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  • Handling incremental Data Modeling Changes in Functional Programming

    - by Adam Gent
    Most of the problems I have to solve in my job as a developer have to do with data modeling. For example in a OOP Web Application world I often have to change the data properties that are in a object to meet new requirements. If I'm lucky I don't even need to programmatically add new "behavior" code (functions,methods). Instead I can declarative add validation and even UI options by annotating the property (Java). In Functional Programming it seems that adding new data properties requires lots of code changes because of pattern matching and data constructors (Haskell, ML). How do I minimize this problem? This seems to be a recognized problem as Xavier Leroy states nicely on page 24 of "Objects and Classes vs. Modules" - To summarize for those that don't have a PostScript viewer it basically says FP languages are better than OOP languages for adding new behavior over data objects but OOP languages are better for adding new data objects/properties. Are there any design pattern used in FP languages to help mitigate this problem? I have read Phillip Wadler's recommendation of using Monads to help this modularity problem but I'm not sure I understand how?

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  • MySQL-python 1.2.3 and OS X 10.5: 64- or 32-bit?

    - by Dave Everitt
    I've been happily using Django and MySQL in development on an existing machine running OS X 10.4 Tiger, and have set up a similar environment in 10.5 Leopard on a new 64-bit MacBook, with a working MySQL and Python 2.6.4. However, now I want them to communicate, easy_install MySQL-python gave ld warnings that the file is not of the required architecture, which led me to test my Python 2.4.6 install (from the Mac OS X disc image): >>> import sys >>> sys.maxint 2147483647 Ah. So my Python install appears to be 32-bit and (I think?) won't install MySQL-python for my 64-bit MySQL. There are lots of hacks out there for MySQL-python on OS X (mostly 1.2.2), but - after hours of reading - I'm pretty sure they won't fix this architecture mismatch. So I'm stuck because I can't decide whether to: give up, remove the 64-bit MySQL install (thorough methods, please?) and use the 32-bit MySQL disc image instead; re-install Python in 64-bit mode from the tarball, --with-universal archs-64-bit and --enable-universalsdk= as detailed in Python.org's 2.6 news. So my questions for anyone who has encountered this issue are: Is installing 64-bit Python on OS X 10.5 worth bothering with? If so, (naive, lazy question!) how are the two required arguments combined? If I just skip along in 32-bit (as on my working setup) what am I missing? I'm after a hassle-free install that's easy to reproduce on other machines (possible student use) so I'd really welcome your opinions, please!

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  • Autorotation and multiple view controllers

    - by alku83
    I'm creating an iPad application which should only work in portrait and portait upsidedown modes. For performance reasons in my applicationDidFinishLaunching method I'm creating several viewControllers, and adding them to my main window as subviews. I then hide the ones I don't want to see straight away. There is no tab bar or navigation controller. My problem is that only the first viewController seems to be receiving the rotate calls. I have verified this by swapping around the order in which I add the subviews to the main window and NSLog's. Is there some way I can force all the controllers to receive the calls? Some of my views are designed to lay over the top of another view, but this behind view will not always be the same one - so it seems to make sense to have the overlay view in a separate view controller. Am I doing something fundamentally wrong, and that's why it's not behaving as I would expect? EDIT: The accepted answer for this question seems to indicate the exact problem I'm facing: http://stackoverflow.com/questions/548142/uiviewcontroller-rotate-methods

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  • Interface and partial classes

    - by Tomek Tarczynski
    According to rule SA1201 in StyleCop elements in class must appear in correct order. The order is following: Fields Constructors Finalizers (Destructors) Delegates Events Enums Interfaces Properties Indexers Methods Structs Classes Everything is ok, except of Interfaces part, because Interface can contain mehtods, events, properties etc... If we want to be strict about this rule then we won't have all members of Interface in one place which is often very useful. According to StyleCop help this problem can be solved by spliting class into partial classes. Example: /// <summary> /// Represents a customer of the system. /// </summary> public partial class Customer { // Contains the main functionality of the class. } /// <content> /// Implements the ICollection class. /// </content> public partial class Customer : ICollection { public int Count { get { return this.count; } } public bool IsSynchronized { get { return false; } } public object SyncRoot { get { return null; } } public void CopyTo(Array array, int index) { throw new NotImplementedException(); } } Are there any other good solutions to this problem?

