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• Recommended textbook for machine-level programming?

  - by Norman Ramsey

  I'm looking at textbooks for an undergraduate course in machine-level programming. If the perfect book existed, this is what it would look like: Uses examples written in C or assembly language, or both. Covers machine-level operations such as two's-complement integer arithmetic, bitwise operations, and floating-point arithmetic. Explains how caches work and how they affect performance. Explains machine instructions or assembly instructions. Bonus if the example assembly language includes x86; triple bonus if it includes x86-64 (aka AMD64). Explains how C values and data structures are represented using hardware registers and memory. Explains how C control structures are translated into assembly language using conditional and unconditional branch instructions. Explains something about procedure calling conventions and how procedure calls are implemented at the machine level. Books I might be interested in would probably have the words "machine organization" or "computer architecture" in the title. Here are some books I'm considering but am not quite happy with: Computer Systems: A Programmer's Perspective by Randy Bryant and Dave O'Hallaron. This is quite a nice book, but it's a book for a broad, shallow course in systems programming, and it contains a great deal of material my students don't need. Also, it is just out in a second edition, which will make it expensive. Computer Organization and Design: The Hardware/Software Interface by Dave Patterson and John Hennessy. This is also a very nice book, but it contains way more information about how the hardware works than my students need. Also, the exercises look boring. Finally, it has a show-stopping bug: it is based very heavily on MIPS hardware and the use of a MIPS simulator. My students need to learn how to use DDD, and I can't see getting this to work on a simulator. Not to mention that I can't see them cross-compiling their code for the simulator, and so on and so forth. Another flaw is that the book mentions the x86 architecture only to sneer at it. I am entirely sympathetic to this point of view, but news flash! You guys lost! Write Great Code Vol I: Understanding the Machine by Randall Hyde. I haven't evaluated this book as thoroughly as the other two. It has a lot of what I need, but the translation from high-level language to assembler is deferred to Volume Two, which has mixed reviews. My students will be annoyed if I make them buy a two-volume series, even if the price of those two volumes is smaller than the price of other books. I would really welcome other suggestions of books that would help students in a class where they are to learn how C-language data structures and code are translated to machine-level data structures and code and where they learn how to think about performance, with an emphasis on the cache.

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• Should an event-sourced aggregate root have access to the event sourcing repository?

  - by JD Courtoy

  I'm working on an event-sourced CQRS implementation, using DDD in the application / domain layer. I have an object model that looks like this: public class Person : AggregateRootBase { private Guid? _bookingId; public Person(Identification identification) { Apply(new PersonCreatedEvent(identification)); } public Booking CreateBooking() { // Enforce Person invariants var booking = new Booking(); Apply(new PersonBookedEvent(booking.Id)); return booking; } public void Release() { // Enforce Person invariants // Should we load the booking here from the aggregate repository? // We need to ensure that booking is released as well. var booking = BookingRepository.Load(_bookingId); booking.Release(); Apply(new PersonReleasedEvent(_bookingId)); } [EventHandler] public void Handle(PersonBookedEvent @event) { _bookingId = @event.BookingId; } [EventHandler] public void Handle(PersonReleasedEvent @event) { _bookingId = null; } } public class Booking : AggregateRootBase { private DateTime _bookingDate; private DateTime? _releaseDate; public Booking() { //Enforce invariants Apply(new BookingCreatedEvent()); } public void Release() { //Enforce invariants Apply(new BookingReleasedEvent()); } [EventHandler] public void Handle(BookingCreatedEvent @event) { _bookingDate = SystemTime.Now(); } [EventHandler] public void Handle(BookingReleasedEvent @event) { _releaseDate = SystemTime.Now(); } // Some other business activities unrelated to a person } With my understanding of DDD so far, both Person and Booking are seperate aggregate roots for two reasons: There are times when business components will pull Booking objects separately from the database. (ie, a person that has been released has a previous booking modified due to incorrect information). There should not be locking contention between Person and Booking whenever a Booking needs to be updated. One other business requirement is that a Booking can never occur for a Person more than once at a time. Due to this, I'm concerned about querying the query database on the read side as there could potentially be some inconsistency there (due to using CQRS and having an eventually consistent read database). Should the aggregate roots be allowed to query the event-sourced backing store by id for objects (lazy-loading them as needed)? Are there any other avenues of implementation that would make more sense?

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• question about book example - Java Concurrency in Practice, Listing 4.12

  - by mike

  Hi, I am working through an example in Java Concurrency in Practice and am not understanding why a concurrent-safe container is necessary in the following code. I'm not seeing how the container "locations" 's state could be modified after construction; so since it is published through an 'unmodifiableMap' wrapper, it appears to me that an ordinary HashMap would suffice. EG, it is accessed concurrently, but the state of the map is only accessed by readers, no writers. The value fields in the map are syncronized via delegation to the 'SafePoint' class, so while the points are mutable, the keys for the hash, and their associated values (references to SafePoint instances) in the map never change. I think my confusion is based on what precisely the state of the collection is in the problem. Thanks!! -Mike Listing 4.12, Java Concurrency in Practice, (this listing available as .java here, and also in chapter form via google) /////////////begin code @ThreadSafe public class PublishingVehicleTracker { private final Map<String, SafePoint> locations; private final Map<String, SafePoint> unmodifiableMap; public PublishingVehicleTracker( Map<String, SafePoint> locations) { this.locations = new ConcurrentHashMap<String, SafePoint>(locations); this.unmodifiableMap = Collections.unmodifiableMap(this.locations); } public Map<String, SafePoint> getLocations() { return unmodifiableMap; } public SafePoint getLocation(String id) { return locations.get(id); } public void setLocation(String id, int x, int y) { if (!locations.containsKey(id)) throw new IllegalArgumentException( "invalid vehicle name: " + id); locations.get(id).set(x, y); } } // monitor protected helper-class @ThreadSafe public class SafePoint { @GuardedBy("this") private int x, y; private SafePoint(int[] a) { this(a[0], a[1]); } public SafePoint(SafePoint p) { this(p.get()); } public SafePoint(int x, int y) { this.x = x; this.y = y; } public synchronized int[] get() { return new int[] { x, y }; } public synchronized void set(int x, int y) { this.x = x; this.y = y; } } ///////////end code

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• What is the best way to read and write cXML documents in C# ?

