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  • My QFileSystemModel doesn't work as expected in PyQt

    - by Skilldrick
    I'm learning the Qt Model/View architecture at the moment, and I've found something that doesn't work as I'd expect it to. I've got the following code (adapted from Qt Model Classes): from PyQt4 import QtCore, QtGui model = QtGui.QFileSystemModel() parentIndex = model.index(QtCore.QDir.currentPath()) print model.isDir(parentIndex) #prints True print model.data(parentIndex).toString() #prints name of current directory childIndex = model.index(0, 0, parentIndex) print model.data(childIndex).toString() rows = model.rowCount(parentIndex) print rows #prints 0 (even though the current directory has directory and file children) The question: Is this a problem with PyQt, have I just done something wrong, or am I completely misunderstanding QFileSystemModel? According to the documentation, model.rowCount(parentIndex) should return the number of children in the current directory. The QFileSystemModel docs say that it needs an instance of a Gui application, so I've also placed the above code in a QWidget as follows, but with the same result: import sys from PyQt4 import QtCore, QtGui class Widget(QtGui.QWidget): def __init__(self, parent=None): QtGui.QWidget.__init__(self, parent) model = QtGui.QFileSystemModel() parentIndex = model.index(QtCore.QDir.currentPath()) print model.isDir(parentIndex) print model.data(parentIndex).toString() childIndex = model.index(0, 0, parentIndex) print model.data(childIndex).toString() rows = model.rowCount(parentIndex) print rows def main(): app = QtGui.QApplication(sys.argv) widget = Widget() widget.show() sys.exit(app.exec_()) if __name__ == '__main__': main()

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  • Trying to make a plugin system in C++/Qt

    - by Pirate for Profit
    I'm making a task-based program that needs to have plugins. Tasks need to have properties which can be easily edited, I think this can be done with Qt's Meta-Object Compiler reflection capabilities (I could be wrong, but I should be able to stick this in a QtPropertyBrowser?) So here's the base: class Task : public QObject { Q_OBJECT public: explicit Task(QObject *parent = 0) : QObject(parent){} virtual void run() = 0; signals: void taskFinished(bool success = true); } Then a plugin might have this task: class PrinterTask : public Task { Q_OBJECT public: explicit PrinterTask(QObject *parent = 0) : Task(parent) {} void run() { Printer::getInstance()->Print(this->getData()); // fictional emit taskFinished(true); } inline const QString &getData() const; inline void setData(QString data); Q_PROPERTY(QString data READ getData WRITE setData) // for reflection } In a nutshell, here's what I want to do: // load plugin // find all the Tasks interface implementations in it // have user able to choose a Task and edit its specific Q_PROPERTY's // run the TASK It's important that one .dll has multiple tasks, because I want them to be associated by their module. For instance, "FileTasks.dll" could have tasks for deleting files, making files, etc. The only problem with Qt's plugin setup is I want to store X amount of Tasks in one .dll module. As far as I can tell, you can only load one interface per plugin (I could be wrong?). If so, the only possible way to do accomplish what I want is to create a FactoryInterface with string based keys which return the objects (as in Qt's Plug-And-Paint example), which is a terrible boilerplate that I would like to avoid. Anyone know a cleaner C++ plugin architecture than Qt's to do what I want? Also, am I safely assuming Qt's reflection capabilities will do what I want (i.e. able to edit an unknown dynamically loaded tasks' properties with the QtPropertyBrowser before dispatching)?

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  • What hash algorithms are paralellizable? Optimizing the hashing of large files utilizing on mult-co

    - by DanO
    I'm interested in optimizing the hashing of some large files (optimizing wall clock time). The I/O has been optimized well enough already and the I/O device (local SSD) is only tapped at about 25% of capacity, while one of the CPU cores is completely maxed-out. I have more cores available, and in the future will likely have even more cores. So far I've only been able to tap into more cores if I happen to need multiple hashes of the same file, say an MD5 AND a SHA256 at the same time. I can use the same I/O stream to feed two or more hash algorithms, and I get the faster algorithms done for free (as far as wall clock time). As I understand most hash algorithms, each new bit changes the entire result, and it is inherently challenging/impossible to do in parallel. Are any of the mainstream hash algorithms parallelizable? Are there any non-mainstream hashes that are parallelizable (and that have at least a sample implementation available)? As future CPUs will trend toward more cores and a leveling off in clock speed, is there any way to improve the performance of file hashing? (other than liquid nitrogen cooled overclocking?) or is it inherently non-parallelizable?

