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  • How to transform vertical table into horizontal table?

    - by avivo
    Hello, I have one table Person: Id Name 1 Person1 2 Person2 3 Person3 And I have its child table Profile: Id PersonId FieldName Value 1 1 Firstname Alex 2 1 Lastname Balmer 3 1 Email [email protected] 4 1 Phone +1 2 30004000 And I want to get data from these two tables in one row like this: Id Name Firstname Lastname Email Phone 1 Person1 Alex Balmer [email protected] +1 2 30004000 What is the most optimized query to get these vertical (key, value) values in one row like this? Now I have a problem that I done four joins of child table to parent table because I need to get these four fields. Some optimization is for sure possible. I would like to be able to modify this query in easy way when I add new field (key,value). What is the best way to do this? To create some StoreProcedure? I would like to have strongly types in my DB layer (C#) and using LINQ (when programming) so it means when I add some new Key, Value pair in Profile table I would like to do minimal modifications in DB and C# if possible. Actually I am trying to get some best practices in this case.

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  • C# Multithreaded Domain Design

    - by Thijs Cramer
    Let's say i have a Domain Model that im trying to make compatible with multithreading. The prototype domain is a game domain that consists of Space, SpaceObject, and Location objects. A SpaceObject has the Move method and Asteroid and Ship extend this object with specific properties for the object (Ship has a name and Asteroid has a color) Let's say i want to make the Move method for each object run in a seperate thread. That would be stupid because with 10000 objects, i would have 10000 threads. What would be the best way to seperate the workload between cores/threads? I'm trying to learn the basics of concurrency, and building a small game to prototype a lot of concepts. What i've already done, is build a domain, and a threading model with a timer that launches events based on intervals. If the event occurs i want to update my entire model with the new locations of any SpaceObject. But i don't know how and when to launch new threads with workloads when the event occurs. Some people at work told me that u can't update your core domain multithreaded, because you have to synch everything. But in that case i can't run my game on a dual quadcore server, because it would only use 1 CPU for the hardest tasks. Anyone know what to do here?

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  • PHP Post Count in Forum

    - by Chris
    I'm currently desiging a forum application, I considered using a premade but decided against it as it's useful for me to learn some of the techniques. So I've written a fairly full featured forum... great. One of the problems I want to solve is to include user data for each post, at the minute the post table includes the poster ID (obviously) and I added the poster's username at a later date so I didn't have to query the User DB for X number of posts in a thread. However, it's become apparent I now want to do this, usernames don't need to update retrospectively, however avatars, sigs, and especially post counts need to update actively, so data in some form needs keeping up to date somewhere... What would be a good way of implementing this? I obviously don't want to include any more user data on the Posts DB table than necessary, but I'm struggling to find an easy way to do this short of querying the DB for each post in a thread, which is potentially going to create a lot of traffic. How have other people solved this, I've been examining the code on some other open source apps but I can't find what I'm looking for. Is it possible to select multiple records in one query? In which case I could build an array dynamically on each page request (eg 'SQL blah blah' then a for each loop to insert the ID's). Could I join the tables each time? Do I submit a query for each post? Hmm.

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  • Looks like COM object is created, but JScript fails to get a reference

    - by damix911
    I'm using the following code to create a COM component that I have developed and registered. var mycom = new ActiveXObject("Mirabilis.ComponentServices.1"); mycom.SetFirstNumber(5); mycom.SetSecondNumber(3); The first line runs fine, while if I alter the ProgID (that is, the string passed to ActiveXObject) I get the message Automation server can't create object. This suggests that at least the basics of the registration mechanism are working properly. I integrated some logging calls into the DLL. When I run the script I get the proof into the log file that both this call to QueryInterface: STDAPI DllGetClassObject( const CLSID &clsid, const IID &iid, void **ppv) { ... CAddFactory *pAddFact = new CAddFactory; ... HRESULT hr = pAddFact->QueryInterface(iid, ppv); if (hr == S_OK) writeToLogFile("Class QueryInterface returned S_OK"); else writeToLogFile("Class QueryInterface failed"); return hr; ... } and this one: HRESULT __stdcall CAddFactory::CreateInstance( IUnknown *pUnknownOuter, const IID &iid, void **ppv) { ... CAddObj *pObject = new CAddObj; ... HRESULT hr = pObject->QueryInterface(iid, ppv); if (hr == S_OK) writeToLogFile("Object QueryInterface returned S_OK"); else writeToLogFile("Object QueryInterface failed"); return hr; ... } return S_OK. However, when JScript gets to line 3 of the script, I get the following error message: 'mycom' is null or not an object Why is this happening? It looks like JScript should be able to obtain a reference. Some attempts I made I tried to return S_FALSE from DllCanUnloadNow to be sure that the DLL will not be unloaded, just in case, but with no luck.

