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• WM_NOTIFY and superclass chaining issue in Win32

  - by DasMonkeyman

  For reference I'm using the window superclass method outlined in this article. The specific issue occurs if I want to handle WM_NOTIFY messages (i.e. for custom drawing) from the base control in the superclass I either need to reflect them back from the parent window or set my own window as the parent (passed inside CREATESTRUCT for WM_(NC)CREATE to the base class). This method works fine if I have a single superclass. If I superclass my superclass then I run into a problem. Now 3 WindowProcs are operating in the same HWND, and when I reflect WM_NOTIFY messages (or have them sent to myself from the parent trick above) they always go to the outermost (most derived) WindowProc. I have no way to tell if they're messages intended for the inner superclass (base messages are supposed to go to the first superclass) or messages intended for the outer superclass (messages from the inner superclass are intended for the outer superclass). These messages are indistinguishable because they all come from the same HWND with the same control ID. Is there any way to resolve this without creating a new window to encapsulate each level of inheritance? Sorry about the wall of text. It's a difficult concept to explain. Here's a diagram. single superclass: SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------/ superclass of a superclass: SuperB::WindowProc() - SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------+-----------------------/ ^--------WM_NOTIFY(A)-----------/ The WM_NOTIFY messages in the second case all come from the same HWND and control ID, so I cannot distinguish between the messages intended for SuperA (from Base) and messages intended for SuperB (from SuperA). Any ideas?

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• Why do bind1st and bind2nd require constant function objects?

  - by rlbond

  So, I was writing a C++ program which would allow me to take control of the entire world. I was all done writing the final translation unit, but I got an error: error C3848: expression having type 'const `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>' would lose some const-volatile qualifiers in order to call 'void `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>::operator ()(const point::Point &,const int &)' with [ T=SideCounter, BinaryFunction=std::plus<int> ] c:\program files (x86)\microsoft visual studio 9.0\vc\include\functional(324) : while compiling class template member function 'void std::binder2nd<_Fn2>::operator ()(point::Point &) const' with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] c:\users\****\documents\visual studio 2008\projects\TAKE_OVER_THE_WORLD\grid_divider.cpp(361) : see reference to class template instantiation 'std::binder2nd<_Fn2>' being compiled with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] I looked in the specifications of binder2nd and there it was: it took a const AdaptibleBinaryFunction. So, not a big deal, I thought. I just used boost::bind instead, right? Wrong! Now my take-over-the-world program takes too long to compile (bind is used inside a template which is instantiated quite a lot)! At this rate, my nemesis is going to take over the world first! I can't let that happen -- he uses Java! So can someone tell me why this design decision was made? It seems like an odd decision. I guess I'll have to make some of the elements of my class mutable for now...

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• Create a new delegate class for each asynchronous image download?

  - by Charles S.

  First, I'm using an NSURLConnection to download JSON data from twitter. Then, I'm using a second NSURLConnection to download corresponding user avatar images (the urls to the images are parsed from the first data download). For the first data connection, I have my TwitterViewController set as the NSURLConnection delegate. I've created a separate class (ImageDownloadDelegate) to function as the delegate for a second NSURLConnection that handles the images. After the tweets are finished downloading, I'm using this code to get the avatars: for(int j=0; j<[self.tweets count]; j++){ ImageDownloadDelegate *imgDelegate = [[ImageDownloadDelegate alloc] init]; Tweet *myTweet = [self.tweets objectAtIndex:j]; imgDelegate.tweet = myTweet; imgDelegate.table = timeline; NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL URLWithString:myTweet.imageURL] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60]; imgConnection = [[NSURLConnection alloc] initWithRequest:request delegate:imgDelegate]; [imgDelegate release]; } So basically a new instance of the delegate class is created for each image that needs to be downloaded. Is this the best way to go about this? But then there's no way to figure out which image is associate with which tweet, correct? The algorithm works fine... I'm just wondering if I'm going about it the most efficient way.

