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• Soon to be PhD in Computer Science - Which Path to Follow?

  - by mttr

  I am going to submit my PhD thesis within the next six months. My PhD is on managing the availabiity of large-scale distributed systems, so I have some experience actually building non-trivial systems (+ I have four years experience working as a programmer). I am now trying to figure out what I should do following the PhD. I enjoy research (a quick definition: identify problem, come up with solution, ask interesting questions, find ways to answer them, build system, experiment, contribute some new knowledge and publish). I also like teaching and supervising students. It would seem that a career in academia is the ideal thing to do (can work on non-trivial problems and contribute something of use to some or more people). However, a career in academia has two significant drawbacks. First, it can be difficult to gain access to real systems with real users which then display real problems. This creates the danger that you do work that seems important (to you and maybe to some of your colleagues), but is not really relevant to anything or anyone. Second, the pay is pretty sad. Apparently, you have to sacrifice this for the privilege of doing research. I enjoy programming, but don't just want to hack some web-based system for the rest of my life. That is, working in IT for a bank is not a future I see myself enjoying. I want to work on interesting problms (that's difficult to define clearly): things where you don't know how to start, that take some time to figure out and attack, that require a rigorous approach to demonstrate that the problem has been solved, and problems that need a solution in the real world. Give the experience of people on stackoverflow, what do you think suitable options are and why (or alternatively, what gaps in my thinking does the above reveal)? Is industrial research (aka IBM Research, Microsoft Research) the only alternative avenue to a career in academia? What other areas, companies, occupations, etc. could provide me with stimulating, inspiring work? Which regions, countries am I most likely to find such work? Please share your experience.

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• django image upload forms

  - by gramware

  I am having problems with django forms and image uploads. I have googled, read the documentations and even questions ere, but cant figure out the issue. Here are my files my models class UserProfile(User): """user with app settings. """ DESIGNATION_CHOICES=( ('ADM', 'Administrator'), ('OFF', 'Club Official'), ('MEM', 'Ordinary Member'), ) onames = models.CharField(max_length=30, blank=True) phoneNumber = models.CharField(max_length=15) regNo = models.CharField(max_length=15) designation = models.CharField(max_length=3,choices=DESIGNATION_CHOICES) image = models.ImageField(max_length=100,upload_to='photos/%Y/%m/%d', blank=True, null=True) course = models.CharField(max_length=30, blank=True, null=True) timezone = models.CharField(max_length=50, default='Africa/Nairobi') smsCom = models.BooleanField() mailCom = models.BooleanField() fbCom = models.BooleanField() objects = UserManager() #def __unicode__(self): # return '%s %s ' % (User.Username, User.is_staff) def get_absolute_url(self): return u'%s%s/%s' % (settings.MEDIA_URL, settings.ATTACHMENT_FOLDER, self.id) def get_download_url(self): return u'%s%s/%s' % (settings.MEDIA_URL, settings.ATTACHMENT_FOLDER, self.name) ... class reports(models.Model): repID = models.AutoField(primary_key=True) repSubject = models.CharField(max_length=100) repRecepients = models.ManyToManyField(UserProfile) repPoster = models.ForeignKey(UserProfile,related_name='repposter') repDescription = models.TextField() repPubAccess = models.BooleanField() repDate = models.DateField() report = models.FileField(max_length=200,upload_to='files/%Y/%m/%d' ) deleted = models.BooleanField() def __unicode__(self): return u'%s ' % (self.repSubject) my forms from django import forms from django.http import HttpResponse from cms.models import * from django.contrib.sessions.models import Session from django.forms.extras.widgets import SelectDateWidget class UserProfileForm(forms.ModelForm): class Meta: model= UserProfile exclude = ('designation','password','is_staff', 'is_active','is_superuser','last_login','date_joined','user_permissions','groups') ... class reportsForm(forms.ModelForm): repPoster = forms.ModelChoiceField(queryset=UserProfile.objects.all(), widget=forms.HiddenInput()) repDescription = forms.CharField(widget=forms.Textarea(attrs={'cols':'50', 'rows':'5'}),label='Enter Report Description here') repDate = forms.DateField(widget=SelectDateWidget()) class Meta: model = reports exclude = ('deleted') my views @login_required def reports_media(request): user = UserProfile.objects.get(pk=request.session['_auth_user_id']) if request.user.is_staff== True: repmedform = reportsForm(request.POST, request.FILES) if repmedform.is_valid(): repmedform.save() repmedform = reportsForm(initial = {'repPoster':user.id,}) else: repmedform = reportsForm(initial = {'repPoster':user.id,}) return render_to_response('staffrepmedia.html', {'repfrm':repmedform, 'rep_media': reports.objects.all()}) else: return render_to_response('reports_&_media.html', {'rep_media': reports.objects.all()}) ... @login_required def settingchng(request): user = UserProfile.objects.get(pk=request.session['_auth_user_id']) form = UserProfileForm(instance = user) if request.method == 'POST': form = UserProfileForm(request.POST, request.FILES, instance = user) if form.is_valid(): form.save() return HttpResponseRedirect('/settings/') else: form = UserProfileForm(instance = user) if request.user.is_staff== True: return render_to_response('staffsettingschange.html', {'form': form}) else: return render_to_response('settingschange.html', {'form': form}) ... @login_required def useradd(request): if request.method == 'POST': form = UserAddForm(request.POST,request.FILES ) if form.is_valid(): password = request.POST['password'] request.POST['password'] = set_password(password) form.save() else: form = UserAddForm() return render_to_response('staffadduser.html', {'form':form}) Example of my templates {% if form.errors %} <ol> {% for field in form %} <H3 class="title"> <p class="error"> {% if field.errors %}<li>{{ field.errors|striptags }}</li>{% endif %}</p> </H3> {% endfor %} </ol> {% endif %} <form method="post" id="form" action="" enctype="multipart/form-data" class="infotabs accfrm"> {{ repfrm.as_p }} <input type="submit" value="Submit" /> </form>

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• Rail test case fixtures not loading