  - by tetranz

  I know this is a vague open ended question. I'm hoping to get some general direction. I need to add cXML punchout to an ASP.NET C# site / application. This is replacing something that I wrote years ago in ColdFusion. I'm a reasonably experienced C# developer but I haven't done much with XML. There seems to be lots of different options for processing XML in .NET. Here's the open ended question: Assuming that I have an XML document in some form, eg a file or a string, what is the best way to read it into my code? I want to get the data and then query databases etc. The cXML document size and our traffic volumes are easily small enough so that loading the a cXML document into memory is not a problem. Should I: 1) Manually build classes based on the dtd and use the XML Serializer? 2) Use a tool to generate classes. There are sample cXML files downloadable from Ariba.com. I tried xsd.exe to generate an xsd and then xsd.exe /c to generate classes. When I try to deserialize I get errors because there seems to be "confusion" around whether some elements should be single values or arrays. I tried the CodeXS online tool but that gives errors in it's log and errors if I try to deserialize a sample document. 2) Create a dataset and ReadXml()? 3) Create a typed dataset and ReadXml()? 4) Use Linq to XML. I often use Linq to Objects so I'm familiar with Linq in general but I'm struggling to see what it gives me in this situation. 5) Some other means. I guess I need to improve my understanding of XML in general but even so ... am I missing some obvious way of doing this? In the old ColdFusion site I found a free component ("tag") which basically ignored any schema and read the XML into a "structure" which is essentially a series of nested hash tables which was then easy to read in code. That was probably quite sloppy but it worked. I also need to generate XML files from my C# objects. Maybe Linq to XML will be good for that. I could start with a default "template" document and manipulate it before saving. Thanks for any pointers ...

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• protobuf-net NOT faster than binary serialization?

  - by Ashish Gupta

  I wrote a program to serialize a 'Person' class using XMLSerializer, BinaryFormatter and ProtoBuf. I thought protobuf-net should be faster than the other two. Protobuf serialization was faster than XMLSerialization but much slower than the binary serialization. Is my understanding incorrect? Please make me understand this. Thank you for the help. Following is the output:- Person got created using protocol buffer in 347 milliseconds Person got created using XML in 1462 milliseconds Person got created using binary in 2 milliseconds Code below using System; using System.Collections.Generic; using System.Linq; using System.Text; using ProtoBuf; using System.IO; using System.Diagnostics; using System.Runtime.Serialization.Formatters.Binary; namespace ProtocolBuffers { class Program { static void Main(string[] args) { string XMLSerializedFileName = "PersonXMLSerialized.xml"; string ProtocolBufferFileName = "PersonProtocalBuffer.bin"; string BinarySerializedFileName = "PersonBinary.bin"; var person = new Person { Id = 12345, Name = "Fred", Address = new Address { Line1 = "Flat 1", Line2 = "The Meadows" } }; Stopwatch watch = Stopwatch.StartNew(); watch.Start(); using (var file = File.Create(ProtocolBufferFileName)) { Serializer.Serialize(file, person); } watch.Stop(); Console.WriteLine(watch.ElapsedMilliseconds.ToString()); Console.WriteLine("Person got created using protocol buffer in " + watch.ElapsedMilliseconds.ToString() + " milliseconds " ); watch.Reset(); watch.Start(); System.Xml.Serialization.XmlSerializer x = new System.Xml.Serialization.XmlSerializer(person.GetType()); using (TextWriter w = new StreamWriter(XMLSerializedFileName)) { x.Serialize(w, person); } watch.Stop(); Console.WriteLine(watch.ElapsedMilliseconds.ToString()); Console.WriteLine("Person got created using XML in " + watch.ElapsedMilliseconds.ToString() + " milliseconds"); watch.Reset(); watch.Start(); using (Stream stream = File.Open(BinarySerializedFileName, FileMode.Create)) { BinaryFormatter bformatter = new BinaryFormatter(); //Console.WriteLine("Writing Employee Information"); bformatter.Serialize(stream, person); } watch.Stop(); Console.WriteLine(watch.ElapsedMilliseconds.ToString()); Console.WriteLine("Person got created using binary in " + watch.ElapsedMilliseconds.ToString() + " milliseconds"); Console.ReadLine(); } } [ProtoContract] [Serializable] public class Person { [ProtoMember(1)] public int Id {get;set;} [ProtoMember(2)] public string Name { get; set; } [ProtoMember(3)] public Address Address {get;set;} } [ProtoContract] [Serializable] public class Address { [ProtoMember(1)] public string Line1 {get;set;} [ProtoMember(2)] public string Line2 {get;set;} } }

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• Simaltaneous connections with PHP and SOAP?

  - by Dov

  I'm new to using SOAP and understanding the utmost basics of it. I create a client resource/connection, I then run some queries in a loop and I'm done. The issue I am having is when I increase the iterations of the loop, ie: from 100 to 1000, it seems to run out of memory and drops an internal server error. How could I possibly run either a) multiple simaltaneous connections or b) create a connection, 100 iterations, close connection, create connection.. etc. "a)" looks to be the better option but I have no clue as to how to get it up and running whilst keeping memory (I assume opening and closing connections) at a minimum. Thanks in advance! index.php <?php // set loops to 0 $loops = 0; // connection credentials and settings $location = 'https://theconsole.com/'; $wsdl = $location.'?wsdl'; $username = 'user'; $password = 'pass'; // include the console and client classes include "class_console.php"; include "class_client.php"; // create a client resource / connection $client = new Client($location, $wsdl, $username, $password); while ($loops <= 100) { $dostuff; } ?> class_console.php <?php class Console { // the connection resource private $connection = NULL; /** * When this object is instantiated a connection will be made to the console */ public function __construct($location, $wsdl, $username, $password, $proxyHost = NULL, $proxyPort = NULL) { if(is_null($proxyHost) || is_null($proxyPort)) $connection = new SoapClient($wsdl, array('login' => $username, 'password' => $password)); else $connection = new SoapClient($wsdl, array('login' => $username, 'password' => $password, 'proxy_host' => $proxyHost, 'proxy_port' => $proxyPort)); $connection->__setLocation($location); $this->connection = $connection; return $this->connection; } /** * Will print any type of data to screen, where supported by print_r * * @param $var - The data to print to screen * @return $this->connection - The connection resource **/ public function screen($var) { print '<pre>'; print_r($var); print '</pre>'; return $this->connection; } /** * Returns a server / connection resource * * @return $this->connection - The connection resource */ public function srv() { return $this->connection; } } ?>

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• Assembly Load and loading the "sub-modules" dependencies - "cannot find the file specified"