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  • SQL Server log backups "stalling"

    - by MattK
    I have interited a box running SQL Server 2008 and Windows 2003, and have had a few events where largeish (35GB) log backups "stall", both before and after the installation of SQL 2008 SP1. The server log ships to a standby, so regular log backups are taken at 15 minute intervals. However, after an index reorg causes the log to grow to about 35GB (on a DB with about 17GB of data), the next log backup runs to ~95% completion, then seems to stop. The process shows as suspended, with a wait state of BACKUPIO. CPU, read, and write activity on the SPID also does not change, and the process stays in this state for hours, when normally a backup of this size should complete in about 20 minutes. This server has a single RAID-1 volume, thus the source database files and destination backup files are on the same volume. However, I cannot determine if another process is blocking the backup. The backup SPID cannot be killed, and the only way to terminate the log backup and clear the lock on the backup file is to cycle the SQL Server service. There was one event where the backup terminated completely, with an error that another process had locked the backup file, but no details about what that process was. Can anyone suggest a cause or diagnostic process to this situation?

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  • Rails wont install at create Makefile stage

    - by mattc
    I am getting this error after running sudo gem install rails /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb creating Makefile make xcrun cc -I. - I/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/universal-darwin12.0 -I/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/universal-darwin12.0 -I. -DJSON_GENERATOR -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -fno-common -arch i386 -arch x86_64 -g -O3 -pipe -fno-common -DENABLE_DTRACE -fno-common -pipe -fno-common -c generator.c xcrun: Error: failed to exec real xcrun. (No such file or directory) cc -arch i386 -arch x86_64 -pipe -bundle -undefined dynamic_lookup -o generator.bundle generator.o -L. -L/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib -L. -arch i386 -arch x86_64 -lruby -lpthread -ldl -lobjc i686-apple-darwin11-llvm-gcc-4.2: generator.o: No such file or directory i686-apple-darwin11-llvm-gcc-4.2: generator.o: No such file or directory lipo: can't figure out the architecture type of: /var/tmp//ccHCNNwM.out make: *** [generator.bundle] Error 1 I have Homebrew installed, Xcode 4.4 with command line tools installed, Osx 10.6.2 I run gem env and get this but not sure what I'm looking for: RubyGems Environment: - RUBYGEMS VERSION: 1.8.24 - RUBY VERSION: 1.8.7 (2012-02-08 patchlevel 358) [universal-darwin12.0] - INSTALLATION DIRECTORY: /Library/Ruby/Gems/1.8 - RUBY EXECUTABLE: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby - EXECUTABLE DIRECTORY: /usr/bin - RUBYGEMS PLATFORMS: - ruby - universal-darwin-12 - GEM PATHS: - /Library/Ruby/Gems/1.8 - /Users/matthewcleghorn/.gem/ruby/1.8 - /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8 - GEM CONFIGURATION: - :update_sources => true - :verbose => true - :benchmark => false - :backtrace => false - :bulk_threshold => 1000 - REMOTE SOURCES: - http://rubygems.org/ Any help greatly appreciated. Thanks.

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  • Is it possible for two VS2008 C# class library projects to share a single namespace?

    - by jeah
    I am trying to share a common namespace between two projects in a single solution. The projects are "Blueprint" and "Repositories". Blueprint contains Interfaces for the entire application and serves as a reference for the application structure. In the Blueprint project, I have an interface with the following declaration: namespace Application.Repositories{ public interface IRepository{ IEntity Get(Guid id); } } In the Repositories project I have a class the following class: namespace Application.Repositories{ public class STDRepository: IRepository { STD Get(Guid id){ return new SkankyExGirlfriendDataContext() .FirstOrDefault<STD>(x=>x.DiseaseId == id); } } } However, this does not work. The Repositories project has a reference to the Blueprint project. I receive a VS error: "The type or namespace name 'IRepository' could not be found (are you missing a using directive or an assembly reference?) - Normally, this is easy to fix but adding a using statement doesn't make sense since they have the same namespace. I tried it anyway and it didn't work. The reference has been added, and without the line of code referencing that interface, both projects compile successfully. I am lost here. I have searched all over and have found nothing, so I am assuming that there is something fundamentally wrong with what I'm doing ... but I don't know what it is. So, I would appreciate some explanation or guidance as to how to fix this problem. I hope you guys can help. Note: The reason I want to do it this way and keep the interfaces under the same namespace is because I want a solid project to keep all the interfaces in, in order to have a reference for the full architecture of the application. I have considered work arounds, such as putting all of the interfaces in the Blueprint.Application namespace instead of the application namespace. However, that would require me to write the using statement on virtually every page in the application...and my fingers get tired. Thanks again guys...

