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  • JAVA: how to load database url from web.xml?

    - by user357255
    I'm using persistence API and want to load jdbc URL from web.xml. URL should be a context parameter of servlet. I can't find how to construct EntityManagerFactory not using persistence.xml. May be I should create PersistenceUnit in servlet and set some parameters? Can you give me some short example? Thank you

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  • .NET 4.0 Dynamic object used statically?

    - by Kevin Won
    I've gotten quite sick of XML configuration files in .NET and want to replace them with a format that is more sane. Therefore, I'm writing a config file parser for C# applications that will take a custom config file format, parse it, and create a Python source string that I can then execute in C# and use as a static object (yes that's right--I want a static (not the static type dyanamic) object in the end). Here's an example of what my config file looks like: // my custom config file format GlobalName: ExampleApp Properties { ExternalServiceTimeout: "120" } Python { // this allows for straight python code to be added to handle custom config def MyCustomPython: return "cool" } Using ANTLR I've created a Lexer/Parser that will convert this format to a Python script. So assume I have that all right and can take the .config above and run my Lexer/Parser on it to get a Python script out the back (this has the added benefit of giving me a validation tool for my config). By running the resultant script in C# // simplified example of getting the dynamic python object in C# // (not how I really do it) ScriptRuntime py = Python.CreateRuntime(); dynamic conf = py.UseFile("conftest.py"); dynamic t = conf.GetConfTest("test"); I can get a dynamic object that has my configuration settings. I can now get my config file settings in C# by invoking a dynamic method on that object: //C# calling a method on the dynamic python object var timeout = t.GetProperty("ExternalServiceTimeout"); //the config also allows for straight Python scripting (via the Python block) var special = t.MyCustonPython(); of course, I have no type safety here and no intellisense support. I have a dynamic representation of my config file, but I want a static one. I know what my Python object's type is--it is actually newing up in instance of a C# class. But since it's happening in python, it's type is not the C# type, but dynamic instead. What I want to do is then cast the object back to the C# type that I know the object is: // doesn't work--can't cast a dynamic to a static type (nulls out) IConfigSettings staticTypeConfig = t as IConfigSettings Is there any way to figure out how to cast the object to the static type? I'm rather doubtful that there is... so doubtful that I took another approach of which I'm not entirely sure about. I'm wondering if someone has a better way... So here's my current tactic: since I know the type of the python object, I am creating a C# wrapper class: public class ConfigSettings : IConfigSettings that takes in a dynamic object in the ctor: public ConfigSettings(dynamic settings) { this.DynamicProxy = settings; } public dynamic DynamicProxy { get; private set; } Now I have a reference to the Python dynamic object of which I know the type. So I can then just put wrappers around the Python methods that I know are there: // wrapper access to the underlying dynamic object // this makes my dynamic object appear 'static' public string GetSetting(string key) { return this.DynamicProxy.GetProperty(key).ToString(); } Now the dynamic object is accessed through this static proxy and thus can obviously be passed around in the static C# world via interface, etc: // dependency inject the dynamic object around IBusinessLogic logic = new BusinessLogic(IConfigSettings config); This solution has the benefits of all the static typing stuff we know and love while at the same time giving me the option of 'bailing out' to dynamic too: // the DynamicProxy property give direct access to the dynamic object var result = config.DynamicProxy.MyCustomPython(); but, man, this seems rather convoluted way of getting to an object that is a static type in the first place! Since the whole dynamic/static interaction world is new to me, I'm really questioning if my solution is optimal or if I'm missing something (i.e. some way of casting that dynamic object to a known static type) about how to bridge the chasm between these two universes.

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  • Where is meta.local_fields set in django.db.models.base.py ?