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• xml to hashmap - php

  - by csU

  Hi, Given an xml structure like this <gesmes:Envelope> <gesmes:subject>Reference rates</gesmes:subject> <gesmes:Sender> <gesmes:name>European Central Bank</gesmes:name> </gesmes:Sender> <Cube> <Cube time="2010-03-26"> <Cube currency="USD" rate="1.3353"/> <Cube currency="JPY" rate="124.00"/> <Cube currency="BGN" rate="1.9558"/> <Cube currency="CZK" rate="25.418"/> ... ... </Cube> </Cube> </gesmes:Envelope> how can i go about getting the values stored in to a hashmap or similar structure in php? Have been trying to do this for the last few hours now but cant manage it :D It is homework so i guess no full solutuins please( tho the actual assignment is to use the web services, i am just stuck with parsing it :D ). Maybe someone could show me a brief example for a made up xml file that i could apply to mine? Thanks

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• wcf trying to set up tracing to debug, not writing to log file

  - by joey j

  here's my web.config, running a WCF service in an application on IIS7, but nothing is being written to the specified file. permission on the file has been granted for everyone. </listeners> I can add a service reference just fine. I then try to call the service from a windows app and, after a few minutes, get an error on the machine running the windows app "Client is unable to finish the security negotiation within the configured timeout (00:00:00). The current negotiation leg is 1 (00:00:00)." but absolutely nothing is written to the trace log file specified in config. Is there something else I need to do to enable tracing? thanks for your help EDIT: "sources" section now matches the section recommended here: http://msdn.microsoft.com/en-us/library/aa702726.aspx I've added the "diagnostics and the event viewer shows: "Message Logging has been turned on. Sensitive information may be logged in the clear, even if it was encrypted on the wire: for example, message bodies. Process Name: w3wp Process ID: 1784 " but the log file is still empty

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• how to find a control inside ItemsPanelTemplate in wpf?

  - by kakopappa

  I am trying to access a Grid inside the DataTemplate while the ItemsControl is binded by ItemsSource. this is the full XMAL code, How do i find a certain element from outside? for (int i = 0; i < allViewControl.Items.Count; i++) { var container = allViewControl.ItemContainerGenerator.ContainerFromItem(allViewControl.Items[i]) as FrameworkElement; var grid = allViewControl.ItemTemplate.FindName("grid", container) as DataGrid; } i found this always returning null ? <ScrollViewer Grid.Row="0" HorizontalScrollBarVisibility="Disabled" VerticalScrollBarVisibility="Auto"> <ItemsControl x:Name="allViewControl" Focusable="False" HorizontalContentAlignment="Center" Grid.IsSharedSizeScope="true" ItemsSource="{Binding AllClassCharacters}" ItemTemplate="{StaticResource CharacterViewModelTemplate}" > <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <Extensions:AnimatedWrapPanel IsItemsHost="true" /> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> </ItemsControl> </ScrollViewer> <DataTemplate x:Key="CharacterViewModelTemplate" DataType="{x:Type ViewModel:CharacterViewModel}"> <Grid x:Name="grid" Width="200" Height="Auto" MinHeight="115" Margin="1" MinWidth="130" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" RenderTransformOrigin="0.5,0.5" Background="#66000000" > <Grid.RowDefinitions> <RowDefinition Height="70"/> <RowDefinition Height="*"/> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition Width="*" /> <ColumnDefinition Width="*" /> </Grid.ColumnDefinitions> <ProgressBar x:Name="playerProgressBar" VerticalAlignment="Top" Background="Transparent" Height="5" Width="Auto" Value="0" Visibility="Collapsed" Grid.Column="0" Grid.Row="0" Grid.ColumnSpan ="2" Grid.RowSpan="2" Foreground="White" BorderThickness="0" Style="{DynamicResource ProgressBarStyle1}" /> </Grid>

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• Common NSNotification mistakes?

  - by Ben Packard

  A simplification... A building has an array of apartment objects. Each apartment has a single currentTenant. These tenants are of type Person. Note that currentTenant doesn't have a reference to the apartment, so can't send information back up the chain. When a tenant has a plumbing issue he raises an NSNotification: [nc postNotificationName:@"PlumbingIssue" object:self]; Each Apartment observes notifications ONLY FROM it's own current tenant (this is set up when the apartment is built, before there is a current tenant): [nc addObserver:self selector:@selector(alertBuildingManager:) name:@"PlumbingIssue" object:[self currentTenant]; When the apartment receives a notification from it's own currentTenant, it sends it's own notification, "PlumberRequired", along with the apartment number and the currentTenant in an NSDictionary. Apartment observes these notifications, which it will take from any apartment (or other object): [nc addObserver:self selector:@selector(callPlumber) name:@"PlumberRequired" object:nil]; Is there something I could be getting fundamentally wrong here? What's happening is that the apartment is receiving notifications from any and all currentTenants, rather than jus it's own. Sorry that the actual code is a bit too unwieldy to post. Was just wondering if there's a gap in my understanding about observing notifications from a particular sender?