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  • How does one convert from a Java resultset to ColdFusion query in Railo?

    - by Shawn Grigson
    The following works fine in CFMX 7 and CF8, and I'd assume CF9 as well: <!--- 'conn' is a JDBC connection ---> <cfset stat = conn.createStatement() /> <cfset rs = stat.executeQuery(trim(arguments.sql)) /> <!--- convert this Java resultset to a CF query recordset ---> <cfset queryTable = CreateObject("java", "coldfusion.sql.QueryTable")> <cfset queryTable.init(rs) > <cfset query = queryTable.FirstTable() /> This creates a statement using a JDBC driver, executes a query against it, putting it into a java resultset, and then coldfusion.sql.QueryTable is instantiated, passed the Java resulset object, and then queryTable.FirstTable() is called, which returns an actual coldfusion resultset (for cfloop and the like). The problem comes with a difference in Railo's implementation. Running this code in Railo returns the following error: No matching Constructor for coldfusion.sql.QueryTable(org.sqlite.RS) found. I've dumped the Railo java object, and don't see init() among the methods. Am I missing something simple? I'd love to get this working in Railo as well. Please note: I am doing a DSN-less connection to a SQLite db. I understand how to set up a CF datasource. My only hiccup at this point is doing the translation from a Java result set to a Railo query.

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  • what is wrong in java AES decrypt function?

    - by rohit
    hi, i modified the code available on http://java.sun.com/developer/technicalArticles/Security/AES/AES_v1.html and made encrypt and decrypt methods in program. but i am getting BadpaddingException.. also the function is returning null.. why it is happing?? whats going wrong? please help me.. these are variables i am using: kgen = KeyGenerator.getInstance("AES"); kgen.init(128); raw = new byte[]{(byte)0x00,(byte)0x11,(byte)0x22,(byte)0x33,(byte)0x44,(byte)0x55,(byte)0x66,(byte)0x77,(byte)0x88,(byte)0x99,(byte)0xaa,(byte)0xbb,(byte)0xcc,(byte)0xdd,(byte)0xee,(byte)0xff}; skeySpec = new SecretKeySpec(raw, "AES"); cipher = Cipher.getInstance("AES"); plainText=null; cipherText=null; following is decrypt function.. public String decrypt(String cipherText) { try { cipher.init(Cipher.DECRYPT_MODE, skeySpec); byte[] original = cipher.doFinal(cipherText.getBytes()); plainText = new String(original); } catch(BadPaddingException e) { } return plainText; }

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  • MongoDB architectural question

    - by pex
    I have to store 4 Models. Let's say a Post that has many and belongs to many Categories. Category on the other hand has many Qualities. At the moment I'm of the opinion, that Post and Categories are Documents. Qualities becomes an EmbeddedDocument of Categories. We're coming to the root problem: There are a lot of Votes on Qualities that belong to a Post. I thought about embed Votes in Post and give it a quality_id. I am really expecting a lot of Votes and there has to be a possibility to filter them (e.g by Username / Usergroup / Date voted). I worked with MongoMapper and I think the missing existence of find methods for EmbeddedDocuments could become a killer. On the other hand I'm wondering about performance issues. What if I want to provide a Post without all the Votes, but only a few. Or, what if I define an own Document for Votes and have tons of Vote-Documents? Wouldn't that become a performance killer?

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  • Why use Django on Google App Engine?

    - by Travis Bradshaw
    When researching Google App Engine (GAE), it's clear that using Django is wildly popular for developing in Python on GAE. I've been scouring the web to find information on the costs and benefits of using Django, to find out why it's so popular. While I've been able to find a wide variety of sources on how to run Django on GAE and the various methods of doing so, I haven't found any comparative analysis on why Django is preferable to using the webapp framework provided by Google. To be clear, it's immediately apparent why using Django on GAE is useful for developers with an existing skillset in Django (a majority of Python web developers, no doubt) or existing code in Django (where using GAE is more of a porting exercise). My team, however, is evaluating GAE for use on an all-new project and our existing experience is with TurboGears, not Django. It's been quite difficult to determine why Django is beneficial to a development team when the BigTable libraries have replaced Django's ORM, sessions and authentication are necessarily changed, and Django's templating (if desirable) is available without using the entire Django stack. Finally, it's clear that using Django does have the advantage of providing an "exit strategy" if we later wanted to move away from GAE and need a platform to target for the exodus. I'd be extremely appreciative for help in pointing out why using Django is better than using webapp on GAE. I'm also completely inexperienced with Django, so elaboration on smaller features and/or conveniences that work on GAE are also valuable to me. Thanks in advance for your time!