  - by Deano

  Rails appears to not be loading any fixtures for unit or functional tests. I have a simple 'products.yml' that parses and appears correct: ruby: title: Programming Ruby 1.9 description: Ruby is the fastest growing and most exciting dynamic language out there. If you need to get working programs delivered fast, you should add Ruby to your toolbox. price: 49.50 image_url: ruby.png My controller functional test begins with: require 'test_helper' class ProductsControllerTest < ActionController::TestCase fixtures :products setup do @product = products(:one) @update = { :title => 'Lorem Ipsum' , :description => 'Wibbles are fun!' , :image_url => 'lorem.jpg' , :price => 19.95 } end According to the book, Rails should "magically" load the fixtures (as my test_helper.rb has fixtures :all in it. I also added the explicit fixtures load (seen above). Yes Rails complains: user @ host ~/Dropbox/Rails/depot > rake test:functionals (in /Somewhere/Users/user/Dropbox/Rails/depot) /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby -Ilib:test "/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rake-0.8.3/lib/rake/rake_test_loader.rb" "test/functional/products_controller_test.rb" Loaded suite /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rake-0.8.3/lib/rake/rake_test_loader Started EEEEEEE Finished in 0.062506 seconds. 1) Error: test_should_create_product(ProductsControllerTest): NoMethodError: undefined method `products' for ProductsControllerTest:Class /test/functional/products_controller_test.rb:7 2) Error: test_should_destroy_product(ProductsControllerTest): NoMethodError: undefined method `products' for ProductsControllerTest:Class /test/functional/products_controller_test.rb:7 ... I did come across the other Rails test fixture question http://stackoverflow.com/questions/1547634/rails-unit-testing-doesnt-load-fixtures, but that leads to a plugin issue (something to do with the order of loading fixtures). BTW, I am developing on Mac OS X 10.6 with Rail 2.3.5 and Ruby 1.8.7, no additional plugins (beyond the base install). Any pointers on how to debug, why the magic of Rails appears to be failing here? Is it a version problem? Can I trace code into the libraries and find the answer? There are so many "mixin" modules I can't find where the fixtures method really lives.

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• Asp.net hosting equivalent of Dreamhost (pricing, features and support)

  - by Cherian

  Disclaimer: I have browsed http://stackoverflow.com/questions/tagged/asp.net+hosting and didn’t find anything quite similar in value to Dreamhost. One of the biggest impediments IMHO for developing web applications on asp.net is the cost of deployment. I am not talking about building sites like Stackoverflow.com or plentyoffish.com. This is about sites that are bigger than brochureware and smaller than ones that require dedicated servers. Let me give you an example. xmec.org is an asp.net site I maintain for my college alumni. On an average it’s slated to hit around 1000-1100 views per day. At present it’s hosted on godaddy. The service is so damn pathetic; I am using it only because of the lack of options. The site doesn’t scale (no, it’s not the code) and the web control panels are extremely slow. The money I pay doesn’t justify the service or the performance. Every deployment push is a visit to the infuriating web control panel to set the permissions and the root directories. Had I developed it in python, this would have been deployed on Dreamhost.com with $10/year hosting fees (they have offers running all throughout) 50 GB space 5 MySQL Databases Shell / FTP Users POP / SMTP Access Unlimited Domains hosting Unlimited Sub domains hosting Unlimited Domains Forwarded/Mirrored Custom DNS (These are the only ones I could think of. More at the feature page) With a dream host shell, I even have a svn checked-out version of wordpress for my blog. Now, that’s control! To my question: Is there any asp.net (preferably .net 3.5. Dreamhost keeps on updating versions every fortnight) hosting company providing remotely similar feature-sets and pricing like Dreamhost. My requirements are: Less than $15-25/ year Typical WISP minus PHP .net 3.5 SP1 Full Trust mode(I can live with medium trust, if not for the IL emitting libraries) Isolated Application Pool 5 – 10 MySQL db’s Unlimited domain hosting MsSql 2005 or 2008 FTP support At Least 5 GB space SMTP IIS 7 Log files Accessibility Moderately good control panel Scripting, shell support Nominal bandwidth Another case in point: Recently I’ve been contemplating building a tool-website to find duplicates and weird characters in my Google contacts and fix them. With asp.net, the best part is that I can do this with LINQ to XML in less than 100 lines of code. What’s bad is the hosting part. I don’t think I stand to make any money out of this and therefore can’t afford to host it on GoGrid or DiscountAsp.net. Godaddy is not an option either. If I do this in python, I can push to this my existing $10 Dreamhost account with another domain pointed. No extra cost. Svn exported with scripts (capability) to change the connection string! Looking at the problem holistically, I think I represent a large breed of programmers playing it cheap and experimenting different things on a regular basis, one of which will become the next twitter/digg.

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• Entity Framework in n-layered application - Lazy loading vs. Eager loading patterns

  - by Marconline

  Hi all. This questions doesn't let me sleep as it's since one year I'm trying to find a solution but... still nothing happened in my mind. Probably you can help me, because I think this is a very common issue. I've a n-layered application: presentation layer, business logic layer, model layer. Suppose for simplicity that my application contains, in the presentation layer, a form that allows a user to search for a customer. Now the user fills the filters through the UI and clicks a button. Something happens and the request arrives to presentation layer to a method like CustomerSearch(CustomerFilter myFilter). This business logic layer now keeps it simple: creates a query on the model and gets back results. Now the question: how do you face the problem of loading data? I mean business logic layer doesn't know that that particular method will be invoked just by that form. So I think that it doesn't know if the requesting form needs just the Customer objects back or the Customer objects with the linked Order entities. I try to explain better: our form just wants to list Customers searching by surname. It has nothing to do with orders. So the business logic query will be something like: (from c in ctx.CustomerSet where c.Name.Contains(strQry) select c).ToList(); now this is working correctly. Two days later your boss asks you to add a form that let you search for customers like the other and you need to show the total count of orders created by each customer. Now I'd like to reuse that query and add the piece of logic that attach (includes) orders and gets back that. How would you front this request? Here is the best (I think) idea I had since now. I'd like to hear from you: my CustomerSearch method in BLL doesn't create the query directly but passes through private extension methods that compose the ObjectQuery like: private ObjectQuery<Customer> SearchCustomers(this ObjectQuery<Customer> qry, CustomerFilter myFilter) and private ObjectQuery<Customer> IncludeOrders(this ObjectQuery<Customer> qry) but this doesn't convince me as it seems too complex. Thanks, Marco

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• Should Application_End fire on an automatic App Pool Recycle?