    - by BryanWheelock
    I'm getting the error: Exception Value: (1110, "Column 'about' specified twice") As I was reviewing the Django error page, I noticed that the customizations the model User, seem to be appended to the List twice. This seems to be happening here in django/db/model/base.py in base_save(): values = [(f, f.get_db_prep_save(raw and getattr(self, f.attname) or f.pre_save(self, True))) for f in meta.local_fields] this is what Django error page shows values to be: values = [(<django.db.models.fields.CharField object at 0xa78996c>, u'kallie'), (<django.db.models.fields.CharField object at 0xa7899cc>, ''), (<django.db.models.fields.CharField object at 0xa789a2c>, ''), (<django.db.models.fields.EmailField object at 0xa789a8c>, u'[email protected]'), (<django.db.models.fields.CharField object at 0xa789b2c>, 'sha1$d4a80$0e5xxxxxxxxxxxxxxxxxxxxddadfb07'), (<django.db.models.fields.BooleanField object at 0xa789bcc>, False), (<django.db.models.fields.BooleanField object at 0xa789c6c>, True), (<django.db.models.fields.BooleanField object at 0xa789d2c>, False), (<django.db.models.fields.DateTimeField object at 0xa789dcc>, u'2010-02-03 14:54:35'), (<django.db.models.fields.DateTimeField object at 0xa789e2c>, u'2010-02-03 14:54:35'), # this is where the values from the User model customizations show up (<django.db.models.fields.BooleanField object at 0xa8c69ac>, False), (<django.db.models.fields.CharField object at 0xa8c688c>, None), (<django.db.models.fields.PositiveIntegerField object at 0xa8c69cc>, 1), (<django.db.models.fields.CharField object at 0xa8c69ec>, 'b5ab1603b2308xxxxxxxxxxx75bca1'), (<django.db.models.fields.SmallIntegerField object at 0xa8c6dac>, 0), (<django.db.models.fields.SmallIntegerField object at 0xa8c6e4c>, 0), (<django.db.models.fields.SmallIntegerField object at 0xa8c6e8c>, 0), (<django.db.models.fields.SmallIntegerField object at 0xa8c6ecc>, 10), (<django.db.models.fields.DateTimeField object at 0xa8c6eec>, u'2010-02-03 14:54:35'), (<django.db.models.fields.CharField object at 0xa8c6f2c>, ''), (<django.db.models.fields.URLField object at 0xa8c6f6c>, ''), (<django.db.models.fields.CharField object at 0xa8c6fac>, ''), (<django.db.models.fields.DateField object at 0xa8c6fec>, None), (<django.db.models.fields.TextField object at 0xa8cb04c>, ''), # at this point User model customizations repeats itself (<django.db.models.fields.BooleanField object at 0xa663b0c>, False), (<django.db.models.fields.CharField object at 0xaa1e94c>, None), (<django.db.models.fields.PositiveIntegerField object at 0xaa1e34c>, 1), (<django.db.models.fields.CharField object at 0xaa1e40c>, 'b5ab1603b2308050ebd62f49ca75bca1'), (<django.db.models.fields.SmallIntegerField object at 0xa8c6d8c>, 0), (<django.db.models.fields.SmallIntegerField object at 0xaa2378c>, 0), (<django.db.models.fields.SmallIntegerField object at 0xaa237ac>, 0), (<django.db.models.fields.SmallIntegerField object at 0xaa237ec>, 10), (<django.db.models.fields.DateTimeField object at 0xaa2380c>, u'2010-02-03 14:54:35'), (<django.db.models.fields.CharField object at 0xaa2384c>, ''), (<django.db.models.fields.URLField object at 0xaa2388c>, ''), (<django.db.models.fields.CharField object at 0xaa238cc>, ''), (<django.db.models.fields.DateField object at 0xaa2390c>, None), (<django.db.models.fields.TextField object at 0xaa2394c>, '')] Since this app is in Production, I can't figure out how to use pdb.set_trace() to see what's going on inside of save_base. The customizations to User are: User.add_to_class('email_isvalid', models.BooleanField(default=False)) User.add_to_class('email_key', models.CharField(max_length=16, null=True)) User.add_to_class('reputation', models.PositiveIntegerField(default=1)) User.add_to_class('gravatar', models.CharField(max_length=32)) User.add_to_class('email_feeds', generic.GenericRelation(EmailFeed)) User.add_to_class('favorite_questions', models.ManyToManyField(Question, through=FavoriteQuestion, related_name='favorited_by')) User.add_to_class('badges', models.ManyToManyField(Badge, through=Award, related_name='awarded_to')) User.add_to_class('gold', models.SmallIntegerField(default=0)) User.add_to_class('silver', models.SmallIntegerField(default=0)) User.add_to_class('bronze', models.SmallIntegerField(default=0)) User.add_to_class('questions_per_page', models.SmallIntegerField(choices=QUESTIONS_PER_PAGE_CHOICES, default=10)) User.add_to_class('last_seen', models.DateTimeField(default=datetime.datetime.now)) User.add_to_class('real_name', models.CharField(max_length=100, blank=True)) User.add_to_class('website', models.URLField(max_length=200, blank=True)) User.add_to_class('location', models.CharField(max_length=100, blank=True)) User.add_to_class('date_of_birth', models.DateField(null=True, blank=True)) User.add_to_class('about', models.TextField(blank=True)) Django1.1.1 Python 2.5