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  • CPU friendly infinite loop

    - by Adi
    Writing an infinite loop is simple: while(true){ //add whatever break condition here } But this will trash the CPU performance. This execution thread will take as much as possible from CPU's power. What is the best way to lower the impact on CPU? Adding some Thread.Sleep(n) should do the trick, but setting a high timeout value for Sleep() method may indicate an unresponsive application to the operating system. Let's say I need to perform a task each minute or so in a console app. I need to keep Main() running in an "infinite loop" while a timer will fire the event that will do the job. I would like to keep Main() with the lowest impact on CPU. What methods do you suggest. Sleep() can be ok, but as I already mentioned, this might indicate an unresponsive thread to the operating system. LATER EDIT: I want to explain better what I am looking for: I need a console app not Windows service. Console apps can simulate the Windows services on Windows Mobile 6.x systems with Compact Framework. I need a way to keep the app alive as long as the Windows Mobile device is running. We all know that the console app runs as long as its static Main() function runs, so I need a way to prevent Main() function exit. In special situations (like: updating the app), I need to request the app to stop, so I need to infinitely loop and test for some exit condition. For example, this is why Console.ReadLine() is no use for me. There is no exit condition check. Regarding the above, I still want Main() function as resource friendly as possible. Let asside the fingerprint of the function that checks for the exit condition.

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  • How is it that json serialization is so much faster than yaml serialization in python?

    - by guidoism
    I have code that relies heavily on yaml for cross-language serialization and while working on speeding some stuff up I noticed that yaml was insanely slow compared to other serialization methods (e.g., pickle, json). So what really blows my mind is that json is so much faster that yaml when the output is nearly identical. >>> import yaml, cjson; d={'foo': {'bar': 1}} >>> yaml.dump(d, Dumper=yaml.SafeDumper) 'foo: {bar: 1}\n' >>> cjson.encode(d) '{"foo": {"bar": 1}}' >>> import yaml, cjson; >>> timeit("yaml.dump(d, Dumper=yaml.SafeDumper)", setup="import yaml; d={'foo': {'bar': 1}}", number=10000) 44.506911039352417 >>> timeit("yaml.dump(d, Dumper=yaml.CSafeDumper)", setup="import yaml; d={'foo': {'bar': 1}}", number=10000) 16.852826118469238 >>> timeit("cjson.encode(d)", setup="import cjson; d={'foo': {'bar': 1}}", number=10000) 0.073784112930297852 PyYaml's CSafeDumper and cjson are both written in C so it's not like this is a C vs Python speed issue. I've even added some random data to it to see if cjson is doing any caching, but it's still way faster than PyYaml. I realize that yaml is a superset of json, but how could the yaml serializer be 2 orders of magnitude slower with such simple input?

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  • ASP.NET 2.0 and COM Port Communication

    - by theaviator
    ASP.NET 2.0 and COM Port Communication Hello Guys, I have a managed DLL which communicates with the devices attached on COM/Serial ports. The desktop Winforms application sends requests on ports and receives/stores data in memory. In Winforms app I have added a reference to DLL and I am using the methods. This works well. Now, there is a situation where I need to show this data from serial/com port on a web-page. And also users should be able to send requests to the ports using this DLL. I have made a web app in ASP.NET (2.0). Added a reference to the DLL. I am able to use this DLL, the DLL communicates on the COM upon button click on web-page and also the response is shown on web page. However I am not happy with the approach and strongly feel that this is a bad approach. Also the development server crashes after 3 -4 requests. What is the best approach in this scenario. If I use a windows service then how would my ASP.net app will communicate with the Weindows service. Or can this be easily done using WCF. I have not used WCF any time nor any of .net remoting technique. Please suggest me the best architecture in this scenario. Thank you

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  • NHibernate.MappingException - Troubles Shooting Checklist (no persister for)