  - by Laramie

  I have read this, this, this and this plus a dozen other posts/blogs. I have an ASP.Net app in shared hosting that is frequently recycling. We use NLog and have the following code in global.asax void Application_Start(object sender, EventArgs e) { NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger(); logger.Debug("\r\n\r\nAPPLICATION STARTING\r\n\r\n"); } protected void Application_OnEnd(Object sender, EventArgs e) { NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger(); logger.Debug("\r\n\r\nAPPLICATION_OnEnd\r\n\r\n"); } void Application_End(object sender, EventArgs e) { HttpRuntime runtime = (HttpRuntime)typeof(System.Web.HttpRuntime).InvokeMember("_theRuntime", BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.GetField, null, null, null); if (runtime == null) return; string shutDownMessage = (string)runtime.GetType().InvokeMember("_shutDownMessage", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.GetField, null, runtime, null); string shutDownStack = (string)runtime.GetType().InvokeMember("_shutDownStack", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.GetField, null, runtime, null); ApplicationShutdownReason shutdownReason = System.Web.Hosting.HostingEnvironment.ShutdownReason; NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger(); logger.Debug(String.Format("\r\n\r\nAPPLICATION END\r\n\r\n_shutDownReason = {2}\r\n\r\n _shutDownMessage = {0}\r\n\r\n_shutDownStack = {1}\r\n\r\n", shutDownMessage, shutDownStack, shutdownReason)); } void Application_Error(object sender, EventArgs e) { NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger(); logger.Debug("\r\n\r\nApplication_Error\r\n\r\n"); } Our log file is littered with "APPLICATION STARTING" entries, but neither Application_OnEnd, Application_End, nor Application_Error are ever fired during these spontaneous restarts. I know they are working because there are entries for touching the web.config or /bin files. We also ran a memory overload test and can trigger an OutOfMemoryException which is caught in Application_Error. We are trying to determine whether the virtual memory limit is causing the recycling. We have added GC.GetTotalMemory(false) throughout the code, but this is for all of .Net, not just our App´s pool, correct? We've also tried var oPerfCounter = new PerformanceCounter(); oPerfCounter.CategoryName = "Process"; oPerfCounter.CounterName = "Virtual Bytes"; oPerfCounter.InstanceName = "iisExpress"; logger.Debug("Virtual Bytes: " + oPerfCounter.RawValue + " bytes"); but don't have permission in shared hosting. I've monitored the app on a dev server with the same requests that caused the recycles in production with ANTS Memory Profiler attached and can't seem to find a culprit. We have also run it with a debugger attached in dev to check for uncaught exceptions in spawned threads that might cause the app to abort. My questions are these: How can I effectively monitor memory usage in shared hosting to tell how much my application is consuming prior to an application recycle? Why are the Application_[End/OnEnd/Error] handlers in global.asax not being called? How else can I determine what is causing these recycles? Thanks.

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• PHP - static DB class vs DB singleton object

  - by Marco Demaio

  I don't want to create a discussion about singleton better than static or better than global, etc. I read dozens of questions about it on SO, but I couldn't come up with an answer to this SPECIFIC question, so I hope someone could now illuminate me buy answering this question with one (or more) real simple EXAMPLES, and not theoretical discussions. In my app I have the typical DB class needed to perform tasks on DB without having to write everywhere in code mysql_connect/mysql_select_db/mysql... (moreover in future I might decide to use another type of DB engine in place of mySQL so obviously I need a class of abstration). I could write the class either as a static class: class DB { private static $connection = FALSE; //connection to be opened //DB connection values private static $server = NULL; private static $usr = NULL; private static $psw = NULL; private static $name = NULL; public static function init($db_server, $db_usr, $db_psw, $db_name) { //simply stores connections values, withour opening connection } public static function query($query_string) { //performs query over alerady opened connection, if not open, it opens connection 1st } ... } or as a Singletonm class: class DBSingleton { private $inst = NULL; private $connection = FALSE; //connection to be opened //DB connection values private $server = NULL; private $usr = NULL; private $psw = NULL; private $name = NULL; public static function getInstance($db_server, $db_usr, $db_psw, $db_name) { //simply stores connections values, withour opening connection if($inst === NULL) $this->inst = new DBSingleton(); return $this->inst; } private __construct()... public function query($query_string) { //performs query over already opened connection, if connection is not open, it opens connection 1st } ... } Then after in my app if I wanto to query the DB i could do //Performing query using static DB object DB:init(HOST, USR, PSW, DB_NAME); DB::query("SELECT..."); //Performing query using DB singleton $temp = DBSingleton::getInstance(HOST, USR, PSW, DB_NAME); $temp->query("SELECT..."); My simple brain sees Singleton has got the only advantage to avoid declaring as 'static' each method of the class. I'm sure some of you could give me an EXAMPLE of real advantage of singleton in this specific case. Thanks in advance.

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• DropDownList not updating value

  - by annelie

  Hello, I posted a question earlier but have another problem after making those changes. The previous thread can be found here: http://stackoverflow.com/questions/2700028/binding-a-dropdownlist-inside-a-detailsview Basically, I've got a dropdownlist that's dynamically populated with a list of regions. It selects the correct region when viewing the dropdown, but when I try to edit it changes the value to null. I think it might be because it doesn't know which field to update. Previously, when the dropdown list was hardcoded, I had SelectedValue='<%# Bind("region_id")%' set on the dropdown list, and when I updated it worked fine. However, I had to move the setting of the selected value into the code behind and now it just gets set to null every time I update. Here's the aspx code: <asp:DetailsView id="DetailsView1" runat="server" AutoGenerateRows="false" DataSourceID="myMySqlDataSrc" DataKeyNames="id" AutoGenerateDeleteButton="True" AutoGenerateEditButton="True" AutoGenerateInsertButton="False" OnDataBound="DetailsView1_DataBound" > <Fields> <snip> <asp:TemplateField HeaderText="Region"> <ItemTemplate><%# Eval("region_name") %></ItemTemplate> <EditItemTemplate> <asp:DropDownList ID="RegionDropdownList" runat="server"> </asp:DropDownList> </EditItemTemplate> </asp:TemplateField> </Fields> </asp:DetailsView> And here's the code behind: protected void DetailsView1_DataBound(object sender, EventArgs e) { ArrayList regionsList = BPBusiness.getRegions(); if (DetailsView1.CurrentMode == DetailsViewMode.Edit) { DropDownList ddlRegions = (DropDownList)DetailsView1.FindControl("RegionDropdownList"); if (ddlRegions != null) { ddlRegions.DataSource = regionsList; ddlRegions.DataValueField = "Value"; ddlRegions.DataTextField = "Text"; ddlRegions.DataBind(); if (ddlRegions.Items.Contains(ddlRegions.Items.FindByValue(objBusiness.iRegionID.ToString()))) { ddlRegions.SelectedIndex = ddlRegions.Items.IndexOf(ddlRegions.Items.FindByValue(objBusiness.iRegionID.ToString())); } } } } EDIT: The database is MySql, and the update statement looks like this: myMySqlDataSrc.UpdateCommand = "UPDATE myTable SET business_name = ?, addr_line_1 = ?, addr_line_2 = ?, addr_line_3 = ?, postcode = ?, county = ?, town_city = ?, tl_url = ?, customer_id = ?, region_id = ?, description = ?, approval_status = ?, tl_user_name = ?, phone = ?, uploaders_own = ? WHERE id = ?"; Thanks, Annelie