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  • Hibernate Persistence problems with Bean Mapping (Dozer)

    - by BuffaloBuffalo
    I am using Hibernate 3, and having a particular issue when persisting a new Entity which has an association with an existing detached entity. Easiest way to explain this is via code samples. I have two entities, FooEntity and BarEntity, of which a BarEntity can be associated with many FooEntity: @Entity public class FooEntity implements Foo{ @Id private Long id; @ManyToOne(targetEntity = BarEntity.class) @JoinColumn(name = "bar_id", referencedColumnName = "id") @Cascade(value={CascadeType.ALL}) private Bar bar; } @Entity public class BarEntity implements Bar{ @Id private Long id; @OneToMany(mappedBy = "bar", targetEntity = FooEntity.class) private Set<Foo> foos; } Foo and Bar are interfaces that loosely define getters for the various fields. There are corresponding FooImpl and BarImpl classes that are essentially just the entity objects without the annotations. What I am trying to do is construct a new instance of FooImpl, and persist it after setting a number of fields. The new Foo instance will have its 'bar' member set to an existing Bar (runtime being a BarEntity) from the database (retrieved via session.get(..)). After the FooImpl has all of its properties set, Apache Dozer is used to map between the 'domain' object FooImpl and the Entity FooEntity. What Dozer is doing in the background is instantiating a new FooEntity and setting all of the matching fields. BarEntity is cloned as well via instantiation and set the FooEntity's 'bar' member. After this occurs, passing the new FooEntity object to persist. This throws the exception: org.hibernate.PersistentObjectException: detached entity passed to persist: com.company.entity.BarEntity Below is in code the steps that are occurring FooImpl foo = new FooImpl(); //returns at runtime a persistent BarEntity through session.get() Bar bar = BarService.getBar(1L); foo.setBar(bar); ... //This constructs a new instance of FooEntity, with a member 'bar' which itself is a new instance that is detached) FooEntity entityToPersist = dozerMapper.map(foo, FooEntity.class); ... session.persist(entityToPersist); I have been able to resolve this issue by either removing or changing the @Cascade annotation, but that limits future use for say adding a new Foo with a new Bar attached to it already. Is there some solution here I am missing? I would be surprised if this issue hasn't been solved somewhere before, either by altering how Dozer Maps the children of Foo or how Hibernate reacts to a detached Child Entity.

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  • Why cant we create Object if constructor is in private section?

    - by Abhi
    Dear all I want to know why cant we create object if the constructor is in private section. I know that if i make a method static i can call that method using <classname> :: <methodname(...)>; But why cant we create object is my doubt... I also know if my method is not static then also i can call function by the following... class A { A(); public: void fun1(); void fun2(); void fun3(); }; int main() { A *obj =(A*)malloc(sizeof(A)); //Here we can't use new A() because constructor is in private //but we can use malloc with it, but it will not call the constructor //and hence it is harmful because object may not be in usable state. obj->fun1(); obj->fun2(); obj->fun3(); } So only doubt is why cant we create object when constructor is in private section? Thanks in advance

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  • How do I add an object to a binary tree based on the value of a member variable?

    - by Max
    How can I get a specific value from an object? I'm trying to get a value of an instance for eg. ListOfPpl newListOfPpl = new ListOfPpl(id, name, age); Object item = newListOfPpl; How can I get a value of name from an Object item?? Even if it is easy or does not interest you can anyone help me?? Edited: I was trying to build a binary tree contains the node of ListOfPpl, and need to sort it in the lexicographic. Here's my code for insertion on the node. Any clue?? public void insert(Object item){ Node current = root; Node follow = null; if(!isEmpty()){ root = new Node(item, null, null); return; }boolean left = false, right = false; while(current != null){ follow = current; left = false; right = false; //I need to compare and sort it if(item.compareTo(current.getFighter()) < 0){ current = current.getLeft(); left = true; }else { current = current.getRight(); right = true; } }if(left) follow.setLeft(new Node(item, null, null)); else follow.setRight(new Node(item, null, null)); }

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  • [javascript] Can I overload an object with a function?