    - by Berryl
    Here's a starter list: 1) if hbm is hand generated, is it an embedded resource? 2) if using FNH, does it pass a PerssistenceSpecification test? 3) if not using FNH, can you save and then load the persisted class? 4) more? I'm sure many of you have gotten this one at one point or another. But have you ever gotten it when you knew your mapping was set up correctly? I started getting this exception after I started using a new repository design, but only in one scenario! PersistenceSpecification tests pass, as do all repository methods (using SQLite). The scenario that leads to the exception is when legacy projects from a different db are converted to green field system. The legacy system is from a different database and has it's own session factory, which should be irrelevant because the error comes after previously unconverted Projects are retrieved and in memory. As the routine tries to save these unconverted Projects into the new database, the exception is thrown, full stack trace below. Any ideas on how to build up the trouble shooting check list and solves this problem? Cheers, Berryl === the Exception trace ===== failed: NHibernate.MappingException : No persister for: Smack.ConstructionAdmin.Domain.Model.Projects.Project at NHibernate.Impl.SessionFactoryImpl.GetEntityPersister(String entityName) at NHibernate.Impl.SessionImpl.GetEntityPersister(String entityName, Object obj) at NHibernate.Engine.ForeignKeys.IsTransient(String entityName, Object entity, Nullable`1 assumed, ISessionImplementor session) at NHibernate.Event.Default.AbstractSaveEventListener.GetEntityState(Object entity, String entityName, EntityEntry entry, ISessionImplementor source) at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.PerformSaveOrUpdate(SaveOrUpdateEvent event) at NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.OnSaveOrUpdate(SaveOrUpdateEvent event) at NHibernate.Impl.SessionImpl.FireSaveOrUpdate(SaveOrUpdateEvent event) at NHibernate.Impl.SessionImpl.SaveOrUpdate(Object obj) NHibernate\Repository\FabioNHibRepository.cs(46,0): at Smack.Core.Data.NHibernate.Repository.FabioNHibRepository`1.Add(T item) LegacyConversion\LegacyBatchUpdater.cs(20,0): at Smack.ConstructionAdmin.Data.LegacyConversion.LegacyBatchUpdater.ConvertOpenLegacyProjects(ILegacyProjectDao legacyProjectDao, IProjectRepository greenProjectRepository) Data\Brownfield\ProjectBatchUpdate_SQLiteTests.cs(19,0): at Smack.ConstructionAdmin.Tests.Data.Brownfield.ProjectBatchUpdate_SQLiteTests.Test()

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  • Send parameters to a web service.

    - by Alejandra Meraz
    Before I start: I'm programming for Iphone, using objective C. I have already implemented a call to a web service function using NSURLRequest and NSURLConnection. The function then returns a XML with the info I need. The code is as follows: NSURL *url = [NSURL URLWithString:@"http://myWebService/function"]; NSMutableURLRequest theRequest = [[NSMutableURLRequest alloc] initWithURL:url]; NSURLConnection theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; i also implemented the methods didRecieveResponse didRecieveAuthenticationChallenge didRecievedData didFailWithError connectionDidFinishLoading. And it works perfectly. Now I need to send 2 parameters to the function: "location" and "module". I tried using the following modification: NSMutableURLRequest theRequest = [[NSMutableURLRequest alloc] initWithURL:url]; [theRequest setValue:@"USA" forHTTPHeaderField:@"location"]; [theRequest setValue:@"DEVELOPMENT" forHTTPHeaderField:@"module"]; NSURLConnection theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; But it doesn't seem to work. I'm doing something wrong? is there a way to know if I'm using the wrong names for the parameters (as maybe it is "Location" or "LOCATION" or it doesn't matter?)? or a way to know which parameters is the function waiting for... Extra info: I don't have access to the source of the web service so I can't modify it. But I can access the WSDL. The person who made the function say is all there... but I can't make any sense of it .< Any help would be appreciated. :)

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  • How to mimic built-in .NET serialization idioms?

    - by Matt Enright
    I have a library (written in C#) for which I need to read/write representations of my objects to disk (or to any Stream) in a particular binary format (to ensure compatibility with C/Java library implementations). The format requires a fair amount of bit-packing and some DEFLATE'd bytestreams. I would like my library, however, to be as idiomatic .NET as possible, however, and so would like to provide an API as close as possible to the normal binary serialization process. I'm aware of the ability to implement the IFormatter interface, but being that I really am unable to reuse any part of the built-in serialization stack, is it worth doing this, or will it just bring unnecessary overhead. In other words: Implement IFormatter and co. OR Just provide "Serialize"/"Deserialize" methods that act on a Stream? A good point brought up below about needing the serialization semantics for any case involving Remoting. In a case where using MarshalByRef objects is feasible, I'm pretty sure that this won't be an issue, so leaving that aside are there any benefits or drawbacks to using the ISerializable/IFormatter versus a custom stack (or, is my understanding remoting incorrectly)?