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  • How do I access the CodeDomProvider from a class inheriting from Microsoft.VisualStudio.TextTemplating.VSHost.BaseCodeGeneratorWithSite?

    - by Charlie
    Does anyone know how to get a CodeDomProvider in the new Microsoft.VisualStudio.TextTemplating.VSHost.BaseCodeGeneratorWithSite from the Visual Studio 2010 SDK? I used to get access to it just by in mere inheritance of the class Microsoft.CustomTool.BaseCodeGeneratorWithSite, but now with this new class it is not there. I see a GlobalServiceProvider and a SiteServiceProvider but I can't find any example on how to use them. Microsoft.VisualStudio.TextTemplating.VSHost.BaseCodeGeneratorWithSite: http://msdn.microsoft.com/en-us/library/bb932625.aspx I was to do this: public class Generator : Microsoft.VisualStudio.TextTemplating.VSHost.BaseCodeGeneratorWithSite { public override string GetDefaultExtension() { // GetDefaultExtension IS ALSO NOT ACCESSIBLE... return this.InputFilePath.Substring(this.InputFilePath.LastIndexOf(".")) + ".designer" + base.GetDefaultExtension(); } // This method is being called every time the attached xml is saved. protected override byte[] GenerateCode(string inputFileName, string inputFileContent) { try { // Try to generate the wrapper file. return GenerateSourceCode(inputFileName); } catch (Exception ex) { // In case of a faliure - print the exception // as a comment in the source code. return GenerateExceptionCode(ex); } } public byte[] GenerateSourceCode(string inputFileName) { Dictionary<string, CodeCompileUnit> oCodeUnits; // THIS IS WHERE CodeProvider IS NOT ACCESSIBLE CodeDomProvider oCodeDomProvider = this.CodeProvider; string[] aCode = new MyCustomAPI.GenerateCode(inputFileName, ref oCodeDomProvider); return Encoding.ASCII.GetBytes(String.Join(@" ", aCode)); } private byte[] GenerateExceptionCode(Exception ex) { CodeCompileUnit oCode = new CodeCompileUnit(); CodeNamespace oNamespace = new CodeNamespace("System"); oNamespace.Comments.Add(new CodeCommentStatement(MyCustomAPI.Print(ex))); oCode.Namespaces.Add(oNamespace); string sCode = null; using (StringWriter oSW = new StringWriter()) { using (IndentedTextWriter oITW = new IndentedTextWriter(oSW)) { this.CodeProvider.GenerateCodeFromCompileUnit(oCode, oITW, null); sCode = oSW.ToString(); } } return Encoding.ASCII.GetBytes(sCode ); } } Thanks for your help!

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  • Can I return JSON from an .asmx Web Service if the ContentType is not JSON?

    - by Click Ahead
    I would like to post a form using ajax and jquery to a .asmx webservice and return the value from the webservice as JSON. I'm using ASP.NET 4.0. I know that in order to return JSON from a webservice the following needs to be set (1) dataType: "json" (2) contentType: "application/json; charset=utf-8", (3) type: "POST" (4) set the Data to something. I have tested this and it works fine (i.e. my webservice returns the data as JSON) if all *four are set*. But, lets say in my case I want to do a standard form post i.e. test1=value1&test2=value2 so the contentType is not JSON but I want back JSON {test1:value1}. This doesn't seem to work because the contentType is "application/x-www-form-urlencoded" not "application/json; charset=utf-8". Can anyone tell me why I can't do this? It seems crazy to me that you have to explicitly send JSON to get JSON back, yet if you don't use JSON (i.e. post urlencoded contenttype) then the webservice will return XML. Any insights are greatly appreciated :)

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  • Counting elements and reading attributes with .net2.0 ?