    - by user257493
    Lets say I have an object of functions/values. I'm interested in overloading based on calling behavior. For example, this block of code below demonstrates what I wish to do. var main_thing = { initalized: false, something: "Hallo, welt!", something_else: [123,456,789], load: { sub1 : function() { //Some stuff }, sub2 : function() { //Some stuff }, all : function() { this.load.sub1(); this.load.sub2(); } } init: function () { this.initalized=true; this.something="Hello, world!"; this.something_else = [0,0,0]; this.load(); //I want this to call this.load.all() instead. } } The issue to me is that main_thing.load is assigned to an object, and to call main_thing.load.all() would call the function inside of the object (the () operator). What can I do to set up my code so I could use main_thing.load as an access the object, and main_thing.load() to execute some code? Or at least, similar behavior. Basically, this would be similar to a default constructor in other languages where you don't need to call main_thing.constructor(). If this isn't possible, please explain with a bit of detail.

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  • How to design a scalable notification system?

    - by Trent
    I need to write a notification system manager. Here is my requirements: I need to be able to send a Notification on different platforms, which may be totally different (for exemple, I need to be able to send either an SMS or an E-mail). Sometimes the notification may be the same for all recipients for a given platform, but sometimes it may be a notification per recipients (or several) per platform. Each notification can contain platform specific payload (for exemple an MMS can contains a sound or an image). The system need to be scalable, I need to be able to send a very large amount of notification without crashing either the application or the server. It is a two step process, first a customer may type a message and choose a platform to send to, and the notification(s) should be created to be processed either real-time either later. Then the system needs to send the notification to the platform provider. For now, I end up with some though but I don't know how scalable it will be or if it is a good design. I've though of the following objects (in a pseudo language): a generic Notification object: class Notification { String $message; Payload $payload; Collection<Recipient> $recipients; } The problem with the following objects is what if I've 1.000.000 recipients ? Even if the Recipient object is very small, it'll take too much memory. I could also create one Notification per recipient, but some platform providers requires me to send it in batch, meaning I need to define one Notification with several Recipients. Each created notification could be stored in a persistent storage like a DB or Redis. Would it be a good it to aggregate this later to make sure it is scalable? On the second step, I need to process this notification. But how could I distinguish the notification to the right platform provider? Should I use an object like MMSNotification extending an abstract Notification? or something like Notification.setType('MMS')? To allow to process a lot of notification at the same time, I think a messaging queue system like RabbitMQ may be the right tool. Is it? It would allow me to queue a lot of notification and have several worker to pop notification and process them. But what if I need to batch the recipients as seen above? Then I imagine a NotificationProcessor object for which I could I add NotificationHandler each NotificationHandler would be in charge to connect the platform provider and perform notification. I can also use an EventManager to allow pluggable behavior. Any feedbacks or ideas? Thanks for giving your time. Note: I'm used to work in PHP and it is likely the language of my choice.

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  • Difference between "Data Binding'","Data Hiding","Data Wraping" and "Encapsulation"?

    - by krishna Chandra
    I have been studying the conpects of Object oriented programming. Still I am not able to distinguish between the following concepts of object oriented programming.. a) Data Binding b) Data Hiding c) Data Wrapping d) encapsulation e) Data Abstraction I have gone through a lot of books ,and I also search the difference in google. but still I am not able to make the difference between these? Could anyone please help me ?

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  • First toe in the water with Object Databases : DB4O

