard that blue-tooth communicate only between 2 mobiles. I want to dig the background before I continue. That's why I ask this. I appreciate your ideas about this and any hints to develop this application also are appreciated. thanks in advance.

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  • WP7 databinding displays int but not string?

    - by user1794106
    Whenever I test my app.. it binds the data from Note class and displays it if it isn't a string. But for the string variables it wont bind. What am I doing wrong? Inside my main: <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0"> <ListBox x:Name="Listbox" SelectionChanged="listbox_SelectionChanged" ItemsSource="{Binding}"> <ListBox.ItemTemplate> <DataTemplate> <Border Width="800" MinHeight="60"> <StackPanel> <TextBlock x:Name="Title" VerticalAlignment="Center" FontSize="{Binding TextSize}" Text="{Binding Name}"/> <TextBlock x:Name="Date" VerticalAlignment="Center" FontSize="{Binding TextSize}" Text="{Binding Modified}"/> </StackPanel> </Border> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Grid> </Grid> in code behind: protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e) { MessageBox.Show("enters onNav Main"); DataContext = null; DataContext = Settings.NotesList; Settings.CurrentNoteIndex = -1; Listbox.SelectedIndex = -1; if (Settings.NotesList != null) { if (Settings.NotesList.Count == 0) { Notes.Text = "No Notes"; } else { Notes.Text = ""; } } } and public static class Settings { public static ObservableCollection<Note> NotesList; static IsolatedStorageSettings settings; private static int currentNoteIndex; static Settings() { NotesList = new ObservableCollection<Note>(); settings = IsolatedStorageSettings.ApplicationSettings; MessageBox.Show("enters constructor settings"); } notes class: public class Note { public DateTimeOffset Modified { get; set; } public string Title { get; set; } public string Content { get; set; } public int TextSize { get; set; } public Note() { MessageBox.Show("enters Note Constructor"); Modified = DateTimeOffset.Now; Title = "test"; Content = "test"; TextSize = 32; } }

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  • Error while compiling Hello world program for CUDA

    - by footy
    I am using Ubuntu 12.10 and have sucessfully installed CUDA 5.0 and its sample kits too. I have also run sudo apt-get install nvidia-cuda-toolkit Below is my hello world program for CUDA: #include <stdio.h> /* Core input/output operations */ #include <stdlib.h> /* Conversions, random numbers, memory allocation, etc. */ #include <math.h> /* Common mathematical functions */ #include <time.h> /* Converting between various date/time formats */ #include <cuda.h> /* CUDA related stuff */ __global__ void kernel(void) { } /* MAIN PROGRAM BEGINS */ int main(void) { /* Dg = 1; Db = 1; Ns = 0; S = 0 */ kernel<<<1,1>>>(); /* PRINT 'HELLO, WORLD!' TO THE SCREEN */ printf("\n Hello, World!\n\n"); /* INDICATE THE TERMINATION OF THE PROGRAM */ return 0; } /* MAIN PROGRAM ENDS */ The following error occurs when I compile it with nvcc -g hello_world_cuda.cu -o hello_world_cuda.x /tmp/tmpxft_000033f1_00000000-13_hello_world_cuda.o: In function `main': /home/adarshakb/Documents/hello_world_cuda.cu:16: undefined reference to `cudaConfigureCall' /tmp/tmpxft_000033f1_00000000-13_hello_world_cuda.o: In function `__cudaUnregisterBinaryUtil': /usr/include/crt/host_runtime.h:172: undefined reference to `__cudaUnregisterFatBinary' /tmp/tmpxft_000033f1_00000000-13_hello_world_cuda.o: In function `__sti____cudaRegisterAll_51_tmpxft_000033f1_00000000_4_hello_world_cuda_cpp1_ii_b81a68a1': /tmp/tmpxft_000033f1_00000000-1_hello_world_cuda.cudafe1.stub.c:1: undefined reference to `__cudaRegisterFatBinary' /tmp/tmpxft_000033f1_00000000-1_hello_world_cuda.cudafe1.stub.c:1: undefined reference to `__cudaRegisterFunction' /tmp/tmpxft_000033f1_00000000-13_hello_world_cuda.o: In function `cudaError cudaLaunch<char>(char*)': /usr/lib/nvidia-cuda-toolkit/include/cuda_runtime.h:958: undefined reference to `cudaLaunch' collect2: ld returned 1 exit status I am also making sure that I use gcc and g++ version 4.4 ( As 4.7 there is some problem with CUDA)

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  • How to sort a hash by value in descending order and output a hash in ruby?

