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  • ejb3-persistence.jar source

    - by Randy Stegbauer
    Well, I must be brain-damaged, because I can't find the java source for Sun's persistence.jar or JBoss's ejb3-persistence.jar JPA package. They are open-source aren't they? I looked all over the java.sun.com site as well as the GlassFish wiki, but came up empty. I'd like a src.zip or folder like Sun delivers with Java JDKs. Of course, I really don't have to have it, but I think it's fun to browse the source once in a while. And it helps me to debug my code sometimes. Thank you, Randy Stegbauer

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  • Creating database desktop application with data manipulation in Netbeans using Java Persistence

    - by Lulu
    It's my first time to use Persistence in developing a Java program because I usually connect via JDBC. I read that for large amounts of data, it is best to use persistence. I tried playing with the CRUD example of Netbeans. It's not very helpful thought because it only connects to the DB and allows addition and deletion of records. I need something that will allow me to manipulate the data like if the value from column C1 of table T1 is such, it will retrieve data from table t2. In short, I need to apply conditions before knowing what to retrieve exactly. The example in CRUD example already has a specific table to retrieve and only acts like a database manager. How is it possible to retrieve a specific item first then from this, will determine the next steps to be done. I'm also using embedded JavaDB/Derby as my database (also my first time to use because I usually use remote mysql)

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  • JQuery Delegate and using traveral options in function

    - by Brian
    I am having trouble figuring out how to use the JQuery delegate function to do what I require. Basically, I need to allow users to add Panels (i.e. divs) to a form dynamically by selecting a button. Then when a user clicks a button within a given Panel, I want to be able to to something to that Panel (like change the color in this example). Unfortunately, it seems that references to the JQuery traversing functions don't work in this instance. Can anybody explain how to achieve this effect? Is there anyway to bind a different delegate to the each panel as its added. $('.addPanels').delegate('*', 'click', function() { $(this).parent.css('background-color', 'black'); $('.placeholder').append('Add item'); }); <div class="addPanels"> <div class="panel"> <a href="#" class="addLink">Add item</a> text</div> <div class="placeholder"/> </div> </div>

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  • WPF: Reloading app parts to handle persistence as well as memory management.

    - by Ingó Vals
    I created a app using Microsoft's WPF. It mostly handles data reading and input as well as associating relations between data within specific parameters. As a total beginner I made some bad design decision ( not so much decisions as using the first thing I got to work ) but now understanding WPF better I'm getting the urge to refactor my code with better design principles. I had several problems but I guess each deserves it's own question for clarity. Here I'm asking for proper ways to handle the data itself. In the original I wrapped each row in a object when fetched from database ( using LINQ to SQL ) somewhat like Active Record just not active or persistence (each app instance had it's own data handling part). The app has subunits handling different aspects. However as it was setup it loaded everything when started. This creates several problems, for example often it wouldn't be neccesary to load a part unless we were specifically going to work with that part so I wan't some form of lazy loading. Also there was problem with inner persistance because you might create a new object/row in one aspect and perhaps set relation between it and different object but the new object wouldn't appear until the program was restarted. Persistance between instances of the app won't be huge problem because of the small amount of people using the program. While I could solve this now using dirty tricks I would rather refactor the program and do it elegantly, Now the question is how. I know there are several ways and a few come to mind: 1) Each aspect of the program is it's own UserControl that get's reloaded/instanced everytime you navigate to it. This ensures you only load up the data you need and you get some persistancy. DB server located on same LAN and tables are small so that shouldn't be a big problem. Minor drawback is that you would have to remember the state of each aspect so you wouldn't always start at beginners square. 2) Having a ViewModel type object at the base level of the app with lazy loading and some kind of timeout. I would then propegate this object down the visual tree to ensure every aspect is getting it's data from the same instance 3) Semi active record data layer with static load methods. 4) Some other idea What in your opinion is the most practical way in WPF, what does MVVM assume?

