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  • How to create a Clob in JPA in an implementation agnostic way

    - by kazanaki
    Hello I am using Ejb3 and JPA (based on Hibernate and Oracle 10g at the moment) I have an entity that contains a clob @Entity @Table(name = "My_TAB") public class ExampleEntity implements java.io.Serializable { private Clob someText; public void setSomeText(Clob someText) { this.someText= someText; } @Column(name = "COLUMN_NAME") public Clob getSomeText() { return this.someText; } Then I want to save an entity of this type. At the moment I am doing the following which works perfectly ExampleEntity exampleEntity = new ExampleEntity(); exampleEntity.setSomeText(Hibernate.createClob(aStringValue)); someOtherDao.save(exampleEntity); However this ties my code to Hibernate! I have specifically avoided so far Hibernate extensions and used only JPA annotations. The code works because indeed Hibernate is my current implementation. Is there some sort of JPA API that allows me to create a clob in a generic way? So if later I decide to switch to Toplink/EclipseLink or something else I won't have to change a thing?

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  • Studying MySQL, SQLite source code to learn about RDBMS implementation

    - by Yang
    I know implementing database is a huge topic, but I want to have a basic understanding of how database systems work (e.g. memory management, binary tree, transaction, sql parsing, multi-threading, partitions, etc) by investigating the source code of the database. Since there are a few already proven very robust open source databases like mysql, sqlite and so on. However, the code are very complicated and I have no clue where to start. Also I find that the old school database textbooks are only explaining the theory, not the implementation details. Can anyone suggest how I should get started and if there are any books that emphasis on the technology and techniques of building dbms used in modern database industry?

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  • [C++] Write connected components of a graph using Boost Graph

    - by conradlee
    I have an file that is a long list of weighted edges, in the following form node1_id node2_id weight node1_id node3_id weight and so on. So one weighted edge per line. I want to load this file into boost graph and find the connected components in the graph. Each of these connected components is a subgraph. For each of these component subgraphs, I want to write the edges in the above-described format. I want to do all this using boost graph. This problem is in principle simple, it's just I'm not sure how to implement it neatly because I don't know my way around Boost Graph. I have already spent some hours and have code that will find the connected components, but my version is surely much longer and more complicated that necessary---I'm hoping there's a boost-graph ninja out there that can show me the right, easy way.

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  • Proper implementation of NLog and Prism

    - by WiT8litZ
    What would be the best way to implement NLog in my Prism / CAL WPF application. This might be an amateur question, I am a bit new to the whole Prism framework :) I thought about putting the reference to the NLog dll in the Infrastructure module and make a wrapper singleton class e.g. MyLogger. My thinking was to be able to have the reference to 1 logger implementation somewhere in a central place that everything has reference to, and the only thing that I know of in Prism would be your Infrastructure module. The obvious other way is to add a reference to NLog to each module but I think that would defeat the purpose of decoupling and all of that. Any ideas would be most helpful Regards

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  • Singleton: How should it be used

    - by Loki Astari
    Edit: From another question I provided an answer that has links to a lot of questions/answers about singeltons: More info about singletons here: So I have read the thread Singletons: good design or a crutch? And the argument still rages. I see Singletons as a Design Pattern (good and bad). The problem with Singleton is not the Pattern but rather the users (sorry everybody). Everybody and their father thinks they can implement one correctly (and from the many interviews I have done, most people can't). Also because everybody thinks they can implement a correct Singleton they abuse the Pattern and use it in situations that are not appropriate (replacing global variables with Singletons!). So the main questions that need to be answered are: When should you use a Singleton How do you implement a Singleton correctly My hope for this article is that we can collect together in a single place (rather than having to google and search multiple sites) an authoritative source of when (and then how) to use a Singleton correctly. Also appropriate would be a list of Anti-Usages and common bad implementations explaining why they fail to work and for good implementations their weaknesses. So get the ball rolling: I will hold my hand up and say this is what I use but probably has problems. I like "Scott Myers" handling of the subject in his books "Effective C++" Good Situations to use Singletons (not many): Logging frameworks Thread recycling pools /* * C++ Singleton * Limitation: Single Threaded Design * See: http://www.aristeia.com/Papers/DDJ_Jul_Aug_2004_revised.pdf * For problems associated with locking in multi threaded applications * * Limitation: * If you use this Singleton (A) within a destructor of another Singleton (B) * This Singleton (A) must be fully constructed before the constructor of (B) * is called. */ class MySingleton { private: // Private Constructor MySingleton(); // Stop the compiler generating methods of copy the object MySingleton(MySingleton const& copy); // Not Implemented MySingleton& operator=(MySingleton const& copy); // Not Implemented public: static MySingleton& getInstance() { // The only instance // Guaranteed to be lazy initialized // Guaranteed that it will be destroyed correctly static MySingleton instance; return instance; } }; OK. Lets get some criticism and other implementations together. :-)