    - by Prix
    I have an application that is on .net 2.0 and I am having some difficult with it as I am more use to linq. The xml file look like this: <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <updates> <files> <file url="files/filename.ext" checksum="06B9EEA618EEFF53D0E9B97C33C4D3DE3492E086" folder="bin" system="0" size="40448" /> <file url="files/filename.ext" checksum="CA8078D1FDCBD589D3769D293014154B8854D6A9" folder="" system="0" size="216" /> <file url="files/filename.ext" checksum="CA8078D1FDCBD589D3769D293014154B8854D6A9" folder="" system="0" size="216" /> </files> </updates> The file is downloaded and readed on the fly: XmlDocument readXML = new XmlDocument(); readXML.LoadXml(xmlData); Initially i was thinking it would go with something like this: XmlElement root = doc.DocumentElement; XmlNodeList nodes = root.SelectNodes("//files"); foreach (XmlNode node in nodes) { ... im reading it ... } But before reading them I need to know how many they are to use on my progress bar and I am also clueless on how to grab the attribute of the file element in this case. How could I count how many "file" ELEMENTS I have (count them before entering the foreach ofc) and read their attributes ? I need the count because it will be used to update the progress bar. Overall it is not reading my xml very well.

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  • What do I name this class whose sole purpose is to report failure?

    - by Blair Holloway
    In our system, we have a number of classes whose construction must happen asynchronously. We wrap the construction process in another class that derives from an IConstructor class: class IConstructor { public: virtual void Update() = 0; virtual Status GetStatus() = 0; virtual int GetLastError() = 0; }; There's an issue with the design of the current system - the functions that create the IConstructor-derived classes are often doing additional work which can also fail. At that point, instead of getting a constructor which can be queried for an error, a NULL pointer is returned. Restructuring the code to avoid this is possible, but time-consuming. In the meantime, I decided to create a constructor class which we create and return in case of error, instead of a NULL pointer: class FailedConstructor : public IConstructor public: virtual void Update() {} virtual Status GetStatus() { return STATUS_ERROR; } virtual int GetLastError() { return m_errorCode; } private: int m_errorCode; }; All of the above this the setup for a mundane question: what do I name the FailedConstructor class? In our current system, FailedConstructor would indicate "a class which constructs an instance of Failed", not "a class which represents a failed attempt to construct another class". I feel like it should be named for one of the design patterns, like Proxy or Adapter, but I'm not sure which.

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  • Regex for removing certain variable numeric values from some text

    - by stephemurdoch
    I want to substitute all 4 instances of the number 300 from the code below, with 470. <div> <object width="300" height="300"> <embed src="link-removed" width="300" height="300"></embed> </object> <p> <a href="another-link">link</a> </p> </div> The width and height of the code being pasted might not always be 300 by 300. So I figure I probably need a regular expression that subs any numeric value that follows the strings "width=" and "height=", whilst remembering to account for the quotations marks that surround the number. Can anyone tell me if that's the best way, and if so, what would be the best regex? In case it matters, the code being pasted is stored as "text" in the db rather than as a string, as it's quite lengthy (i've removed a few hundred chars from what you see pasted here)...

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  • C# webservice async callback not getting called on HTTP 407 error.