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  • Django: how to cleanup form fields and avoid code duplication

    - by Alexander Konstantinov
    Quite often I need to filter some form data before using it (saving to database etc.) Let's say I want to strip whitespaces and replace repeating whitespaces with a single one in most of the text fields, in many forms. It's not difficult to do this using clean_<fieldname> methods: # Simplified model with two text fields class MyModel(models.Model): title = models.CharField() description = models.CharField() # Model-based form class MyForm(forms.ModelForm): class Meta: model = MyModel def clean_title(self): title = self.cleaned_data['title'] return re.sub(r'\s{2,}', ' ', title.strip()) def clean_description(self): description = self.cleaned_data['description'] return re.sub(r'\s{2,}', ' ', description.strip()) It does exactly what I need, and has a nice side effect which I like: if user enters only whitespaces, the field will be considered empty and therefore invalid (if it is required) and I don't even have to throw a ValidationError. The obvious problem here is code duplication. Even if I'll create some function for that, say my_text_filter, I'll have to call it for every text field in all my forms: from myproject.filters import my_text_filter class MyForm(forms.ModelForm): class Meta: model = MyModel def clean_title(self): return my_text_filter(self.cleaned_data['title']) def clean_description(self): return my_text_filter(self.cleaned_data['description']) The question: is there any standard and simple way in Django (I use version 1.2 if that matters) to do this (like, for example, by adding property validators = {'title': my_text_filter, 'description': my_text_filter} to MyModel), or at least some more or less standard workaround? I've read about form validation and validators in the documentation, but couldn't find what I need there.

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  • Getting the first result from a LINQ query - why does ElementAt<T>(0) fails when First<T>() succeeds

    - by Mr Roys
    I have a method AddStudent() which looks for a student with the same name and returns an existing student from the database if there is a student with the same name, otherwise it creates a new student and adds it to the database. I'm curious why se = students.First<StudentEntity>(); succeeds when se = students.ElementAt<StudentEntity>(0); fails when I try to get the first result from the LINQ query. Aren't the two methods the same? The full code for the method is shown below. public Student AddStudent(string name) { using (SchoolEntities db = new SchoolEntities()) { // find student with same name via LINQ var students = from s in db.StudentEntitySet where s.name == name select s; StudentEntity se = default(StudentEntity); // if student with the same name is already present, return // that student if (students.Count<StudentEntity>() > 0) { // if i use ElementAt, if fails with a "LINQ to Entities does not // recognize the method 'StudentEntity ElementAt[StudentEntity] // (System.Linq.IQueryable`1[StudentEntity], Int32)' method, // and this method cannot be translated into a store expression.", // but not when I use First. Why? // se = students.ElementAt<StudentEntity>(0); se = students.First<StudentEntity>(); } else { // passing 0 for first parameter (id) since it's represented by // a BigInt IDENTITY field in the database so any value // doesn't matter. se = StudentEntity.CreateStudentEntity(0, name); db.AddToStudentEntitySet(se); db.SaveChanges(); } // create a Student object from the Entity object return new Student(se); } } Thanks!

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  • PHPUnit and autoloaders: Determining whether code is running in test-scope?

    - by pinkgothic
    Premise I know that writing code to act differently when a test is run is hilariously bad practise, but I may've actually come across a scenario in which it may be necessary. Specifically, I'm trying to test a very specific wrapper for HTML Purifier in the Zend framework - a View Helper, to be exact. The HTML Purifier autoloader is necessary because it uses a different logic to the autoloaders we otherwise have. Problem require()-ing the autoloader at the top of my View Helper class, gives me the following in test-scope: HTML Purifier autoloader registrar is not compatible with non-static object methods due to PHP Bug #44144; Please do not use HTMLPurifier.autoload.php (or any file that includes this file); instead, place the code: spl_autoload_register(array('HTMLPurifier_Bootstrap', 'autoload')) after your own autoloaders. Replacing the require() with spl_autoload_register(array('HTMLPurifier_Bootstrap', 'autoload')) as advertised means the test runs fine, but the View Helper dies a terrible death claiming: Zend_Log[3707]: ErrorController caught LogicException "Passed array does not specify an existing static method (class 'HTMLPurifier_Bootstrap' not found)" (Our test folder structure is slightly different to our Zend folder structure by necessity.) Question(s) After tinkering with it, I'm thinking I'll need to pick an autoloader-loading depending on whether things are in the test scope or not. Do I have another option to include HTMLPurifier's autoloading routine in both cases that I'm not seeing due to tunnel vision? If not, do I have to find a means to differentiate between test-environment and production-environment this with my own code (e.g. APPLICATION_ENV) - or does PHPUnit support this godawful hackery of mine natively by setting a constant that I could check whether its been defined(), or similar shenanigans? (My Google-fu here is weak! I'm probably just doing it wrong.)