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• How can I tackle 'profoundly found elsewhere' syndrome (inverse of NIH)?

  - by Alistair Knock

  How can I encourage colleagues to embrace small-scale innovation within our team(s), in order to get things done quicker and to encourage skills development? (the term 'profoundly found elsewhere' comes from Wikipedia, although it is scarcely used anywhere else apart from a reference to Proctor & Gamble) I've worked in both environments where there is a strong opposition to software which hasn't been developed in-house (usually because there's a large community of developers), and more recently (with far fewer central developers) where off-the-shelf products are far more favoured for the usual reasons: maintenance, total cost over product lifecycle, risk management and so on. I think the off the shelf argument works in the majority of cases for the majority of users, even though as a developer the product never quite does what I'd like it to do. However, in some cases there are clear gaps where the market isn't able to provide specifically what we would need, or at least it isn't able to without charging astronomical consultancy rates for a bespoke solution. These can be small web applications which provide a short-term solution to a particular need in one specific department, or could be larger developments that have the potential to serve a wider audience, both across the organisation and into external markets. The problem is that while development of these applications would be incredibly cheap in terms of developer hours, and delivered very quickly without the need for glacial consultation, the proposal usually falls flat because of risk: 'Who'll maintain the project tracker that hasn't had any maintenance for the past 7 years while you're on holiday for 2 weeks?' 'What if one of our systems changes and the connector breaks?' 'How can you guarantee it's secure/better/faster/cheaper/holier than Company X's?' With one developer behind these little projects, the answers are invariably: 'Nobody, but...' 'It will break, just like any other application would...' 'I, uh...' How can I better answer these questions and encourage people to take a little risk in order to stimulate creativity and fast-paced, short-lifecycle development instead of using that 6 months to consult about what tender process we might use?

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• Python's asyncore to periodically send data using a variable timeout. Is there a better way?

  - by Nick Sonneveld

  I wanted to write a server that a client could connect to and receive periodic updates without having to poll. The problem I have experienced with asyncore is that if you do not return true when dispatcher.writable() is called, you have to wait until after the asyncore.loop has timed out (default is 30s). The two ways I have tried to work around this is 1) reduce timeout to a low value or 2) query connections for when they will next update and generate an adequate timeout value. However if you refer to 'Select Law' in 'man 2 select_tut', it states, "You should always try to use select() without a timeout." Is there a better way to do this? Twisted maybe? I wanted to try and avoid extra threads. I'll include the variable timeout example here: #!/usr/bin/python import time import socket import asyncore # in seconds UPDATE_PERIOD = 4.0 class Channel(asyncore.dispatcher): def __init__(self, sock, sck_map): asyncore.dispatcher.__init__(self, sock=sock, map=sck_map) self.last_update = 0.0 # should update immediately self.send_buf = '' self.recv_buf = '' def writable(self): return len(self.send_buf) > 0 def handle_write(self): nbytes = self.send(self.send_buf) self.send_buf = self.send_buf[nbytes:] def handle_read(self): print 'read' print 'recv:', self.recv(4096) def handle_close(self): print 'close' self.close() # added for variable timeout def update(self): if time.time() >= self.next_update(): self.send_buf += 'hello %f\n'%(time.time()) self.last_update = time.time() def next_update(self): return self.last_update + UPDATE_PERIOD class Server(asyncore.dispatcher): def __init__(self, port, sck_map): asyncore.dispatcher.__init__(self, map=sck_map) self.port = port self.sck_map = sck_map self.create_socket(socket.AF_INET, socket.SOCK_STREAM) self.bind( ("", port)) self.listen(16) print "listening on port", self.port def handle_accept(self): (conn, addr) = self.accept() Channel(sock=conn, sck_map=self.sck_map) # added for variable timeout def update(self): pass def next_update(self): return None sck_map = {} server = Server(9090, sck_map) while True: next_update = time.time() + 30.0 for c in sck_map.values(): c.update() # <-- fill write buffers n = c.next_update() #print 'n:',n if n is not None: next_update = min(next_update, n) _timeout = max(0.1, next_update - time.time()) asyncore.loop(timeout=_timeout, count=1, map=sck_map)

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• window.setInterval from inside an object