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• log4net logging problem

  - by Dotnet_user

  Hello everyone, I'm not sure if this is the right forum to post this question. But I'm just hoping someone here might have used log4net in the past, so hoping to get some help. I'm using log4net to log my exceptions. The configuration settings look like this: <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/> </configSections> <log4net debug="false"> <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender"> <file value="C:\Logs\sample.log" /> <appendToFile value="true"/> <rollingStyle value="Size"/> <maxSizeRollBackups value="10"/> <maximumFileSize value="10MB"/> <staticLogFileName value="true"/> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%-5level %date %logger.%method[line %line] - %message%newline"/> </layout> </appender> <root> <level value="INFO"/> <appender-ref ref="RollingLogFileAppender"/> </root> </log4net> </configuration> I started out by adding this configuration to web.config, but I got an error (VS studio could not find a schema for log4net-"Could not find schema information for the element log4net"). So I followed this link (http://stackoverflow.com/questions/174430/log4net-could-not-find-schema-information-messages) and configured my settings in a separate xml file and added the following line of code in my AssemblyInfo.cs: [assembly: log4net.Config.XmlConfigurator(ConfigFile = "xmlfile.xml", Watch = true)] And in the actual code, I placed this line: public void CreateUser(String username, String password) { try { log.Info("Inside createuser"); //code for creating user } catch(exception e) { log.Info("something happened in create user", e); } } The problem is that the log file is not being created. I can't see anything inside C:\Logs. Can anybody tell me what I'm doing wrong here? Any suggestions/inputs will be very helpful. Thank you all in advance.

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• ArrayAdapter need to be clear even i am creating a new one

  - by Roi

  Hello I'm having problems understanding how the ArrayAdapter works. My code is working but I dont know how.(http://amy-mac.com/images/2013/code_meme.jpg) I have my activity, inside it i have 2 private classes.: public class MainActivity extends Activity { ... private void SomePrivateMethod(){ autoCompleteTextView.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, new ArrayList<String>(Arrays.asList("")))); autoCompleteTextView.addTextChangedListener(new MyTextWatcher()); } ... private class MyTextWatcher implements TextWatcher { ... } private class SearchAddressTask extends AsyncTask<String, Void, String[]> { ... } } Now inside my textwatcher class i call the search address task: @Override public void afterTextChanged(Editable s) { new SearchAddressTask().execute(s.toString()); } So far so good. In my SearchAddressTask I do some stuff on doInBackground() that returns the right array. On the onPostExecute() method i try to just modify the AutoCompleteTextView adapter to add the values from the array obtained in doInBackground() but the adapter cannot be modified: NOT WORKING CODE: protected void onPostExecute(String[] addressArray) { ArrayAdapter<String> adapter = (ArrayAdapter<String>) autoCompleteDestination.getAdapter(); adapter.clear(); adapter.addAll(new ArrayList<String>(Arrays.asList(addressArray))); adapter.notifyDataSetChanged(); Log.d("SearchAddressTask", "adapter isEmpty : " + adapter.isEmpty()); // Returns true!!??! } I dont get why this is not working. Even if i run it on UI Thread... I kept investigating, if i recreate the arrayAdapter, is working in the UI (Showing the suggestions), but i still need to clear the old adapter: WORKING CODE: protected void onPostExecute(String[] addressArray) { ArrayAdapter<String> adapter = (ArrayAdapter<String>) autoCompleteDestination.getAdapter(); adapter.clear(); autoCompleteDestination.setAdapter(new ArrayAdapter<String>(NewDestinationActivity.this,android.R.layout.simple_spinner_dropdown_item, new ArrayList<String>(Arrays.asList(addressArray)))); //adapter.notifyDataSetChanged(); // no needed Log.d("SearchAddressTask", "adapter isEmpty : " + adapter.isEmpty()); // keeps returning true!!??! } So my question is, what is really happening with this ArrayAdapter? why I cannot modify it in my onPostExecute()? Why is working in the UI if i am recreating the adapter? and why i need to clear the old adapter then? I dont know there are so many questions that I need some help in here!! Thanks!!

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• How can I pass latitude and longitude values from UIViewController to MKMapView?

  - by jerincbus

  I have a detail view that includes three UIButtons, each of which pushes a different view on to the stack. One of the buttons is connected to a MKMapView. When that button is pushed I need to send the latitude and longitude variables from the detail view to the map view. I'm trying to add the string declaration in the IBAction: - (IBAction)goToMapView { MapViewController *mapController = [[MapViewController alloc] initWithNibName:@"MapViewController" bundle:nil]; mapController.mapAddress = self.address; mapController.mapTitle = self.Title; mapController.mapLat = self.lat; mapController.mapLng = self.lng; //Push the new view on the stack [[self navigationController] pushViewController:mapController animated:YES]; [mapController release]; //mapController = nil; } And on my MapViewController.h file I have: #import <UIKit/UIKit.h> #import <MapKit/MapKit.h> #import "DetailViewController.h" #import "CourseAnnotation.h" @class CourseAnnotation; @interface MapViewController : UIViewController <MKMapViewDelegate> { IBOutlet MKMapView *mapView; NSString *mapAddress; NSString *mapTitle; NSNumber *mapLat; NSNumber *mapLng; } @property (nonatomic, retain) IBOutlet MKMapView *mapView; @property (nonatomic, retain) NSString *mapAddress; @property (nonatomic, retain) NSString *mapTitle; @property (nonatomic, retain) NSNumber *mapLat; @property (nonatomic, retain) NSNumber *mapLng; @end And on the pertinent parts of the MapViewController.m file I have: @synthesize mapView, mapAddress, mapTitle, mapLat, mapLng; - (void)viewDidLoad { [super viewDidLoad]; [mapView setMapType:MKMapTypeStandard]; [mapView setZoomEnabled:YES]; [mapView setScrollEnabled:YES]; MKCoordinateRegion region = { {0.0, 0.0 }, { 0.0, 0.0 } }; region.center.latitude = mapLat; //40.105085; region.center.longitude = mapLng; //-83.005237; region.span.longitudeDelta = 0.01f; region.span.latitudeDelta = 0.01f; [mapView setRegion:region animated:YES]; [mapView setDelegate:self]; CourseAnnotation *ann = [[CourseAnnotation alloc] init]; ann.title = mapTitle; ann.subtitle = mapAddress; ann.coordinate = region.center; [mapView addAnnotation:ann]; } But I get this when I try to build: 'error: incompatible types in assignment' for both lat and lng variables. So my questions are am I going about passing the variables from one view to another the right way? And does the MKMapView accept latitude and longitude as a string or a number?

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• Most efficient method to query a Young Tableau

  - by Matthieu M.