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  • .delegate equivalent of an existing .hover method in jQuery 1.4.2

    - by kim3er
    I have an event handler bound to the hover event using the .hover method, which is below: $(".nav li").hover(function () { $(this).addClass("hover"); }, function () { $(this).removeClass("hover"); }); It is important to note, that I require both functions within the handler to ensure synchronisation. Is it possible to rewrite the function using .delegate, as the following does not work? $(".nav").delegate("li", "hover", function () { $(this).addClass("hover"); }, function () { $(this).removeClass("hover"); }); Rich

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  • .delegate equivalent of an existing .live method in jQuery 1.4.2

    - by kim3er
    I have an event handler bound to the hover event using the .live method, which is below: $(".nav li").hover(function () { $(this).addClass("hover"); }, function () { $(this).removeClass("hover"); }); It is important to note, that I require both functions within the handler to ensure synchronisation. Is it possible to rewrite the function using .delegate, as the following does not work? $(".nav").delegate("li", "hover", function () { $(this).addClass("hover"); }, function () { $(this).removeClass("hover"); }); Rich

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  • how to set a tableview delegate

    - by dubbeat
    Hi, I'm trying to use a tableview without using a nib and without using a UITableViewController. I have added a UITableView instance to a UIViewController Like So mytable = [[UITableView alloc] initWithFrame:CGRectMake(22, 207, 270, 233)]; [mytable setDelegate:self]; [self.view mytable]; Also I have added the following table view methods to my UIViewController (cut for brevities sake) - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { I am getting a warning saying that my UIViewController does not implement UITableView delegate protocol. Whats the correct way to tell the table view where its delegate methods are? (This is my first attempt at trying to use a UITableView without selecting the UITableTableview controller from the new file options)