    - by Ben
    Hi, I am trying to test the use-case of a customer having a proxy with login credentials, trying to use our webservice from our client. If the request is synchronous, my job is easy. Catch the WebException, check for the 407 code, and prompt the user for the login credentials. However, for async requests, I seem to be running into a problem: the callback is never getting called! I ran a wireshark trace and did indeed see that the HTTP 407 error was being passed back, so I am bewildered as to what to do. Here is the code that sets up the callback and starts the request: TravelService.TravelServiceImplService svc = new TravelService.TravelServiceImplService(); svc.Url = svcUrl; svc.CreateEventCompleted += CbkCreateEventCompleted; svc.CreateEventAsync(crReq, req); And the code that was generated when I consumed the WSDL: public void CreateEventAsync(TravelServiceCreateEventRequest CreateEventRequest, object userState) { if ((this.CreateEventOperationCompleted == null)) { this.CreateEventOperationCompleted = new System.Threading.SendOrPostCallback(this.OnCreateEventOperationCompleted); } this.InvokeAsync("CreateEvent", new object[] { CreateEventRequest}, this.CreateEventOperationCompleted, userState); } private void OnCreateEventOperationCompleted(object arg) { if ((this.CreateEventCompleted != null)) { System.Web.Services.Protocols.InvokeCompletedEventArgs invokeArgs = ((System.Web.Services.Protocols.InvokeCompletedEventArgs)(arg)); this.CreateEventCompleted(this, new CreateEventCompletedEventArgs(invokeArgs.Results, invokeArgs.Error, invokeArgs.Cancelled, invokeArgs.UserState)); } } Debugging the WS code, I found that even the SoapHttpClientProtocol.InvokeAsync method was not calling its callback as well. Am I missing some sort of configuration?

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  • How should I generate the partitions / pairs for the Chinese Postman problem?

    - by Simucal
    I'm working on a program for class that involves solving the Chinese Postman problem. Our assignment only requires us to write a program to solve it for a hard-coded graph but I'm attempting to solve it for the general case on my own. The part that is giving me trouble is generating the partitions of pairings for the odd vertices. For example, if I had the following labeled odd verticies in a graph: 1 2 3 4 5 6 I need to find all the possible pairings / partitions I can make with these vertices. I've figured out I'll have i paritions given: n = num of odd verticies k = n / 2 i = ((2k)(2k-1)(2k-2)...(k+1))/2 So, given the 6 odd verticies above, we will know that we need to generate i = 15 partitions. The 15 partions would look like: 1 2 3 4 5 6 1 2 3 5 4 6 1 2 3 6 4 5 ... 1 6 ... Then, for each partition, I take each pair and find the shortest distance between them and sum them for that partition. The partition with the total smallest distance between its pairs is selected, and I then double all the edges between the shortest path between the odd vertices (found in the selected partition). These represent the edges the postman will have to walk twice. At first I thought I had worked out an appropriate algorithm for generating these partitions / pairs but it is flawed. I found it wasn't a simple permutation/combination problem. Does anyone who has studied this problem before have any tips that can help point me in the right direction for generating these partitions?

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  • How to get the equivalent of the accuracy in Google Map Geocoder V3

    - by Scorpi0
    Hi, I want to get geocode from google, and I used to do it with the V2 of the API. Google send in the json a pretty good information, the accuracy, reference here : http://code.google.com/intl/fr-FR/apis/maps/documentation/javascript/v2/reference.html#GGeoAddressAccuracy In V3, Google doesn't seem to send me exactly the same information. There is the array "adresse_component", which seem bigger if the accuracy is better, but not exactly. For example, I have a request accuracy to the street number, the array is of size 8. Another query is accuracy to the route, so less accuracy, but the array is style of size 8, as there is a row 'sublocality', which not appear in the first case. Ok, for a result, Google send a data 'types', which have the 'best' accuracy. This types are here : http://code.google.com/intl/fr-FR/apis/maps/documentation/geocoding/#Types But, there is no real order, and if I wan't the result better than postal_code, I have no clue to how to do that. So, how can I get this equivalent of the V2 accuracy, whithout some dumb and horrible code ?