    - by tipsywacky
    output.sort_by {|k, v| v}.reverse and for keys h = {"a"=>1, "c"=>3, "b"=>2, "d"=>4} => {"a"=>1, "c"=>3, "b"=>2, "d"=>4} Hash[h.sort] Right now I have these two. But I'm trying to sort hash in descending order by value so that it will return => {"d"=>4, "c"=>3, "b"=>2, "a"=>1 } Thanks in advance. Edit: let me post the whole code. def count_words(str) # YOUR CODE HERE output = Hash.new(0) sentence = str.gsub(/,/, "").gsub(/'/,"").gsub(/-/, "").downcase words = sentence.split() words.each do |item| output[item] += 1 end puts Hash[output.sort_by{ |_, v| -v }] return Hash[output.sort_by{|k, v| v}.reverse] end

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  • Javascript mouseover image failure

    - by CaptainTeancum
    This is what I have so far, I have been watching a ton of Javascript videos and I feel I mimicked them solid but this is still not functioning as I want. Than being, it changes from logo1 to logo2 on mousover. This is homework. However homework that is important to me so any help or guidance would be appreciated. </head> <body> <p> <div> <script type="text/javascript"> // Pre load images for rollover function imgOver(id) { document.getElementById(id).src="logo1.jpg"; } function imgOut(id) { document.getElementById(id).src="logo2.jpg"; } </script> <a href="#" onmouseover="imgOver('logo1');" onmouseout="imgOut('logo2')"> <img alt="logo" height="150" src="images/Logo1.jpeg" width="110" /> </a> </div> </body> </html>

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  • jquery - targetting a select using $this

    - by Maureen
    I am trying to get individual selects (which have the same class as other selects) to respond to a .change function, however it only works on one of the selects. If you test out this code it will make more sense. Try to add a few "ON/OFF events", and then select "Specified Time" in the various selects. You'll see only the first one responds. Any ideas? Thanks! Please see the following code: $(document).ready(function() { var neweventstring = '<div class="event">Turns <select name="ONOFF"><option value="On">ON</option><option value="Off">OFF</option></select> at: <select name="setto" class="setto"><option>Select Time</option><option value="Sunrise">Sunrise</option><option value="Sunset">Sunset</option><option value="specifiedtime">Specified Time</option></select></div>'; $('#addmondaysevent').click(function () { $('#monday .events').append(neweventstring); }); $('.setto').change(function() { alert('The function is called'); if($("option:selected", this).val() =="specifiedtime"){ alert('If returns true'); $(this).css("background-color", "#cc0000"); $(this).after('<div class="specifictime"><input type="text" value="00" style="width:30px"/> : <input type="text" value="00" style="width:30px"> <select name="ampm"><option value="AM" selected>AM</option><option value="PM">PM</option></select></div>') } }); }); And my HTML: <div id="monday"> <h2>Mondays</h2> <div class="events"> <div class="event"> Turn <select name="ONOFF"> <option value="On">ON</option> <option value="Off">OFF</option> </select> at: <select name="setto" class="setto"> <option>Select Time</option> <option value="Sunrise">Sunrise</option> <option value="Sunset">Sunset</option> <option value="specifiedtime">Specified Time</option> </select> </div> [<a id="addmondaysevent">Add an ON/OFF event</a>] </div> </div>

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  • Painted JPanel won't show up in JFrame