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  • C#/.NET Little Wonders: The Predicate, Comparison, and Converter Generic Delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last three weeks, we examined the Action family of delegates (and delegates in general), the Func family of delegates, and the EventHandler family of delegates and how they can be used to support generic, reusable algorithms and classes. This week I will be completing my series on the generic delegates in the .NET Framework with a discussion of three more, somewhat less used, generic delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>. These are older generic delegates that were introduced in .NET 2.0, mostly for use in the Array and List<T> classes.  Though older, it’s good to have an understanding of them and their intended purpose.  In addition, you can feel free to use them yourself, though obviously you can also use the equivalents from the Func family of delegates instead. Predicate<T> – delegate for determining matches The Predicate<T> delegate was a very early delegate developed in the .NET 2.0 Framework to determine if an item was a match for some condition in a List<T> or T[].  The methods that tend to use the Predicate<T> include: Find(), FindAll(), FindLast() Uses the Predicate<T> delegate to finds items, in a list/array of type T, that matches the given predicate. FindIndex(), FindLastIndex() Uses the Predicate<T> delegate to find the index of an item, of in a list/array of type T, that matches the given predicate. The signature of the Predicate<T> delegate (ignoring variance for the moment) is: 1: public delegate bool Predicate<T>(T obj); So, this is a delegate type that supports any method taking an item of type T and returning bool.  In addition, there is a semantic understanding that this predicate is supposed to be examining the item supplied to see if it matches a given criteria. 1: // finds first even number (2) 2: var firstEven = Array.Find(numbers, n => (n % 2) == 0); 3:  4: // finds all odd numbers (1, 3, 5, 7, 9) 5: var allEvens = Array.FindAll(numbers, n => (n % 2) == 1); 6:  7: // find index of first multiple of 5 (4) 8: var firstFiveMultiplePos = Array.FindIndex(numbers, n => (n % 5) == 0); This delegate has typically been succeeded in LINQ by the more general Func family, so that Predicate<T> and Func<T, bool> are logically identical.  Strictly speaking, though, they are different types, so a delegate reference of type Predicate<T> cannot be directly assigned to a delegate reference of type Func<T, bool>, though the same method can be assigned to both. 1: // SUCCESS: the same lambda can be assigned to either 2: Predicate<DateTime> isSameDayPred = dt => dt.Date == DateTime.Today; 3: Func<DateTime, bool> isSameDayFunc = dt => dt.Date == DateTime.Today; 4:  5: // ERROR: once they are assigned to a delegate type, they are strongly 6: // typed and cannot be directly assigned to other delegate types. 7: isSameDayPred = isSameDayFunc; When you assign a method to a delegate, all that is required is that the signature matches.  This is why the same method can be assigned to either delegate type since their signatures are the same.  However, once the method has been assigned to a delegate type, it is now a strongly-typed reference to that delegate type, and it cannot be assigned to a different delegate type (beyond the bounds of variance depending on Framework version, of course). Comparison<T> – delegate for determining order Just as the Predicate<T> generic delegate was birthed to give Array and List<T> the ability to perform type-safe matching, the Comparison<T> was birthed to give them the ability to perform type-safe ordering. The Comparison<T> is used in Array and List<T> for: Sort() A form of the Sort() method that takes a comparison delegate; this is an alternate way to custom sort a list/array from having to define custom IComparer<T> classes. The signature for the Comparison<T> delegate looks like (without variance): 1: public delegate int Comparison<T>(T lhs, T rhs); The goal of this delegate is to compare the left-hand-side to the right-hand-side and return a negative number if the lhs < rhs, zero if they are equal, and a positive number if the lhs > rhs.  Generally speaking, null is considered to be the smallest value of any reference type, so null should always be less than non-null, and two null values should be considered equal. In most sort/ordering methods, you must specify an IComparer<T> if you want to do custom sorting/ordering.  The Array and List<T> types, however, also allow for an alternative Comparison<T> delegate to be used instead, essentially, this lets you perform the custom sort without having to have the custom IComparer<T> class defined. It should be noted, however, that the LINQ OrderBy(), and ThenBy() family of methods do not support the Comparison<T> delegate (though one could easily add their own extension methods to create one, or create an IComparer() factory class that generates one from a Comparison<T>). So, given this delegate, we could use it to perform easy sorts on an Array or List<T> based on custom fields.  