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  • Determining whether a class implements a generic list in a T4 template

    - by James Hollingworth
    I'm writing a T4 template which loads some classes from an assembly, does some analysis of the classes and then generates some code. One particular bit of analysis I need to do is to determine whether the class implements a generic list. I can do this pretty simply in C#, e.g. public class Foo : List<string> { } var t = typeof(Foo); if (t.BaseType != null && t.BaseType.IsGenericType && t.BaseType.GetGenericTypeDefinition() == typeof(List<>))) Console.WriteLine("Win"); However T4 templates use the FXCop introspection engine and so you do not have access to the .net reflection API. I've spent the past couple of hours in Reflector but still can't figure it out. Does anyone have any clues about how to do this?

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  • Where and why JVM checks that the return type of entry method main(String args[]) is void and not an

    - by akjain
    I will try to answer both, please correct me if I am wrong: Where: If a static method is being called using Classname.method() or using reflection then it doesn’t matter even if you change the return type of the calling method, the same method will still be called. So JVM probably checks this in one of the native methods of jvm.cpp methodHandle m (THREAD, init_klass-find_method(vmSymbols::object_initializer_name(), vmSymbols::void_method_signature())); if (m.is_null()) { ------ THROW_MSG_0 ……….. Why: Although it’s of useless to return a value from main, as java does not do anything with it but if we try to change the return type of main to int for example, JVM throws public static int main(String[] args) { return 1; } java.lang.NoSuchMethodError: main Exception in thread "main" So may be Java mandates the use of same signature for entry method main() to maintain a symmetry in all Java programs written.

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  • What scenarios/settings will result in a query on SQL Server (2008) return stale data

    - by s1mm0t
    Most applications rarely need to display 100% accurate data. For example if this stack overflow question displays that there have been 0 views, when there have really been 10, it doesn't really matter. This is one way that the (perceived) performance of applications can be improved, by caching results and therefore sometimes not showing 100% accurate results. There are some cases where the data does need to be 100% accurate though. So if I run the query select * from Foo I want to be sure that the results are not stale. Now depending on how my database is set up, other activity on the database, use of transactions and isolation levels etc this query may or may not be a true reflection of the world. What scenario's and settings can people think of that will result in this query returning stale results or given that another connection is part way through a transaction that has updated this table, how can I guarantee that when the above query returns, the results will be accurate.

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  • Finding all properties of a javascript class

    - by uzay95
    I have classes looks like below: function Student(name, surname, lossons){ this.Name = name; this.Surname = surname; this.Lessons = lessons; } function Lesson(){ this.Name = name; this.studentCount = count; } And i want to write ToString method to them. But i don't want to write and add them one by one. Is there any way to do this like reflection in C# or Java ? Any help would be appreciated...

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  • Guidance on using drop in DLLs

    - by Scott Chamberlain
    I have been giving the task to rewrite a internal utility in .net for my work. One of program requirements the new system has is have a dll that implements a set of interfaces and have the program call the DLL. Now this dll will be changed out a lot per deployment. My question is what is the best way to do it from a development standpoint? Do I add a template DLL (one that only has the interfaces but no implementation) to the project references like I would do any other dll that I would use. Or do I need to use somthing like this every time I want to use code from the dll? var DropIn = System.Reflection.Assembly.LoadFrom("DropInDll.dll"); var getActions = DropIn.GetType("Main").GetMethod("GetActions"); List<IAction> ActionList = (List<IAction>)getActions.Invoke(null, null);

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  • Where is the 'indeterminate type'?

    - by Daniel
    I'm defining the following type extension: type System.Reflection.MemberInfo with member x.GetAttribute<'T when 'T :> Attribute>(required, inherit') = match required, Attribute.GetCustomAttribute(x, typeof<'T>, inherit') with | true, null -> invalidOp (sprintf "Missing required attribute: %s" typeof<'T>.FullName) | _, attr -> attr :> 'T The last match expression (attr :> 'T) gives the error: The static coercion from Attribute to 'T involves an indeterminate type based on information prior to this program point. Static coercions are not allowed on some types. Further type annotations are needed. I've tried annotating the function return type, but got the same result. I would hate to change this to a dynamic cast. Is there a way to make the static cast work?