  - by Ted

  There are several questions out there that ask the same question. However the answers they received I cannot understand, so here goes: Similar questions: http://stackoverflow.com/questions/1874277/dynamically-load-assembly-and-manually-force-path-to-get-referenced-assemblies ; http://stackoverflow.com/questions/22012/loading-assemblies-and-its-dependencies-closed The question in short: I need to figure out how dependencies, ie References in my modules can be loaded dynamically. Right now I am getting "The system cannot find the file specified" on Assemblies referenced in my so called modules. I cannot really get how to use the AssemblyResolve event... The longer version I have one application, MODULECONTROLLER, that loads separate modules. These "separate modules" are located in well-known subdirectories, like appBinDir\Modules\Module1 appBinDir\Modules\Module2 Each directory contains all the DLLs that exists in the bin-directory of those projects after a build. So the MODULECONTROLLER loads all the DLLs contained in those folders using this code: byte[] bytes = File.ReadAllBytes(dllFileFullPath); Assembly assembly = null; assembly = Assembly.Load(bytes); I am, as you can see, loading the byte[]-array (so I dont lock the DLL-files). Now, in for example MODULE1, I have a static reference called MyGreatXmlProtocol. The MyGreatXmlProtocol.dll then also exists in the directory appBinDir\Modules\Module1 and is loaded using the above code When code in the MODULE1 tries to use this MyGreatXmlProtocol, I get: Could not load file or assembly 'MyGreatXmlProtocol, Version=1.0.3797.26527, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified. So, in a post (like this one) they say that To my understanding reflection will load the main assembly and then search the GAC for the referenced assemblies, if it cannot find it there, you can then incorparate an assemblyResolve event: First; is it really needed to use the AssemblyResolve-event to make this work? Shouldnt my different MODULEs themself load their DLLs, as they are statically referenced? Second; if AssemblyResolve is the way to go - how do I use it? I have attached a handler to the Event but I never get anything on MyGreatXmlProctol... === EDIT === CODE regarding the AssemblyResolve-event handler: public GUI() { InitializeComponent(); AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(CurrentDomain_AssemblyResolve); ... } // Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args) { Console.WriteLine(args.Name); return null; } Hope I wasnt too fuzzy =) Thx

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• polymorphism, inheritance in c# - base class calling overridden method?

  - by Andrew Johns

  This code doesn't work, but hopefully you'll get what I'm trying to achieve here. I've got a Money class, which I've taken from http://www.noticeablydifferent.com/CodeSamples/Money.aspx, and extended it a little to include currency conversion. The implementation for the actual conversion rate could be different in each project, so I decided to move the actual method for retrieving a conversion rate (GetCurrencyConversionRate) into a derived class, but the ConvertTo method contains code that would work for any implementation assuming the derived class has overriden GetCurrencyConversionRate so it made sense to me to keep it in the parent class? So what I'm trying to do is get an instance of SubMoney, and be able to call the .ConvertTo() method, which would in turn use the overriden GetCurrencyConversionRate, and return a new instance of SubMoney. The problem is, I'm not really understanding some concepts of polymorphism and inheritance yet, so not quite sure what I'm trying to do is even possible in the way I think it is, as what is currently happening is that I end up with an Exception where it has used the base GetCurrencyConversionRate method instead of the derived one. Something tells me I need to move the ConvertTo method down to the derived class, but this seems like I'll be duplicating code in multiple implementations, so surely there's a better way? public class Money { public CurrencyConversionRate { get { return GetCurrencyConversionRate(_regionInfo.ISOCurrencySymbol); } } public static decimal GetCurrencyConversionRate(string isoCurrencySymbol) { throw new Exception("Must override this method if you wish to use it."); } public Money ConvertTo(string cultureName) { // convert to base USD first by dividing current amount by it's exchange rate. Money someMoney = this; decimal conversionRate = this.CurrencyConversionRate; decimal convertedUSDAmount = Money.Divide(someMoney, conversionRate).Amount; // now convert to new currency CultureInfo cultureInfo = new CultureInfo(cultureName); RegionInfo regionInfo = new RegionInfo(cultureInfo.LCID); conversionRate = GetCurrencyConversionRate(regionInfo.ISOCurrencySymbol); decimal convertedAmount = convertedUSDAmount * conversionRate; Money convertedMoney = new Money(convertedAmount, cultureName); return convertedMoney; } } public class SubMoney { public SubMoney(decimal amount, string cultureName) : base(amount, cultureName) {} public static new decimal GetCurrencyConversionRate(string isoCurrencySymbol) { // This would get the conversion rate from some web or database source decimal result = new Decimal(2); return result; } }

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• JAVA - Strange problem (probably thread problem) with JTable & Model

  - by Stefanos Kargas

  I am using 2 Tables (JTable) with their DefaultTableModels. The first table is already populated. The second table is populated for each row of the first table (using an SQL Query). My purpose is to export every line of the first table with it's respective lines of the second in an Excel File. I am doing it with a for (for each line of 1st table), in which I write a line of the 1st table in the Excel File, then I populate the 2nd table (for this line of 1st Table), I get every line from the Table (from it's Model actually) and put it in the Excel File under the current line of 1st table. This means that if I have n lines in first table I will clear and populate again the second table n times. All this code is called in a seperate thread. THE PROBLEM IS: Everything works perfectly fine ecxept that I am getting some exceptions. The strange thing is that I'm not getting anything false in my result. The Excel file is perfect. Some of the lines of the exceptions are: Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 0 = 0 at java.util.Vector.elementAt(Vector.java:427) at javax.swing.table.DefaultTableModel.getValueAt(DefaultTableModel.java:632) at javax.swing.JComponent.paint(JComponent.java:1017) at javax.swing.RepaintManager.paint(RepaintManager.java:1220) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:803) I am assuming that the problem lies in the fact that the second table needs some more time to be populated before I try to get any data from it. That's why I see RepaintManager and paintDirtyRegions in my exceptions. Another thing I did is that I ran my program in debug mode and I put a breakpoint after each population of the 2nd table. Then I pressed F5 to continue for each population of 2nd table and no exception appeared. The program came to it's end without any exceptions. This is another important fact that tells me that maybe in this case I gave the table enough time to be populated. Of course you will ask me: If your program works fine, why do you care about the exceptions? I care for avoiding any future problems and I care to have a better understanding of Java and Java GUI and threads. Why do you depend on a GUI component (and it's model) to get your information and why don't you recreate the resultset that populates your tables using an SQL Query and get your info from the resultset? That would be the best and the right way. The fact is that I have the tables code ready and it was easier for me to just get the info from them. But the right way would be to get everything direct from database. Anyway what I did brought out my question, and answering it would help me understand more things about java. So I posted it.