    - by javawarrior
    When I run my code, I expect to see a JPanel in my JFrame, but nothing shows up. I had a button in the frame, and it shows up. But the JPanel doesn't show up, I even colored it in red. Here is the code for my JPanel: import java.awt.*; import javax.swing.JPanel; public class graphic extends JPanel { private static final long serialVersionUID = -3458717449092499931L; public Game game; public graphic(Game game){ this.game = game; this.setPreferredSize(new Dimension(400,400)); this.setBackground(Color.RED); } public void paintComponent(Graphics g){ for (Line l:game.mirrors){ g.setColor(Color.BLACK); g.drawLine(l.start.x, l.start.y, l.end.x, l.end.y); } } } And my JFrame code: import java.awt.Container; import java.awt.event.*; import java.util.Timer; import java.util.TimerTask; import javax.swing.*; public class Viewer implements ActionListener { public JFrame frame; public JButton drawShoot; public boolean draw; public Game game; public graphic graphic; public TimerTask timert; public Timer timer; public Viewer(){ draw = true; game = new Game(); } public static void main(String args[]){ Viewer v = new Viewer(); v.setup(); } public void setup(){ frame = new JFrame("Laser Stimulator"); drawShoot = new JButton("Edit Mode"); graphic = new graphic(game); graphic.repaint(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setBounds(300, 300, 600, 600); Container contentPane = frame.getContentPane(); SpringLayout layout = new SpringLayout(); contentPane.setLayout(layout); drawShoot.addActionListener(this); timert = new TimerTask() { @Override public void run() { } }; timer =new Timer(); timer.scheduleAtFixedRate(timert, 0, 1000/30); contentPane.add(graphic); layout.putConstraint(SpringLayout.NORTH, graphic, 0, SpringLayout.NORTH, contentPane); layout.putConstraint(SpringLayout.WEST, graphic, 0, SpringLayout.WEST, contentPane); frame.setVisible(true); } @Override public void actionPerformed(ActionEvent e) { if (e.getSource()==drawShoot){ draw = !draw; drawShoot.setText((draw)?"Edit Mode":"Shoot Mode"); } } }

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  • Adapting pseudocode to java implementation for finding the longest word in a trie

    - by user1766888
    Referring to this question I asked: How to find the longest word in a trie? I'm having trouble implementing the pseudocode given in the answer. findLongest(trie): //first do a BFS and find the "last node" queue <- [] queue.add(trie.root) last <- nil map <- empty map while (not queue.empty()): curr <- queue.pop() for each son of curr: queue.add(son) map.put(son,curr) //marking curr as the parent of son last <- curr //in here, last indicate the leaf of the longest word //Now, go up the trie and find the actual path/string curr <- last str = "" while (curr != nil): str = curr + str //we go from end to start curr = map.get(curr) return str This is what I have for my method public static String longestWord (DTN d) { Queue<DTN> holding = new ArrayQueue<DTN>(); holding.add(d); DTN last = null; Map<DTN,DTN> test = new ArrayMap<DTN,DTN>(); DTN curr; while (!holding.isEmpty()) { curr = holding.remove(); for (Map.Entry<String, DTN> e : curr.children.entries()) { holding.add(curr.children.get(e)); test.put(curr.children.get(e), curr); } last = curr; } curr = last; String str = ""; while (curr != null) { str = curr + str; curr = test.get(curr); } return str; } I'm getting a NullPointerException at: for (Map.Entry<String, DTN> e : curr.children.entries()) How can I find and fix the cause of the NullPointerException of the method so that it returns the longest word in a trie?

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  • Loop through Array with conditional output based on key/value pair

    - by Daniel C
    I have an array with the following columns: Task Status I would like to print out a table that shows a list of the Tasks, but not the Status column. Instead, for Tasks where the Status = 0, I want to add a tag <del> to make the completed task be crossed out. Here's my current code: foreach ($row as $key => $val){ if ($key != 'Status') print "<td>$val</td>"; else if ($val == '0') print "<td><del>$val</del></td>"; } This seems to be correct, but when I print it out, it prints all the tasks with the <del> tag. So basically the "else" clause is being run every time. Here is the var_dump($row): array 'Task' => string 'Task A' (length=6) 'Status' => string '3' (length=1) array 'Task' => string 'Task B' (length=6) 'Status' => string '0' (length=1)

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  • Reloading a Flickr request from author

    - by user1797325
    I have my flickr gallery coded, but I want to be able to click on the Author's name and the page will reload just with the images from that author. Here is my current code <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Outbrain Test Gallery</title> <link href="styles.css" rel="stylesheet" type="text/css" /> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script> <script src="jquery.masonry.min.js"></script> <script type="text/javascript"> $(window).load(function(){ $('#flkr').masonry({ // options itemSelector : '.tiles', isResizable: true, }); }); </script> <script type="text/javascript">$(document).ready(function() { $('<ul />').prependTo('#flkr'); $.getJSON('http://api.flickr.com/services/feeds/photos_public.gne?lang=en-us&format=json&jsoncallback=?', function(data) { $.each(data.items, function(i,item) { var squares = (item.media.m).replace('_m.jpg', '_q.jpg'); if(i <= 20){ $('<img/>').attr({ alt: item.title, src: squares, height: '150', width: '150' }).appendTo('#flkr ul').wrap('<li class="tiles"><a href="' + item.link + '"></a><p class="title">' + item.title + '</p><p class="author"><strong>By:</strong> ' + item.author + '</p><p class="date"><strong>Uploaded: </strong>' + item.published + '</p></li>'); } }); }); }); </script> </head> <body> <ul id="flkr"></ul> </body> </html>