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  • Implementation of a general-purpose object structure (property bag)

    - by Thomas Wanner
    We need to implement some general-purpose object structure, much like an object in dynamic languages, that would give us a possibility of creating the whole object graph on-the-fly. This class has to be serializable and somehow user friendly. So far we have made some experiments with class derived from Dictionary<string, object> using the dot notation path to store properties and collections in the object tree. We have also find an article that implements something similar, but it doesn't seem to fit completely into our picture either. Do you know about some good implementations / libraries that deal with a similar problem or do you have any (non-trivial) ideas that could help us with our own implementation ? Also, I probably have to say that we are using .NET 3.5, so we can't take advantage of the new features in .NET 4.0 like dynamic type etc. (as far as I know it's also not possible to use any subset of it in .NET 3.5 solution).

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  • Objective-C partial implementation of classes in separate files

    - by Aran Mulholland
    I am using core data and am generating classes from my data model. I implement custom methods in these classes, however when i regenerate i generate over the top so i end up copying and pasting a bit. What i would like to do is split my implementation files ('.m') so i can have one header file with multiple '.m' files. then i can keep my custom methods in one and not have to worry about erasing them when i regenerate. I use this technique in .NET a lot with its partial keyword. Is there anything similar in objective-C

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  • How to implement a web app with blazeds+java+flex+tomcat?

    - by ARYAD
    Hi, i'm doing a web app in flex blazeds and java, i installed the eclipse plugs for using WTP mixed project, i use the flex's server that uses an emulate of tomcat when i ran my flex service the web app got the datas, everythings is ok. the problem is when i copy the proyect with all files generated by flex in my tomcat or the blazeds's tomcat, it doesn't work, this is becasue i want to implement my app on a server the error is: "(mx.messaging.messages::ErrorMessage)#0 body = (Object)#1 clientId = (null) correlationId = "B425A2A7-7D12-A982-7779-8CCBF669413C" destination = "" extendedData = (null) faultCode = "Client.Error.MessageSend" faultDetail = "Channel.Connect.Failed error NetConnection.Call.Failed: HTTP: Failed: url: 'http://172.16.8.245:8400/IEC-BLAZEDS/messagebroker/amf'" faultString = "Send failed" headers = (Object)#2 messageId = "1CBC6020-0ED8-C4CC-3B77-8CCBF6D6621D" rootCause = (mx.messaging.events::ChannelFaultEvent)#3 bubbles = false cancelable = false channel = (mx.messaging.channels::AMFChannel)#4 authenticated = false channelSets = (Array)#5 [0] (mx.messaging::ChannelSet)#6 authenticated = false channelIds = (Array)#7 [0] "my-amf" channels = (Array)#8 [0] (mx.messaging.channels::AMFChannel)#4 clustered = false connected = false currentChannel = (mx.messaging.channels::AMFChannel)#4 initialDestinationId = (null) messageAgents = (Array)#9 [0] (mx.rpc::AsyncRequest)#10 authenticated = false autoConnect = true channelSet = (mx.messaging::ChannelSet)#6 clientId = (null) connected = false defaultHeaders = (null) destination = "ADEscenario" id = "7D92EDF2-CF62-9545-BA11-8CCBF6691E6B" reconnectAttempts = 0 reconnectInterval = 0 requestTimeout = -1 subtopic = "" connected = false connectTimeout = -1 enableSmallMessages = true endpoint = "http://172.16.8.245:8400/IEC-BLAZEDS/messagebroker/amf" failoverURIs = (Array)#11 id = "my-amf" mpiEnabled = false netConnection = (flash.net::NetConnection)#12 client = (mx.messaging.channels::AMFChannel)#4 connected = false objectEncoding = 3 proxyType = "none" uri = "http://172.16.8.245:8400/IEC-BLAZEDS/messagebroker/amf" piggybackingEnabled = false polling = false pollingEnabled = true pollingInterval = 3000 protocol = "http" reconnecting = false recordMessageSizes = false recordMessageTimes = false requestTimeout = -1 uri = "http://{server.name}:{server.port}/IEC-BLAZEDS/messagebroker/amf" url = "http://{server.name}:{server.port}/IEC-BLAZEDS/messagebroker/amf" useSmallMessages = false channelId = "my-amf" connected = false currentTarget = (mx.messaging.channels::AMFChannel)#4 eventPhase = 2 faultCode = "Channel.Connect.Failed" faultDetail = "NetConnection.Call.Failed: HTTP: Failed: url: 'http://172.16.8.245:8400/IEC-BLAZEDS/messagebroker/amf'" faultString = "error" reconnecting = false rejected = false rootCause = (Object)#13 code = "NetConnection.Call.Failed" description = "HTTP: Failed" details = "http://172.16.8.245:8400/IEC-BLAZEDS/messagebroker/amf" level = "error" target = (mx.messaging.channels::AMFChannel)#4 type = "channelFault" timestamp = 0 timeToLive = 0" i don't know why tomcat doesn't find the class of flex.messaging.endpoints.AMFEndpoint that is used for my-amf 'http://172.16.8.245:8400/IEC-BLAZEDS/messagebroker/amf'. all works well in the emulated server that flex has.