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  • debugging scaffolding contingent upon degbugging boolean (java)

    - by David
    Recently i've found myself writing a lot of methods with what i can only think to call debugging scaffolding. Here's an example: public static void printArray (String[] array, boolean bug) { for (int i = 0; i<array.lenght; i++) { if (bug) System.out.print (i) ; //this line is what i'm calling the debugging scaffolding i guess. System.out.println(array[i]) ; } } in this method if i set bug to true, wherever its being called from maybe by some kind of user imput, then i get the special debugging text to let me know what index the string being printed as at just in case i needed to know for the sake of my debugging (pretend a state of affairs exists where its helpful). All of my questions more or less boil down to the question: is this a good idea? but with a tad bit more objectivity: Is this an effective way to test my methods and debug them? i mean effective in terms of efficiency and not messing up my code. Is it acceptable to leave the if (bug) stuff ; code in place after i've got my method up and working? (if a definition of "acceptability" is needed to make this question objective then use "is not a matter of programing controversy such as ommiting brackets in an if(boolean) with only one line after it, though if you've got something better go ahead and use your definition i won't mind) Is there a more effective way to accomplish the gole of making debugging easier than what i'm doing? Anything you know i mean to ask but that i have forgotten too (as much information as makes sense is appreciated).

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  • IF expression in SQL

    - by chupinette
    INSERT INTO item_quotation (item_id, quotation_id,name_searched,item_name,other_name,selling_price,discounted_price) SELECT DISTINCT I.item_id," . $quotation_id . ",T.item_name, I.name,I.other_name, INV.selling_price, I.discounted_price FROM temp_quotations T, item I, inventory INV<br/> WHERE ( I.name LIKE CONCAT( '%', T.item_name, '%' ) OR I.other_name LIKE CONCAT( '%', T.item_name, '%' )) AND INV.item_id = I.item_id; I have a table called temp_quotations(temp_item_id,item_name)having values (1,grinder), (2,drill), (3,kit) I have another table called item(item_id,name,other_name,discounted_price) having values (1,grinder A,100),(2,kit A,200) When I execute this sql, it insert values in table item_quotation(item_id, quotation_id,name_searched,item_name,other_name,selling_price,discounted_price) for example in this case it will insert (1,1,grinder,grinder A,150,100) (2,1,kit,kit A, 250,200) Since the item drill is not found in table item, it wont display it in table item_quotations. I want to write an if statement within that sql so that when the item_name from temp_quotation does not match the name from item, it displays not found in the place of item_name. This is what i tried but it does not display "not found": INSERT INTO item_quotation (item_id, quotation_id,name_searched,item_name,other_name,selling_price,discounted_price) SELECT DISTINCT I.item_id," . $quotation_id . ",T.item_name, IF(I.name LIKE CONCAT( '%', T.item_name, '%' ),I.name,'not found'),I.other_name, INV.selling_price, I.discounted_price FROM temp_quotations T, item I, inventory INV WHERE ( I.name LIKE CONCAT( '%', T.item_name, '%' ) OR I.other_name LIKE CONCAT( '%', T.item_name, '%' )) AND INV.item_id = I.item_id;

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  • Protected and Private methods

    - by cabaret
    I'm reading through Beginning Ruby and I'm stuck at the part about private and protected methods. This is a newbie question, I know. I searched through SO for a bit but I couldn't manage to find a clear and newbie-friendly explanation of the difference between private and protected methods. The book gives two examples, the first one for private methods: class Person def initialize(name) set_name(name) end def name @first_name + ' ' + @last_name end private def set_name(name) first_name, last_name = name.split(/\s+/) set_first_name(first_name) set_last_name(last_name) end def set_first_name(name) @first_name = name end def set_last_name(name) @last_name = name end end In this case, if I try p = Person.new("Fred Bloggs") p.set_last_name("Smith") It will tell me that I can't use the set_last_name method, because it's private. All good till there. However, in the other example, they define an age method as protected and when I do fred = Person.new(34) chris = Person.new(25) puts chris.age_difference_with(fred) puts chris.age It gives an error: :20: protected method 'age' called for #<Person:0x1e5f28 @age=25> (NoMethodError) I honestly fail to see the difference between the private and protected methods, it sounds the same to me. Could someone provide me with a clear explanation so I'll never get confused about this again? I'll provide the code for the second example if necessary.