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  • Objective-C properties are not being recognized in header file?

    - by Greg
    Hey folks, I wonder if I'm doing something completely stupid here... I'm clearly missing something. I've gotten used to the pattern of defining properties of a custom class, however I seem to be hitting a point where extended classes do not recognize new properties. Case of point, here's my header file: import import "MyTableViewController.h" @interface MyRootController : MyTableViewController { NSMutableArray *sectionList; } @property (nonatomic, retain) NSMutableArray *sectionList; @end Now, for some reason that "sectionList" property is not turning green within my interface file (ie: it's not being recognized as custom property it seems). As a result, I'm getting all kinds of errors down in my implementation. The first is right at the top of my implementation where I try to synthesize the property: import "MyRootController.h" @implementation MyRootController @synthesize sectionList; That synthesize line throws the error "No declaration of property 'sectionList' found in the interface". So, this is really confusing. I'm clearly doing something wrong, although I can't put my finger on what. One thought: I am extending another custom class of my own. Do I need to specify some kind of super-class declaration to keep the architecture from getting sealed one level up? Thanks!

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  • Progressively stream the output of an ASP.NET page - or render a page outside of an HTTP request

    - by Evgeny
    I have an ASP.NET 2.0 page with many repeating blocks, including a third-party server-side control (so it's not just plain HTML). Each is quite expensive to generate, in terms of both CPU and RAM. I'm currently using a standard Repeater control for this. There are two problems with this simple approach: The entire page must be rendered before any of it is returned to the client, so the user must wait a long time before they see any data. (I write progress messages using Response.Write, so there is feedback, but no actual results.) The ASP.NET worker process must hold everything in memory at the same time. There is no inherent needs for this: once one block is processed it won't be changed, so it could be returned to the client and the memory could be freed. I would like to somehow return these blocks to the client one at a time, as each is generated. I'm thinking of extracting the stuff inside the Repeater into a separate page and getting it repeatedly using AJAX, but there are some complications involved in that and I wonder if there is some simper approach. Ideally I'd like to keep it as one page (from the client's point of view), but return it incrementally. Another way would be to do something similar, but on the server: still create a separate page, but have the server access it and then Response.Write() the HTML it gets to the response stream for the real client request. Is there a way to avoid an HTTP request here, though? Is there some ASP.NET method that would render a UserControl or a Page outside of an HTTP request and simply return the HTML to me as a string? I'm open to other ideas on how to do this as well.

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  • Do all C compilers allow functions to return structures?

    - by Jordan S
    I am working on a program in C and using the SDCC compiler for a 8051 architecture device. I am trying to write a function called GetName that will read 8 characters from Flash Memory and return the character array in some form. I know that it is not possible to return an array in C so I am trying to do it using a struct like this: //********************FLASH.h file******************************* MyStruct GetName(int i); //Function prototype #define NAME_SIZE 8 typedef struct { char Name[NAME_SIZE]; } MyStruct; extern MyStruct GetName(int i); // *****************FLASH.c file*********************************** #include "FLASH.h" MyStruct GetName( int i) { MyStruct newNameStruct; //... // Fill the array by reading data from Flash //... return newNameStruct; } I don't have any references to this function yet but for some reason, I get a compiler error that says "Function cannot return aggregate." Does this mean that my compiler does not support functions that return structs? Or am I just doing something wrong?

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  • NSNotification vs. Delegate Protocols?