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  • Spring factory beans not always initialised before being used.

    - by aos
    Hi, I am using spring to initialise my beans. I have configured a bean which I intend to use as a factory bean. <bean id="jsServicesFactory" class="x.y.z.JSServicesFactory" /> It is a very basic class - which has 4 getter methods. One example is public final PortletRegistry getPortletRegistry() { PortletRegistry registry = (PortletRegistry) JetspeedPortletServices .getSingleton().getService("PortletRegistryComponent"); return registry; } I have a 2nd bean which uses this factory beans to set one of its properties <bean id="batchManagerService" class="x.y.z.BatchManagerService"> ... <property name="portletRegistry"> <bean factory-bean="jsServicesFactory" factory-method="getPortletRegistry" /> </property> ... When I start my server in RAD, this all works perfectly. However when I deploy to Linux I sometimes get the following error ERROR org.springframework.web.context.ContextLoader - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'batchManagerService' defined in ServletContext resource [/WEB-INF/context/root/batchManagerContext.xml]: Cannot create inner bean 'jsServicesFactory$created#70be70be' while setting bean property 'portletRegistry'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jsServicesFactory$created#70be70be' defined in ServletContext resource [/WEB-INF/context/root/batchManagerContext.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanDefinitionStoreException: Factory method [public final org.apache.jetspeed.components.portletregistry.PortletRegistry x.y.z.JSServicesFactory.getPortletRegistry()] threw exception; nested exception is java.lang.NullPointerException I have tried adding depends-on="jsServicesFactory" to my bean batchManagerService but it didn't work. Any ideas? Thanks

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  • Calling MethodBase's Invoke on a constructor (reflection)

    - by Alix
    Hi everyone. First of all, sorry if this has been asked before. I've done a pretty comprehensive search and found nothing quite like it, but I may have missed something. And now to the question: I'm trying to invoke a constructor through reflection, with no luck. Basically, I have an object that I want to clone, so I look up the copy constructor for its type and then want to invoke it. Here's what I have: public Object clone(Object toClone) { MethodBase copyConstructor = type.GetConstructor( new Type[] { toClone.GetType() }); return method.Invoke(toClone, new object[] { toClone }); //<-- doesn't work } I call the above method like so: List list = new List(new int[] { 0, 1, 2 }); List clone = (List) clone(list); Now, notice the invoke method I'm using is MethodBase's invoke. ConstructorInfo provides an invoke method that does work if invoked like this: return ((ConstructorInfo) method).Invoke(new object[] { toClone }); However, I want to use MethodBase's method, because in reality instead of looking up the copy constructor every time I will store it in a dictionary, and the dictionary contains both methods and constructors, so it's a Dictionary<MethodBase>, not Dictionary<ConstructorInfo>. I could of course cast to ConstructorInfo as I do above, but I'd rather avoid the casting and use the MethodBase method directly. I just can't figure out the right parameters. Any help? Thanks so much.