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  • Call Generic method using runtime type and cast return object

    - by markpirvine
    I'm using reflection to call a generic method with a type determined at runtime. My code is as follows: Type tType = Type.GetType(pLoadOut.Type); MethodInfo method = typeof(ApiSerialiseHelper).GetMethod("Deserialise", new Type[] { typeof(string) }); MethodInfo generic = method.MakeGenericMethod(tType); generic.Invoke(obj, new object[] { pLoadOut.Data }); This works ok. However the generic.Invoke method returns an object, but what I would like is the type determined at runtime. Is this possible with this approach, or is there a better option? Mark

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  • Get a property value with only the object and the name of the property (but not the type)

    - by Vaccano
    Suppose I have a method that passes in the name of a property (as a string) and the object that the property is on (as object). How could I get the value of the property? Here is some code to make it a bit more concrete: protected override void Paint(Graphics g, Rectangle bounds, CurrencyManager source, int rowNum, Brush backBrush, Brush foreBrush, bool alignToRight) { // The next line is made up code var currentValue = source.Current.CoolMethodToTakePropertyNameAndReturnValue(MappingName); // Paint out the retrieved value g.DrawString(currentValue.ToString() , _gridFont, new SolidBrush(Color.Black), bounds.Left + 1, bounds.Top); } MappingName is the name of the property I want to get the value for. What I need is CoolMethodToTakePropertyNameAndReturnValue. Any ideas? I am running on the Compact Framework. I would also prefer to avoid reflection (but if that is my only recourse then so be it). Thanks for any help.

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  • outofmemoryerror when running jar but not when running in netbeans/ apache poi

    - by Laughy
    I basically have a program that filters records from one excel file to another excel file using the apache poi. My program runs fine when it runs using netbeans. However, upon doing a clean and build and double clicking the .jar file inside the dist folder, it runs for very long( too long!) and gives me the following error( that I got by running the program from command prompt ). Is there any work around for it? I have already increase the heap size to be -Xms1500m inside netbeans before cleaning and building. Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap space at org.apache.xmlbeans.impl.store.Saver$TextSaver.resize(Saver.java:1592) at org.apache.xmlbeans.impl.store.Saver$TextSaver.preEmit(Saver.java:1223) at org.apache.xmlbeans.impl.store.Saver$TextSaver.emit(Saver.java:1144) at org.apache.xmlbeans.impl.store.Saver$TextSaver.emitElement(Saver.java:926) at org.apache.xmlbeans.impl.store.Saver.processElement(Saver.java:456) at org.apache.xmlbeans.impl.store.Saver.process(Saver.java:307) at org.apache.xmlbeans.impl.store.Saver$TextSaver.saveToString(Saver.java:1727) at org.apache.xmlbeans.impl.store.Cursor._xmlText(Cursor.java:546) at org.apache.xmlbeans.impl.store.Cursor.xmlText(Cursor.java:2436) at org.apache.xmlbeans.impl.values.XmlObjectBase.xmlText(XmlObjectBase.java:1455) at org.apache.poi.xssf.model.SharedStringsTable.getKey(SharedStringsTable.java:130) at org.apache.poi.xssf.model.SharedStringsTable.addEntry(SharedStringsTable.java:176) at org.apache.poi.xssf.usermodel.XSSFCell.setCellType(XSSFCell.java:755) at equity.EquityFrame_Updated.copyRowsFromOldToNew(EquityFrame_Updated.java:646) at equity.EquityFrame_Updated.init(EquityFrame_Updated.java:133) at equity.EquityFrame_Updated.createAndShowGUI(EquityFrame_Updated.java:71) at equity.EquityFrame_Updated.<init>(EquityFrame_Updated.java:50) at equity.FileOpener.generateButtonPressed(FileOpener.java:160) at equity.FileOpener.access$100(FileOpener.java:17) at equity.FileOpener$2.actionPerformed(FileOpener.java:61) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source) at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source) at javax.swing.DefaultButtonModel.setPressed(Unknown Source) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source) at java.awt.Component.processMouseEvent(Unknown Source) at javax.swing.JComponent.processMouseEvent(Unknown Source) at java.awt.Component.processEvent(Unknown Source) at java.awt.Container.processEvent(Unknown Source) at java.awt.Component.dispatchEventImpl(Unknown Source) at java.awt.Container.dispatchEventImpl(Unknown Source) at java.awt.Component.dispatchEvent(Unknown Source)

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  • How to break WinDbg in an anonymous method?