    - by jr
    I have an iPhone application which basically is getting information from an API (in XML, but maybe JSON eventually). The result objects are typically displayed in view controllers (tables mainly). Here is the architecture right now. I have NSOperation classes which fetch the different objects from the remote server. Each of these NSOperation classes, will take a custom delegate method which will fire back the resulting objects as they are parsed, and then finally a method when no more results are available. So, the protocol for the delegates will be something like: (void) ObjectTypeResult:(ObjectType *)result; (void) ObjectTypeNoMoreResults; I think the solution works well, but I do end up with a bunch of delegate protocols around and then my view controllers have to implement all these delegate methods. I don't think its that bad, but I'm always on the lookout for a better design. So, I'm thinking about using NSNotifications to remove the use of the delegates. I could include the object in the userInfo part of the notification and just post objects as received, and then a final event when no more are available. Then I could just have one method in each view controller to receive all the data, even when using multiple objects in one controller.† So, can someone share with me some pros/cons of each approach. Should I consider refactoring my code to use Events rather then the delegates? Is one better then the other in certain situations? In my scenario I'm really not looking to receive notifications in multiple places, so maybe the protocol based delegates are the way to go. Thanks!

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  • User to kernel mode big picture?

    - by fsdfa
    I've to implement a char device, a LKM. I know some basics about OS, but I feel I don't have the big picture. In a C programm, when I call a syscall what I think it happens is that the CPU is changed to ring0, then goes to the syscall vector and jumps to a kernel memmory space function that handle it. (I think that it does int 0x80 and in eax is the offset of the syscall vector, not sure). Then, I'm in the syscall itself, but I guess that for the kernel is the same process that was before, only that it is in kernel mode, I mean the current PCB is the process that called the syscall. So far... so good?, correct me if something is wrong. Others questions... how can I write/read in process memory?. If in the syscall handler I refer to address, say, 0xbfffffff. What it means that address? physical one? Some virtual kernel one?

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  • Flex profiling - what is [enterFrameEvent] doing?

    - by Herms
    I've been tasked with finding (and potentially fixing) some serious performance problems with a Flex application that was delivered to us. The application will consistently take up 50 to 100% of the CPU at times when it is simply idling and shouldn't be doing anything. My first step was to run the profiler that comes with FlexBuilder. I expected to find some method that was taking up most of the time, showing me where the bottleneck was. However, I got something unexpected. The top 4 methods were: [enterFrameEvent] - 84% cumulative, 32% self time [reap] - 20% cumulative and self time [tincan] - 8% cumulative and self time global.isNaN - 4% cumulative and self time All other methods had less than 1% for both cumulative and self time. From what I've found online, the [bracketed methods] are what the profiler lists when it doesn't have an actual Flex method to show. I saw someone claim that [tincan] is the processing of RTMP requests, and I assume [reap] is the garbage collector. Does anyone know what [enterFrameEvent] is actually doing? I assume it's essentially the "main" function for the event loop, so the high cumulative time is expected. But why is the self time so high? What's actually going on? I didn't expect the player internals to be taking up so much time, especially since nothing is actually happening in the app (and there are no UI updates going on). Is there any good way to find dig into what's happening? I know something is going on that shouldn't be (it looks like there must be some kind of busy wait or other runaway loop), but the profiler isn't giving me any results that I was expecting. My next step is going to be to start adding debug trace statements in various places to try and track down what's actually happening, but I feel like there has to be a better way.

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  • Serializing Configurations for a Dependency Injection / Inversion of Control

    - by Joshua Starner
    I've been researching Dependency Injection and Inversion of Control practices lately in an effort to improve the architecture of our application framework and I can't seem to find a good answer to this question. It's very likely that I have my terminology confused, mixed up, or that I'm just naive to the concept right now, so any links or clarification would be appreciated. Many examples of DI and IoC containers don't illustrate how the container will connect things together when you have a "library" of possible "plugins", or how to "serialize" a given configuration. (From what I've read about MEF, having multiple declarations of [Export] for the same type will not work if your object only requires 1 [Import]). Maybe that's a different pattern or I'm blinded by my current way of thinking. Here's some code for an example reference: public abstract class Engine { } public class FastEngine : Engine { } public class MediumEngine : Engine { } public class SlowEngine : Engine { } public class Car { public Car(Engine e) { engine = e; } private Engine engine; } This post talks about "Fine-grained context" where 2 instances of the same object need different implementations of the "Engine" class: http://stackoverflow.com/questions/2176833/ioc-resolve-vs-constructor-injection Is there a good framework that helps you configure or serialize a configuration to achieve something like this without hard coding it or hand-rolling the code to do this? public class Application { public void Go() { Car c1 = new Car(new FastEngine()); Car c2 = new Car(new SlowEngine()); } } Sample XML: <XML> <Cars> <Car name="c1" engine="FastEngine" /> <Car name="c2" engine="SlowEngine" /> </Cars> </XML>

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  • What is the fastest way to do division in C for 8bit MCUs?