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  • DataTable vs. Collection in .Net

    - by B Pete
    I am writing a program that needs to read a set of records that describe the register map of a device I need to communicate with. Each record will have a handfull of fields that describe the properties of each register. I don't really need to edit or modify the data in my VB or C# program, though I would like to be able to display the data on a grid. I would like to store the data in a CSV file, or perhaps an XML file. I need to enable users to edit the data off-line, preferably in excel. I am considering using a DataTable or a Collection of "Register" objects (which I would define). I prototyped a DataTable, and found I can read/write XML easily using the built in methods and I can easily bind to a DataGridView. I was not able to find a way to retreive info on a single register without using a query that returns a collection of rows, even though I defined a unique primaty key column. The syntax to get a value from a column is also complex, though I could be missing something on both counts. I'm tempted to use a collection of "Register" objects that I can access via a unique key. It would be a little more coding up front, but seems like a cleaner solution overall. I should still be able to use LINQ to dataset to query subsets of registers when I need them, but would also be able to grab a single field using a the key value, something like this: Registers(keyValue).fieldName). Which would be a cleaner approach to the problem? Is there a way to read/write XML into a Collection without needing custom code? Could this be accomplished using String for a key?

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  • QT: custom widget in QScrollArea

    - by slimscsi
    I am attempting to create a custom widget. My Widget renders itself unless it is inside a scroll area. The code below works. If I change the if(0) to an if(1) inside the MainWindow constructor, it will not render the "Hello World" string. I assume that I must (re)implement some additional methods, but so far I have not been able to find the correct ones with trial and error. // hellowidget.h #ifndef HELLOWIDGET_H #define HELLOWIDGET_H #include <QtGui> class HelloWidget : public QWidget { Q_OBJECT public: HelloWidget(QWidget *parent = 0); void paintEvent(QPaintEvent *event); }; #endif // HELLOWIDGET_H // hellowidget.cpp #include "hellowidget.h" HelloWidget::HelloWidget(QWidget *parent) : QWidget(parent) { } void HelloWidget::paintEvent(QPaintEvent *event) { QPainter painter(this); painter.drawText(rect(), Qt::AlignCenter, "Hello World"); } // mainwindow.h #ifndef MAINWINDOW_H #define MAINWINDOW_H #include <QtGui> class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = 0); ~MainWindow(); private: }; #endif // MAINWINDOW_H // mainwindow.cpp #include "mainwindow.h" #include "hellowidget.h" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { HelloWidget *hello = new HelloWidget; QWidget *central = hello; if( 0 ) { QScrollArea *scroll = new QScrollArea ; scroll->setWidget(hello); central = scroll; } setCentralWidget( central ); } MainWindow::~MainWindow() { } // main.cpp #include <QtGui/QApplication> #include "mainwindow.h" int main(int argc, char *argv[]) { QApplication a(argc, argv); MainWindow w; w.show(); return a.exec(); }

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  • Print a string that contains a certain pattern in Java

    - by jjpotter
    I am trying to find a regular expression within a line of a .csv file, so I can eventually save all the matches to another file, and lose all the other junk. So a line in my file might look like: MachineName,User,IP,VariableData,Location The VariableData is what I want to match, and if there's a match, print the line. I am using a pattern for this because I only want 3 out of 10 of variations of VariableData, and out of those 3, they are numbered differently(example, "pc104, pccrt102, pccart65"). I am trying to do this using the Scanner Class and keeping it simple as possible so I can understand it. Here is where I was heading with this...(the pattern isn't complete, just have it like this for testing). import java.io.File; import java.util.Scanner; import java.util.regex.Pattern; public class pcv { public static void main(String[] args) { File myFile = new File("c:\\temp\\report.csv"); Pattern myPat = Pattern.compile("pc"); try{ Scanner myScan = new Scanner(myFile); while(myScan.hasNext()){ if(myScan.hasNext(myPat)){ System.out.println("Test"); } } }catch(Exception e){ } } } This code loops, im guessing the .hasNext() methods are resetting themselves. I've played around with the Matcher class a little bit, but only found a way to match the expression but not get the whole line. My other throught was maybe somehow count the line that contains the pattern, then go back and print the line that corresponds to the counts.

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  • Is it possible to update old database from dbml file ? (C#, .Net 4, Linq, SQL Server)

    - by Emil
    Hi all, I began recently a new job, a very interesting project (C#,.Net 4, Linq, VS 2010 and SQL Server). And immediately I got a very exciting challenge: I must implement either a new tool or integrate the logic when program start, or whatever, but what must happen is the following: the customers have previous application and database (full with their specific data). Now a new version is ready and the customer gets the update. In the mean time we made some modification on DB (new table, columns, maybe an old column deleted, or whatever). I’m pretty new in Linq and also SQL databases and my first solution can be: I check the applications/databases version and implement all the changes step by step comparing all tables, columns, keys, constrains, etc. (all this new information I have in my dbml and the old I asked from the existing DB). And I’ll do this each time the version changed. But somehow I feel, this is NOT a smart solution so I look for a general solution of this problem. Is there a way to update customers DB from the dbml file? To create a new one is not a problem (CreateDatabase with DataContext), is there any update/alter database methods? I guess I’m not the only one who search for such a solution (I found nothing in internet – or I looked for bad keywords). How did you solve this problem? I look also for an external tool, but first for a solution with C#, Linq or something similar. For any idea thank you in advance! Best regards, Emil