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  • Calling recursive function twice consecutively

    - by Zack
    #include <stdio.h> #define LENGTH 16 void makeBranches(int, int); void display(int, int); int main(){ makeBranches(0, LENGTH-1); } void makeBranches(int left, int right){ if(left >= right){ return; } else{ display(left, right); makeBranches(left, (right+left)/2); makeBranches((right+left/2)+1, right); } } void display(int left, int right){ printf("%d, %d", left, right); int mid = (left+right)/2; int i; for(i = left; i <= right; i++){ if(i == mid) printf("X"); else printf("-"); } if(right == LENGTH-1) printf("\n"); } The problem that I am having is the second call of makeBranches only executes with the values that caused the first call of makeBranches to return and not the original values that the first call used.

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  • Why slim reader/writer exclusive lock outperformance the shared one?

    - by Jichao
    I have tested the performance of slim reader/writer lock under windows 7 using the codefrom Windows Via C/C++. The result surprised me that the exclusive lock out performance the shared one. Here are the code and the result. unsigned int __stdcall slim_reader_writer_exclusive(void *arg) { //SRWLOCK srwLock; //InitializeSRWLock(&srwLock); for (int i = 0; i < 1000000; ++i) { AcquireSRWLockExclusive(&srwLock); g_value = 0; ReleaseSRWLockExclusive(&srwLock); } _endthreadex(0); return 0; } unsigned int __stdcall slim_reader_writer_shared(void *arg) { int b; for (int i = 0; i < 1000000; ++i) { AcquireSRWLockShared(&srwLock); //b = g_value; g_value = 0; ReleaseSRWLockShared(&srwLock); } _endthreadex(0); return 0; } g_value is a global int volatile variable. Could you kindly explain why this could happen?

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  • Online graphing and data visualization frameworks

    - by Marques
    I have been looking around at web applications and websites with rich graphs, charts, and data visualization and for the most part have been able to determine which frameworks or tools websites are using. However I was looking over 'resumup.com' and couldn't determine what they are using. Does anyone know off hand or can you tell? It doesn't seem like any javascript framework i've seen unless its custom...is it some sort of flash or flex framework? Any help would be greatly appreciated. Thanks, Marques

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  • gitk without X11 [closed]

    - by svnpenn
    It has been noted here that Tcl/Tk, and in turn gitk now require X11 under Cygwin. Having run it before and after this change it seems like extreme overkill. I use gitk very lightly, mostly sticking to simply command line git. How could I go about using gitk without X11, perhaps manually installing old version of Tcl/Tk? After some tinkering, I came up with this script that allows gitk without X11 #!/bin/sh # Requires Cygwin packages: git, make, mingw64-i686-gcc-core, wget # Install Tcl wget prdownloads.sf.net/tcl/tcl8.5.12-src.tar.gz tar xf tcl8.5.12-src.tar.gz cd tcl8.5.12/win ./configure --host i686-w64-mingw32 make install cd - # Install Tk wget prdownloads.sf.net/tcl/tk8.5.12-src.tar.gz tar xf tk8.5.12-src.tar.gz cd tk8.5.12/win ./configure --host i686-w64-mingw32 make install cd - # Install gitk cd /usr/local/bin wget raw.github.com/git/git/master/gitk-git/gitk chmod 700 gitk echo 'cygpath -m "$1" | xargs -I% wish85 % -- ${@:3}' > wish cd -

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  • Show wordpress posts outside of the blog

    - by way2project
    I have two wordpress blogs on my site and now I want to show the posts of categories of both blogs on the home page. I am using the following code. <?php require($_SERVER['DOCUMENT_ROOT'] . '/projects/wp-load.php'); query_posts('cat=9& showposts=8'); if (have_posts()) : while (have_posts()) : the_post(); ?> <ul><li> <a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php $shorttitle4 = substr(the_title('','',FALSE),0,25)."..."; echo $shorttitle4; ?></a> </li></ul> <?php endwhile; else: echo "no posts"; endif; ?> <?php wp_reset_query(); ?> One of my blogs is placed in the "projects" folder and another one is placed in "technology folder". but this code is showing the posts only from projects blogs if I changed the folder in as "technology" in the above code. I think this is because of wp-load.php file. Can you help me? Thanks