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• Java: file write on finalize method

  - by sowrov

  In my understanding a singleton object will destroy only when the application is about to terminate. So in C++ I write a Singleton class to log my application and in that Singleton logger's destructor I log the time when my application was terminated. Things worked perfectly in C++. Now I want to have that same logger in Java, as in java there is no destructor so I implemented the finalize method for that singleton logger. But it seem that finalize method actually never get called. So, I add that System.runFinalizersOnExit(true); line, somewhere in my code (though I know it is deprecated) and that finalize method get called every time before termination of the app. But still there is a problem! If I try to write anything on file in that finalize method, It does not work, though System.out work without any problem! :( Can you guys help me on this problem? Here is a sample code of what I am try to do: Singleton Logger Class: public class MyLogger { FileWriter writer; private MyLogger() { try { this.writer = new FileWriter("log.txt"); } catch (IOException ex) { } } public static MyLogger getInstance() { return MyLoggerHolder.INSTANCE; } private static class MyLoggerHolder { private static final MyLogger INSTANCE = new MyLogger(); } @Override protected void finalize () { try { super.finalize(); System.out.println("Here"); //worked correctly. this.writer.write(new Date().toString()+System.getProperty("line.separator")); this.writer.write("End"); this.writer.flush(); //does not work! this.writer.close(); } catch (Throwable ex) { } } public synchronized void log(String str) { try { this.writer.write(new Date().toString()+System.getProperty("line.separator")); this.writer.write(str+"\n"); this.writer.flush(); } catch (IOException ex) { } } } Main: public class Main { public static void main(String[] args) { System.runFinalizersOnExit(true); MyLogger logger = MyLogger.getInstance(); logger.log("test"); } }

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• Two seperate tm structs mirroring each other

  - by BSchlinker

  Here is my current situation: I have two tm structs, both set to the current time I make a change to the hour in one of the structs The change is occurring in the other struct magically.... How do I prevent this from occurring? I need to be able to compare and know the number of seconds between two different times -- the current time and a time in the future. I've been using difftime and mktime to determine this. I recognize that I don't technically need two tm structs (the other struct could just be a time_t loaded with raw time) but I'm still interested in understanding why this occurs. void Tracker::monitor(char* buffer){ // time handling time_t systemtime, scheduletime, currenttime; struct tm * dispatchtime; struct tm * uiuctime; double remainingtime; // let's get two structs operating with current time dispatchtime = dispatchtime_tm(); uiuctime = uiuctime_tm(); // set the scheduled parameters dispatchtime->tm_hour = 5; dispatchtime->tm_min = 05; dispatchtime->tm_sec = 14; uiuctime->tm_hour = 0; // both of these will now print the same time! (0:05:14) // what's linking them?? // print the scheduled time printf ("Current Time : %2d:%02d:%02d\n", uiuctime->tm_hour, uiuctime->tm_min, uiuctime->tm_sec); printf ("Scheduled Time : %2d:%02d:%02d\n", dispatchtime->tm_hour, dispatchtime->tm_min, dispatchtime->tm_sec); } struct tm* Tracker::uiuctime_tm(){ time_t uiucTime; struct tm *ts_uiuc; // give currentTime the current time time(&uiucTime); // change the time zone to UIUC putenv("TZ=CST6CDT"); tzset(); // get the localtime for the tz selected ts_uiuc = localtime(&uiucTime); // set back the current timezone unsetenv("TZ"); tzset(); // set back our results return ts_uiuc; } struct tm* Tracker::dispatchtime_tm(){ time_t currentTime; struct tm *ts_dispatch; // give currentTime the current time time(&currentTime); // get the localtime for the tz selected ts_dispatch = localtime(&currentTime); // set back our results return ts_dispatch; }

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• C++ Virtual Constructor, without clone()

  - by Julien L.

  I want to perform "deep copies" of an STL container of pointers to polymorphic classes. I know about the Prototype design pattern, implemented by means of the Virtual Ctor Idiom, as explained in the C++ FAQ Lite, Item 20.8. It is simple and straightforward: struct ABC // Abstract Base Class { virtual ~ABC() {} virtual ABC * clone() = 0; }; struct D1 : public ABC { virtual D1 * clone() { return new D1( *this ); } // Covariant Return Type }; A deep copy is then: for( i = 0; i < oldVector.size(); ++i ) newVector.push_back( oldVector[i]->clone() ); Drawbacks As Andrei Alexandrescu states it: The clone() implementation must follow the same pattern in all derived classes; in spite of its repetitive structure, there is no reasonable way to automate defining the clone() member function (beyond macros, that is). Moreover, clients of ABC can possibly do something bad. (I mean, nothing prevents clients to do something bad, so, it will happen.) Better design? My question is: is there another way to make an abstract base class clonable without requiring derived classes to write clone-related code? (Helper class? Templates?) Following is my context. Hopefully, it will help understanding my question. I am designing a class hierarchy to perform operations on a class Image: struct ImgOp { virtual ~ImgOp() {} bool run( Image & ) = 0; }; Image operations are user-defined: clients of the class hierarchy will implement their own classes derived from ImgOp: struct CheckImageSize : public ImgOp { std::size_t w, h; bool run( Image &i ) { return w==i.width() && h==i.height(); } }; struct CheckImageResolution; struct RotateImage; ... Multiple operations can be performed sequentially on an image: bool do_operations( std::vector< ImgOp* > v, Image &i ) { std::for_each( v.begin(), v.end(), /* bind2nd(mem_fun(&ImgOp::run), i ...) don't remember syntax */ ); } int main( ... ) { std::vector< ImgOp* > v; v.push_back( new CheckImageSize ); v.push_back( new CheckImageResolution ); v.push_back( new RotateImage ); Image i; do_operations( v, i ); } If there are multiple images, the set can be split and shared over several threads. To ensure "thread-safety", each thread must have its own copy of all operation objects contained in v -- v becomes a prototype to be deep copied in each thread.

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• In a PHP project, how do you organize and access your helper objects?