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  • fast algorithm implementation to sort very small set

    - by aaa
    hello. This is the problem I ran into long time ago. I thought I may ask your for your ideas. assume I have very small set of numbers (integers), 4 or 8 elements, that need to be sorted, fast. what would be the best approach/algorithm? my approach was to use the max/min functions. I guess my question pertains more to implementation, rather than type of algorithm. At this point it becomes somewhat hardware dependent , so let us assume Intel 64-bit processor with SSE3 . Thanks

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  • "Method definition not in @implementation context"?

    - by Nathan Hess
    I put this in X-code: - (void)viewDidLoad { [super viewDidLoad]; NSString *path = [[NSBundle mainBundle] pathForResource:@"DrinkArray" ofType:@"plist"]; NSMutableArray* tmpArray = [[NSMutableArray alloc] initWithContentsOfFile:path]; self.drinks = tmpArray; [tmpArray release]; // Uncomment the following line to display an Edit button in the navigation bar for this view controller. // self.navigationItem.rightBarButtonItem = self.editButtonItem; } And it says this on the first line: "Method Definition not an @implementation context" Could anyone help?

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  • How do you implement Software Transactional Memory?

    - by Joseph Garvin
    In terms of actual low level atomic instructions and memory fences (I assume they're used), how do you implement STM? The part that's mysterious to me is that given some arbitrary chunk of code, you need a way to go back afterward and determine if the values used in each step were valid. How do you do that, and how do you do it efficiently? This would also seem to suggest that just like any other 'locking' solution you want to keep your critical sections as small as possible (to decrease the probability of a conflict), am I right? Also, can STM simply detect "another thread entered this area while the computation was executing, therefore the computation is invalid" or can it actually detect whether clobbered values were used (and thus by luck sometimes two threads may execute the same critical section simultaneously without need for rollback)?

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  • Castle Windsor - Resolving a generic implementation to a base type

    - by arootbeer
    I'm trying to use Windsor as a factory to provide specification implementations based on subtypes of XAbstractBase (an abstract message base class in my case). I have code like the following: public abstract class XAbstractBase { } public class YImplementation : XAbstractBase { } public class ZImplementation : XAbstractBase { } public interface ISpecification<T> where T : XAbstractBase { bool PredicateLogic(); } public class DefaultSpecificationImplementation : ISpecification<XAbstractBase> { public bool PredicateLogic() { return true; } } public class SpecificSpecificationImplementation : ISpecification<YImplementation> { public bool PredicateLogic() { /*do real work*/ } } My component registration code looks like this: container.Register( AllTypes.FromAssembly(Assembly.GetExecutingAssembly()) .BasedOn(typeof(ISpecification<>)) .WithService.FirstInterface() ) This works fine when I try to resolve ISpecification<YImplementation>; it correctly resolves SpecificSpecificationImplementation. However, when I try to resolve ISpecification<ZImplementation> Windsor throws an exception: "No component for supporting the service ISpecification'1[ZImplementation, AssemblyInfo...] was found" Does Windsor support resolving generic implementations down to base classes if no more specific implementation is registered?