Say for example we have a data class called Employee with some basic employee information: 1: public sealed class Employee 2: { 3: public string Name { get; set; } 4: public int Id { get; set; } 5: public double Salary { get; set; } 6: } And say we had a List<Employee> that contained data, such as: 1: var employees = new List<Employee> 2: { 3: new Employee { Name = "John Smith", Id = 2, Salary = 37000.0 }, 4: new Employee { Name = "Jane Doe", Id = 1, Salary = 57000.0 }, 5: new Employee { Name = "John Doe", Id = 5, Salary = 60000.0 }, 6: new Employee { Name = "Jane Smith", Id = 3, Salary = 59000.0 } 7: }; Now, using the Comparison<T> delegate form of Sort() on the List<Employee>, we can sort our list many ways: 1: // sort based on employee ID 2: employees.Sort((lhs, rhs) => Comparer<int>.Default.Compare(lhs.Id, rhs.Id)); 3:  4: // sort based on employee name 5: employees.Sort((lhs, rhs) => string.Compare(lhs.Name, rhs.Name)); 6:  7: // sort based on salary, descending (note switched lhs/rhs order for descending) 8: employees.Sort((lhs, rhs) => Comparer<double>.Default.Compare(rhs.Salary, lhs.Salary)); So again, you could use this older delegate, which has a lot of logical meaning to it’s name, or use a generic delegate such as Func<T, T, int> to implement the same sort of behavior.  All this said, one of the reasons, in my opinion, that Comparison<T> isn’t used too often is that it tends to need complex lambdas, and the LINQ ability to order based on projections is much easier to use, though the Array and List<T> sorts tend to be more efficient if you want to perform in-place ordering. Converter<TInput, TOutput> – delegate to convert elements The Converter<TInput, TOutput> delegate is used by the Array and List<T> delegate to specify how to convert elements from an array/list of one type (TInput) to another type (TOutput).  It is used in an array/list for: ConvertAll() Converts all elements from a List<TInput> / TInput[] to a new List<TOutput> / TOutput[]. The delegate signature for Converter<TInput, TOutput> is very straightforward (ignoring variance): 1: public delegate TOutput Converter<TInput, TOutput>(TInput input); So, this delegate’s job is to taken an input item (of type TInput) and convert it to a return result (of type TOutput).  Again, this is logically equivalent to a newer Func delegate with a signature of Func<TInput, TOutput>.  In fact, the latter is how the LINQ conversion methods are defined. So, we could use the ConvertAll() syntax to convert a List<T> or T[] to different types, such as: 1: // get a list of just employee IDs 2: var empIds = employees.ConvertAll(emp => emp.Id); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.ConvertAll(emp => (int)emp.Salary); Note that the expressions above are logically equivalent to using LINQ’s Select() method, which gives you a lot more power: 1: // get a list of just employee IDs 2: var empIds = employees.Select(emp => emp.Id).ToList(); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.Select(emp => (int)emp.Salary).ToList(); The only difference with using LINQ is that many of the methods (including Select()) are deferred execution, which means that often times they will not perform the conversion for an item until it is requested.  This has both pros and cons in that you gain the benefit of not performing work until it is actually needed, but on the flip side if you want the results now, there is overhead in the behind-the-scenes work that support deferred execution (it’s supported by the yield return / yield break keywords in C# which define iterators that maintain current state information). In general, the new LINQ syntax is preferred, but the older Array and List<T> ConvertAll() methods are still around, as is the Converter<TInput, TOutput> delegate. Sidebar: Variance support update in .NET 4.0 Just like our descriptions of Func and Action, these three early generic delegates also support more variance in assignment as of .NET 4.0.  Their new signatures are: 1: // comparison is contravariant on type being compared 2: public delegate int Comparison<in T>(T lhs, T rhs); 3:  4: // converter is contravariant on input and covariant on output 5: public delegate TOutput Contravariant<in TInput, out TOutput>(TInput input); 6:  7: // predicate is contravariant on input 8: public delegate bool Predicate<in T>(T obj); Thus these delegates can now be assigned to delegates allowing for contravariance (going to a more derived type) or covariance (going to a less derived type) based on whether the parameters are input or output, respectively. Summary Today, we wrapped up our generic delegates discussion by looking at three lesser-used delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>.  All three of these tend to be replaced by their more generic Func equivalents in LINQ, but that doesn’t mean you shouldn’t understand what they do or can’t use them for your own code, as they do contain semantic meanings in their names that sometimes get lost in the more generic Func name.   Tweet Technorati Tags: C#,CSharp,.NET,Little Wonders,delegates,generics,Predicate,Converter,Comparison