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  • Login control doesnt work in Internet Explorer

    - by kamiar3001
    I use asp.net cookie in my application here is my web config : <authentication mode="Forms"> <forms path="/" defaultUrl="Default.aspx" loginUrl="Login.aspx" name=".ASPXAUTH" slidingExpiration="true" timeout="3000" domain="www.mysite.com" cookieless="UseDeviceProfile"/> </authentication> it works fine but I have a problem, after some days when a user has been working with the site application, suddenly my login control didn't work. I found out it will work after deleting temporary files. Edit : Please pay attention to domain when User request www.mysite.com every thing is okay but without "www" login doesn't work. in firefox they are working very good. this is IE problem. How I can solve this ?

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  • jqGrid - how to change title based on colModel sortable property

    - by Greg
    When the mouse hovers over each column I'd like the tooltip to indicate whether that column is sortable. I am able to change the title attribute with something like this: $("#List .ui-th-column").each(function(i) { var isSortable = i % 2; $(this).attr('title', isSortable ? "Not Sortable" : "Click header to sort."); }); I'd like to replace the demo expression 'i % 2' with a check of the colMode's sortable property, but I can't figure out how to get the value of the colModel's sortable property. colModel: [ { name: 'Name', index: 'Name', width: 100, sortable: true }, { name: 'Note', index: 'Note', width: 200, sortable: false } ] I've tried .getGridParam and .getColProp but I don't think the syntax I'm using is correct.

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  • sql server mdf file database attachment

    - by jnsohnumr
    hello all i'm having a bear of a time getting visual studio 2010 (ultimate i think) to properly attach to my database. it was moved from original spot to #MYAPP#/#MYAPP#.Web/App_Data/#MDF_FILE#.mdf. I have three instances of sql server running on this machine. i have tried to replace the old mdf file with my new one and cannot get the connectionstring right for it. what i'm really wanting to do is to just open some DB instance, run a DB create script. Then I can have a DB that was generated via my edmx (generate database from model) in silverlight business application (c#) right now, when i go to server explorer in VS, choose add new connection, choose MS SQL Server Database FIle (SqlClient), choose my file location (app_data directory), use windows authentication, and hit the Test Connection button I get the following error: Unable to open the physical file "". Operating system error 5: "5(Access Denied.)". An attempt to attach to an auto-named database for file"" failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share. The mdf file was created on the same machine by connecting to (local) on the sql server management studio, getting a new query, pasting in the SQL from the generated ddl file, adding a CREATE DATABASE [NcrCarDatabase]; GO before the pasted SQL, and executing the query. I then disconnected from the DB in management studio, closed management studio, navigated to the DATA directory for that instance, and copying the mdf and ldf files to my application's app_data folder. I am then trying to connect to the same file inside visual studio. I hope that gives more clarity to my problems :). Connection string is: Data Source=.\SQLEXPRESS;AttachDbFilename=C:\SourceCode\NcrCarDatabase\NcrCarDatabase.Web\App_Data\NcrCarDatabase.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True

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  • django test client trouble