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  • Login Website, curious Cookie Problem

    - by Collin Peters
    Hello, Language: C# Development Environment: Visual Studio 2008 Sorry if the english is not perfect. I want to login to a Website and get some Data from there. My Problem is that the Cookies does not work. Everytime the Website says that I should activate Cookies but i activated the Cookies trough a Cookiecontainer. I sniffed the traffic serveral times for the login progress and I see no problem there. I tried different methods to login and I have searched if someone else have this Problem but no results... Login Page is: "www.uploaded.to", Here is my Code to Login in Short Form: private void login() { //Global CookieContainer for all the Cookies CookieContainer _cookieContainer = new CookieContainer(); //First Login to the Website HttpWebRequest _request1 = (HttpWebRequest)WebRequest.Create("http://uploaded.to/login"); _request1.Method = "POST"; _request1.CookieContainer = _cookieContainer; string _postData = "email=XXXXX&password=XXXXX"; byte[] _byteArray = Encoding.UTF8.GetBytes(_postData); Stream _reqStream = _request1.GetRequestStream(); _reqStream.Write(_byteArray, 0, _byteArray.Length); _reqStream.Close(); HttpWebResponse _response1 = (HttpWebResponse)_request1.GetResponse(); _response1.Close(); //######################## //Follow the Link from Request1 HttpWebRequest _request2 = (HttpWebRequest)WebRequest.Create("http://uploaded.to/login?coo=1"); _request2.Method = "GET"; _request2.CookieContainer = _cookieContainer; HttpWebResponse _response2 = (HttpWebResponse)_request2.GetResponse(); _response2.Close(); //####################### //Get the Data from the Page after Login HttpWebRequest _request3 = (HttpWebRequest)WebRequest.Create("http://uploaded.to/home"); _request3.Method = "GET"; _request3.CookieContainer = _cookieContainer; HttpWebResponse _response3 = (HttpWebResponse)_request3.GetResponse(); _response3.Close(); } I'm stuck at this problem since many weeks and i found no solution that works, please help...

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  • CGContext problems

    - by Peyman
    Hi I have a CALayer tree hierarchy A B C D where A is the view's root layer (and I create and add B,C and D layers. I am using the same delegate method `- (void) drawLayer:(CALayer *) theLayer inContext:(CGContextRef)context to provide content to each of these layers (implemented through a switch statement in the above method). At initiation A's content is drawn (A.contents) sequentially through these methods `- (void) drawLayer:(CALayer *) theLayer inContext:(CGContextRef)context -(void) drawCircle:(CALayer *) theLayer inContext:(CGContextRef)context where drawCircle does CGContextSaveGState(context); / draws circle and other paths here / CGContextRestoreGState(context); CGImageRef contentImage = CGBitmapContextCreateImage(context); theLayer.contents = (id) contentImage; CGImageRelease(contentImage); (i.e I save the Context, do the drawing, restore the context, make a bitmap of the context, update the layer's contents, in this case A's, then release the contentimage). When the user then clicks somewhere in the circle at touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event delegate method I then try to paint the content of B by (still in touchesEnded:) CGContextRef context = UIGraphicsGetCurrentContext(); [self drawLayer:self.B inContext:context]; [self.B setNeedsDisplay]; the setNeedsDisplay call the delegate - drawLayer:(CALayer *) theLayer inContext:(CGContextRef)context again but this time the switch statement (using a layer flag) calls [self drawCircle:theLayer inContext:context]; with color red. The problem I am facing is that when -drawCircle: inContext: is called I get a long list of CGContext errors, starting with <Error>: CGContextSaveGState: invalid context and ending with CGBitmapContextCreateImage: invalid context I played around with making context the view's ivar and it worked so i am sure the context is the problem but I don't know what. I've tried CGContextFlush but it didn't help. Any help would be appreciated thank you

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