    - by REA_ANDREW
    I have been wanting to have a play with Object Databases for a while now, and today I have done just that.  One of the obvious choices I had to make was which one to use.  My criteria for choosing one today was simple, I wanted one which I could literally wack in and start using, which means I wanted one which either had a .NET API or was designed/ported to .NET.  My decision was between two being: db4o MongoDb I went for db4o for the single reason that it looked like I could get it running and integrated the quickest.  I am making a Blogging application and front end as a project with which I can test and learn with these object databases.  Another requirement which I thought I would mention is that I also want to be able to use the said database in a shared hosting environment where I cannot install, run and maintain a server instance of said object database.  I can do exactly this with db4o. I have not tried to do this with MongoDb at time of writing.  There are quite a few in the industry now and you read an interesting post about different ones and how they are used with some of the heavy weights in the industry here : http://blog.marcua.net/post/442594842/notes-from-nosql-live-boston-2010 In the example which I am building I am using StructureMap as my IOC.  To inject the object for db4o I went with a Singleton instance scope as I am using a single file and I need this to be available to any thread on in the process as opposed to using the server implementation where I could open and close client connections with the server handling each one respectively.  Again I want to point out that I have chosen to stick with the non server implementation of db4o as I wanted to use this in a shared hosting environment where I cannot have such servers installed and run.     public static class Bootstrapper    {        public static void ConfigureStructureMap()        {            ObjectFactory.Initialize(x => x.AddRegistry(new MyApplicationRegistry()));        }    }    public class MyApplicationRegistry : Registry    {        public const string DB4O_FILENAME = "blog123";        public string DbPath        {            get            {                return Path.Combine(Path.GetDirectoryName(Assembly.GetAssembly(typeof(IBlogRepository)).Location), DB4O_FILENAME);            }        }        public MyApplicationRegistry()        {            For<IObjectContainer>().Singleton().Use(                () => Db4oEmbedded.OpenFile(Db4oEmbedded.NewConfiguration(), DbPath));            Scan(assemblyScanner =>            {                assemblyScanner.TheCallingAssembly();                assemblyScanner.WithDefaultConventions();            });        }    } So my code above is the structure map plumbing which I use for the application.  I am doing this simply as a quick scratch pad to play around with different things so I am simply segregating logical layers with folder structure as opposed to different assemblies.  It will be easy if I want to do this with any segment but for the purposes of example I have literally just wacked everything in the one assembly.  You can see an example file structure I have on the right.  I am planning on testing out a few implementations of the object databases out there so I can program to an interface of IBlogRepository One of the things which I was unsure about was how it performed under a multi threaded environment which it will undoubtedly be used 9 times out of 10, and for the reason that I am using the db context as a singleton, I assumed that the library was of course thread safe but I did not know as I have not read any where in the documentation, again this is probably me not reading things correctly.  In short though I threw together a simple test where I simply iterate to a limit each time kicking a common task off with a thread from a thread pool.  This task simply created and added an random Post and added it to the storage. The execution of the threads I put inside the Setup of the Test and then simply ensure the number of posts committed to the database is equal to the number of iterations I made; here is the code I used to do the multi thread jobs: [TestInitialize] public void Setup() { var sw = new System.Diagnostics.Stopwatch(); sw.Start(); var resetEvent = new ManualResetEvent(false); ThreadPool.SetMaxThreads(20, 20); for (var i = 0; i < MAX_ITERATIONS; i++) { ThreadPool.QueueUserWorkItem(delegate(object state) { var eventToReset = (ManualResetEvent)state; var post = new Post { Author = MockUser, Content = "Mock Content", Title = "Title" }; Repository.Put(post); var counter = Interlocked.Decrement(ref _threadCounter); if (counter == 0) eventToReset.Set(); }, resetEvent); } WaitHandle.WaitAll(new[] { resetEvent }); sw.Stop(); Console.WriteLine("{0:00}.{1:00} seconds", sw.Elapsed.Seconds, sw.Elapsed.Milliseconds); }   I was not doing this to test out the speed performance of db4o but while I was doing this I could not help but put in a StopWatch and see out of sheer interest how fast it would take to insert a number of Posts.  I tested it out in this case with 10000 inserts of a small, simple POCO and it resulted in an average of:  899.36 object inserts / second.  Again this is just  simple crude test which came out of my curiosity at how it performed under many threads when using the non server implementation of db4o. The spec summary of the computer I used is as follows: With regards to the actual Repository implementation itself, it really is quite straight forward and I have to say I am very surprised at how easy it was to integrate and get up and running.  One thing I have noticed in the exposure I have had so far is that the Query returns IList<T> as opposed to IQueryable<T> but again I have not looked into this in depth and this could be there already and if not they have provided everything one needs to make there own repository.  An example of a couple of methods from by db4o implementation of the BlogRepository is below: public class BlogRepository : IBlogRepository { private readonly IObjectContainer _db; public BlogRepository(IObjectContainer db) { _db = db; } public void Put(DomainObject obj) { _db.Store(obj); } public void Delete(DomainObject obj) { _db.Delete(obj); } public Post GetByKey(object key) { return _db.Query<Post>(post => post.Key == key).FirstOrDefault(); } … Anyways I hope to get a few more implementations going of the object databases and literally just get familiarized with them and the concept of no sql databases. Cheers for now, Andrew