    - by Jordan S
    I am working on the firmware for a device that uses an 8bit mcu (8051 architecture). I am using SDCC (Small Device C Compiler). I have a function that I use to set the speed of a stepper motor that my circuit is driving. The speed is set by loading a desired value into the reload register for a timer. I have a variable, MotorSpeed that is in the range of 0 to 1200 which represents pulses per second to the motor. My function to convert MotorSpeed to the correct 16bit reload value is shown below. I know that float point operations are pretty slow and I am wondering if there is a faster way of doing this... void SetSpeed() { float t = MotorSpeed; unsigned int j = 0; t = 1/t ; t = t / 0.000001; j = MaxInt - t; TMR3RL = j; // Set reload register for desired freq return; }

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  • C++ Builder 2010 Exception Dead Lock ???

    - by James
    Hello Is this some kind of exception dead lock i am facing? How to avoid it ? Have a look at below line where i have TIdContext objects of connected clients stored in an objlist and at times i need to process it. But if one user is disconnected while another thread is processing the list, then for that freed TIdContext-Data object I am getting Access voilation, Ok its fine i am using try/catch but problem is that at below line there is some kind of dead lock and process hangs , if i attach a debuger it show Access voilation Again and Again and Again, and cpu coonsumption goes up because of that exception dead lock. AnsiString UserID = ((Tmyobject*) ((TIdContext*) ObjList->Objects[i])->Data)->UserID; i know i can check before accessing the object, if object is not Null, It works.. But my question is what if once in a blue moon the Data object is freed at the point when NULL check is performed and on next line when again i am accessing the object i get same dead lock ??? So how to avoid/handle this dead lock exception ? Here is the call stack... :005F07C0 System::AnsiStringBase::AnsiStringBase(this=:0285FCE0, src=????) :0040223F System::AnsiStringT<0>::AnsiStringT<0>(this=:0285FCE0, src=:00000008) :00457996 TSomeClass::SomeFunction(this=:009D8230, UserID={ }, DataSize={ }, ) :0047BFF1 __linkproc__ ThreadProc(Thread=:009561C0) :004AD00E __linkproc__ ThreadWrapper(Parameter=:009EAA30) :7c80b729 ; C:\WINDOWS\system32\kernel32.dll Please helppppppppppppppppppppp Thanks

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  • Desktop-like UI implementations for Java web applications?

    - by localshred
    At work we're discussing upgrading our view layer for our web application. We're currently running an old and "modified" version of FreeMarker Classic, which is a pain to work with. One of our developers suggested using a Component UI style architecture similar to desktop style environments. Essentially, this would mean that you would build custom HTML components as Java Classes that the controller would render into the Document view. This would completely take away the need to write HTML into a view layer. The Components would generate the view layer for you. For instance, the following rendered HTML: <h1>I am a title</h1> <p>I am a paragraph.</p> Would be generated by doing something like: String titleString = "I am a title"; html.elements.Heading heading = new html.elements.Heading(Heading.H1, titleString); String paraString = "I am a paragraph."; html.elements.Paragraph paragraph = new html.elements.Paragraph(paraString); PrintWriter somePrintWriter = new PrintWriter(); Document document = new Document(); document.addElement(heading); document.addElement(paragraph); document.compose(somePrintWriter); The above code is just an example, don't critique the names or style, I just wrote it for a quick demonstration of what we may be trying to accomplish. I'm trying to determine if this has been done before in Java, and if so if there are any links I can be pointed to. I've been researching it as much as I can, but haven't found any implementations that completely remove the template layer (such as JSP or JSF). Thanks!