  - by Pekka

  How do you organize and manage your helper objects like the database engine, user notification, error handling and so on in a PHP based, object oriented project? Say I have a large PHP CMS. The CMS is organized in various classes. A few examples: the database object user management an API to create/modify/delete items a messaging object to display messages to the end user a context handler that takes you to the right page a navigation bar class that shows buttons a logging object possibly, custom error handling etc. I am dealing with the eternal question, how to best make these objects accessible to each part of the system that needs it. my first apporach, many years ago was to have a $application global that contained initialized instances of these classes. global $application; $application->messageHandler->addMessage("Item successfully inserted"); I then changed over to the Singleton pattern and a factory function: $mh =&factory("messageHandler"); $mh->addMessage("Item successfully inserted"); but I'm not happy with that either. Unit tests and encapsulation become more and more important to me, and in my understanding the logic behind globals/singletons destroys the basic idea of OOP. Then there is of course the possibility of giving each object a number of pointers to the helper objects it needs, probably the very cleanest, resource-saving and testing-friendly way but I have doubts about the maintainability of this in the long run. Most PHP frameworks I have looked into use either the singleton pattern, or functions that access the initialized objects. Both fine approaches, but as I said I'm happy with neither. I would like to broaden my horizon on what is possible here and what others have done. I am looking for examples, additional ideas and pointers towards resources that discuss this from a long-term, real-world perspective. Also, I'm interested to hear about specialized, niche or plain weird approaches to the issue. Bounty I am following the popular vote in awarding the bounty, the answer which is probably also going to give me the most. Thank you for all your answers!

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• Problem adding Viewport2DVisual3D from Code

  - by Jeff

  I'm trying to add a Viewport2DVisual3D to a Viewport3D in code, but the visual isn't showing up. Any help understanding why not would be appreciated. The following is the code for the main window. Is it sufficient to just add the Viewport2DVisual3D to the children of the Viewport3D in order for it to be rendered? public partial class Window1 : System.Windows.Window { public Window1() { InitializeComponent(); this.Loaded += new RoutedEventHandler(temp); } public void temp(object sender, RoutedEventArgs e) { Viewport2DVisual3D test = new Viewport2DVisual3D(); MeshGeometry3D testGeometry = new MeshGeometry3D(); Vector3D CameraLookDirection = Main_Target_CameraOR20.LookDirection; // Calculate the Positions based on the Camera Point3DCollection myPoint3DCollection = new Point3DCollection(); myPoint3DCollection.Add(new Point3D(-1, 1, 0)); myPoint3DCollection.Add(new Point3D(-1, -1, 0)); myPoint3DCollection.Add(new Point3D(1, -1, 0)); myPoint3DCollection.Add(new Point3D(1, 1, 0)); testGeometry.Positions = myPoint3DCollection; PointCollection myPointCollection = new PointCollection(); myPointCollection.Add(new Point(0, 0)); myPointCollection.Add(new Point(0, 1)); myPointCollection.Add(new Point(1, 1)); myPointCollection.Add(new Point(1, 0)); testGeometry.TextureCoordinates = myPointCollection; Int32Collection triangleIndicesCollection = new Int32Collection(); triangleIndicesCollection.Add(0); triangleIndicesCollection.Add(1); triangleIndicesCollection.Add(2); triangleIndicesCollection.Add(2); triangleIndicesCollection.Add(3); triangleIndicesCollection.Add(0); testGeometry.TriangleIndices = triangleIndicesCollection; DiffuseMaterial myDiffuseMaterial = new DiffuseMaterial(Brushes.White); Viewport2DVisual3D.SetIsVisualHostMaterial(myDiffuseMaterial, true); Transform3DGroup myTransform3DGroup = new Transform3DGroup(); ScaleTransform3D myScaleTransform3D = new ScaleTransform3D(); myScaleTransform3D.ScaleX = 2; myScaleTransform3D.ScaleY = 2; myScaleTransform3D.ScaleZ = 2; TranslateTransform3D myTranslateTransform3D = new TranslateTransform3D(); myTranslateTransform3D.OffsetX = -27; myTranslateTransform3D.OffsetY = 13; myTranslateTransform3D.OffsetZ = 6; RotateTransform3D rotateTransform = new RotateTransform3D() { Rotation = new AxisAngleRotation3D { Angle = -50, Axis = new Vector3D(0, 1, 0) } }; myTransform3DGroup.Children.Add(myTranslateTransform3D); myTransform3DGroup.Children.Add(myScaleTransform3D); myTransform3DGroup.Children.Add(rotateTransform); test.Transform = myTransform3DGroup; Button myButton = new Button(); myButton.Content = "Test Button"; test.Material = myDiffuseMaterial; test.Geometry = testGeometry; test.Visual = myButton; ZAM3DViewport3D.Children.Add(test); } }

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• gcc, strict-aliasing, and casting through a union

  - by Joseph Quinsey

  About a year ago the following paragraph was added to the GCC Manual, version 4.3.4, regarding -fstrict-aliasing: Similarly, access by taking the address, casting the resulting pointer and dereferencing the result has undefined behavior [emphasis added], even if the cast uses a union type, e.g.: union a_union { int i; double d; }; int f() { double d = 3.0; return ((union a_union *)&d)->i; } Does anyone have an example to illustrate this undefined behavior? Note this question is not about what the C99 standard says, or does not say. It is about the actual functioning of gcc, and other existing compilers, today. My simple, naive, attempt fails. For example: #include <stdio.h> union a_union { int i; double d; }; int f1(void) { union a_union t; t.d = 3333333.0; return t.i; // gcc manual: 'type-punning is allowed, provided ...' } int f2(void) { double d = 3333333.0; return ((union a_union *)&d)->i; // gcc manual: 'undefined behavior' } int main(void) { printf("%d\n", f1()); printf("%d\n", f2()); return 0; } works fine, giving on CYGWIN: -2147483648 -2147483648 Also note that taking addresses is obviously wrong (or right, if you are trying to illustrate undefined behavior). For example, just as we know this is wrong: extern void foo(int *, double *); union a_union t; t.d = 3.0; foo(&t.i, &t.d); // UD behavior so is this wrong: extern void foo(int *, double *); double d = 3.0; foo(&((union a_union *)&d)->i, &d); // UD behavior For background discussion about this, see for example: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1422.pdf http://gcc.gnu.org/ml/gcc/2010-01/msg00013.html http://davmac.wordpress.com/2010/02/26/c99-revisited/ http://cellperformance.beyond3d.com/articles/2006/06/understanding-strict-aliasing.html http://stackoverflow.com/questions/98650/what-is-the-strict-aliasing-rule http://stackoverflow.com/questions/2771023/c99-strict-aliasing-rules-in-c-gcc/2771041#2771041 The first link, draft minutes of an ISO meeting seven months ago, notes in section 4.16: Is there anybody that thinks the rules are clear enough? No one is really able to interpret tham.