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  • Detach an entity from a JPA persistence context (JPA 2.0 / Hibernate / EJB 3 / J2EE 6)

    - by Julien
    Hi, I wrote a stateless EJB method allowing to get an entity in "read-only" mode. The way to do this is to get the entity with the EntityManager then detach it (using the JPA 2.0 EntityManager). My code is the following: @PersistenceContext private EntityManager entityManager; public T getEntity(int entityId, Class<T> specificClass, boolean readOnly) throws Exception{ try{ T entity = (T)entityManager.find(specificClass, entityId); if (readOnly){ entityManager.detach(entity); } return entity; }catch (Exception e){ logger.error("", e); throw e; } } Getting the entity works fine, but the call to the detach method returns the following error: GRAVE: javax.ejb.EJBException at ... Caused by: java.lang.AbstractMethodError: org.hibernate.ejb.EntityManagerImpl.detach(Ljava/lang/Object;)V at com.sun.enterprise.container.common.impl.EntityManagerWrapper.detach(EntityManagerWrapper.java:973) at com.mycomp.dal.MyEJB.getEntity(MyEJB.java:37) I can't get more information and don't understand what the problem is... Could somebody help ?

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  • Changes in gcc/persistence of optimization flags gcc/C

    - by gnometorule
    Just curious. Using gcc/gdb under Ubuntu 9.10. Reading a C book that also often gives the disassembly of the object file. When reading in January, my disassembly looks a lot like the book's; now, it's quite different - possibly more optimized (I notice some re-arrangements in the assembly code now that, at least in the files I checked, look optimized). I have used optimization options -O1 - -O3 for gcc between the first and second read, but not before the first. (1) Is the use of optimization options persistent, aka, if you use them once, you'll use them until switching them off? That would be weird (browsed man file and at least did not see anything to that sort). In the unlikely case that it is true, how do you switch them off? (2) Has gcc's assembly changed through any recent upgrade? (3) Does gcc sometimes produce (significantly) different assembly code although same compile options are chosen? Thanks much.

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  • PERSISTENCE LOB WITH JPA

    - by rfders
    Hi, Folks. I have this problem using JBOSS, EJB3 and MSSQL Express . i'm trying to persist an entity with an Blob attribute which was converted into a byte[], apparently it create the entity perfectly, no error was logged at jboss's console. but when i check into database the column is null. i already checked the Object to byte[] method and it is fine. i tried assigning Image and varbinary(Max) data type to this column. so i really don't know what it happening, why the column is not inserted into database. thanks a lot.

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  • Can I create object names from a text file in Python 2.7?

    - by user560100
    I'm working on a game project. I've created an object, Star(Object). I want to assign the name of the variables, dynamically, from a text file. If I have a text file with: Sol Centauri Vega I want the program to create the Star(Object) with variable names from the text file. I want the process automated, because I'm looking to create hundreds of stars. I could write the code out by hand: Sol = Star(Sol) Centauri = Star(Centauri) Vega = Star(Vega) But isn't there a way to automate this? Essentially, what I eventually want is a tuple with the list of stars, as their own objects. Then, when I am doing game maintenance, I can just iterate over all the objects in the tuple.

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  • How can I get a value out of a jQuery object?

    - by Jannis
    I am returning some data (example below) and saving it to a jQuery object (or is this an array and I am confusing the two?) when I log the variable that is the object it has the values I am looking for but how do I access the data inside this object? code $itemPosition = { 'top': $item.offset().top, 'left':$item.offset().left }, console.log($itemPosition); This would log out (the in this case expected) top: 0 & left: 490. But how can I know work with those values? Also, while this it is probably obvious I am still in the early stages of learning jQuery/Javascript rest assured that reference books are on their way, but so far the SO community has been invaluable to my learning, so thanks for reading! J.

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  • How can I dynamically add an <object> tag with JavaScript in IE?

    - by Detlef D. Doerscheln
    I have to add either an embed tag for Firefox or an object tag for Internet Explorer with JavaScript to address the appropriate ActiveX / Plugin depending on the browser. The plugin could be missing and needs to get downloaded in this case. The dynamically added embed tag for Firefox works as expected. The dynamically added object tag for Internet Explorer seems to do nothing at all. The object tag needs the following attributes to function properly. id ="SomeId" classid = "CLSID:{GUID}" codebase = "http://www.MyActicexSource.com/MyCuteActivex.CAB#Version=2,0,0,1" Even a general working idea or method would be nice. Thanks!