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  • Possible to Inspect Innards of Core C# Functionality

    - by Nick Babcock
    I was struck today, with the inclination to compare the innards of Buffer.BlockCopy and Array.CopyTo. I am curious to see if Array.CopyTo called Buffer.BlockCopy behind the scenes. There is no practical purpose behind this, I just want to further my understanding of the C# language and how it is implemented. Don't jump the gun and accuse me of micro-optimization, but you can accuse me of being curious! When I ran ILasm on mscorlib.dll I received this for Array.CopyTo .method public hidebysig newslot virtual final instance void CopyTo(class System.Array 'array', int32 index) cil managed { // Code size 0 (0x0) } // end of method Array::CopyTo and this for Buffer.BlockCopy .method public hidebysig static void BlockCopy(class System.Array src, int32 srcOffset, class System.Array dst, int32 dstOffset, int32 count) cil managed internalcall { .custom instance void System.Security.SecuritySafeCriticalAttribute::.ctor() = ( 01 00 00 00 ) } // end of method Buffer::BlockCopy Which, frankly, baffles me. I've never run ILasm on a dll/exe I didn't create. Does this mean that I won't be able to see how these functions are implemented? Searching around only revealed a stackoverflow question, which Marc Gravell said [Buffer.BlockCopy] is basically a wrapper over a raw mem-copy While insightful, it doesn't answer my question if Array.CopyTo calls Buffer.BlockCopy. I'm specifically interested in if I'm able to see how these two functions are implemented, and if I had future questions about the internals of C#, if it is possible for me to investigate it. Or am I out of luck?

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  • Loops in ada and the implementation

    - by maddy
    HI all, Below is a piece of code shown and doubts are regarding the implementation of loops C := character'last; I := 1; K : loop Done := C = character'first; Count2 := I; Exit K when Done; C := character'pred(c); I := I + 1; end loop K; Can anyone please tell me what does 'K' stands for.I guess its not a variable.How does 'K' control the execution of the loop? Thanks Maddy

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  • How do you implement Software Transactional Memory?

    - by Joseph Garvin
    In terms of actual low level atomic instructions and memory fences (I assume they're used), how do you implement STM? The part that's mysterious to me is that given some arbitrary chunk of code, you need a way to go back afterward and determine if the values used in each step were valid. How do you do that, and how do you do it efficiently? This would also seem to suggest that just like any other 'locking' solution you want to keep your critical sections as small as possible (to decrease the probability of a conflict), am I right? Also, can STM simply detect "another thread entered this area while the computation was executing, therefore the computation is invalid" or can it actually detect whether clobbered values were used (and thus by luck sometimes two threads may execute the same critical section simultaneously without need for rollback)?

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  • Good Perlin noise resources/implementation?

    - by Chumpy
    Are there any good resources out there detailing Perlin noise generation? I understand that most languages have noise generating libraries available, but I'm interested in creating my own for fun/experience. I've already looked at this, which seems pretty popular, but it only gives an in-depth explanation of one dimensional noise. Google searches have been relatively unhelpful so far, as most of them focus on applications instead of how to create a generator. Books and/or websites are welcome, even if their focus is not the generation itself so long as it gives a thorough explanation of an implementation, or at least the concepts involved so I can "discover" my own.

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  • MSDN: How can I see what inherits/implements a class/interface?

    - by d03boy
    One thing I really, really miss from Javadoc is the ability to see which classes inherit the class you're looking at. So if you are looking at an abstract class (such as List) then you would be able to see all classes that inherit/implement the class/interface you're looking at. Is this available in the MSDN and I'm just missing it or is this really a missing feature?