    - by Richard Berg
    Title kinda says it all. The usual SOS command !bpmd doesn't do a lot of good without a name. Some ideas I had: dump every method, then use !bpmd -md when you find the corresponding MethodDesc not practical in real world usage, from what I can tell. Even if I wrote a macro to limit the dump to anonymous types/methods, there's no obvious way to tell them apart. use Reflector to dump the MSIL name doesn't help when dealing with dynamic assemblies and/or Reflection.Emit. Visual Studio's inability to read local vars inside such scenarios is the whole reason I turned to Windbg in the first place... set the breakpoint in VS, wait for it to hit, then change to Windbg using the noninvasive trick attempting to detach from VS causes it to hang (along with the app). I think this is due to the fact that the managed debugger is a "soft" debugger via thread injection instead of a standard "hard" debugger. Or maybe it's just a VS bug specific to Silverlight (would hardly be the first I've encountered). set a breakpoint on some other location known to call into the anonymous method, then single-step your way in my backup plan, though I'd rather not resort to it if this Q&A reveals a better way

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  • XMLOutputStream, repairing namespaces, and attributes without namespaces

    - by comment_bot
    A simple task: write an element with an unnamespaced attribute: String nsURI = "http://example.com/"; XMLOutputFactory outF = XMLOutputFactory.newFactory(); outF.setProperty(XMLOutputFactory.IS_REPAIRING_NAMESPACES, true); XMLStreamWriter out = outF.createXMLStreamWriter(System.out); out.writeStartElement(XMLConstants.DEFAULT_NS_PREFIX, "element", nsURI); out.writeAttribute(XMLConstants.DEFAULT_NS_PREFIX, XMLConstants.NULL_NS_URI, "attribute", "value"); out.writeEndElement(); out.close(); Woodstox's answer: <element xmlns="http://example.com/" attribute="value"></element> JDK 6 answer: <zdef-159241566:element xmlns="" xmlns:zdef-159241566="http://example.com/" attribute="value"></zdef-159241566:element> What?! Further, if we add a prefix to the element: out.writeStartElement(ns, "element", nsURI); JDK 6 no longer attempts to emit xmlns="": <ns:element xmlns:ns="http://example.com/" attribute="value"></ns:element> I'm fairly sure this is a bug in JDK 6. Am I right? And could anyone suggest a work around that will keep both libraries (and any others) happy? I don't want to require woodstox if I can help it.

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  • appstats broken filename in callstack

    - by Ray Yun
    When I visit appstats page and expand callstack, the file path has <path[N]> prefix. So click the file link then emit no such file or directory error. Stack: /google/appengine/datastore/datastore_rpc.py:951 make_rpc_call() /google/appengine/datastore/datastore_query.py:993 _make_query_result_rpc_call() /google/appengine/datastore/datastore_query.py:714 run_async() /google/appengine/datastore/datastore_query.py:685 run() /google/appengine/api/datastore.py:1281 GetBatcher() /google/appengine/api/datastore.py:1351 Get() /google/appengine/ext/db/init.py:1831 fetch() /google/appengine/ext/db/init.py:1778 get() /apps/fbapp/fbutil.py:232 oauth_load_fb_user() /apps/fbapp/fbutil.py:84 require_account() the error message for appengine source: [Errno 2] No such file or directory: u'/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/ipaddr/google/appengine/datastore/datastore_rpc.py' the error message for my source: IOError [Errno 2] No such file or directory: u'/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/antlr3/apps/fbapp/fbutil.py' I guess this was path problem and found some official comment from google. If your request handlers modify sys.path, you must make the same modifications to sys.path in appengine_config.py so the Appstats web interface can see all files. Actually I'm using appengine_django and two path was inserted to sys.path. I did it same again at appengine_django.py but also failed. Maybe some custom setting with appengine_config.py can solve this problem but doesn't figure out how to fix it. What can I do?