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  • Is it possible to create an enum whose object can't be created but can be used for readonly purpose

    - by Shantanu Gupta
    I created an enum where I stored some table names. I want it to be used to get the name of the table like ds.Tables[BGuestInfo.TableName.L_GUEST_TYPE.ToString()]. public enum TableName : byte { L_GUEST_TYPE = 0 ,L_AGE_GROUP = 1 ,M_COMPANY = 2 ,L_COUNTRY = 3 ,L_EYE_COLOR = 4 ,L_GENDER = 5 ,L_HAIR_COLOR = 6 ,L_STATE_PROVINCE = 7 ,L_STATUS = 8 ,L_TITLE = 9 ,M_TOWER = 10 ,L_CITY = 11 ,L_REGISTER_TYPE = 12 } This is my enum. Now I have not created any object of this enum so that no one can use it for other than read only purpose. For this enum to be accessible in outer classes as well I have to make it public which means some outer class can create its object as well. So what can i do so as to restrict its object creation.

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  • How to refer to object in JavaScript event handler?

    - by George Edison
    Note: This question uses jQuery but the question has nothing to do with jQuery! Okay so I have this object: var box = new BigBox(); This object has a method named Serialize(): box.AddToPage(); Here is the method AddToPage(): function AddToPage() { $('#some_item').html("<div id='box' onclick='this.OnClick()'></div>"); } The problem above is the this.OnClick() (which obviously does not work). I need the onclick handler to invoke a member of the BigBox class. How can I do this? How can an object refer to itself in an event handler?

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  • How can I find out how much memory an object of a C++ class consumes?

    - by Shadow
    Hi, I am developing a Graph-class, based on boost-graph-library. A Graph-object contains a boost-graph, so to say an adjacency_list, and a map. When monitoring the total memory usage of my program, it consumes quite a lot (checked with pmap). Now, I would like to know, how much of the memory is exactly consumed by a filled object of this Graph-class? With filled I mean when the adjacency_list is full of vertices and edges. I found out, that using sizeof() doesn't bring me far. Using valgrind is also not an alternative as there is quite some memory allocation done previously and this makes the usage of valgrind impractical for this purpose. I'm also not interested in what other parts of the program cost in memory, I want to focus on one single object. Thank you.

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  • JPA - Performance with using multiple entity manager

    - by Nguyen Tuan Linh
    My situation is: The code is not mine I have two kinds of database: one is Dad, one is Son. In Dad, I have a table to store JNDI name. I will look up Dad using JNDI, create entity manager, and retrieve this table. From these retrieved JNDI names, I will create multiple entity managers using multiple Son databases. The problem is: Son have thousands of entities. It takes each Son database around 10 minutes to load all entities. If there is 4 Son databases, it will be 40 minutes. My question: Is there any way to load all entities and use them for all entity manager? Please look at the code below For each Son JNDI: Map<String, String> puSonProperties = new HashMap<String, String>(); puSonProperties.put("javax.persistence.jtaDataSource", sonJndi); EntityManagerFactory emf = Persistence.createEntityManagerFactory("PUSon", puSonProperties); PUSon - All of them use the same persistence unit log.info("Verify entity manager for son: {0} - {1}", sonCode, emSon.find(Son_configuration.class, 0) != null ? "ok" : "failed!"); This is the actual code where the loading of all entities begins. 10 mins.

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  • Understanding UML composition better

    - by Prog
    The technical difference between Composition and Aggregation in UML (and sometimes in programming too) is that with Composition, the lifetime of the objects composing the composite (e.g. an engine and a steering wheel in a car) is dependent on the composite object. While with Aggregation, the lifetime of the objects making up the composite is independent of the composite. However I'm not sure about something related to composition in UML. Say ClassA is composed of an object of ClassB: class ClassA{ ClassB bInstance; public ClassA(){ bInstance = new ClassB(); } } This is an example of composition, because bInstance is dependent on the lifetime of it's enclosing object. However, regarding UML notation - I'm not sure if I would notate the relationship between ClassA and ClassB with a filled diamond (composition) or a white diamond (aggregation). This is because while the lifetime of some ClassB instances is dependent of ClassA instances - there could be ClassB instances anywhere else in the program - not only within ClassA instances. The question is: if ClassA objects are composed of ClassB objects - but other ClassB objects are free to be used anywhere else in the program: Should the relationship between ClassA and ClassB be notated as aggregation or as composition?

