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  • How to make TwoWay binding on properties of ObservableCollection of custom class using mvvm pattern?

    - by mill
    I have the following class: public class UserGroup { public string GroupName { get; set; } public bool IsIntheGroup{ get; set; } } I want to bind an ObservableCollection of UserGroup items to listbox containing checkbox’s for each item in the collection and the checkbox is cheked based on the IsIntheGroup property of the UserGroup. In my ViewModel I made an ObservableCollection of the UserGroup class: public ObservableCollection Groups { get; set; } and loaded its contents (instances of UserGroup) from my database model I used the following code in my view: ListBox ItemsSource="{Binding Groups, ValidatesOnDataErrors=True, UpdateSourceTrigger=PropertyChanged}" ListBox.ItemTemplate DataTemplate StackPanel Orientation="Horizontal" CheckBox IsChecked="{Binding IsIntheGroup, Mode=TwoWay}"/ TextBlock Text="{Binding GroupName}" / /StackPanel /DataTemplate /ListBox.ItemTemplate /ListBox The problem is I am not notified when the user checks/unchecks a check box in the list so my two way binding failed… How do I do a two way binding in such a case?

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  • How might I wrap the FindXFile-style APIs to the STL-style Iterator Pattern in C++?

    - by BillyONeal
    Hello everyone :) I'm working on wrapping up the ugly innards of the FindFirstFile/FindNextFile loop (though my question applies to other similar APIs, such as RegEnumKeyEx or RegEnumValue, etc.) inside iterators that work in a manner similar to the Standard Template Library's istream_iterators. I have two problems here. The first is with the termination condition of most "foreach" style loops. STL style iterators typically use operator!= inside the exit condition of the for, i.e. std::vector<int> test; for(std::vector<int>::iterator it = test.begin(); it != test.end(); it++) { //Do stuff } My problem is I'm unsure how to implement operator!= with such a directory enumeration, because I do not know when the enumeration is complete until I've actually finished with it. I have sort of a hack together solution in place now that enumerates the entire directory at once, where each iterator simply tracks a reference counted vector, but this seems like a kludge which can be done a better way. The second problem I have is that there are multiple pieces of data returned by the FindXFile APIs. For that reason, there's no obvious way to overload operator* as required for iterator semantics. When I overload that item, do I return the file name? The size? The modified date? How might I convey the multiple pieces of data to which such an iterator must refer to later in an ideomatic way? I've tried ripping off the C# style MoveNext design but I'm concerned about not following the standard idioms here. class SomeIterator { public: bool next(); //Advances the iterator and returns true if successful, false if the iterator is at the end. std::wstring fileName() const; //other kinds of data.... }; EDIT: And the caller would look like: SomeIterator x = ??; //Construct somehow while(x.next()) { //Do stuff } Thanks! Billy3

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  • How Do I Remove The First 4 Characters From A String If It Matches A Pattern In Ruby

    - by James
    I have the following string: "h3. My Title Goes Here" I basically want to remove the first 4 characters from the string so that I just get back: "My Title Goes Here". The thing is I am iterating over an array of strings and not all have the h3. part in front so I can't just ditch the first 4 characters blindly. I have checked the docs and the closest think I could find was chomp, but that only works for the end of a string. Right now I am doing this: "h3. My Title Goes Here".reverse.chomp(" .3h").reverse This gives me my desired output, but there has to be a better way right? I mean I don't want to reverse a string twice for no reason. I am new to programming so I might have missed something obvious, but I didn't see the opposite of chomp anywhere in the docs. Is there another method that will work? Thanks!

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  • c++ Design pattern for CoW, inherited classes, and variable shared data?