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  • Errors rose when a Netbean Maven Project tries to run

    - by Zakaria
    Hi everybody, I installed NetBeans 6.8 on Vista and and I'm trying to execute a simple Maven Project. When I ran the project, I got this set of errors: WARNING: You are running embedded Maven builds, some build may fail due to incompatibilities with latest Maven release. To set Maven instance to use for building, click here. Scanning for projects... [#process-resources] [resources:resources] Using default encoding to copy filtered resources. [#compile] [compiler:compile] Nothing to compile - all classes are up to date [exec:exec] [EL Info]: 2010-04-04 18:22:54.907--ServerSession(15532856)--EclipseLink, version: Eclipse Persistence Services - 2.0.0.v20091127-r5931 [EL Severe]: 2010-04-04 18:22:54.929--ServerSession(15532856)--Local Exception Stack: Exception [EclipseLink-4003] (Eclipse Persistence Services - 2.0.0.v20091127-r5931): org.eclipse.persistence.exceptions.DatabaseException Exception in thread "main" javax.persistence.PersistenceException: Exception [EclipseLink-4003] (Eclipse Persistence Services - 2.0.0.v20091127-r5931): org.eclipse.persistence.exceptions.DatabaseException Exception Description: Configuration error. Class [org.apache.derby.jdbc.ClientDriver] not found. Exception Description: Configuration error. Class [org.apache.derby.jdbc.ClientDriver] not found. at org.eclipse.persistence.exceptions.DatabaseException.configurationErrorClassNotFound(DatabaseException.java:82) at org.eclipse.persistence.sessions.DefaultConnector.loadDriverClass(DefaultConnector.java:267) at org.eclipse.persistence.sessions.DefaultConnector.connect(DefaultConnector.java:85) at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:392) at org.eclipse.persistence.sessions.DatasourceLogin.connectToDatasource(DatasourceLogin.java:162) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.getServerSession(EntityManagerFactoryImpl.java:151) at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:584) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManagerImpl(EntityManagerFactoryImpl.java:207) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:228) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:195) at com.mycompany.chapter2_ex1.Main.main(Main.java:31) Caused by: Exception [EclipseLink-4003] (Eclipse Persistence Services - 2.0.0.v20091127-r5931): org.eclipse.persistence.exceptions.DatabaseException Exception Description: Configuration error. Class [org.apache.derby.jdbc.ClientDriver] not found. at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:368) at org.eclipse.persistence.exceptions.DatabaseException.configurationErrorClassNotFound(DatabaseException.java:82) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.getServerSession(EntityManagerFactoryImpl.java:151) at org.eclipse.persistence.sessions.DefaultConnector.loadDriverClass(DefaultConnector.java:267) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManagerImpl(EntityManagerFactoryImpl.java:207) at org.eclipse.persistence.sessions.DefaultConnector.connect(DefaultConnector.java:85) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:195) at org.eclipse.persistence.sessions.DatasourceLogin.connectToDatasource(DatasourceLogin.java:162) at com.mycompany.chapter2_ex1.Main.main(Main.java:31) at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:584) at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:228) at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:368) ... 4 more [ERROR]The following mojo encountered an error while executing: [ERROR]Group-Id: org.codehaus.mojo [ERROR]Artifact-Id: exec-maven-plugin [ERROR]Version: 1.1.1 [ERROR]Mojo: exec [ERROR]brought in via: Direct invocation [ERROR]While building project: [ERROR]Group-Id: com.mycompany [ERROR]Artifact-Id: chapter2_ex1 [ERROR]Version: 1.0-SNAPSHOT [ERROR]From file: C:\Users\Charlotte\Documents\NetBeansProjects\chapter2_ex1\pom.xml [ERROR]Reason: Result of cmd.exe /X /C ""C:\Program Files\Java\jdk1.6.0_11\bin\java.exe" -classpath C:\Users\Charlotte\Documents\NetBeansProjects\chapter2_ex1\target\classes;C:\Users\Charlotte\.m2\repository\javax\persistence\persistence-api\1.0\persistence-api-1.0.jar;C:\Users\Charlotte\.m2\repository\org\eclipse\persistence\javax.persistence\2.0.0\javax.persistence-2.0.0.jar;C:\Users\Charlotte\.m2\repository\org\eclipse\persistence\eclipselink\2.0.0-RC1\eclipselink-2.0.0-RC1.jar com.mycompany.chapter2_ex1.Main" execution is: '1'. ------------------------------------------------------------------------ For more information, run with the -e flag ------------------------------------------------------------------------ BUILD FAILED ------------------------------------------------------------------------ Total time: 3 seconds Finished at: Sun Apr 04 18:22:55 CEST 2010 Final Memory: 47M/94M ------------------------------------------------------------------------ Theses exceptions rose even if I can run the database by using the console (ij) and when I connect the Database, no errors are showing. Can you help me please? Thank you very much. Regards.

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  • Best Persistence API for use with GWT

    - by KevMo
    What is the best persistence API for use with GWT? Sadly, the application will be hosted on my own java server, as I will need more control than GAE will give me. I know I will need to have two sets of my entities, one for the server side, and some pojo's for the client side. I'm looking to make the mapping of the data as simple as possible between the two, but these will be deeply nested objects so it has to be robust. I was looking at Dozer for my mapping needs. Previously I've used EJB3 with TopLink, so that's very familiar to me, but I would like to get community input on what other API's work well with Dozer and GWT.

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  • Persistence provider for Java that supports final fields

    - by naeron84
    I'm very new to Java but I've been developing a habit to use final wherever possible declaring immutability which i think is a good thing. (Consider f#) I've read that JPA does not support final fields. Hibernate, TopLink? I'm not sure about these but i prefer JPA for now. Is that even possible theoretically - let's say through reflection - to modify final fields after creation? My guess would be... NO :) What would be certainly possible for a persistence solution is to support constructors with parameters. At least i see no reason that would make this impossible. Mapping would be a little tricky i guess. This is an alternative solution. Suggestions?