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  • Can I autogenerate/compile code on-the-fly, at runtime, based upon values (like key/value pairs) parsed out of a configuration file?

    - by Kumba
    This might be a doozy for some. I'm not sure if it's even 100% implementable, but I wanted to throw the idea out there to see if I'm really off of my rocker yet. I have a set of classes that mimics enums (see my other questions for specific details/examples). For 90% of my project, I can compile everything in at design time. But the remaining 10% is going to need to be editable w/o re-compiling the project in VS 2010. This remaining 10% will be based on a templated version of my Enums class, but will generate code at runtime, based upon data values sourced in from external configuration files. To keep this question small, see this SO question for an idea of what my Enums class looks like. The templated fields, per that question, will be the MaxEnums Int32, Names String() array, and Values array, plus each shared implementation of the Enums sub-class (which themselves, represent the Enums that I use elsewhere in my code). I'd ideally like to parse values from a simple text file (INI-style) of key/value pairs: [Section1] Enum1=enum_one Enum2=enum_two Enum3=enum_three So that the following code would be generated (and compiled) at runtime (comments/supporting code stripped to reduce question size): Friend Shared ReadOnly MaxEnums As Int32 = 3 Private Shared ReadOnly _Names As String() = New String() _ {"enum_one", "enum_two", "enum_three"} Friend Shared ReadOnly Enum1 As New Enums(_Names(0), 1) Friend Shared ReadOnly Enum2 As New Enums(_Names(1), 2) Friend Shared ReadOnly Enum3 As New Enums(_Names(2), 4) Friend Shared ReadOnly Values As Enums() = New Enums() _ {Enum1, Enum2, Enum3} I'm certain this would need to be generated in MSIL code, and I know from reading that the two components to look at are CodeDom and Reflection.Emit, but I was wondering if anyone had working examples (or pointers to working examples) versus really long articles. I'm a hands-on learner, so I have to have example code to play with. Thanks!

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  • Developing a GPS car tracking system in C#

    - by Click Ok
    I'm in the brainstorming phase to develop a GPS car tracking system requested by a customer. I myself know the directions to build some GPS system to mobile phones and etc. But sincerely I don't know how to start in that project. That is the scenario: 1) The cars will get a device with a SIM CARD that will emit GPS signals. 2) My customer will in any place (home, work, etc) with a web connection will see in the map where the car is located. For me, I have not problems at get the GPS data, convert to usable info and show the position in some map system (like Google Maps or MS Bing Maps, by example). My problem is, how I do to retrieve that "GPS Signal" from device in the car? I will need some kind of "Receiver Device" connected to a web server machine in order to my application to consume that data? Or "automagically" my sodtware will receive the info from a third-party web-service? Or what? I thank for any help!

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  • How can I combine several Expressions into a fast method?

    - by chillitom
    Suppose I have the following expressions: Expression<Action<T, StringBuilder>> expr1 = (t, sb) => sb.Append(t.Name); Expression<Action<T, StringBuilder>> expr2 = (t, sb) => sb.Append(", "); Expression<Action<T, StringBuilder>> expr3 = (t, sb) => sb.Append(t.Description); I'd like to be able to compile these into a method/delegate equivalent to the following: void Method(T t, StringBuilder sb) { sb.Append(t.Name); sb.Append(", "); sb.Append(t.Description); } What is the best way to approach this? I'd like it to perform well, ideally with performance equivalent to the above method. UPDATE So, whilst it appears that there is no way to do this directly in C#3 is there a way to convert an expression to IL so that I can use it with System.Reflection.Emit?