    - by krunk
    I've designed a copy-on-write base class. The class holds the default set of data needed by all children in a shared data model/CoW model. The derived classes also have data that only pertains to them, but should be CoW between other instances of that derived class. I'm looking for a clean way to implement this. If I had a base class FooInterface with shared data FooDataPrivate and a derived object FooDerived. I could create a FooDerivedDataPrivate. The underlying data structure would not effect the exposed getters/setters API, so it's not about how a user interfaces with the objects. I'm just wondering if this is a typical MO for such cases or if there's a better/cleaner way? What peeks my interest, is I see the potential of inheritance between the the private data classes. E.g. FooDerivedDataPrivate : public FooDataPrivate, but I'm not seeing a way to take advantage of that polymorphism in my derived classes. class FooDataPrivate { public: Ref ref; // atomic reference counting object int a; int b; int c; }; class FooInterface { public: // constructors and such // .... // methods are implemented to be copy on write. void setA(int val); void setB(int val); void setC(int val); // copy constructors, destructors, etc. all CoW friendly private: FooDataPrivate *data; }; class FooDerived : public FooInterface { public: FooDerived() : FooInterface() {} private: // need more shared data for FooDerived // this is the ???, how is this best done cleanly? };

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  • How can I refactor that code ? (state pattern ?)

    - by alex
    Hello guys, How can I refactor that code ? public enum enum1 { value1 = 0x01, value2 = 0x02, value3 = 0x03, value4 = 0x04, value5 = 0x05, UNKNOWN = 0xFF } class class1 { private const string STR_VALUE1 = "some text description of value1"; private const string STR_VALUE2 = "some text description of value2"; private const string STR_VALUE3 = "some text description of value3"; private const string STR_VALUE4 = "some text description of value4"; private const string STR_VALUE5 = "some text description of value5"; private const string STR_VALUE6 = "some text description of unknown type"; public static string GetStringByTypeCode(enum1 type) { switch(type) { case enum1.value1: return STR_VALUE1; case enum1.value2: return STR_VALUE2; case enum1.value3: return STR_VALUE3; case enum1.value4: return STR_VALUE4; case enum1.value5: return STR_VALUE5; default: return STR_VALUE6; } } } PS: there are many enum1...enumX and GetStringByTypeCode(enum1) ... GetStringByTypeCode(enumX) methods.

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  • What's the best practice or design pattern for user registration ?

    - by Space Cracker
    We have a big portal that needs user registration to allow them use its services. It's already done in .NET and SOL Server 2005. we are in the phase now of discovering all the problems of the current registration system to build a new robust flexible one that can be extended easily and can be more usable for all services. Could any help me find best practices and design patterns to help me rebuild this using good architectural practices?

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  • Which design pattern should be used to create an emulator?

    - by Facon
    I have programmed an emulator, but I have some doubts about how to organizate it properly, because, I see that it has some problems about classes connection (CPU <- Machine Board). For example: I/O ports, interruptions, communication between two or more CPU, etc. I need for the emulator to has the best performance and good understanding of the code. PD: Sorry for my bad English. EDITED - Asking for multiple patterns.

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  • JPA: what is the proper pattern for iterating over large result sets?

    - by Caffeine Coma
    Let's say I have a table with millions of rows. Using JPA, what's the proper way to iterate over a query against that table, such that I don't have all an in-memory List with millions of objects? I suspect that the following will blow up if the table is large: List<Model> models = entityManager().createQuery("from Model m", Model.class).getResultList(); for (Model model : models) { // do something with model } Is pagination (looping and manually updating setFirstResult()/setMaxResult()) really the best solution?

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  • What design pattern should be used to create an emulator?

    - by Facon
    I have programmed an emulator, but I have some doubts about how to organizate it properly, because, I see that it has some problems about classes connection (CPU <- Machine Board). For example: I/O ports, interruptions, communication between two or more CPU, etc. I need for the emulator to has the best performance and good understanding of the code. PD: Sorry for my bad English.

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  • How do I push `sed` matches to the shell call in the replacement pattern?