  - by Keith Rousseau

  I'm currently having an issue where I have a javascript object that is trying to use setInterval to call a private function inside of itself. However, it can't find the object when I try to call it. I have a feeling that it's because window.setInterval is trying to call into the object from outside but doesn't have a reference to the object. FWIW - I can't get it to work with the function being public either. The basic requirement is that I may need to have multiple instances of this object to track multiple uploads that are occurring at once. If you have a better design than the current one or can get the current one working then I'm all ears. The following code is meant to continuously ping a web service to get the status of my file upload: var FileUploader = function(uploadKey) { var intervalId; var UpdateProgress = function() { $.get('someWebService', {}, function(json) { alert('success'); }); }; return { BeginTrackProgress: function() { intervalId = window.setInterval('UpdateProgress()', 1500); }, EndTrackProgress: function() { clearInterval(intervalId); } }; }; This is how it is being called: var fileUploader = new FileUploader('myFileKey'); fileUploader.BeginTrackProgress();

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• C Nested Structure Pointer Problem

  - by Halo

  I have a shared structure, and inside it a request structure: struct shared_data { pthread_mutex_t th_mutex_queue; struct request_queue { int min; int max; char d_name[DIR_SIZE]; pid_t pid; int t_index; } request_queue[BUFSIZE]; int count; int data_buffer_allocation[BUFSIZE]; int data_buffers[BUFSIZE][100]; }; Then I prepare a request; struct shared_data *sdata_ptr; ... ... sdata_ptr->request_queue[index].pid = pid; strcpy(sdata_ptr->request_queue[index].d_name, dir_path_name); sdata_ptr->request_queue[index].min = min; sdata_ptr->request_queue[index].max = max; And the compiler warns me that I'm doing an incompatible implicit declaration in the strcpy function. I guess that's a problem with the pointers, but isn't what I wrote above supposed to be true?

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• How to retrieve the Description property from SettingsProperty?

  - by BadNinja

  For each item in my application's settings, I've added text to its Description Property which I want to retrieve at runtime. I'm sure I'm missing some basic logical nuance here, but everything I've tried has failed. Clearly, my understanding of what value needs to be passed to the Attributes property of the SettingsProperty class is wrong. I'm further confused by the fact that when I iterate through all they keys returned by SettingsProperty.Attributes.Keys, I can see "System.Configuration.SettingsDescriptionAttribute", but when I pass that string in as the key to the Attributes property, null is returned. Any insight into how to properly retrieve the value Description Property would be very much appreciated. Thanks. :) public void MyMethod() { SettingsPropertyCollection MyAppProperties = Properties.Settings.Default.Properties; IEnumerator enumerator = MyAppProperties.GetEnumerator(); // Iterate through all the keys to see what we have.... while (enumerator.MoveNext()) { SettingsProperty property = (SettingsProperty)enumerator.Current; ICollection myKeys = property.Attributes.Keys; foreach (object theKey in myKeys) System.Diagnostics.Debug.Print(theKey.ToString()); // One of the keys returned is: System.Configuration.SettingsDescriptionAttribute } enumerator.Reset(); while (enumerator.MoveNext()) { SettingsProperty property = (SettingsProperty)enumerator.Current; string propertyValue = property.DefaultValue.ToString(); // This fails: Null Reference string propertyDescription = property.Attributes["System.Configuration.SettingsDescriptionAttribute"].ToString(); // Do stuff with strings... } }

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• Dangling pointers and double free

  - by user151410

  After some painful experiences, I understand the problem of dangling pointers and double free. I am seeking proper solutions. aStruct has a number of fields including other arrays. aStruct *A=NULL, *B = NULL; A = (aStruct*) calloc(1, sizeof(sStruct)); B = A; free_aStruct(A); ... //bunch of other code in various places. ... free_aStruct(B); Is there any way to write free_aStruct(X) so that free_aStruct(B) exists gracefully?? void free_aStruct(aStruct *X){ if (X ! = NULL){ if (X->a != NULL){free(X->a); x->a = NULL;} free(X); X = NULL; } } Doing above only sets A = NULL when free_aStruct(A); is called. B is now dangling. How can this situation be avoided / remedied? Is reference counting the only viable solution? or, are there other "defensive" free approaches, to prevent free_aStruct(B); from exploding? Thanks, Russ

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• How to hand-over a TCP listening socket with minimal downtime?