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  • Formal definition for term "pure OO language"?

    - by Yauhen Yakimovich
    I can't think of a better place among SO siblings to pose such a question. Originally I wanted to ask "Is python a pure OO language?" but considering troubles and some sort of discomfort people experience while trying to define the term I decided to start with obtaining a clear definition for the term itself. It would be rather fair to start with correspondence by Dr. Alan Kay, who has coined the term (note the inspiration in biological analogy to cells or other living objects). There are following ways to approach the task: Give a comparative analysis by listing programming languages that exhibits certain properties unique and sufficient to define the term (although Smalltalk and Java are passing examples but IMO this way seems neither really complete or nor fruitful) Give a formal definition (or close to it, e.g. in more academic or mathematical style). Give a philosophical definition that would totally rely on semantical context of concrete language or a priori programming experience (there must be some chance of successful explanation by the community). My current version: "If a certain programing (formal) language that can (grammatically) differentiate between operations and operands as well as infer about the type of each operand whether this type is an object (in sense of OOP) or not then we call such a language an OO-language as long as there is at least one type in this language which is an object. Finally, if all types of the language are also objects we define such language to be pure OO-language." Would appreciate any possible improvement of it. As you can see I just made the definition dependent on the term "object" (often fully referenced as class of objects).

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  • About shared (static) Members and its behavior

    - by Allende
    I just realized that I can access shared members from instances of classes (probably this is not correct, but compile and run), and also learn/discover that, I can modify shared members, then create a new instance and access the new value of the shared member. My question is, what happens to the shared members, when it comes back to the "default" value (class declaration), how dangerous is it do this ? is it totally bad ? is it valid in some cases ?. If you want to test my point here is the code (console project vb.net) that I used to test shared members, as you can see/compile/run, the shared member "x" of the class "Hello" has default value string "Default", but at runtime it changes it, and after creating a new object of that class, this object has the new value of the shared member. Module Module1 Public Class hello Public Shared x As String = "Default" Public Sub New() End Sub End Class Sub Main() Console.WriteLine("hello.x=" & hello.x) Dim obj As New hello() Console.WriteLine("obj.x=" & obj.x) obj.x = "Default shared memeber, modified in object" Console.WriteLine("obj.x=" & obj.x) hello.x = "Defaul shared member, modified in class" Console.WriteLine("hello.x=" & hello.x) Dim obj2 As New hello() Console.WriteLine("obj2.x=" & obj2.x) Console.ReadLine() End Sub End Module UPDATE: First at all, thanks to everyone, each answer give feedback, I suppose, by respect I should choose one as "the answer", I don't want to be offensive to anyone, so please don't take it so bad if I didn't choose you answer.

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  • Empty interface to combine multiple interfaces

    - by user1109519
    Suppose you have two interfaces: interface Readable { public void read(); } interface Writable { public void write(); } In some cases the implementing objects can only support one of these but in a lot of cases the implementations will support both interfaces. The people who use the interfaces will have to do something like: // can't write to it without explicit casting Readable myObject = new MyObject(); // can't read from it without explicit casting Writable myObject = new MyObject(); // tight coupling to actual implementation MyObject myObject = new MyObject(); None of these options is terribly convenient, even more so when considering that you want this as a method parameter. One solution would be to declare a wrapping interface: interface TheWholeShabam extends Readable, Writable {} But this has one specific problem: all implementations that support both Readable and Writable have to implement TheWholeShabam if they want to be compatible with people using the interface. Even though it offers nothing apart from the guaranteed presence of both interfaces. Is there a clean solution to this problem or should I go for the wrapper interface? UPDATE It is in fact often necessary to have an object that is both readable and writable so simply seperating the concerns in the arguments is not always a clean solution. UPDATE2 (extracted as answer so it's easier to comment on) UPDATE3 Please beware that the primary usecase for this is not streams (although they too must be supported). Streams make a very specific distinction between input and output and there is a clear separation of responsibilities. Rather, think of something like a bytebuffer where you need one object you can write to and read from, one object that has a very specific state attached to it. These objects exist because they are very useful for some things like asynchronous I/O, encodings,...

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