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• NSArraycontroller selectionIndexes bindings

  - by Michael Scherbaum

  Hi all, I have the following set-up: A Window that has a splitView in which I display I NSCollectionView in the left view and a detailView in the right view. Both views are set-up in separate xibs. Furthermore I have a Datacontroller (of class NSArrayController) that manages a mutable Array of NSMutableDictionaries (moviesForChoice). The dataController is set-up as application delegate. The movie objects in the array have properties like (name, plot, genre etc.) so far so good... In the xib for the NScollectionview I bound a NSArraycontroller content property to my datacontroller via Application.delegate.moviesForChoice The collectionView accesses the arraycontroller.arrrangedObjects and arraycontroller.selectionIndexes. This works fine the contents are displayed and the selection works fine in the collectionview (my collectionviewItem renders a selection color) In the xib for the detailView I want to display information for the selected object in the collectionview. Therefore I also added an arraycontroller to the xib, bound the content aray to Application.delegate.moviesForChoice and bound the NSTextfields in the view to e.g. arraycontroller.selection.name Here comes my issue: everytime I open the window with the two xibs, my collectionview displays all movies that are for choice correctly, and the detailview displays the information for the 1st object in my collectionview. Whenever I click on a different movie in the collectionView the res. item renders a selection color, but the detailView doesn't update. My understanding of it would be that the DataController is not informed about updates in the selectionIndexes and can therefore not trigger an update in the detailView. Correct me if I'm wrong... To remedy this I tried to bind the selectionIndexes property of the arraycontroller in the collectionView xib to Application.delegate.moviesForChoice.selecionIndexes but this failed with: addObserver:forKeyPath:options:context:] is not supported. Key path: selectionIndexes I could imagine that this means that the datacontroller is not KVO compliant for my Array moviesForChoice, but I implemented the following methods for it: -(void)insertObject:(NSDictionary *)dict inMoviesForChoiceAtIndex:(NSUInteger)index { [moviesForChoice insertObject:dict atIndex:index]; } -(void)removeObjectFromMoviesForChoiceAtIndex:(NSUInteger)index { [moviesForChoice removeObjectAtIndex:index]; } -(void)setMoviesForChoice:(NSMutableArray *)a { moviesForChoice = a; } -(NSArray*)moviesForChoice { return moviesForChoice; } -(NSUInteger)countOfMoviesForChoice { return [moviesForChoice count]; } - (void)addMovieForChoiceObject:(Movie *)anObject { [moviesForChoice addObject:anObject]; } So where am I wrong? How do I correctly bind to the selectionIndexes? You help is much appreciated! M

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• Memory management with Objective-C Distributed Objects: my temporary instances live forever!

  - by jkp

  I'm playing with Objective-C Distributed Objects and I'm having some problems understanding how memory management works under the system. The example given below illustrates my problem: Protocol.h #import <Foundation/Foundation.h> @protocol DOServer - (byref id)createTarget; @end Server.m #import <Foundation/Foundation.h> #import "Protocol.h" @interface DOTarget : NSObject @end @interface DOServer : NSObject < DOServer > @end @implementation DOTarget - (id)init { if ((self = [super init])) { NSLog(@"Target created"); } return self; } - (void)dealloc { NSLog(@"Target destroyed"); [super dealloc]; } @end @implementation DOServer - (byref id)createTarget { return [[[DOTarget alloc] init] autorelease]; } @end int main() { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; DOServer *server = [[DOServer alloc] init]; NSConnection *connection = [[NSConnection new] autorelease]; [connection setRootObject:server]; if ([connection registerName:@"test-server"] == NO) { NSLog(@"Failed to vend server object"); } else [[NSRunLoop currentRunLoop] run]; [pool drain]; return 0; } Client.m #import <Foundation/Foundation.h> #import "Protocol.h" int main() { unsigned i = 0; for (; i < 3; i ++) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; id server = [NSConnection rootProxyForConnectionWithRegisteredName:@"test-server" host:nil]; [server setProtocolForProxy:@protocol(DOServer)]; NSLog(@"Created target: %@", [server createTarget]); [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:1.0]]; [pool drain]; } return 0; } The issue is that any remote objects created by the root proxy are not released when their proxy counterparts in the client go out of scope. According to the documentation: When an object’s remote proxy is deallocated, a message is sent back to the receiver to notify it that the local object is no longer shared over the connection. I would therefore expect that as each DOTarget goes out of scope (each time around the loop) it's remote counterpart would be dellocated, since there is no other reference to it being held on the remote side of the connection. In reality this does not happen: the temporary objects are only deallocate when the client application quits, or more accurately, when the connection is invalidated. I can force the temporary objects on the remote side to be deallocated by explicitly invalidating the NSConnection object I'm using each time around the loop and creating a new one but somehow this just feels wrong. Is this the correct behaviour from DO? Should all temporary objects live as long as the connection that created them? Are connections therefore to be treated as temporary objects which should be opened and closed with each series of requests against the server? Any insights would be appreciated.

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• Hierarchy inheritance

  - by reito

  I had faced the problem. In my C++ hierarchy tree I have two branches for entities of difference nature, but same behavior - same interface. I created such hierarchy trees (first in image below). And now I want to work with Item or Base classes independetly of their nature (first or second). Then I create one abstract branch for this use. My mind build (second in image below). But it not working. Working scheme seems (third in image below). It's bad logic, I think... Do anybody have some ideas about such hierarchy inheritance? How make it more logical? More simple for understanding? Image Sorry for my english - russian internet didn't help:) Update: You ask me to be more explicit, and I will be. In my project (plugins for Adobe Framemaker) I need to work with dialogs and GUI controls. In some places I working with WinAPI controls, and some other places with FDK (internal Framemaker) controls, but I want to work throw same interface. I can't use one base class and inherite others from it, because all needed controls - is a hierarchy tree (not one class). So I have one hierarchy tree for WinAPI controls, one for FDK and one abstract tree to use anyone control. For example, there is an Edit control (WinEdit and FdkEdit realization), a Button control (WinButton and FdkButton realization) and base entity - Control (WinControl and FdkControl realization). For now I can link my classes in realization trees (Win and Fdk) with inheritence between each of them (WinControl is base class for WinButton and WinEdit; FdkControl is base class for FdkButton and FdkEdit). And I can link to abstract classes (Control is base class for WinControl and FdkControl; Edit is base class for WinEdit and FdkEdit; Button is base class for WinButton and FdkButton). But I can't link my abstract tree - compiler swears. In fact I have two hierarchy trees, that I want to inherite from another one. Update: I have done this quest! :) I used the virtual inheritence and get such scheme (http://img12.imageshack.us/img12/7782/99614779.png). Abstract tree has only absolute abstract methods. All inheritence in abstract tree are virtual. Link from realization tree to abstract are virtual. On image shown only one realization tree for simplicity. Thanks for help!