  - by Shtééf

  While this question is tagged EventMachine, generic BSD-socket solutions in any language are much appreciated too. Some background: I have an application listening on a TCP socket. It is started and shut down with a regular System V style init script. My problem is that it needs some time to start up before it is ready to service the TCP socket. It's not too long, perhaps only 5 seconds, but that's 5 seconds too long when a restart needs to be performed during a workday. It's also crucial that existing connections remain open and are finished normally. Reasons for a restart of the application are patches, upgrades, and the like. I unfortunately find myself in the position that, every once in a while, I need to do this kind of thing in production. The question: I'm looking for a way to do a neat hand-over of the TCP listening socket, from one process to another, and as a result get only a split second of downtime. I'd like existing connections / sockets to remain open and finish processing in the old process, while the new process starts servicing new connectinos. Is there some proven method of doing this using BSD-sockets? (Bonus points for an EventMachine solution.) Are there perhaps open-source libraries out there implementing this, that I can use as is, or use as a reference? (Again, non-Ruby and non-EventMachine solutions are appreciated too!)

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• C# ref Confusion

  - by Rahat

  I have a confusion that when i pass a variable by refrence in the constructor of another class and after passing that object by refrence i recreate the refrence object with the new keyword. Now the class in which i have passed the refrenced object dosen't reflect the updated data. An exabple of the above problem is shown below: Object to be passed by Refrence: public class DummyObject { public string Name = "My Name"; public DummyObject() { } } Class which is passing the Refrence: public partial class Form1 : Form { // Object to be passed as refrence DummyObject dummyObject = new DummyObject(); public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { // assigning value dummyObject.Name = "I am Dummy"; // Passing object Form2 frm = new Form2(ref dummyObject); frm.Show(); } private void button2_Click(object sender, EventArgs e) { // Displaying Name MessageBox.Show(this.dummyObject.Name); } private void button3_Click(object sender, EventArgs e) { // Assigning new object this.dummyObject = new DummyObject(); // Changing Name Variable this.dummyObject.Name = "I am Rechanged"; // Displaying Name MessageBox.Show(this.dummyObject.Name); } } Class to which Object is passed by Reference: public partial class Form2 : Form { private DummyObject dummyObject = null; public Form2(ref DummyObject DummyObject) { InitializeComponent(); this.dummyObject = DummyObject; this.dummyObject.Name = "I am Changed"; } private void button2_Click(object sender, EventArgs e) { MessageBox.Show(this.dummyObject.Name); } } whn i reaasign the object in Form 1 and cdisplay its value in form 2 it still displays "I am Changed" instead of "I am Rechanged". How to keep the data synchronized?

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• XML Schema: How to specify an attribute with a custom 'simpleType' type?

  - by mackenir

  In my XML schema definition, I'm trying to restrict the value of an attribute to be an integer between 0 and 100. With reference to the sample schema below, I want attribute 'attr' on element 'root' to have this restriction. To achieve this I define a simpleType 'Percentage' and set this as the 'type' of 'attr'. However, my XML schema editor (VS 2008) flags the attribute up as having a problem: "Type 'Percentage' is not declared or is not a simple type". <?xml version="1.0" encoding="utf-8"?> <xs:schema elementFormDefault="qualified" id="test" xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://testtttt"> <xs:simpleType name="Percentage"> <xs:restriction base="xs:integer"> <xs:minInclusive value="0"/> <xs:maxInclusive value="100"/> </xs:restriction> </xs:simpleType> <xs:element name="root"> <xs:complexType> <xs:attribute name="attr" type="Percentage" use="optional" /> </xs:complexType> </xs:element>

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• Is there a way to implement Caliburn-like co-routines in VB.NET since there's no yield keyword

  - by Miroslav Popovic

  Note that I'm aware of other yield in vb.net questions here on SO. I'm playing around with Caliburn lately. Bunch of great stuff there, including co-routines implementation. Most of the work I'm doing is C# based, but now I'm also creating an architecture guideline for a VB.NET only shop, based on Rob's small MVVM framework. Everything looks very well except using co-routines from VB. Since VB 10 is used, we can try something like Bill McCarthy's suggestion: Public Function Lines(ByVal rdr as TextReader) As IEnumerable(Of String) Return New GenericIterator(Of String) (Function(ByRef nextItem As String) As Boolean nextItem = rdr.ReadLine Return nextItem IsNot Nothing End Function) End Function I'm just failing to comprehend how a little more complex co-routine method like the one below (taken from Rob's GameLibrary) could be written in VB: public IEnumerable<IResult> ExecuteSearch() { var search = new SearchGames { SearchText = SearchText }.AsResult(); yield return Show.Busy(); yield return search; var resultCount = search.Response.Count(); if (resultCount == 0) SearchResults = _noResults.WithTitle(SearchText); else if (resultCount == 1 && search.Response.First().Title == SearchText) { var getGame = new GetGame { Id = search.Response.First().Id }.AsResult(); yield return getGame; yield return Show.Screen<ExploreGameViewModel>() .Configured(x => x.WithGame(getGame.Response)); } else SearchResults = _results.With(search.Response); yield return Show.NotBusy(); } Any idea how to achieve that, or any thoughts on using Caliburn co-routines in VB?