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  • Large number of simultaneous long-running operations in Qt

    - by Hostile Fork
    I have some long-running operations that number in the hundreds. At the moment they are each on their own thread. My main goal in using threads is not to speed these operations up. The more important thing in this case is that they appear to run simultaneously. I'm aware of cooperative multitasking and fibers. However, I'm trying to avoid anything that would require touching the code in the operations, e.g. peppering them with things like yieldToScheduler(). I also don't want to prescribe that these routines be stylized to be coded to emit queues of bite-sized task items...I want to treat them as black boxes. For the moment I can live with these downsides: Maximum # of threads tend to be O(1000) Cost per thread is O(1MB) To address the bad cache performance due to context-switches, I did have the idea of a timer which would juggle the priorities such that only idealThreadCount() threads were ever at Normal priority, with all the rest set to Idle. This would let me widen the timeslices, which would mean fewer context switches and still be okay for my purposes. Question #1: Is that a good idea at all? One certain downside is it won't work on Linux (docs say no QThread::setPriority() there). Question #2: Any other ideas or approaches? Is QtConcurrent thinking about this scenario? (Some related reading: how-many-threads-does-it-take-to-make-them-a-bad-choice, many-threads-or-as-few-threads-as-possible, maximum-number-of-threads-per-process-in-linux)

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  • Sending custom PyQt signals?

    - by Enfors
    I'm practicing PyQt and (Q)threads by making a simple Twitter client. I have two Qthreads. Main/GUI thread. Twitter fetch thread - fetches data from Twitter every X minutes. So, every X minutes my Twitter thread downloads a new set of status updates (a Python list). I want to hand this list over to the Main/GUI thread, so that it can update the window with these statuses. I'm assuming that I should be using the signal / slot system to transfer the "statuses" Python list from the Twitter thread, to the Main/GUI thread. So, my question is twofold: How do I send the statuses from the Twitter thread? How do I receive them in the Main/GUI thread? As far as I can tell, PyQt can by default only send PyQt-objects via signals / slots. I think I'm supposed to somehow register a custom signal which I can then send, but the documentation on this that I've found is very unclear to a newbie like me. I have a PyQt book on order, but it won't arrive in another week, and I don't want to wait until then. :-) I'm using PyQt 4.6-1 on Ubuntu Update: This is an excert from the code that doesn't work. First, I try to "connect" the signal ("newStatuses", a name I just made up) to the function self.update_tweet_list in the Main/GUI thread: QtCore.QObject.connect(self.twit_in, QtCore.SIGNAL("newStatuses (statuses)"), self.update_tweet_list) Then, in the Twitter thread, I do this: self.emit(SIGNAL("newStatuses (statuses)"), statuses) When this line is called, I get the following message: QObject::connect: Cannot queue arguments of type 'statuses' (Make sure 'statuses' is registered using qRegisterMetaType().) I did a search for qRegisterMetaType() but I didn't find anything relating to Python that I could understand.

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  • Qt - no such signal error

    - by bullettime
    I'm trying to trigger a signal when a double click happens in one of the draggable widgets on the fridge magnets example. Here's the changes I made to the example source: DragLabel: class DragLabel : public QLabel { public: DragLabel(const QString &text, QWidget *parent); QString labelText() const; public slots: void testSlot(){qDebug()<<"testSlot";} //<-- implemented this slot protected: void mouseDoubleClickEvent(QMouseEvent *ev){emit testSignal();} //<-- overriden this method private: QString m_labelText; signals: void testSignal(); //<-- added this signal }; The only thing I changed in the implementation file is adding connect(this,SIGNAL(testSignal()),this,SLOT(testSlot())); to DragLabel's constructor. Trying to compile the project resulted in 'undefined reference to `DragLabel::testSignal()' and 'collect2: ld returned 1 exit status' errors. When I comment out the call to the signal, it compiles and runs, but gives off 'Object::connect: No such signal QLabel::testSignal() in draglabel.cpp' warning in the application output. Apparently testSignal() isn't being recognized as a signal. What am I missing?