    - by Anton Koval'
    I've got a problem... we're writing project using django, and i'm trying to use django.test.client with nose test-framework for tests. Our code is like this: from simplejson import loads from urlparse import urljoin from django.test.client import Client TEST_URL = "http://smakly.localhost:9090/" def test_register(): cln = Client() ref_data = {"email": "[email protected]", "name": "???????", "website": "http://hot.bear.com", "xhr": "true"} print urljoin(TEST_URL, "/accounts/register/") response = loads(cln.post(urljoin(TEST_URL, "/accounts/register/"), ref_data)) print response["message"] and in nose output I catch: Traceback (most recent call last): File "/home/psih/work/svn/smakly/eggs/nose-0.11.1-py2.6.egg/nose/case.py", line 183, in runTest self.test(*self.arg) File "/home/psih/work/svn/smakly/src/smakly.tests/smakly/tests/frontend/test_profile.py", line 25, in test_register response = loads(cln.post(urljoin(TEST_URL, "/accounts/register/"), ref_data)) File "/home/psih/work/svn/smakly/parts/django/django/test/client.py", line 313, in post response = self.request(**r) File "/home/psih/work/svn/smakly/parts/django/django/test/client.py", line 225, in request response = self.handler(environ) File "/home/psih/work/svn/smakly/parts/django/django/test/client.py", line 69, in __call__ response = self.get_response(request) File "/home/psih/work/svn/smakly/parts/django/django/core/handlers/base.py", line 78, in get_response urlconf = getattr(request, "urlconf", settings.ROOT_URLCONF) File "/home/psih/work/svn/smakly/parts/django/django/utils/functional.py", line 273, in __getattr__ return getattr(self._wrapped, name) AttributeError: 'Settings' object has no attribute 'ROOT_URLCONF' My settings.py file does have this attribute. If I get the data from the server with standard urllib2.urllopen().read() it works in the proper way. Any ideas how I can solve this case?

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  • Change Sprite Anchorpoint without moving it?

    - by Oscar Gomez
    I am trying to change my Sprite anchor point so that I can rotate over a 0.0f,0.0f anchorpoint. At first my object is rotation at the default anchor point (0.5f,0.5f). However later on I need it to rotate over a 0.0,0.0 AnchorPoint. The problem is I cannot change the anchor point and change the position accordingly, so it stays on the same position, without the object appearing to quickly move and reposition to its original point. Is there a way I can set the anchor point and the position of my Sprite at once, without it moving at all?. Thank you. -Oscar

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  • Back to Basics: When does a .NET Assembly Dependency get loaded