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  • Advantages/Disadvantages of different implementations for Comparing Objects using .NET

    - by Kevin Crowell
    This questions involves 2 different implementations of essentially the same code. First, using delegate to create a Comparison method that can be used as a parameter when sorting a collection of objects: class Foo { public static Comparison<Foo> BarComparison = delegate(Foo foo1, Foo foo2) { return foo1.Bar.CompareTo(foo2.Bar); }; } I use the above when I want to have a way of sorting a collection of Foo objects in a different way than my CompareTo function offers. For example: List<Foo> fooList = new List<Foo>(); fooList.Sort(BarComparison); Second, using IComparer: public class BarComparer : IComparer<Foo> { public int Compare(Foo foo1, Foo foo2) { return foo1.Bar.CompareTo(foo2.Bar); } } I use the above when I want to do a binary search for a Foo object in a collection of Foo objects. For example: BarComparer comparer = new BarComparer(); List<Foo> fooList = new List<Foo>(); Foo foo = new Foo(); int index = fooList.BinarySearch(foo, comparer); My questions are: What are the advantages and disadvantages of each of these implementations? What are some more ways to take advantage of each of these implementations? Is there a way to combine these implementations in such a way that I do not need to duplicate the code? Can I achieve both a binary search and an alternative collection sort using only 1 of these implementations?

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  • Where can I find simple beta cdf implementation.

    - by Gacek
    I need to use beta distribution and inverse beta distribution in my project. There is quite good but complicated implementation in GSL, but I don't want to use such a big library only to get one function. I would like to either, implement it on my own or link some simple library. Do you know any sources that could help me? I'm looking for any books/articles about numerical approximation of beta PDF, libraries where it could be implemented. Any other suggestions would be also appreciated. Any programming language, but C++/C# preffered.

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  • How to properly use references with variadic templates

    - by Hippicoder
    I have something like the following code: template<typename T1, typename T2, typename T3> void inc(T1& t1, T2& t2, T3& t3) { ++t1; ++t2; ++t3; } template<typename T1, typename T2> void inc(T1& t1, T2& t2) { ++t1; ++t2; } template<typename T1> void inc(T1& t1) { ++t1; } I'd like to reimplement it using the proposed variadic templates from the upcoming standard. However all the examples I've seen so far online seem to be printf like examples, the difference here seems to be the use of references. I've come up with the following: template<typename T> void inc(T&& t) { ++t; } template<typename T,typename ... Args> void inc(T&& t, Args&& ... args) { ++t inc(args...); } What I'd like to know is: Should I be using r-values instead of references? Possible hints or clues as to how to accomplish what I want correctly. What guarantees does the new proposed standard provide wrt the issue of the recursive function calls, is there some indication that the above variadic version will be as optimal as the original? (should I add inline or some-such?)

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  • What is a good Javascript RDFa parser implementation?

    - by tremoloqui
    I am looking to implement a client side RDFa based formatting for a web application. This would be similar to Mark Birbeck's ubiquity-rdfa project. Mark's project looks fantastic but it has at least two drawbacks: It is slow. Adding RDFa formatting to a simple page causes a noticeable delay in page loading. It is complex. The ubiquity-rdfa project makes use of the w3c fresnel specification which is complex way to add simple annotations to client markup. I am looking for a lighter weight way of adding annotations through client code and I don't mind doing some work to get it. What I would like is a fast and reliable Javascript RDFa parser. Some implementations that I have found include: W3C RDFa bookmarklet parser Elias Torres RDFa extractor I am interested to know if you would recommend one of these, or another, RDFa Javascript implementation. Thanks!

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  • How to efficiently SELECT rows from database table based on selected set of values

    - by Chau Chee Yang
    I have a transaction table of 1 million rows. The table has a field name "Code" to keep customer's ID. There are about 10,000 different customer code. I have an GUI interface allow user to render a report from transaction table. User may select arbitrary number of customers for rendering. I use IN operator first and it works for few customers: SELECT * FROM TRANS_TABLE WHERE CODE IN ('...', '...', '...') I quickly run into problem if I select few thousand customers. There is limitation using IN operator. An alternate way is create a temporary table with only one field of CODE, and inject selected customer codes into the temporary table using INSERT statement. I may then using SELECT A.* FROM TRANS_TABLE A INNER JOIN TEMP B ON (A.CODE=B.CODE) This works nice for huge selection. However, there is performance overhead for temporary table creation, INSERT injection and dropping of temporary table. Do you aware of better solution to handle this situation?

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  • How do you implement an MPVolumeView?

    - by Emil
    Hey! I want the user to be able to change the system volume with a slider, and I realized the only way to do this is with an MPVolumeView. But I can't find any example code for it, and every method I try to implement won't show up. So what is the easiest and correct, working way of implementing a MPVolumeView?

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