  A Young Tableau is a 2D matrix A of dimensions M*N such that: i,j in [0,M)x[0,N): for each p in (i,M), A[i,j] <= A[p,j] for each q in (j,N), A[i,j] <= A[i,q] That is, it's sorted row-wise and column-wise. Since it may contain less than M*N numbers, the bottom-right values might be represented either as missing or using (in algorithm theory) infinity to denote their absence. Now the (elementary) question: how to check if a given number is contained in the Young Tableau ? Well, it's trivial to produce an algorithm in O(M*N) time of course, but what's interesting is that it is very easy to provide an algorithm in O(M+N) time: Bottom-Left search: Let x be the number we look for, initialize i,j as M-1, 0 (bottom left corner) If x == A[i,j], return true If x < A[i,j], then if i is 0, return false else decrement i and go to 2. Else, if j is N-1, return false else increment j This algorithm does not make more than M+N moves. The correctness is left as an exercise. It is possible though to obtain a better asymptotic runtime. Pivot Search: Let x be the number we look for, initialize i,j as floor(M/2), floor(N/2) If x == A[i,j], return true If x < A[i,j], search (recursively) in A[0:i-1, 0:j-1], A[i:M-1, 0:j-1] and A[0:i-1, j:N-1] Else search (recursively) in A[i+1:M-1, 0:j], A[i+1:M-1, j+1:N-1] and A[0:i, j+1:N-1] This algorithm proceed by discarding one of the 4 quadrants at each iteration and running recursively on the 3 left (divide and conquer), the master theorem yields a complexity of O((N+M)**(log 3 / log 4)) which is better asymptotically. However, this is only a big-O estimation... So, here are the questions: Do you know (or can think of) an algorithm with a better asymptotical runtime ? Like introsort prove, sometimes it's worth switching algorithms depending on the input size or input topology... do you think it would be possible here ? For 2., I am notably thinking that for small size inputs, the bottom-left search should be faster because of its O(1) space requirement / lower constant term.

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• "Alert" and "if" changes behaviour of dom copying from iframe to div

  - by lowkey

  Hi guys! Tried to make a little old school ajax (iframe-javascript) script. A bit of mootools is used for DOM navigation Description: HTML: 1 iframe called "buffer" 1 div called "display" JAVASCRIPT: (short: copy iframe content into a div on the page) 1) onLoad on iframe triggers handler(), a counter makes sure it only run once (this is because otherwise firefox will go into feedback loop. What i think happens: iframe on load handler() copyBuffer change src of iframe , and firefox takes that as an onload again) 2) copybuffer() is called, it sets src of iframe then copies iframe content into div, then erases iframe content THE CODE: count=0; function handler(){ if (count==0){ copyBuffer(); count++; } } function copyBuffer(){ $('buffer').set('src','http://www.somelink.com/'); if (window.frames['buffer'] && $('display') ) { $('display').innerHTML = window.frames['buffer'].document.body.innerHTML; window.frames['buffer'].document.body.innerHTML=""; } } problems: QUESTION 1) nothing happens, the content is not loaded into the div. But if i either: A) remove the counter and let the script run in a feedback loop: the content is suddenly copied into the div, but off course there is a feedback loop going on, you can see it keeps loading in the status bar. OR B) insert an alert in the copyBuffer function. The content is copied, without the feedback loop. why does this happen? QUESTION 2) The If wrapped around the copying code i got from a source on the internet. I am not sure what it does? If i remove it the code does not work in: Safari and Chrome. Many thanks in advance! UPDATE: Like the answers said i have created an event handler. They used jQuery, i have made one in mootools: window.addEvent('domready', function() { $('buffer').addEvent('load', function(){ $('display').set('html',window.frames['buffer'].document.body.innerHTML) window.frames['buffer'].document.body.innerHTML=""; }).set('src','somelink'); }); Bonus question: 3) Im new at stackoverflow (what an amazing place!), is it better if i make new threads for follow up questions?

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• Unique ID Defined by Most-Derived Class accessible through Base Class

  - by Narfanator

  Okay, so, the idea is that I have a map of "components", which inherit from componentBase, and are keyed on an ID unique to the most-derived*. Only, I can't think of a good way to get this to work. I tried it with the constructor, but that doesn't work (Maybe I did it wrong). The problem with any virtual, etc, inheritance tricks are that the user has to impliment them at the bottom, which can be forgotten and makes it less... clean. *Right phrase? If - is inheritance; foo is most-derived: foo-foo1-foo2-componentBase Here's some code showing the problem, and why CRTP can't cut it: (No, it's not legit code, but I'm trying to get my thoughts down) #include<map> class componentBase { public: virtual static char idFunction() = 0; }; template <class T> class component : public virtual componentBase { public: static char idFunction(){ return reinterpret_cast<char>(&idFunction); } }; class intermediateDerivations1 : public virtual component<intermediateDerivations1> { }; class intermediateDerivations2 : public virtual component<intermediateDerivations2> { }; class derived1 : public intermediateDerivations1 { }; class derived2 : public intermediateDerivations1 { }; //How the unique ID gets used (more or less) std::map<char, componentBase*> TheMap; template<class T> void addToMap(componentBase * c) { TheMap[T::idFunction()] = c; } template<class T> T * getFromMap() { return TheMap[T::idFunction()]; } int main() { //In each case, the key needs to be different. //For these, the CRTP should do it: getFromMap<intermediateDerivations1>(); getFromMap<intermediateDerivations2>(); //But not for these. getFromMap<derived1>(); getFromMap<derived2>(); return 0; } More or less, I need something that is always there, no matter what the user does, and has a sortable value that's unique to the most-derived class. Also, I realize this isn't the best-asked question, I'm actually having some unexpected difficultly wrapping my head around it in words, so ask questions if/when you need clarification.

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• Network communication for a turn based board game

  - by randooom

  Hi all, my first question here, so please don't be to harsh if something went wrong :) I'm currently a CS student (from Germany, if this info is of any use ;) ) and we got a, free selectable, programming assignment, which we have to write in a C++/CLI Windows Forms Application. My team, two others and me, decided to go for a network-compatible port of the board game Risk. We divided the work in 3 Parts, namely UI, game logic and network. Now we're on the part where we have to get everything working together and the big question mark is, how to get the clients synchronized with each other? Our approach so far is, that each client has all information necessary to calculate and/or execute all possible actions. Actually the clients have all information available at all, aside from the game-initializing phase (add players, select map, etc.), which needs one "super-client" with some extra stuff to control things. This is the standard scenario of our approach: player performs action, the action is valid and got executed on the players client action is sent over the network action is executed on the other clients The design (i.e. no or code so far) we came up with so far, is something like the following pseudo sequence diagram. Gui, Controller and Network implement all possible actions (i.e. all actions which change data) as methods from an interface. So each part can implement the method in a way to get their job done. Example with Action(): On the player side's Client: Player-->Gui.Action() Gui-->Controller.Action() Controller-->Logic.Action (Logic.Action() == NoError)? Controller-->Network.Action() Network-->Parser.ParseAction() Network.Send(msg) On all other clients: Network.Recv(msg) Network-->Parser.Deparse(msg) Parser-->Logic.Action() Logic-->Gui.Action() The questions: Is this a viable approach to our task? Any better/easier way to this? Recommendations, critique? Our knowledge (so you can better target your answer): We are on the beginner side, in regards to programming on a somewhat larger projects with a small team. All of us have some general programming experience and basic understanding of the .Net Libraries and Windows Forms. If you need any further information, please feel free to ask.