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• Hibernate3: Self-Referencing Objects

  - by monojohnny

  Need some help on understanding how to do this; I'm going to be running recursive 'find' on a file system and I want to keep the information in a single DB table - with a self-referencing hierarchial structure: This is my DB Table structure I want to populate. DirObject Table: id int NOT NULL, name varchar(255) NOT NULL, parentid int NOT NULL); Here is the proposed Java Class I want to map (Fields only shown): public DirObject { int id; String name; DirObject parent; ... For the 'root' directory was going to use parentid=0; real ids will start at 1, and ideally I want hibernate to autogenerate the ids. Can somebody provide a suggested mapping file for this please; as a secondary question I thought about doing the Java Class like this instead: public DirObject { int id; String name; List<DirObject> subdirs; Could I use the same data model for either of these two methods ? (With a different mapping file of course). --- UPDATE: so I tried the mapping file suggested below (thanks!), repeated here for reference: <hibernate-mapping> <class name="my.proj.DirObject" table="category"> ... <set name="subDirs" lazy="true" inverse="true"> <key column="parentId"/> <one-to-many class="my.proj.DirObject"/> </set> <many-to-one name="parent" class="my.proj.DirObject" column="parentId" cascade="all" /> </class> ...and altered my Java class to have BOTH 'parentid' and 'getSubDirs' [returning a 'HashSet']. This appears to work - thanks, but this is the test code I used to drive this - I think I'm not doing something right here, because I thought Hibernate would take care of saving the subordinate objects in the Set without me having to do this explicitly ? DirObject dirobject=new DirObject(); dirobject.setName("/files"); dirobject.setParent(dirobject); DirObject d1, d2; d1=new DirObject(); d1.setName("subdir1"); d1.setParent(dirobject); d2=new DirObject(); d2.setName("subdir2"); d2.setParent(dirobject); HashSet<DirObject> subdirs=new HashSet<DirObject>(); subdirs.add(d1); subdirs.add(d2); dirobject.setSubdirs(subdirs); session.save(dirobject); session.save(d1); session.save(d2);

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• Learn C# now or finish up with Java and then learn C#?

  - by Sahat

  Ok here is my situation. I've studied Java in my college for 2 semesters. But you know they teach you jack in there, just the basics. We skipped half of our textbook and even then our professors don't teach from section to section of each chapter. I don't blame them. It's hard as it is for new students to understand even the basic concepts of programming. Now this is a community college we are talking about and not Stanford, MIT or Berkeley. So like I said I've done 2 semester of Java. I really like our textbook because it has some challenging projects to do at the end of each chapter. This textbook is pretty clear and i have no problem understanding it (although 2-D and 3-D Arrays have given me some trouble). I have tried reading a few C# books such as Pro C# 2008 and .NET 3.5 and C# 4.0 in a Nutshell. I found these books to be dry and overloaded with information that put me to sleep (No offense to the authors of those 2 wonderful, according to amazon ratings, books). Would you suggest I finish my Java textbook, brush up my knowledge of Arrays, Polymorphism, and etc that are universal to most programming languages. And then switch to C#, plus the syntax is very similar so it should be easy to switch. Or should I just start learning C# right now from the very beginning? If it's the latter then could you recommend some free online resources that will keep me engaged and at the same time teach me everything I need to know about C#. Someone has recommended me to learn .NET first, but I found it to be not the brightest idea. .NET is just a big monster full of libraries. How am I going to apply it if I don't even know the C# or VB!? Anyway back to my question: Master Java and switch to C# or just go with C#? DISCLAIMER: I don't want to start .NET vs J2EE or C# vs Java flame war. I am going with C#. I've decided that I want to work in a Microsoft shop in the future. .NET is what I want to learn. Thanks! Will be waiting for the answers.

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• disabling dropdownlist inside a gridview based on value selected on another dropdownlist inside the gridview from javascript or jquery

  - by Joy

  what i m trying is i hav two dropdownlists inside the gridview... namely say ddonsiteoffsite and ddhours... now what i want is if the selectedtext of ddonsiteoffsite is "onsite" the ddhours should b disabled... i tried the code snippet but ... its not disabling the ddhours... can someone help me please.. <asp:TemplateColumn HeaderText=" OnSite/OffSite" > <ItemTemplate> <asp:DropDownList ID="ddOnsiteOffside" runat="server" onchange="ToggleOnOff(this)"><asp:ListItem Text = "Offsite" Value="Offsite"></asp:ListItem> <asp:ListItem Text = "Onsite" Value="Onsite"></asp:ListItem> </asp:DropDownList> </ItemTemplate> </asp:TemplateColumn> <asp:TemplateColumn> <ItemTemplate> <asp:DropDownList ID="ddhours" runat="server"> <asp:ListItem Text = "1" Value="1" ></asp:ListItem> <asp:ListItem Text = "2" Value="2" ></asp:ListItem> <asp:ListItem Text = "3" Value="3" ></asp:ListItem> <asp:ListItem Text = "4" Value="4" ></asp:ListItem> <asp:ListItem Text = "5" Value="5" ></asp:ListItem> <asp:ListItem Text = "6" Value="6" ></asp:ListItem> <asp:ListItem Text = "7" Value="7" ></asp:ListItem> <asp:ListItem Text = "8" Value="8" ></asp:ListItem> <asp:ListItem Text = "9" Value="9" ></asp:ListItem> </asp:DropDownList> </ItemTemplate> </asp:TemplateColumn> and the corresponding javascript i am using is : enter code here function ToggleOnOff(ddonoff) { var row = chk.parentNode.parentNode; if(ddonoff.value=="Onsite") { row.getElementsByTagName("ddhours")[0].disabled = true; } else row.getElementsByTagName("ddhours")[0].disabled = false; } can someone help to achieve this ?? using javascript or jquery ? i m not understanding where i went wrong ...

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• .NET and C# Exceptions. What is it reasonable to catch.