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  • ViewModel updates after Model server roundtrip

    - by Pavel Savara
    I have stateless services and anemic domain objects on server side. Model between server and client is POCO DTO. The client should become MVVM. The model could be graph of about 100 instances of 20 different classes. The client editor contains diverse tab-pages all of them live-connected to model/viewmodel. My problem is how to propagate changes after server round-trip nice way. It's quite easy to propagate changes from ViewModel to DTO. For way back it would be possible to throw away old DTO and replace it whole with new one, but it will cause lot of redrawing for lists/DataTemplates. I could gather the server side changes and transmit them to client side. But the names of fields changed would be domain/DTO specific, not ViewModel specific. And the mapping seems nontrivial to me. If I should do it imperative way after round-trip, it would break SOC/modularity of viewModels. I'm thinking about some kind of mapping rule engine, something like automappper or emit mapper. But it solves just very plain use-cases. I don't see how it would map/propagate/convert adding items to list or removal. How to identify instances in collections so it could merge values to existing instances. As well it should propagate validation/error info. Maybe I should implement INotifyPropertyChanged on DTO and try to replay server side events on it ? And then bind ViewModel to it ? Would binding solve the problems with collection merges nice way ? Is EventAgregator from PRISM useful for that ? Is there any event record-replay component ? Is there better client side pattern for architecture with server side logic ?

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  • CssClass and default images in ServerContol

    - by Jeff Dege
    I'm writing a ServerControl in ASP.NET 3.5, and I'm exposing CssClass, so the user can manipulate the visual appearance of the control. My problem is that I want to establish reasonable defaults, so that the user doesn't have to configure CSS unless he wants to change the defaults. My specific problem is that my control is emitting html divs, that need to display background images. I want the user to be able to specify a different image in CSS, but I want to display a default background image, and I can't make that work. The entire server control is emitted as a div, with a class name set to the value the user provided in CssClass. The div that needs the background image is enclosed within this outer div, with a class name of its own. I am currently setting the background image in CSS on the page that contains the control: <style type="text/css"> .cssClass .innerDiv { background-image: url("http://...."); } </style> With this the proper image is drawn. But if it's not there, no image is drawn. What I want is for the ServerControl to emit some CSS that will define these image urls, that would be over-ridden by any css that was added by the user, and for that default CSS to include URLs to images embedded in the ServerControl's assembly. And I'm not sure of how to do either. Nor, for that matter, am I sure this is the best approach. Any ideas?

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  • Discover periodic patterns in a large data-set

    - by Miner
    I have a large sequence of tuples on disk in the form (t1, k1) (t2, k2) ... (tn, kn) ti is a monotonically increasing timestamp and ki is a key (assume a fixed length string if needed). Neither ti nor ki are guaranteed to be unique. However, the number of unique tis and kis is huge (millions). n itself is very large (100 Million+) and the size of k (approx 500 bytes) makes it impossible to store everything in memory. I would like to find out periodic occurrences of keys in this sequence. For example, if I have the sequence (1, a) (2, b) (3, c) (4, b) (5, a) (6, b) (7, d) (8, b) (9, a) (10, b) The algorithm should emit (a, 4) and (b, 2). That is a occurs with a period of 4 and b occurs with a period of 2. If I build a hash of all keys and store the average of the difference between consecutive timestamps of each key and a std deviation of the same, I might be able to make a pass, and report only the ones that have an acceptable std deviation(ideally, 0). However, it requires one bucket per unique key, whereas in practice, I might have very few really periodic patterns. Any better ways?

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  • searching for a programming platform with hot code swap

    - by Andreas
    I'm currently brainstorming over the idea how to upgrade a program while it is running. (Not while debugging, a "production" system.) But one thing that is required for it, is to actually submit the changed source code or compiled byte code into the running process. Pseudo Code var method = typeof(MyClass).GetMethod("Method1"); var content = //get it from a database (bytecode or source code) SELECT content FROM methods WHERE id=? AND version=? method.SetContent(content); At first, I want to achieve the system to work without the complexity of object-orientation. That leads to the following requirements: change source code or byte code of function drop functions add new functions change the signature of a function With .NET (and others) I could inject a class via an IoC and could thus change the source code. But the loading would be cumbersome, because everything has to be in an Assembly or created via Emit. Maybe with Java this would be easier? The whole ClassLoader is replacable, I think. With JavaScript I could achieve many of the goals. Simply eval a new function (MyMethod_V25) and assign it to MyClass.prototype.MyMethod. I think one can also drop functions somehow with "del" Which general-purpose platform can handle such things?