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• DataReader already open when using LINQ

  - by Jamie Dixon

  I've got a static class containing a static field which makes reference to a wrapper object of a DataContext. The DataContext is basically generated by Visual Studio when we created a dbml file & contains methods for each of the stored procedures we have in the DB. Our class basically has a bunch of static methods that fire off each of these stored proc methods & then returns an array based on a LINQ query. Example: public static TwoFieldBarData[] GetAgesReportData(string pct) { return DataContext .BreakdownOfUsersByAge(Constants.USER_MEDICAL_PROFILE_KEY, pct) .Select(x => new TwoFieldBarData(x.DisplayName, x.LeftValue, x.RightValue, x.TotalCount)) .ToArray(); } Every now and then, we get the following error: There is already an open DataReader associated with this Command which must be closed firs This is happening intermittently and I'm curious as to what is going on. My guess is that when there's some lag between one method executing and the next one firing, it's locking up the DataContext and throwing the error. Could this be a case for wrapping each of the DataContext LINQ calls in a lock(){} to obtain exclusivity to that type and ensure other requests are queued?

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• c# delegate and abstract class

  - by BeraCim

  Hi all: I currently have 2 concrete methods in 2 abstract classes. One class contains the current method, while the other contains the legacy method. E.g. // Class #1 public abstract class ClassCurrent<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllRootNodes(int i) { //some code } } // Class #2 public abstract class MyClassLegacy<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllLeafNodes(int j) { //some code } } I want the corresponding method to run in their relative scenarios in the app. I'm planning to write a delegate to handle this. The idea is that I can just call the delegate and write logic in it to handle which method to call depending on which class/project it is called from (at least thats what I think delegates are for and how they are used). However, I have some questions on that topic (after some googling): 1) Is it possible to have a delegate that knows the 2 (or more) methods that reside in different classes? 2) Is it possible to make a delegate that spawns off abstract classes (like from the above code)? (My guess is a no, since delegates create concrete implementation of the passed-in classes) 3) I tried to write a delegate for the above code. But I'm being technically challenged: public delegate List GetAllNodesDelegate(int k); GetAllNodesDelegate del = new GetAllNodesDelegate(ClassCurrent.GetAllRootNodes); I got the following error: An object reference is required for the non-static field, method, property ClassCurrent<BaseNode>.GetAllRootNodes(int) I might have misunderstood something... but if I have to manually declare a delegate at the calling class, AND to pass in the function manually as above, then I'm starting to question whether delegate is a good way to handle my problem. Thanks.

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• python can't start a new thread

  - by Giorgos Komnino

  I am building a multi threading application. I have setup a threadPool. [ A Queue of size N and N Workers that get data from the queue] When all tasks are done I use tasks.join() where tasks is the queue . The application seems to run smoothly until suddently at some point (after 20 minutes in example) it terminates with the error thread.error: can't start new thread Any ideas? Edit: The threads are daemon Threads and the code is like: while True: t0 = time.time() keyword_statuses = DBSession.query(KeywordStatus).filter(KeywordStatus.status==0).options(joinedload(KeywordStatus.keyword)).with_lockmode("update").limit(100) if keyword_statuses.count() == 0: DBSession.commit() break for kw_status in keyword_statuses: kw_status.status = 1 DBSession.commit() t0 = time.time() w = SWorker(threads_no=32, network_server='http://192.168.1.242:8180/', keywords=keyword_statuses, cities=cities, saver=MySqlRawSave(DBSession), loglevel='debug') w.work() print 'finished' When the daemon threads are killed? When the application finishes or when the work() finishes? Look at the thread pool and the worker (it's from a recipe ) from Queue import Queue from threading import Thread, Event, current_thread import time event = Event() class Worker(Thread): """Thread executing tasks from a given tasks queue""" def __init__(self, tasks): Thread.__init__(self) self.tasks = tasks self.daemon = True self.start() def run(self): '''Start processing tasks from the queue''' while True: event.wait() #time.sleep(0.1) try: func, args, callback = self.tasks.get() except Exception, e: print str(e) return else: if callback is None: func(args) else: callback(func(args)) self.tasks.task_done() class ThreadPool: """Pool of threads consuming tasks from a queue""" def __init__(self, num_threads): self.tasks = Queue(num_threads) for _ in range(num_threads): Worker(self.tasks) def add_task(self, func, args=None, callback=None): ''''Add a task to the queue''' self.tasks.put((func, args, callback)) def wait_completion(self): '''Wait for completion of all the tasks in the queue''' self.tasks.join() def broadcast_block_event(self): '''blocks running threads''' event.clear() def broadcast_unblock_event(self): '''unblocks running threads''' event.set() def get_event(self): '''returns the event object''' return event