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  • Upgraded to Xcode 4 -- Endless stream of duplicate symbol errors causing build errors

    - by D-Nice
    Everything was working perfectly fine in Xcode 3 yesterday before I upgraded. So I completed the upgrade, restarted my computer, and opened my old project. I had to reconfigure a few settings like the header paths so that I could begin to compile. I'm using AdWhirl for ad mediation, and at this point my errors begin to read something like duplicate symbol _OBJC_METACLASS_$_SBJSON in /Users/Admin/Desktop/TMapLiteAdwhirl/AdWhirl/MMSDK/libMMSDK.a(SBJSON.o) and /Users/Admin/Library/Developer/Xcode/DerivedData/TruxMapLite-bgpylibztethnlhkfkdumpvrjvgy/Build/Intermediates/TruxMapLite.build/Debug-iphoneos/TruxMapLite.build/Objects-normal/armv6/SBJSON.o for architecture armv6 The library it's referring to is the SDK for one of the ad networks I'm including in AdWhirl. Both of the 'duplicate symbols' refer to the SAME FILE, but they use different paths. If I had still had XCode 3, I would simply try excluding these libraries from the build path, but I have no idea how that can be done in Xcode 4. I've tried everything all the way down to deleting the library and all associated files from my project, but when I do this, i will simply get the same type of error for a different library in the AdWhirl directory. This is incredibly frustrating because before my upgrade everything was working smoothly and I was prepared to submit my binary. If anyone has any advice, id be more than happy to give it a try. Thanks!

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  • Calling delegate methods and calling selectors

    - by Crystal
    I'm new to the concept of delegates and selectors when used with notifications. So my first question is, 1) Let's say you have a button that has a delegate that implements some doWork method. If you want the same functionality that's in the method, is it 'ok' to just call that method? I didn't know if that was considered good coding practices and/or if you should do that, or do something different in getting that type of functionality. Like if that is ok architecture? 2) Similarly, with NSNotificationCenter, I see some code that posts a notification. Then there's a HandleSegmentedControl:(NSNotification *)notification method. If I want to manually have that functionality, but without pressing the segment control, is it 'ok' to just take that functionality out of that method and put it in a new method so it would look like this: Original: - (void)HandleSegmentedControl:(NSNotification *)notification { NSDictionary *dict = [userInfo notification]; // do stuff with the dictionary } New: - (void)HandleSegmentedControl:(NSNotification *)notification { NSDictionary *dict = [userInfo notification]; [self newMethod:dict]; } - (void)newMethod:(NSDictionary *)dict { // do stuff with the dictionary } - (void)myOtherMethodThatNeedsTheSameFunctionality { NSDictionary *dict = // create some dictionary [self newMethod:dict]; } Sorry if these are basic questions. I'm not sure what the best practices are for things like this and wanted to start the right way. Thanks.

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  • Which fieldtype is best for storing PRICE values?

    - by BerggreenDK
    Hi there I am wondering whats the best "price field" in MSSQL for a shoplike structure? Looking at this overview: http://www.teratrax.com/sql_guide/data_types/sql_server_data_types.html We have datatypes called money, smallmoney, then we have decimal/numeric and lastly float and real Name, memory/disk-usage and value ranges: Money: 8 bytes (values: -922,337,203,685,477.5808 to +922,337,203,685,477.5807) Smallmoney: 4 bytes (values: -214,748.3648 to +214,748.3647) Decimal: 9 [default, min. 5] bytes (values: -10^38 +1 to 10^38 -1 ) Float: 8 bytes (values: -1.79E+308 to 1.79E+308 ) Real: 4 bytes (values: -3.40E+38 to 3.40E+38 ) My question is: is it really wise to store pricevalues in those types? what about eg. INT? Int: 4 bytes (values: -2,147,483,648 to 2,147,483,647) Lets say a shop uses dollars, they have cents, but I dont see prices being $49.2142342 so the use of a lot of decimals showing cents seems waste of SQL bandwidth. Secondly, most shops wouldn't show any prices near 200.000.000 (not in normal webshops at least... unless someone is trying to sell me a famous tower in Paris) So why not go for an int? An int is fast, its only 4 bytes and you can easily make decimals, by saving values in cents instead of dollars and then divide when you present the values. The other approach would be to use smallmoney which is 4 bytes too, but this will require the math part of the CPU to do the calc, where as Int is integer power... on the downside you will need to divide every single outcome. Are there any "currency" related problems with regionalsettings when using smallmoney/money fields? what will these transfer too in C#/.NET ? Any pros/cons? Go for integer prices or smallmoney or some other? Whats does your experience tell?