    - by Rick Strahl
    When we work on typical day to day applications, it's easy to forget some of the core features of the .NET framework. For me personally it's been a long time since I've learned about some of the underlying CLR system level services even though I rely on them on a daily basis. I often think only about high level application constructs and/or high level framework functionality, but the low level stuff is often just taken for granted. Over the last week at DevConnections I had all sorts of low level discussions with other developers about the inner workings of this or that technology (especially in light of my Low Level ASP.NET Architecture talk and the Razor Hosting talk). One topic that came up a couple of times and ended up a point of confusion even amongst some seasoned developers (including some folks from Microsoft <snicker>) is when assemblies actually load into a .NET process. There are a number of different ways that assemblies are loaded in .NET. When you create a typical project assemblies usually come from: The Assembly reference list of the top level 'executable' project The Assembly references of referenced projects Dynamically loaded at runtime via AppDomain/Reflection loading In addition .NET automatically loads mscorlib (most of the System namespace) the boot process that hosts the .NET runtime in EXE apps, or some other kind of runtime hosting environment (runtime hosting in servers like IIS, SQL Server or COM Interop). In hosting environments the runtime host may also pre-load a bunch of assemblies on its own (for example the ASP.NET host requires all sorts of assemblies just to run itself, before ever routing into your user specific code). Assembly Loading The most obvious source of loaded assemblies is the top level application's assembly reference list. You can add assembly references to a top level application and those assembly references are then available to the application. In a nutshell, referenced assemblies are not immediately loaded - they are loaded on the fly as needed. So regardless of whether you have an assembly reference in a top level project, or a dependent assembly assemblies typically load on an as needed basis, unless explicitly loaded by user code. The same is true of dependent assemblies. To check this out I ran a simple test: I have a utility assembly Westwind.Utilities which is a general purpose library that can work in any type of project. Due to a couple of small requirements for encoding and a logging piece that allows logging Web content (dependency on HttpContext.Current) this utility library has a dependency on System.Web. Now System.Web is a pretty large assembly and generally you'd want to avoid adding it to a non-Web project if it can be helped. So I created a Console Application that loads my utility library: You can see that the top level Console app a reference to Westwind.Utilities and System.Data (beyond the core .NET libs). The Westwind.Utilities project on the other hand has quite a few dependencies including System.Web. I then add a main program that accesses only a simple utillity method in the Westwind.Utilities library that doesn't require any of the classes that access System.Web: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); } StringUtils.NewStringId() calls into Westwind.Utilities, but it doesn't rely on System.Web. Any guesses what the assembly list looks like when I stop the code on the ReadLine() command? I'll wait here while you think about it… … … So, when I stop on ReadLine() and then fire up Process Explorer and check the assembly list I get: We can see here that .NET has not actually loaded any of the dependencies of the Westwind.Utilities assembly. Also not loaded is the top level System.Data reference even though it's in the dependent assembly list of the top level project. Since this particular function I called only uses core System functionality (contained in mscorlib) there's in fact nothing else loaded beyond the main application and my Westwind.Utilities assembly that contains the method accessed. None of the dependencies of Westwind.Utilities loaded. If you were to open the assembly in a disassembler like Reflector or ILSpy, you would however see all the compiled in dependencies. The referenced assemblies are in the dependency list and they are loadable, but they are not immediately loaded by the application. In other words the C# compiler and .NET linker are smart enough to figure out the dependencies based on the code that actually is referenced from your application and any dependencies cascading down into the dependencies from your top level application into the referenced assemblies. In the example above the usage requirement is pretty obvious since I'm only calling a single static method and then exiting the app, but in more complex applications these dependency relationships become very complicated - however it's all taken care of by the compiler and linker figuring out what types and members are actually referenced and including only those assemblies that are in fact referenced in your code or required by any of your dependencies. The good news here is: That if you are referencing an assembly that has a dependency on something like System.Web in a few places that are not actually accessed by any of your code or any dependent assembly code that you are calling, that assembly is never loaded into memory! Some Hosting Environments pre-load Assemblies The load behavior can vary however. In Console and desktop applications we have full control over assembly loading so we see the core CLR behavior. However other environments like ASP.NET for example will preload referenced assemblies explicitly as part of the startup process - primarily to minimize load conflicts. Specifically ASP.NET pre-loads all assemblies referenced in the assembly list and the /bin folder. So in Web applications it definitely pays to minimize your top level assemblies if they are not used. Understanding when Assemblies Load To clarify and see it actually happen what I described in the first example , let's look at a couple of other scenarios. To see assemblies loading at runtime in real time lets create a utility function to print out loaded assemblies to the console: public static void PrintAssemblies() { var assemblies = AppDomain.CurrentDomain.GetAssemblies(); foreach (var assembly in assemblies) { Console.WriteLine(assembly.GetName()); } } Now let's look at the first scenario where I have class method that references internally uses System.Web. In the first scenario lets add a method to my main program like this: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); PrintAssemblies(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } UpdateFromWebRequest() internally accesses HttpContext.Current to read some information of the ASP.NET Request object so it clearly needs a reference System.Web to work. In this first example, the method that holds the calling code is never called, but exists as a static method that can potentially be called externally at some point. What do you think will happen here with the assembly loading? Will System.Web load in this example? No - it doesn't. Because the WebLogEntry() method is never called by the mainline application (or anywhere else) System.Web is not loaded. .NET dynamically loads assemblies as code that needs it is called. No code references the WebLogEntry() method and so System.Web is never loaded. Next, let's add the call to this method, which should trigger System.Web to be loaded because a dependency exists. Let's change the code to: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.WriteLine("--- Before:"); PrintAssemblies(); WebLogEntry(); Console.WriteLine("--- After:"); PrintAssemblies(); Console.ReadLine(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } Looking at the code now, when do you think System.Web will be loaded? Will the before list include it? Yup System.Web gets loaded, but only after it's actually referenced. In fact, just until before the call to UpdateFromRequest() System.Web is not loaded - it only loads when the method is actually called and requires the reference in the executing code. Moral of the Story So what have we learned - or maybe remembered again? Dependent Assembly References are not pre-loaded when an application starts (by default) Dependent Assemblies that are not referenced by executing code are never loaded Dependent Assemblies are just in time loaded when first referenced in code All of this is nothing new - .NET has always worked like this. But it's good to have a refresher now and then and go through the exercise of seeing it work in action. It's not one of those things we think about everyday, and as I found out last week, I couldn't remember exactly how it worked since it's been so long since I've learned about this. And apparently I'm not the only one as several other people I had discussions with in relation to loaded assemblies also didn't recall exactly what should happen or assumed incorrectly that just having a reference automatically loads the assembly. The moral of the story for me is: Trying at all costs to eliminate an assembly reference from a component is not quite as important as it's often made out to be. For example, the Westwind.Utilities module described above has a logging component, including a Web specific logging entry that supports pulling information from the active HTTP Context. Adding that feature requires a reference to System.Web. Should I worry about this in the scope of this library? Probably not, because if I don't use that one class of nearly a hundred, System.Web never gets pulled into the parent process. IOW, System.Web only loads when I use that specific feature and if I am, well I clearly have to be running in a Web environment anyway to use it realistically. The alternative would be considerably uglier: Pulling out the WebLogEntry class and sticking it into another assembly and breaking up the logging code. In this case - definitely not worth it. So, .NET definitely goes through some pretty nifty optimizations to ensure that it loads only what it needs and in most cases you can just rely on .NET to do the right thing. Sometimes though assembly loading can go wrong (especially when signed and versioned local assemblies are involved), but that's subject for a whole other post…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Network switches for LAN party