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• derived class as default argument g++

  - by Vincent

  Please take a look at this code: template<class T> class A { class base { }; class derived : public A<T>::base { }; public: int f(typename A<T>::base& arg = typename A<T>::derived()) { return 0; } }; int main() { A<int> a; a.f(); return 0; } Compiling generates the following error message in g++: test.cpp: In function 'int main()': test.cpp:25: error: default argument for parameter of type 'A<int>::base&' has type 'A<int>::derived' The basic idea (using derived class as default value for base-reference-type argument) works in visual studio, but not in g++. I have to publish my code to the university server where they compile it with gcc. What can I do? Is there something I am missing?

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• HTML file: add annotations through IHTMLDocument

  - by peterchen

  I need to add "annotations" to existing HTML documents - best in the form of string property values I can read & write by name. Apparently (to me), meta elements in the header seem to be the common way - i.e. adding/modifying elements like <head> <meta name="unique-id_property-name" content="property-value"/> ... </head> Question 1: Ist that "acceptable" / ok, or is there a better way to add meta data? I have a little previous experience with getting/mut(il)ating HTML contents through the document in an web browser control. For this task, I've already loaded the HTML document into a HTMLDocument object, but I'm not sure how to go on: // what I have IHTMLDocument2Ptr doc; doc.CreateInstance(__uuidof(HTMLDocument)); IPersistFile pf = doc; pf->Load(fileName, STGM_READ); // everything ok until here Questions 2: Should I be using anything else than HTMLDocument? Questions 3..N: How do I get the head element? How do I get the value of a meta element with a given name? How do I set the value of a meta element (adding the item if and only if it doesn't exist yet)? doc->all returns a collection of all tags, which I can enumerate even though count returns 0. I could scan that for head, then scan that for all meta where the name starts with a certain string, etc. - but this feels very clumsy.

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• SCD2 + Merge Statement + MSSQL

  - by Nev_Rahd

  I am trying work out with MERGE statment to Insert / Update Dimension Table of Type SCD2 My source is a Table var to Merge with Dimension table. My Merget statement is throwing an error as: The target table 'DM.DATA_ERROR.ERROR_DIMENSION' of the INSERT statement cannot be on either side of a (primary key, foreign key) relationship when the FROM clause contains a nested INSERT, UPDATE, DELETE, or MERGE statement. Found reference constraint 'FK_ERROR_DIMENSION_to_AUDIT_CreatedBy'. My Merge Statement: DECLARE @DATAERROROBJECT AS [ERROR_DIMENSION] INSERT INTO DM.DATA_ERROR.ERROR_DIMENSION SELECT ERROR_CODE, DATA_STREAM_ID, [ERROR_SEVERITY], DATA_QUALITY_RATING, ERROR_LONG_DESCRIPTION, ERROR_DESCRIPTION, VALIDATION_RULE, ERROR_TYPE, ERROR_CLASS, VALID_FROM, VALID_TO, CURR_FLAG, CREATED_BY_AUDIT_SK, UPDATED_BY_AUDIT_SK FROM (MERGE DM.DATA_ERROR.ERROR_DIMENSION ED USING @DATAERROROBJECT OBJ ON(ED.ERROR_CODE = OBJ.ERROR_CODE AND ED.DATA_STREAM_ID = OBJ.DATA_STREAM_ID) WHEN NOT MATCHED THEN INSERT VALUES( OBJ.ERROR_CODE ,OBJ.DATA_STREAM_ID ,OBJ.[ERROR_SEVERITY] ,OBJ.DATA_QUALITY_RATING ,OBJ.ERROR_LONG_DESCRIPTION ,OBJ.ERROR_DESCRIPTION ,OBJ.VALIDATION_RULE ,OBJ.ERROR_TYPE ,OBJ.ERROR_CLASS ,GETDATE() ,'9999-12-13' ,'Y' ,1 ,1 ) WHEN MATCHED AND ED.CURR_FLAG = 'Y' AND ( ED.[ERROR_SEVERITY] <> OBJ.[ERROR_SEVERITY] OR ED.[DATA_QUALITY_RATING] <> OBJ.[DATA_QUALITY_RATING] OR ED.[ERROR_LONG_DESCRIPTION] <> OBJ.[ERROR_LONG_DESCRIPTION] OR ED.[ERROR_DESCRIPTION] <> OBJ.[ERROR_DESCRIPTION] OR ED.[VALIDATION_RULE] <> OBJ.[VALIDATION_RULE] OR ED.[ERROR_TYPE] <> OBJ.[ERROR_TYPE] OR ED.[ERROR_CLASS] <> OBJ.[ERROR_CLASS] ) THEN UPDATE SET ED.CURR_FLAG = 'N', ED.VALID_TO = GETDATE() OUTPUT $ACTION ACTION_OUT, OBJ.ERROR_CODE ERROR_CODE, OBJ.DATA_STREAM_ID DATA_STREAM_ID, OBJ.[ERROR_SEVERITY] [ERROR_SEVERITY], OBJ.DATA_QUALITY_RATING DATA_QUALITY_RATING, OBJ.ERROR_LONG_DESCRIPTION ERROR_LONG_DESCRIPTION, OBJ.ERROR_DESCRIPTION ERROR_DESCRIPTION, OBJ.VALIDATION_RULE VALIDATION_RULE, OBJ.ERROR_TYPE ERROR_TYPE, OBJ.ERROR_CLASS ERROR_CLASS, GETDATE() VALID_FROM, '9999-12-31' VALID_TO, 'Y' CURR_FLAG, 555 CREATED_BY_AUDIT_SK, 555 UPDATED_BY_AUDIT_SK ) AS MERGE_OUT WHERE MERGE_OUT.ACTION_OUT = 'UPDATE'; What am i doing wrong ?