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  • Intellisense for custom config section problem with namespaces

    - by Quick Joe Smith
    I have just rolled a custom configuration section, created an accompanying schema document for Intellisense and added it to the Web.config's Schemas property as per Michael Stum's answer to another similar question. Unfortunately, and possibly due to me creating the XSD by hand with limited knowledge, the Intellisense relies on an xmlns attribute pointing to my XSD file's namespace being present in the custom config element. However, when running the project I get an Unrecognized attribute 'xmlns'. Note that attribute names are case-sensitive error. I could probably just modify my XSD file to define the xmlns attribute for that element, however I am wondering if this is just a bandaid fix to a larger problem. I must confess I don't have a very good understanding of XML namespaces so this might be an oppportunity to set me straight on a few things. Here is the attributes for my XSD file's root xs:schema element: <xs:schema id="awesomeConfig" targetNamespace="http://awesome.com/schemas" xmlns="http://awesome.com/schemas" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"> ... </xs:schema> And on creating the element in the Web.config file, Visual Studio 2008 automatically appends: <awesomeConfig xmlns="http://awesome.com/schemas"></awesomeConfig> So have I misunderstood the meaning of the xs:schema attributes at all, or is the proper solution as simple as it seems?

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  • How to change scope data in controller?

    - by Derooie
    I am a real newbie at angular. I created something now which will let me retrieve and add items via angular and get/put them in mongodb. I use express and mongoose in the app The question is, how can i modify the data before it reaches the DOM in the controller. In this example i have created a way to retrieve data, and i get it exactly as it is stored in mongodb. What i would like is that the field where i store 1 or 0 in the database, to be shown as text. So if mongo has a value 1 i get "the value in mongo is 1" and when the field has a value of 0 get "the value is zero". (just as an example, i like other texts, but it illustrate what i want) I post my controller, html and current output. Any help would be appreciated. Controller function getGuests($scope, $http) { $scope.formData = {}; $http.get('/api/guests') .success(function(data) { $scope.x = data; }) .error(function(data) { console.log('Error: ' + data); }); } HTML <div ng-controller="getGuests"> <div ng-repeat="guest in x"> {{ guest.voornaam }} {{ guest.aanwezig }} </div> </div> The current scope output, what i see in HTML. I like to change only the value of "aanwezig" in case the value of aanwezig is 0 or 1. firstname1 1 firstname2 0 Something else, but would be great to learn, is how i can do a specific mongodb query by the push of a button and get that result.

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  • Get tag name and value of a given node using XMLReader, DOM, Xpath

    - by rossjha
    I need to query an xml document and then display specific tag values, e.g. forename, surname, group(dept), job_title. I'm using XMLReader as i may need to work with large XML files. I using DomXPath to filter the data, but i don't know how to retrieve the nodeName and value for each element. The code below only returns 'member' as the node name? Any help would be appreciated. <?php $reader = new XMLReader(); $reader->open('include/staff.xml'); while ($reader->read()){ switch($reader->nodeType){ case(XMLREADER::ELEMENT): if($reader->localName === 'staff'){ $node = $reader->expand(); $dom = new DomDocument(); $dom->formatOutput = true; $n = $dom->importNode($node, true); $dom->appendChild($n); $xp = new DomXpath($dom); $res = $xp->query("/staff/member[groups='HR']"); } } } echo $res->item(0)->nodeName; echo $res->item(0)->nodeValue; ?>

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  • Django sitemap intermittent www