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• Can a View Controller manage more than 1 nib based view?

  - by Hugo Brynjar

  I have a VC controlling a screen of content that has 2 modes; a normal mode and an edit mode. Can I create a single VC with 2 views, each from separate nibs? In many situations on the iphone, you have a VC which controls an associated view. Then on a button press or other event, a new VC is loaded and its view becomes the top level view etc. But in this situation, I have 2 modes that I want to use the same VC for, because they are closely related. So I want a VC which can swap in/out 2 views. As per here: http://stackoverflow.com/questions/863321/iphone-how-to-load-a-view-using-a-nib-file-created-with-interface-builder/2683153#2683153 I have found that I can load a VC with an associated view from a nib and then later on load a different view from another nib and make that new view the active view. NSArray *nibObjects = [[NSBundle mainBundle] loadNibNamed:@"EditMode" owner:self options:nil]; UIView *theEditView = [nibObjects objectAtIndex:0]; self.editView = theEditView; [self.view addSubview:theEditView]; The secondary nib has outlets wired up to the VC like the primary nib. When the new nib is loaded, the outlets are all connected up fine and everything works nicely. Unfortunately when this edit view is then removed, there doesn't seem to be any elegant way of getting the outlets hooked up again to the (normal mode) view from the original nib. Nib loading and outlet setting seems a once only thing. So, if you want to have a VC that swaps in/out 2 views without creating a new VC, what are the options? 1) You can do everything in code, but I want to use nibs because it makes creating the UI simpler. 2) You have 1 nib for your VC and just hide/show elements using the hidden property of UIView and its subclasses. 3) You load a new nib as described above. This is fine for the new nib, but how do you sort the outlets when you go back to the original nib. 4) Give up and accept having a 1:1 between VCs and nibs. There is a nib for normal mode, a nib for edit mode and each mode has a VC that subclasses a common superclass. In the end, I went with 4) and it works, but requires a fair amount of extra work, because I have a model class that I instantiate in normal mode and then have to pass to the edit mode VC because both modes need access to the model. I'm also using NSTimer and have to start and stop the timer in each mode. It is because of all this shared functionality that I wanted a single VC with 2 nibs in the first place.

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• ckeditor: toggle button in facelets

  - by Shilpa

  I am trying to toggle between CKEditor and textarea in a facelet(.xhtml) file. I have used the same code in a jsp file and it works fine. But in .xhtml file its not doing the toggle between ckeditor and plain editor.It loads ckeditor both the times.Can anyone please let me know what am I missing. Code of xhtml file: <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:ckeditor="http://ckeditor.com"> <head> <title>Welcome PAge</title> <script type="text/javascript" src="ckeditor/ckeditor.js"></script> <script type="text/javascript" src="ckeditor/adapters/jquery.js"></script> <script type="text/javascript" src="ckeditor/config.js"></script> </head> <body> <div>Welcome Page!!</div> <h:form> <center><p><h:outputText value="#{userBean.username} logged in"/></p></center> <center> <p> Questions: <h:inputTextarea id="editor1" class="ckeditor" rows="20" cols="75" /> <br></br> </p> </center> <h:commandButton value="Ckeditor" onclick="ckeditor.replace('editor1');" /> <h:commandButton value="Text editor" onclick="ckeditor.instances.editor1.destroy();" /> <h:commandButton value="Get Data" onclick="alert(ckeditor.instances.editor1.getData());" /> <br></br> <br></br> </h:form> </body> </html> Thanks in advance, Shilpa

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• How to create a compiler in vb.net

  - by Cyclone

  Before answering this question, understand that I am not asking how to create my own programming language, I am asking how, using vb.net code, I can create a compiler for a language like vb.net itself. Essentially, the user inputs code, they get a .exe. By NO MEANS do I want to write my own language, as it seems other compiler related questions on here have asked. I also do not want to use the vb.net compiler itself, nor do I wish to duplicate the IDE. The exact purpose of what I wish to do is rather hard to explain, but all I need is a nudge in the right direction for writing a compiler (from scratch if possible) which can simply take input and create a .exe. I have opened .exe files as plain text before (my own programs) to see if I could derive some meaning from what I assumed would be human readable text, yet I was obviously sorely disappointed to see the random ascii, though it is understandable why this is all I found. I know that a .exe file is simply lines of code, being parsed by the computer it is on, but my question here really boils down to this: What code makes up a .exe? How could I go about making one in a plain text editor if I wanted to? (No, I do not want to do that, but if I understand the process my goals will be much easier to achieve.) What makes an executable file an executable file? Where does the logic of the code fit in? This is intended to be a programming question as opposed to a computer question, which is why I did not post it on SuperUser. I know plenty of information about the System.IO namespace, so I know how to create a file and write to it, I simply do not know what exactly I would be placing inside this file to get it to work as an executable file. I am sorry if this question is "confusing", "dumb", or "obvious", but I have not been able to find any information regarding the actual contents of an executable file anywhere. One of my google searches Something that looked promising EDIT: The second link here, while it looked good, was an utter fail. I am not going to waste hours of my time hitting keys and recording the results. "Use the "Alt" and the 3-digit combinations to create symbols that do not appear on the keyboard but that you need in the program." (step 4) How the heck do I know what symbols I need??? Thank you very much for your help, and my apologies if this question is a nooby or "bad" one. To sum this up simply: I want to create a program in vb.net that can compile code in a particular language to a single executable file. What methods exist that can allow me to do this, and if there are none, how can I go about writing my own from scratch?