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  • Program structure in long running data processing python script

    - by fmark
    For my current job I am writing some long-running (think hours to days) scripts that do CPU intensive data-processing. The program flow is very simple - it proceeds into the main loop, completes the main loop, saves output and terminates: The basic structure of my programs tends to be like so: <import statements> <constant declarations> <misc function declarations> def main(): for blah in blahs(): <lots of local variables> <lots of tightly coupled computation> for something in somethings(): <lots more local variables> <lots more computation> <etc., etc.> <save results> if __name__ == "__main__": main() This gets unmanageable quickly, so I want to refactor it into something more manageable. I want to make this more maintainable, without sacrificing execution speed. Each chuck of code relies on a large number of variables however, so refactoring parts of the computation out to functions would make parameters list grow out of hand very quickly. Should I put this sort of code into a python class, and change the local variables into class variables? It doesn't make a great deal of sense tp me conceptually to turn the program into a class, as the class would never be reused, and only one instance would ever be created per instance. What is the best practice structure for this kind of program? I am using python but the question is relatively language-agnostic, assuming a modern object-oriented language features.

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  • Dependency Properties, change notification and setting values in the constructor

    - by stefan.at.wpf
    Hello, I have a clas with 3 dependency properties A,B,C. The values of these properties are set by the constructor and every time one of the properties A, B or C changes, the method recalculate() is called. Now during execution of the constructor these method is called 3 times, because the 3 properties A, B, C are changed. Hoewever this isn't necessary as the method recalculate() can't do anything really useful without all 3 properties set. So what's the best way for property change notification but circumventing this change notification in the constructor? I thought about adding the property changed notification in the constructor, but then each object of the DPChangeSample class would always add more and more change notifications. Thanks for any hint! class DPChangeSample : DependencyObject { public static DependencyProperty AProperty = DependencyProperty.Register("A", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); public static DependencyProperty BProperty = DependencyProperty.Register("B", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); public static DependencyProperty CProperty = DependencyProperty.Register("C", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); private static void propertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { ((DPChangeSample)d).recalculate(); } private void recalculate() { // Using A, B, C do some cpu intensive caluclations } public DPChangeSample(int a, int b, int c) { SetValue(AProperty, a); SetValue(BProperty, b); SetValue(CProperty, c); } }

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  • This is a great job opportunity!!! [closed]

    - by Stuart Gordon
    ASP.NET MVC Web Developer / London / £450pd / £25-£50,000pa / Interested contact [email protected] ! As a web developer within the engineering department, you will work with a team of enthusiastic developers building a new ASP.NET MVC platform for online products utilising exciting cutting edge technologies and methodologies (elements of Agile, Scrum, Lean, Kanban and XP) as well as developing new stand-alone web products that conform to W3C standards. Key Responsibilities and Objectives: Develop ASP.NET MVC websites utilising Frameworks and enterprise search technology. Develop and expand content management and delivery solutions. Help maintain and extend existing products. Formulate ideas and visions for new products and services. Be a proactive part of the development team and provide support and assistance to others when required. Qualification/Experience Required: The ideal candidate will have a web development background and be educated to degree level in a Computer Science/IT related course plus ASP.NET MVC experience. The successful candidate needs to be able to demonstrate commercial experience in all or most of the following skills: Essential: ASP.NET MVC with C# (Visual Studio), Castle, nHibernate, XHTML and JavaScript. Experience of Test Driven Development (TDD) using tools such as NUnit. Preferable: Experience of Continuous Integration (TeamCity and MSBuild), SQL Server (T-SQL), experience of source control such as Subversion (plus TortioseSVN), JQuery. Learn: Fluent NHibernate, S#arp Architecture, Spark (View engine), Behaviour Driven Design (BDD) using MSpec. Furthermore, you will possess good working knowledge of W3C web standards, web usability, web accessibility and understand the basics of search engine optimisation (SEO). You will also be a quick learner, have good communication skills and be a self-motivated and organised individual.