    - by Jen Z
    The automatic sitemap for my Django site fluctuates between including the www on urls and leaving it out (I'm aiming to have it in all the time). This has ramifications in google not indexing my pages properly so I'm trying to narrow down what would be causing this issue. I have set PREPEND_WWW = True and my site record in the sites framework is set to include the www e.g. it's set to www.example.com as opposed to example.com. I'm using memcached but pages should expire from the cache after 48 hours so I wouldn't have thought that would be causing the issue? You can see the problem in effect at http://www.livingspaceltd.co.uk/sitemap.xml (refresh the page a few times). My sitemaps setup is fairly prosaic so I'm doubtful that that is the issue, but in case it's something obvious I'm missing here's the code: ***urls.py*** sitemaps = { 'subpages': Subpages_Sitemap, 'standalone_pages': Standalone_Sitemap, 'categories': Categories_Sitemap, } urlpatterns = patterns('', (r'^sitemap\.xml$', 'django.contrib.sitemaps.views.sitemap', {'sitemaps': sitemaps}), ... ***sitemaps.py*** # -*- coding: utf-8 -*- from django_ls.livingspace.models import Page, Category, Standalone_Page, Subpage from django.contrib.sitemaps import Sitemap class Subpages_Sitemap(Sitemap): changefreq = "monthly" priority = 0.4 def items(self): return Subpage.objects.filter(restricted_to__isnull=True) class Standalone_Sitemap(Sitemap): changefreq = "weekly" priority = 1 def items(self): return Standalone_Page.objects.all() class Categories_Sitemap(Sitemap): changefreq = "weekly" priority = 0.7 def items(self): return Category.objects.all()

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  • Why doesn't gcc remove this check of a non-volatile variable?

    - by Thomas
    This question is mostly academic. I ask out of curiosity, not because this poses an actual problem for me. Consider the following incorrect C program. #include <signal.h> #include <stdio.h> static int running = 1; void handler(int u) { running = 0; } int main() { signal(SIGTERM, handler); while (running) ; printf("Bye!\n"); return 0; } This program is incorrect because the handler interrupts the program flow, so running can be modified at any time and should therefore be declared volatile. But let's say the programmer forgot that. gcc 4.3.3, with the -O3 flag, compiles the loop body (after one initial check of the running flag) down to the infinite loop .L7: jmp .L7 which was to be expected. Now we put something trivial inside the while loop, like: while (running) putchar('.'); And suddenly, gcc does not optimize the loop condition anymore! The loop body's assembly now looks like this (again at -O3): .L7: movq stdout(%rip), %rsi movl $46, %edi call _IO_putc movl running(%rip), %eax testl %eax, %eax jne .L7 We see that running is re-loaded from memory each time through the loop; it is not even cached in a register. Apparently gcc now thinks that the value of running could have changed. So why does gcc suddenly decide that it needs to re-check the value of running in this case?

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  • Create a strongly typed view which inherites a class which is concrete

    - by Ashwani K
    Hello All: I am having one class called BaseClass which contains some logic applicable to whole web site. In order to create a strongly typed view we need to inherit the page from System.Web.Mvc.ViewPage generic class. But In our case I have to Inherit the BaseClass from System.Web.Mvc.ViewPage to apply some common settings, but the BaseClass should be inherited from System.Web.Mvc.ViewPage< generic version. But I cannot inherit the BaseClass from System.Web.Mvc.ViewPage< as it will change other class also. So I created one more class of type BaseClass< inheriting it from System.Web.Mvc.ViewPage< and copied the whole code of BaseClass in BaseClass<. But the code in BaseClass is controlled by other team so it will be changed frequently so my BaseClass< should be in sync with BaseClass. Please help me in eliminating the code duplication or any other approach to make strongly typed View. Thanks Ashwani

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  • Approach for fixing NoClassDefFoundError?

    - by DJC
    I'm seeing this question is getting asked a lot in many different contexts. Perhaps we can set some strategies for locating and fixing it? I'm noobish myself so all I can contribute are horror stories and questions, sorry... It seems this is thrown when a class is visible at compile time but not at run time... how can this happen? In my case I am developing an app that uses the Google APIs, in Eclipse, for the Android platform. I've configured the Project Properties / Java Build Path / Libraries to include the gdata .jars and all is well. When I execute in the emulator I get a force close and the logcat shows a NoClassDefFoundError on a simple new ContactsService("myApp"); I've also tried a new CalendarService("myApp") with the same results. Is it possible or desirable to statically bind at compile time to avoid the problem? How could dynamic binding of an add-on library work in the mobile environment anyway? Either it has to be bound into my .apk or else I need to "install" it? ... hmmm. Advice much appreciated.

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  • Winsock tcp/ip Socket listening but connection refused, race condition?