    - by rassie
    I need to replace several URLs in a text file with some content dependent on the URL itself. Let's say for simplicity it's the first line of the document at the URL. What I'm trying is this: sed "s/^URL=\(.*\)/TITLE=$(curl -s \1 | head -n 1)/" file.txt This doesn't work, since \1 is not set. However, the shell is getting called. Can I somehow push the sed match variables to that subprocess?

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  • Delegation, is this just opinionated or is there a common pattern?

    - by user1446714
    If I have a java class containing substantial code and I wish to add extra features, am I right in thinking the delegate class would have the additional features added as methods. Then my original class would create the delegate object and just call the extra functionality via the delegate instance? I am being told by somebody else that my original class should become the delegate and that the class containing the new functionality should contain an instance of the original class, to use as a delegate? This seemed a little backward to me, because there would be far more delegate calls because most of the code is now in the delegate.... I was always under the impression the delegate object would contain the additional new behaviour and an instance of it would be in the original class to inboke the new behaviour from?

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  • What types of objects should the ViewModel reference in the MVVM pattern?

    - by Blanthor
    I've seen quite a few examples of MVVM. I can see that the View should reference the ViewModel. I've seen recently an example of a ViewModel referencing a View, which seems wrong to me, as it would result in tighter coupling. Given that ViewModel is often described as an intermediary between the View and the Model, is there more to the ViewModel than a facade to domain objects? I hope I used the term "facade" correctly here.

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  • How to properly handle signals when using the worker thread pattern?

    - by ipartola
    I have a simple server that looks something like this: void *run_thread(void *arg) { // Communicate via a blocking socket } int main() { // Initialization happens here... // Main event loop while (1) { new_client = accept(socket, ...); pthread_create(&thread, NULL, &run_thread, *thread_data*); pthread_detach(thread); } // Do cleanup stuff: close(socket); // Wait for existing threads to finish exit(0); ) Thus when a SIGINT or SIGTERM is received I need to break out of the main event loop to get to the clean up code. Moreover most likely the master thread is waiting on the accept() call so it's not able to check some other variable to see if it should break;. Most of the advice I found was along the lines of this: http://devcry.blogspot.com/2009/05/pthreads-and-unix-signals.html (creating a special signal handling thread to catch all the signals and do processing on those). However, it's the processing portion that I can't really wrap my head around: how can I possibly tell the main thread to return from the accept() call and check on an external variable to see if it should break;?

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  • Make error: target pattern contains no '%'. Stop.

    - by Derek
    Hi all. I have a project that I have been running on IRIX that builds fine with gmake. I copied the source and make files onto a Redhat machine, and running gmake gives me the error posted in the subject. This is during a part of the make that is building .d dependency files, and they are separated by a colon, which I have read is a no-no, but why does it work on one system and not the other? What is the fix? Thanks

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  • How do I combine similar method calls into a delegate pattern?

    - by Daniel T.
    I have three methods: public void Save<T>(T entity) { using (new Transaction()) { Session.Save(entity); } } public void Create<T>(T entity) { using (new Transaction()) { Session.Create(entity); } } public void Delete<T>(T entity) { using (new Transaction()) { Session.Delete(entity); } } As you can see, the only thing that differs is the method call inside the using block. How can I rewrite this so it's something like this instead: public void Save<T>(T entity) { TransactionWrapper(Session.Save(entity)); } public void Create<T>(T entity) { TransactionWrapper(Session.Create(entity)); } public void Save<T>(T entity) { TransactionWrapper(Session.Save(entity)); } So in other words, I pass a method call as a parameter, and the TransactionWrapper method wraps a transaction around the method call.