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  • wpf command pattern

    - by evan
    I have a wpf gui which displays a list of information in separate window and in a separate thread from the main application. As the user performs actions in the main window the side window is updated. (For example if you clicked page down in the main window a listbox in the side window would page down). Right now the architecture for this application feels very messy and I'm sure there is a cleaner way to do it. It looks like this: Main Window contains a singleton SideWindowControl which communicates with an instance of the SideWindowDisplay using events - so, for example, the pagedown button would work like: 1) the event handler of the button on the main window calls SideWindowControl.PageDown() 2) in the PageDown() function a event is created and thrown. 3) finally the gui, ShowSideWindowDisplay is subscribing to the SideWindowControl.Actions event handles the event and actually scrolls the listbox down - note because it is in a different thread it has to do that by running the command via Dispatcher.Invoke() This just seems like a very messy way to this and there must be a clearer way (The only part that can't change is that the main window and the side window must be on different threads). Perhaps using WPF commands? I'd really appreciate any suggestions!! Thanks

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  • Trusted Folder/Drive Picker in the Browser

    - by kylepfritz
    I'd like to write a Folder/Drive picker the runs in the browser and allows a user to select files to upload to a webservice. The primary usage would be selecting folders or a whole CD and uploading them to the web with their directory structure in tact. I'm imagining something akin to Jumploader but which automatically enumerates external drives and CDs. I remember a version of Facebook's picture uploader that could do this sort of enumeration and was java-based but it has since been replaced by a much slicker plugin-based architecture. Because the application needs to run at very high trust, I think I'm limited to old-school java applets. Is there another alternative? I'm hesitant to start down the plugin route because of the necessity of writing one for both IE and Mozilla at a minimum. Are there good places to get started there? On the applet front, I built a clunky prototype to demonstrate that I can enumerate devices and list files. It runs fine in the applet viewer but I don't think I have the security settings configured correctly for it to run in the browser at full trust. Currently I don't get any drives back when I run it in the browser. Applet Prototype: public class Loader extends javax.swing.JApplet { ... private void EnumerateDrives(java.awt.event.ActionEvent evt) { File[] roots = File.listRoots(); StringBuilder b = new StringBuilder(); for (File root : roots) { b.append(root.getAbsolutePath() + ", "); } jLabel.setText(b.toString()); } } Embed Html: <p>Loader:</p> <script src="http://www.java.com/js/deployJava.js" type="text/javascript" ></script> <script> var attributes = {code:'org.exampl.Loader.Loader.class', archive:'Loader/dist/Loader.jar', width:600, height:400} ; var parameters = {}; deployJava.runApplet(attributes, parameters, '1.6');

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  • Threading calls to web service in a web service - (.net 2.0)

    - by Ryan Ternier
    Got a question regarding best practices for doing parallel web service calls, in a web service. Our portal will get a message, split that message into 2 messages, and then do 2 calls to our broker. These need to be on separate threads to lower the timeout. One solution is to do something similar to (pseudo code): XmlNode DNode = GetaGetDemoNodeSomehow(); XmlNode ENode = GetAGetElNodeSomehow(); XmlNode elResponse; XmlNode demResponse; Thread dThread = new Thread(delegate { //Web Service Call GetDemographics d = new GetDemographics(); demResponse = d.HIALRequest(DNode); }); Thread eThread = new Thread(delegate { //Web Service Call GetEligibility ge = new GetEligibility(); elResponse = ge.HIALRequest(ENode); }); dThread.Start(); eThread.Start(); dThread.Join(); eThread.Join(); //combine the resulting XML and return it. //Maybe throw a bit of logging in to make architecture happy Another option we thought of is to create a worker class, and pass it the service information and have it execute. This would allow us to have a bit more control over what is going on, but could add additional overhead. Another option brought up would be 2 asynchronous calls and manage the returns through a loop. When the calls are completed (success or error) the loop picks it up and ends. The portal service will be called about 50,000 times a day. I don't want to gold plate this sucker. I'm looking for something light weight. The services that are being called on the broker do have time out limits set, and are already heavily logged and audited, so I'm not worried on that part. This is .NET 2.0 , and as much as I would love to upgrade I can't right now. So please leave all the goodies of 2.0 out please.

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