    - by guywhoneedsahand
    I am working on setting up the network for a small LAN party (less than 16 people). Most of them do not have wireless cards in their rigs, so I need to set up some way for everyone to a) play LAN games and b) access the internet. The LAN party will probably take place in my basement, where I have enough space. However, the basement is not wired up with the router which is actually on the floor above. I make a cantenna a while back that can boost the wireless performance of my computer significantly. How can I use this to provide internet and LAN to guests? My hope was that I could use a switch like this http://www.newegg.com/Product/Product.aspx?Item=N82E16833181166 for the LAN - but how can I give people access to the internet? Is there such thing as a network extender / 16-port switch? Obviously, the internet performance doesn't need to be super stellar, because the games will be using LAN - so I am looking to provide some usable internet for web browsing, and very high speed LAN for games. Thanks!

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  • Performance data collection for short-running, ephemeral servers

    - by ErikA
    We're building a medical image processing software stack, currently hosted on various AWS resources. As part of this application, we have a handful of long-running servers (database, load balancers, web application, etc.). Collecting performance data on those servers is quite simple - my go-to- recipe of Nagios (for monitoring/notifications) and Munin (for collection of performance data and displaying trends) will work just fine. However - as part of this application, we are constantly starting up and terminating compute instances on EC2. In typical usage, these compute instances start up, configure themselves, receive a job from a message queue, and then get to work processing that job, which takes anywhere from 15 minutes to over 8 hours. After job completion, these instances get terminated, never to be heard from again. What is a decent strategy for collecting performance data on these short-lived instances? I don't necessarily need monitoring on them - if they fail for whatever reason, our application will detect this and handle re-starting the job on another instance or raising the flag so an administrator can take a look at things. However, it still would be useful to collect information like CPU (user, idle, iowait, etc.), memory usage, network traffic, disk read/write data, etc. In our internal database, we track the instance ID of the machine that runs each job, and it would be quite helpful to be able to look up performance data for a specific instance ID for troubleshooting and profiling. Munin doesn't seem like a great candidate, as it requires maintaining a list of munin nodes in a text file - far from ideal for an environment with a high amount of churn, and for the short amount of time each node will be running, I'd rather keep the full-resolution data indefinitely than have RRD water down the data over time. In the end, my guess is that this will require a monitoring engine that: uses a database (MySQL, SQLite, etc.) for configuration and data storage exposes an API for adding/removing hosts and services Are there other things I should be thinking about when evaluating options? Perhaps I'm over-thinking this, though, and just ought to run sar at 1-minute intervals on these short-lived instances and collect the sar db files prior to termination.

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  • Is memcache impacting my performence negatively?

    - by iTech
    I am using pressflow 6 and NewRelic seems to suggest that memcache is infact hurting performance as shown below : My settings.php file : # Varnish reverse proxy on localhost $conf['reverse_proxy'] = TRUE; $conf['reverse_proxy_addresses'] = array('127.0.0.1'); # Memcached configuration $conf['cache_inc'] = './sites/all/modules/memcache/memcache.inc'; $conf['memcache_servers'] = array( '127.0.0.1:11211' => 'default', ); ### END Mercury settings written on 2011-11-01T07:12:49-04:00

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  • Linking FreeNAS Boxes

    - by John
    I have two different FreeNAS boxes that are being used for storage. It is possible to link them in a manner that the linked connection can be presented as a single storage destination for clients? For example, I have one FreeNAS installation that has 6 TB of storage and another one that has 4 TB of storage. I would like to be able to present or have a single mapped drive for clients that would be able to span across both of them; however, the client would only see it as one drive. Is this possible? If not, is there a different way I should be approaching this problem? Is there a different OS distribution that would work better for this?

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