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  • Mysql: how to generate count table by PATTERN / LIKE statement ? very tricky

    - by Abdulrahman Al-Qabandi
    to simplify, I got a database of registered users, I want to count how many emails there are for each email domain name (note I do not know all domain names) for example, Users table- id | email ------------------ 1 | [email protected] 2 | [email protected]<--unknown to me 3 | [email protected]<--unknown to me 4 | [email protected] 5 | [email protected]<--unknown to me 6 | [email protected] 7 | [email protected] 8 | [email protected] ( note: I want to count each email without specifying which email exactly ) so the result I want is suffix | count hotmail.com | 3 somesite.aaa | 2 unknownsite.aaa| 1 yahoo.com | 2 again, I stress this, I do not know unknownsite.aaa nor can i mention it in a statement because it is unknown to me, i hope I am clear. So essentially I want to make a statistic of what my website users use as an email host website. but like I said and I will repeat the third time, I do not know every mailhost that exists. I am going to investigate this more, I have a feeling this is something mysql cannot handle.

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  • How can I refactor this to work without breaking the pattern horribly?

    - by SnOrfus
    I've got a base class object that is used for filtering. It's a template method object that looks something like this. public class Filter { public void Process(User u, GeoRegion r, int countNeeded) { List<account> selected = this.Select(u, r, countNeeded); // 1 List<account> filtered = this.Filter(selected, u, r, countNeeded); // 2 if (filtered.Count > 0) { /* do businessy stuff */ } // 3 if (filtered.Count < countNeeded) this.SendToSuccessor(u, r, countNeeded - filtered) // 4 } } Select(...), Filter(...) are protected abstract methods and implemented by the derived classes. Select(...) finds objects in the based on x criteria, Filter(...) filters those selected further. If the remaining filtered collection has more than 1 object in it, we do some business stuff with it (unimportant to the problem here). SendToSuccessor(...) is called if there weren't enough objects found after filtering (it's a composite where the next class in succession will also be derived from Filter but have different filtering criteria) All has been ok, but now I'm building another set of filters, which I was going to subclass from this. The filters I'm building however would require different params and I don't want to just implement those methods and not use the params or just add to the param list the ones I need and have them not used in the existing filters. They still perform the same logical process though. I also don't want to complicated the consumer code for this (which looks like this) Filter f = new Filter1(); Filter f2 = new Filter2(); Filter f3 = new Filter3(); f.Sucessor = f2; f2.Sucessor = f3; /* and so on adding filters as successors to previous ones */ foreach (User u in users) { foreach (GeoRegion r in regions) { f.Process(u, r, ##); } } How should I go about it?

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  • how to write regular expression using proc in TCL to deal with following pattern ?

    - by Passion
    Hello Guys, I am new to TCL and seeking a help to deal with the following expression. I am getting the i/p string from the user to validate any of these strings below & no others in a line in CLI { GHI GII GJI GKI} and another tricky one is to write regexp to match only the characters which begin with alphabet A & end with B, It also have 1 or more of either YO or OY in between using procedure. Thank you

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  • Can I use the decorator pattern to wrap a method body?

    - by mgroves
    I have a bunch of methods with varying signatures. These methods interact with a fragile data connection, so we often use a helper class to perform retries/reconnects, etc. Like so: MyHelper.PerformCall( () => { doStuffWithData(parameters...) }); And this works fine, but it can make the code a little cluttery. What I would prefer to do is decorate the methods that interact with the data connection like so: [InteractsWithData] protected string doStuffWithData(parameters...) { // do stuff... } And then essentially, whenever doStuffWithData is called, the body of that method would be passed in as an Action to MyHelper.PerformCall(). How do I do this?

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  • PCRE (recursive) pattern that matches a string containing a correctly parenthesized substring. Why d

    - by Anton N. Petrov
    Well, there are other ways (hmmm... or rather working ways) to do it, but the question is why does this one fail? / \A # start of the string ( # group 1 (?: # group 2 [^()]* # something other than parentheses (greedy) | # or \( (?1) \) # parenthesized group 1 ) # -group 2 + # at least once (greedy) ) # -group 1 \Z # end of the string /x Fails to match a string with nested parentheses: "(())"

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