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• C# Configuration Manager . ConnectionStrings

  - by Yoda

  I have a console app containing an application configuration file containing one connection string as shown below: <configuration> <connectionStrings> <add name="Target" connectionString="server=MYSERVER; Database=MYDB; Integrated Security=SSPI;" /> </connectionStrings> </configuration> When I pass this to my Connection using: ConfigurationManager.ConnectionStrings[1].ToString() I have two values in there, hence using the second in the collection, my question is where is this second coming from? I have checked the Bin version and original and its not mine! Its obviously a system generated one but I have not seen this before? Can anyone enlighten me? The mystery connection string is: data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true This isn't a problem as such I would just like to know why this is occuring? Thanks in advance! For future reference to those who may or may not stumble on this, after discovering the machine.config its become apparent it is bad practice to refer to a config by its index as each stack will potentially be different, which is why "Keys" are used. Cheers all!

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• Algorithm detect repeating/similiar strings in a corpus of data -- say email subjects, in Python

  - by RizwanK

  I'm downloading a long list of my email subject lines , with the intent of finding email lists that I was a member of years ago, and would want to purge them from my Gmail account (which is getting pretty slow.) I'm specifically thinking of newsletters that often come from the same address, and repeat the product/service/group's name in the subject. I'm aware that I could search/sort by the common occurrence of items from a particular email address (and I intend to), but I'd like to correlate that data with repeating subject lines.... Now, many subject lines would fail a string match, but "Google Friends : Our latest news" "Google Friends : What we're doing today" are more similar to each other than a random subject line, as is: "Virgin Airlines has a great sale today" "Take a flight with Virgin Airlines" So -- how can I start to automagically extract trends/examples of strings that may be more similar. Approaches I've considered and discarded ('because there must be some better way'): Extracting all the possible substrings and ordering them by how often they show up, and manually selecting relevant ones Stripping off the first word or two and then count the occurrence of each sub string Comparing Levenshtein distance between entries Some sort of string similarity index ... Most of these were rejected for massive inefficiency or likelyhood of a vast amount of manual intervention required. I guess I need some sort of fuzzy string matching..? In the end, I can think of kludgy ways of doing this, but I'm looking for something more generic so I've added to my set of tools rather than special casing for this data set. After this, I'd be matching the occurring of particular subject strings with 'From' addresses - I'm not sure if there's a good way of building a data structure that represents how likely/not two messages are part of the 'same email list' or by filtering all my email subjects/from addresses into pools of likely 'related' emails and not -- but that's a problem to solve after this one. Any guidance would be appreciated.

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