  - by djna

  Disclaimer, I'm from a Java background. I don't do much C#. There's a great deal of transfer between the two worlds, but of course there are differences and one is in the way Exceptions tend to be thought about. I recently answered a C# question suggesting that under some circstances it's reasonable to do this: try { some work } catch (Exeption e) { commonExceptionHandler(); } (The reasons why are immaterial). I got a response that I don't quite understand: until .NET 4.0, it's very bad to catch Exception. It means you catch various low-level fatal errors and so disguise bugs. It also means that in the event of some kind of corruption that triggers such an exception, any open finally blocks on the stack will be executed, so even if the callExceptionReporter fuunction tries to log and quit, it may not even get to that point (the finally blocks may throw again, or cause more corruption, or delete something important from the disk or database). May I'm more confused than I realise, but I don't agree with some of that. Please would other folks comment. I understand that there are many low level Exceptions we don't want to swallow. My commonExceptionHandler() function could reasonably rethrow those. This seems consistent with this answer to a related question. Which does say "Depending on your context it can be acceptable to use catch(...), providing the exception is re-thrown." So I conclude using catch (Exception ) is not always evil, silently swallowing certain exceptions is. The phrase "Until .NET 4 it is very bad to Catch Exception" What changes in .NET 4? IS this a reference to AggregateException, which may give us some new things to do with exceptions we catch, but I don't think changes the fundamental "don't swallow" rule. The next phrase really bothers be. Can this be right? It also means that in the event of some kind of corruption that triggers such an exception, any open finally blocks on the stack will be executed (the finally blocks may throw again, or cause more corruption, or delete something important from the disk or database) My understanding is that if some low level code had lowLevelMethod() { try { lowestLevelMethod(); } finally { some really important stuff } } and in my code I call lowLevel(); try { lowLevel() } catch (Exception e) { exception handling and maybe rethrowing } Whether or not I catch Exception this has no effect whatever on the excution of the finally block. By the time we leave lowLevelMethod() the finally has already run. If the finally is going to do any of the bad things, such as corrupt my disk, then it will do so. My catching the Exception made no difference. If It reaches my Exception block I need to do the right thing, but I can't be the cause of dmis-executing finallys

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• Dynamic Multiple Choice (Like a Wizard) - How would you design it? (e.g. Schema, AI model, etc.)

  - by henry74

  This question can probably be broken up into multiple questions, but here goes... In essence, I'd like to allow users to type in what they would like to do and provide a wizard-like interface to ask for information which is missing to complete a requested query. For example, let's say a user types: "What is the weather like in Springfield?" We recognize the user is interested in weather, but it could be Springfield, Il or Springfield in another state. A follow-up question would be: What Springfield did you want weather for? 1 - Springfield, Il 2 - Springfield, Wi You can probably think of a million examples where a request is missing key data or its ambiguous. Make the assumption the gist of what the user wants can be understood, but there are missing pieces of data required to complete the request. Perhaps you can take it as far back as asking what the user wants to do and "leading" them to a query. This is not AI in the sense of taking any input and truly understanding it. I'm not referring to having some way to hold a conversation with a user. It's about inferring what a user wants, checking to see if there is an applicable service to be provided, identifying the inputs needed and overlaying that on top of what's missing from the request, then asking the user for the remaining information. That's it! :-) How would you want to store the information about services? How would you go about determining what was missing from the input data? My thoughts: Use regex expressions to identify clear pieces of information. These will be matched to the parameters of a service. Figure out which parameters do not have matching data and look up the associated question for those parameters. Ask those questions and capture answers. Re-run the service passing in the newly captured data. These would be more free-form questions. For multiple choice, identify the ambiguity and search for potential matches ranked in order of likelihood (add in user history/preferences to help decide). Provide the top 3 as choices. Thoughts appreciated. Cheers, Henry

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• Switch between speakerphone and headset on Android

  - by user210504

  Hi! I wish to know if there is a way, using which we can switch between the speaker and headset dynamically in an android application. I am using this sample code, I found online for my experiments final float frequency = 440; float increment = (float)(2*Math.PI) * frequency / 44100; // angular increment for each sample float angle = 0; AndroidAudioDevice device = new AndroidAudioDevice( ); AudioManager am = (AudioManager)getSystemService(AUDIO_SERVICE); am.setMode(AudioManager.MODE_IN_CALL); float samples[] = new float[1024]; int count = 0; while( count < 10 ) { count++; for( int i = 0; i < samples.length; i++ ) { samples[i] = (float)Math.sin( angle ) ; angle += increment; } device.writeSamples( samples ); } device.stop(); am.setMode(AudioManager.MODE_NORMAL); ---- next class public class AndroidAudioDevice { AudioTrack track; short[] buffer = new short[1024]; public AndroidAudioDevice( ) { int minSize =AudioTrack.getMinBufferSize( 44100, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT ); track = new AudioTrack( AudioManager.STREAM_VOICE_CALL, 44100, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, minSize, AudioTrack.MODE_STREAM); track.play(); } public void writeSamples(float[] samples) { fillBuffer( samples ); track.write( buffer, 0, samples.length ); } private void fillBuffer( float[] samples ) { if( buffer.length < samples.length ) buffer = new short[samples.length]; for( int i = 0; i < samples.length; i++ ) buffer[i] = (short)(samples[i] * Short.MAX_VALUE);; } public void stop() { track.stop(); } } As per my understanding this should play audio on headset, because we have not enabled the speaker phone. However, the audio is playing on the speaker phone. 1 Am I doing something wrong here? 2 What would be a way to switch between internal speaker and speaker phone dynamically for same code peice Any help will be appreciated.

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• Unlimited SMS API/Gateway (Sending and Receiving)

  - by Naif

  I am creating a chat application which requires that users be able to send and receive sms messages through a web interface. It would be somewhat similar to the text messaging service available in yahoo mail or in aol instant messenger. The situation is this: Given the high quantity of messages that would be sent and received, paying on a per message basis is not economically feasible. How is it that sites such as yahoo, aim, and twitter can send and receive unlimited sms messages? Essentially, I am looking for a way to send and receive unlimited sms from my computer. Below is a list of some approaches I've come up with but have run into problems with as well. If just one of the approaches can be utilized effectively, then I am fine. As a note on the nature of my application: I will only be sending messages to users that explicitly sign up for the service and permit the receiving of messages. They can unsubscribe at any time. This is to prevent spam. I am aware of software such as Kannel which allows one to connect to a providers smsc gateway. However, this adds the risk of not being approved by the provider which would be unacceptable. Is there any way to significantly mitigate this risk? Utilizing a gateway provider eliminates this risk, but adds the issue of per message pricing. I am also aware of email to sms. However, I have done some testing with that and it appears that this method results in many messages being undelivered or delivered VERY late. If it weren't for that, this approach would have been ideal. Is there any way to negotiate with carriers to remove me from their filters (considering the nature of my service as stated before)? I could use a gsm modem, but even with an "unilimited" plan on a sim card, there are still limits (around 100,000 messages or so). Furthermore, from my understanding, gsm modems are capable of only sending out around a dozen messages per minute. I need to be able to send out as much as several hundred messages per second. During the first 2 months, around 10 messages per second would suffice. There are ways to send out ads with messages to cover the per message costs. However, this is a deal-breaker since it has a high chance of tarnishing the quality of service. Furthermore, I know it is possible to do it without such ads since yahoo, aim, and twitter do not send ads with their messages.

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