    - by Wayne
    Hello folks. This involves two automated unit tests which each start up a tcp/ip server that creates a non-blocking socket then bind()s and listen()s in a loop on select() for a client that connects and downloads some data. The catch is that they work perfectly when run separately but when run as a test suite, the second test client will fail to connect with WSACONNREFUSED... UNLESS there is a Thread.Sleep() of several seconds between them??!!! Interestingly, there is retry loop every 1 second for connecting after any failure. So the second test loops for a while until timeout after 10 minutes. During that time, netstat -na shows the correct port number is in the LISTEN state for the server socket. So if it is in the listen state? Why won't it accept the connection? In the code, there are log messages that show the select NEVER even gets a socket ready to read (which means ready to accept a connection when it applies to a listening socket). Obviously the problem must be related to some race condition between finishing one test which means close() and shutdown() on each end of the socket, and the start up of the next. This wouldn't be so bad if the retry logic allowed it to connect eventually after a couple of seconds. However it seems to get "gummed up" and won't even retry. However, for some strange reason the listening socket SAYS it's in the LISTEN state even through keeps refusing connections. So that means it's the Windoze O/S which is actually catching the SYN packet and returning a RST packet (which means "Connection Refused"). The only other time I ever saw this error was when the code had a problem that caused hundreds of sockets to get stuck in TIME_WAIT state. But that's not the case here. netstat shows only about a dozen sockets with only 1 or 2 in TIME_WAIT at any given moment. Please help.

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  • Potential g++ template bug?

    - by Evan Teran
    I've encountered some code which I think should compile, but doesn't. So I'm hoping some of the local standards experts here at SO can help :-). I basically have some code which resembles this: #include <iostream> template <class T = int> class A { public: class U { }; public: U f() const { return U(); } }; // test either the work around or the code I want... #ifndef USE_FIX template <class T> bool operator==(const typename A<T>::U &x, int y) { return true; } #else typedef A<int> AI; bool operator==(const AI::U &x, int y) { return true; } #endif int main() { A<int> a; std::cout << (a.f() == 1) << std::endl; } So, to describe what is going on here. I have a class template (A) which has an internal class (U) and at least one member function which can return an instance of that internal class (f()). Then I am attempting to create an operator== function which compares this internal type to some other type (in this case an int, but it doesn't seem to matter). When USE_FIX is not defined I get the following error: test.cc: In function 'int main()': test.cc:27:25: error: no match for 'operator==' in 'a.A<T>::f [with T = int]() == 1' Which seems odd, because I am clearly (I think) defining a templated operator== which should cover this, in fact if I just do a little of the work for the compiler (enable USE_FIX), then I no longer get an error. Unfortunately, the "fix" doesn't work generically, only for a specific instantiation of the template. Is this supposed to work as I expected? Or is this simply not allowed? BTW: if it matters I am using gcc 4.5.2.

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  • Loading Native library to external Package in Eclipse not working. is it a Bug?

    - by TacB0sS
    I was about to report a but to Eclipse, but I was thinking to give this a chance here first: If I add an external package, the application cannot find the referenced native library, except in the case specified at the below: If my workspace consists of a single project, and I import an external package 'EX_package.jar' from a folder outside of the project folder, I can assign a folder to the native library location via: mouse over package - right click - properties - Native Library - Enter your folder. This does not work. In runtime the application does not load the library, System.mapLibraryName(Path) also does not work. Further more, if I create a User Library, and add the package to it and define a folder for the native library it still does not. If it works for you then I have a major bug since it does not work on my computer I test this in any combination I could think of, including adding the path to the windows PATH parameter, and so many other ways I can't even start to remember, nothing worked, I played with this for hours and had a colleague try to assist me, but we both came up empty. Further more, if I have a main project that is dependent on few other projects in my workspace, and they all need to use the same 'EX_package.jar' I MUST supply a HARD COPY INTO EACH OF THEM, it will ONLY (I can't stress the ONLYNESS, I got freaked out by this) work if I have a hard copy of the package in ALL of the project folders that the main project has a dependency on, and ONLY if I configure the Native path in each of them!! This also didn't do the trick. please tell me there is a solution to this, this drives me nuts... Thanks, Adam Zehavi.

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