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  • MVVM pattern: ViewModel updates after Model server roundtrip

    - by Pavel Savara
    I have stateless services and anemic domain objects on server side. Model between server and client is POCO DTO. The client should become MVVM. The model could be graph of about 100 instances of 20 different classes. The client editor contains diverse tab-pages all of them live-connected to model/viewmodel. My problem is how to propagate changes after server round-trip nice way. It's quite easy to propagate changes from ViewModel to DTO. For way back it would be possible to throw away old DTO and replace it whole with new one, but it will cause lot of redrawing for lists/DataTemplates. I could gather the server side changes and transmit them to client side. But the names of fields changed would be domain/DTO specific, not ViewModel specific. And the mapping seems nontrivial to me. If I should do it imperative way after round-trip, it would break SOC/modularity of viewModels. I'm thinking about some kind of mapping rule engine, something like automappper or emit mapper. But it solves just very plain use-cases. I don't see how it would map/propagate/convert adding items to list or removal. How to identify instances in collections so it could merge values to existing instances. As well it should propagate validation/error info. Maybe I should implement INotifyPropertyChanged on DTO and try to replay server side events on it ? And then bind ViewModel to it ? Would binding solve the problems with collection merges nice way ? Is EventAgregator from PRISM useful for that ? Is there any event record-replay component ? Is there better client side pattern for architecture with server side logic ?

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  • Using map/reduce for mapping the properties in a collection

    - by And
    Update: follow-up to MongoDB Get names of all keys in collection. As pointed out by Kristina, one can use Mongodb 's map/reduce to list the keys in a collection: db.things.insert( { type : ['dog', 'cat'] } ); db.things.insert( { egg : ['cat'] } ); db.things.insert( { type : [] }); db.things.insert( { hello : [] } ); mr = db.runCommand({"mapreduce" : "things", "map" : function() { for (var key in this) { emit(key, null); } }, "reduce" : function(key, stuff) { return null; }}) db[mr.result].distinct("_id") //output: [ "_id", "egg", "hello", "type" ] As long as we want to get only the keys located at the first level of depth, this works fine. However, it will fail retrieving those keys that are located at deeper levels. If we add a new record: db.things.insert({foo: {bar: {baaar: true}}}) And we run again the map-reduce +distinct snippet above, we will get: [ "_id", "egg", "foo", "hello", "type" ] But we will not get the bar and the baaar keys, which are nested down in the data structure. The question is: how do I retrieve all keys, no matter their level of depth? Ideally, I would actually like the script to walk down to all level of depth, producing an output such as: ["_id","egg","foo","foo.bar","foo.bar.baaar","hello","type"] Thank you in advance!

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  • Suppressing PostSharp Multicast with Attribute

    - by Dan Bryant
    I've recently started experimenting with PostSharp and I found a particularly helpful aspect to automate implementation of INotifyPropertyChanged. You can see the example here. The basic functionality is excellent (all properties will be notified), but there are cases where I might want to suppress notification. For instance, I might know that a particular property is set once in the constructor and will never change again. As such, there is no need to emit the code for NotifyPropertyChanged. The overhead is minimal when classes are not frequently instantiated and I can prevent the problem by switching from an automatically generated property to a field-backed property and writing to the field. However, as I'm learning this new tool, it would be helpful to know if there is a way to tag a property with an attribute to suppress the code generation. I'd like to be able to do something like this: [NotifyPropertyChanged] public class MyClass { public double SomeValue { get; set; } public double ModifiedValue { get; private set; } [SuppressNotify] public double OnlySetOnce { get; private set; } public MyClass() { OnlySetOnce = 1.0; } }

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