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• Python form POST using urllib2 (also question on saving/using cookies)

  - by morpheous

  I am trying to write a function to post form data and save returned cookie info in a file so that the next time the page is visited, the cookie information is sent to the server (i.e. normal browser behavior). I wrote this relatively easily in C++ using curlib, but have spent almost an entire day trying to write this in Python, using urllib2 - and still no success. This is what I have so far: import urllib, urllib2 import logging # the path and filename to save your cookies in COOKIEFILE = 'cookies.lwp' cj = None ClientCookie = None cookielib = None logger = logging.getLogger(__name__) # Let's see if cookielib is available try: import cookielib except ImportError: logger.debug('importing cookielib failed. Trying ClientCookie') try: import ClientCookie except ImportError: logger.debug('ClientCookie isn\'t available either') urlopen = urllib2.urlopen Request = urllib2.Request else: logger.debug('imported ClientCookie succesfully') urlopen = ClientCookie.urlopen Request = ClientCookie.Request cj = ClientCookie.LWPCookieJar() else: logger.debug('Successfully imported cookielib') urlopen = urllib2.urlopen Request = urllib2.Request # This is a subclass of FileCookieJar # that has useful load and save methods cj = cookielib.LWPCookieJar() login_params = {'name': 'anon', 'password': 'pass' } def login(theurl, login_params): init_cookies(); data = urllib.urlencode(login_params) txheaders = {'User-agent' : 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'} try: # create a request object req = Request(theurl, data, txheaders) # and open it to return a handle on the url handle = urlopen(req) except IOError, e: log.debug('Failed to open "%s".' % theurl) if hasattr(e, 'code'): log.debug('Failed with error code - %s.' % e.code) elif hasattr(e, 'reason'): log.debug("The error object has the following 'reason' attribute :"+e.reason) sys.exit() else: if cj is None: log.debug('We don\'t have a cookie library available - sorry.') else: print 'These are the cookies we have received so far :' for index, cookie in enumerate(cj): print index, ' : ', cookie # save the cookies again cj.save(COOKIEFILE) #return the data return handle.read() # FIXME: I need to fix this so that it takes into account any cookie data we may have stored def get_page(*args, **query): if len(args) != 1: raise ValueError( "post_page() takes exactly 1 argument (%d given)" % len(args) ) url = args[0] query = urllib.urlencode(list(query.iteritems())) if not url.endswith('/') and query: url += '/' if query: url += "?" + query resource = urllib.urlopen(url) logger.debug('GET url "%s" => "%s", code %d' % (url, resource.url, resource.code)) return resource.read() When I attempt to log in, I pass the correct username and pwd,. yet the login fails, and no cookie data is saved. My two questions are: can anyone see whats wrong with the login() function, and how may I fix it? how may I modify the get_page() function to make use of any cookie info I have saved ?

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• CSS to Replace Table Layout for Forms

  - by Erick

  I've looked at other questions and am unable to find the solution to this. Consider this image: I want to wrap divs and stack them vertically. The GREEN div would be a wrapper on a line. The BLUE div would contain an html label and maybe icon for a tooltip. The ORANGE div would contain some sort of entry (input, select, textarea). Several of these would be stacked vertically to make up a form. I am doing this now, but I have to specify a height for the container div and that really needs to change depending on the content - considering any entry could land there. Images and other stuff could land here, as well. I have a width set on the BLUE div and the ORANGE is float:left. How can I get rid of the height on divs and let that be determined by content? Is there a better way? Changing all to something else would be difficult and would prefer a way to style all elements or something. The code I'm using is like: <div class=EntLine> <div class=EntLbl> <label for="Name">Name</label> </div> <div class=EntFld> <input type=text id="Name" /> </div> </div> The CSS looks like: .EntLine { height: 20px; position: relative; margin-top: 2px; text-align: left; white-space: nowrap; } .EntLbl { float: left; width: 120px; padding: 3px 0px 0px 3px; min-width: 120px; max-width: 120px; vertical-align: text-top; } .EntFld { float: left; height: 20px; padding: 0px; width: 200px; } Thanks!

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• How to efficiently save changes made in UI/main thread with Core Data?

  - by Jaanus

  So, there have been several posts here about importing and saving data from an external data source into Core Data. Apple documents a reasonable pattern for this: "import and save on background thread, merge saved objects to main thread." All fine and good. I have a related but different problem: the user is modifying data in the UI and main thread, and thus modifies state of some objects in the managed object context (MOC). I would like to save these changes from time to time. What is a good way to do that? Now, you could say that I could do the same: create a background thread with its own MOC and pass the changed objectID-s there. The catch-22 for me with this is that an object's ID changes when it is saved, and I cannot guarantee the order of things happening. I may end up passing a different objectID into the background thread for the same object, based on whether the object has been previously saved or not, and I don't know if Core Data can resolve this and see that different objectID-s are pointing to the same object and not create duplicates for me. (I could test this, but I'm lazywebbing with this question first.) One thought I had: I could always do MOC saves on a background thread, and queue them up with operationqueue, so that there is always only one save in progress. I would not create a new MOC, I would just use the same MOC as in main thread. Now, this is not thread safe and when someone modifies the MOC in main thread while it is being saved in background thread, the results will probably be catastrophic. But, minus the thread safety, you can see what kind of solution I'd wish for. To be clear, the problem I need to fix is that if I just do the save in main thread, it blocks the UI for an unacceptably long period of time, I want to move the save to background thread. So, questions: what about the reasoning of an object ID changing during saving, and Core Data being able to resolve them to the same object? Would this be the right way of addressing this problem? any other good ways of doing this?

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• JavaScript: Doing some stuff right before the user exits the page

  - by Mike

  I have seen some questions here regarding what I want to achieve and have based what I have so far on those answer. But there is a slight misbehavior that is still irritating me. What I have is sort of a recovery feature. Whenever you are typing text, the client sends a sync request to the server every 45 seconds. It does 2 things. First, it extends the lease the client has on the record (only one person may edit at one time) for another 60 seconds. Second, it sends the text typed so far to the server in case the server crashes, internet connection fails, etc. In that case, the next time the user enters our application, the user is notified that something has gone wrong and that some text was recovered. Think of Microsoft or OpenOffice recovery whenever they crash! Of course, if the user leaves the page willingly, the user does not need to be notified and as a result, the recovery is deleted. I do that final request via a beforeunload event. Everything went fine until I was asked to make a final adjustment... The same behavior you have here at stack overflow when you exit the editor... a confirm dialogue. This works so far, BUT, the confirm dialogue is shown twice. Here is the code. The event if (local.sync.autosave_textelement) { window.onbeforeunload = exitConfirm; } The function function exitConfirm() { var local = Core; if (confirm('blub?')) { local.sync.autosave_destroy = true; sync(false); return true; } else { return false; } }; Some problem irrelevant clarifications: Core is a global Object that contains a lot of variables that are used everywhere. sync makes an ajax request. The values are based on the values that the Core.sync object contains. The parameter determines if the call should be async (default) or sync.

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• Why is it still so hard to write software?

  - by nornagon

  Writing software, I find, is composed of two parts: the Idea, and the Implementation. The Idea is about thinking: "I have this problem; how do I solve it?" and further, "how do I solve it elegantly?" The answers to these questions are obtainable by thinking about algorithms and architecture. The ideas come partially through analysis and partially through insight and intuition. The Idea is usually the easy part. You talk to your friends and co-workers and you nut it out in a meeting or over coffee. It takes an hour or two, plus revisions as you implement and find new problems. The Implementation phase of software development is so difficult that we joke about it. "Oh," we say, "the rest is a Simple Matter of Code." Because it should be simple, but it never is. We used to write our code on punch cards, and that was hard: mistakes were very difficult to spot, so we had to spend extra effort making sure every line was perfect. Then we had serial terminals: we could see all our code at once, search through it, organise it hierarchically and create things abstracted from raw machine code. First we had assemblers, one level up from machine code. Mnemonics freed us from remembering the machine code. Then we had compilers, which freed us from remembering the instructions. We had virtual machines, which let us step away from machine-specific details. And now we have advanced tools like Eclipse and Xcode that perform analysis on our code to help us write code faster and avoid common pitfalls. But writing code is still hard. Writing code is about understanding large, complex systems, and tools we have today simply don't go very far to help us with that. When I click "find all references" in Eclipse, I get a list of them at the bottom of the window. I click on one, and I'm torn away from what I was looking at, forced to context switch. Java architecture is usually several levels deep, so I have to switch and switch and switch until I find what I'm really looking for -- by which time I've forgotten where I came from. And I do that all day until I've understood a system. It's taxing mentally, and Eclipse doesn't do much that couldn't be done in 1985 with grep, except eat hundreds of megs of RAM. Writing code has barely changed since we were staring at amber on black. We have the theoretical groundwork for much more advanced tools, tools that actually work to help us comprehend and extend the complex systems we work with every day. So why is writing code still so hard?

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• Averaging initial values for rolling series

  - by Dave Jarvis

  Question Given a maximum sliding window size of 40 (i.e., the set of numbers in the list cannot exceed 40), what is the calculation to ensure a smooth averaging transition as the set size grows from 1 to 40? Problem Description Creating a trend line for a set of data has skewed initial values. The complete set of values is unknown at runtime: they are provided one at a time. It seems like a reverse-weighted average is required so that the initial values are averaged differently. In the image below the leftmost data for the trend line are incorrectly averaged. Current Solution Created a new type of ArrayList subclass that calculates the appropriate values and ensures its size never goes beyond the bounds of the sliding window: /** * A list of Double values that has a maximum capacity enforced by a sliding * window. Can calculate the average of its values. */ public class AveragingList extends ArrayList<Double> { private float slidingWindowSize = 0.0f; /** * The initial capacity is used for the sliding window size. * @param slidingWindowSize */ public AveragingList( int slidingWindowSize ) { super( slidingWindowSize ); setSlidingWindowSize( ( float )slidingWindowSize ); } public boolean add( Double d ) { boolean result = super.add( d ); // Prevent the list from exceeding the maximum sliding window size. // if( size() > getSlidingWindowSize() ) { remove( 0 ); } return result; } /** * Calculate the average. * * @return The average of the values stored in this list. */ public double average() { double result = 0.0; int size = size(); for( Double d: this ) { result += d.doubleValue(); } return (double)result / (double)size; } /** * Changes the maximum number of numbers stored in this list. * * @param slidingWindowSize New maximum number of values to remember. */ public void setSlidingWindowSize( float slidingWindowSize ) { this.slidingWindowSize = slidingWindowSize; } /** * Returns the number used to determine the maximum values this list can * store before it removes the first entry upon adding another value. * @return The maximum number of numbers stored in this list. */ public float getSlidingWindowSize() { return slidingWindowSize; } } Resulting Image Example Input The data comes into the function one value at a time. For example, data points (Data) and calculated averages (Avg) typically look as follows: Data: 17.0 Avg : 17.0 Data: 17.0 Avg : 17.0 Data: 5.0 Avg : 13.0 Data: 5.0 Avg : 11.0  Related Sites The following pages describe moving averages, but typically when all (or sufficient) data is known: http://www.cs.princeton.edu/introcs/15inout/MovingAverage.java.html http://stackoverflow.com/questions/2161815/r-zoo-series-sliding-window-calculation http://taragana.blogspot.com/ http://www.dreamincode.net/forums/index.php?showtopic=92508 http://blogs.sun.com/nickstephen/entry/dtrace_and_moving_rolling_averages

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• NoSQL DB for .Net document-based database (ECM)

  - by Dane

  I'm halfway through coding a basic multi-tenant SaaS ECM solution. Each client has it's own instance of the database / datastore, but the .Net app is single instance. The documents are pretty much read only (i.e. an image archive of tiffs or PDFs) I've used MSSQL so far, but then started thinking this might be viable in a NoSQL DB (e.g. MongoDB, CouchDB). The basic premise is that it stores documents, each with their own particular indexes. Each tenant can have multiple document types. e.g. One tenant might have an invoice type, which has Customer ID, Invoice Number and Invoice Date. Another tenant might have an application form, which has Member Number, Application Number, Member Name, and Application Date. So far I've used the old method which Sharepoint (used?) to use, and created a document table which has int_field_1, int_field_2, date_field_1, date_field_2, etc. Then, I've got a "mapping" table which stores the customer specific index name, and the database field that will map to. I've avoided the key-value pair model in the DB due to volume of documents. This way, we can support multiple document types in the one table, and get reasonably high performance out of it, and allow for custom document type searches (i.e. user selects a document type, then they're presented with a list of search fields). However, a NoSQL DB might make this a lot simpler, as I don't need to worry about denormalizing the document. However, I've just got concerns about the rest of the data around a document. We store an "action history" against the document. This tracks views, whether someone emails the document from within the system, and other "future" functionality (e.g. faxing). We have control over the document load process, so we can manipulate the data however it needs to be to get it in the document store (e.g. assign unique IDs). Users will not be adding in their own documents, so we shouldn't need to worry about ACID compliance, as the documents are relatively static. So, my questions I guess : Is a NoSQL DB a good fit Is MongoDB the best for Asp.Net (I saw Raven and Velocity, but they're still kinda beta) Can I store a key for each document, and then store the action history in a MSSQL DB with this key? I don't need to do joins, it would be if a person clicks "View History" against a document. How would performance compare between the two (NoSQL DB vs denormalized "document" table) Volumes would be up to 200,000 new documents per month for a single tenant. My current scaling plan with the SQL DB involves moving the SQL DB into a cluster when certain thresholds are reached, and then reviewing partitioning and indexing structures.

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