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  • Memory-Mapped Files & Transparent Persistence of Java Objects

    - by geeko
    Greeting All, I want to achieve transparent persistence of Java objects through memory-mapped files (utilize the OS paging/swapping mechanism). My problem is: how can I move a Java object to my memory-mapped block ? Plus, how can I force a new object instance to reside in such blocks ? As you all know, a memory-mapped block can be seen as a byte array, and what I am really asking here is how to overlap the address space of Java objects with the one of such arrays ? If Java does not allow me for this, what cross-platform & garbage-collecting OO language would you advise me to use ? Thank you all in advance.

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  • Android Activities UI Persistence

    - by aandroid
    I need to have two activities in an Android app that can be switched between each other with UI persistence as follows: Activity A launches Activity B. User triggers some UI changes in Activity B. Activity B returns to Activity A (by a call to onBackPressed() or something similar) Activity A re-launches Activity B. I would like the changes made in step 2 to be visible in step 4. I have tried using the singleInstance activity tag on Activity B to no avail. I would also prefer a more elegant solution than simply writing all object properties to a file or SQLite table. It seems that this behaviour must be easily achievable given that Android does it automatically for calls to onBackPressed() where the parent Activity's UI is saved. Any help is much appreciated.

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  • Implementing Transparent Persistence

    - by Jules
    Transparent persistence allows you to use regular objects instead of a database. The objects are automatically read from and written to disk. Examples of such systems are Gemstone and Rucksack (for common lisp). Simplified version of what they do: if you access foo.bar and bar is not in memory, it gets loaded from disk. If you do foo.bar = baz then the foo object gets updated on disk. Most systems also have some form of transactions, and they may have support for sharing objects across programs and even across a network. My question is what are the different techniques for implementing these kind of systems and what are the trade offs between these implementation approaches?

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  • VB.NET - Send [Delegate] through the classes to set AddressOf

    - by sv88erik
    How can I put AddressOf, from another class? I get this error 'AddressOf' operand must be the name of a method (without parentheses). " Is there an Eval () function in VB.NET? Or how does one do this? Public Shared Property e As UserControl Public Shared Sub SetButton(ByVal button As String, ByVal Objekt As [Delegate]) Dim errorbuttom1 As Button = e.FindName("errorButton1") AddHandler errorbuttom1.Click, AddressOf Objekt End Sub

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  • What data structure to use / data persistence

    - by Dave
    I have an app where I need one table of information with the following fields: field 1 - int or char field 2 - string (max 10 char) field 3 - string (max 20 char) field 4 - float I need the program to filter on field 1 based upon a segmented control and select a field 2 from a picker. From this data I need to look up field 4 to use in a calculation. Total records will be about 200. I never see it go above 400 - 500. I am going to use a singleton which I am able to do, I just need help with the structure for this with data persistence. What type of data structure should I use for this and should I use NSNumber, NSString, etc. or old data types like float, Char, etc. I thought about a struct put into an array but there is probably a better way. This is new to me so any help or reference to examples would be great. I also thought about a plist or dictionary but it looks like it is just a lookup and a field which obviously won't work. Core data looked like overkill to me. Also, with any recommendation how should I get initial data into it? I want the user to be able to edit and add to the database. Sorry for the old terms, you can see what generation I am from... Thanks in advance!!!!

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  • Why put a DAO layer over a persistence layer (like JDO or Hibernate)

    - by Todd Owen
    Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when dealing with a particular class which contains a map of other objects: public class Book { // Book description in various languages, indexed by ISO language codes private Map<String,BookDescription> descriptions; } JDO is clever enough to map this to a foreign key constraint between the "BOOKS" and "BOOKDESCRIPTIONS" tables. It transparently loads the BookDescription objects (using lazy loading, I believe), and persists them when the Book object is persisted. If I was to introduce a "data access layer" and write a class like BookDao, and encapsulate all the JDO code within this, then wouldn't this JDO's transparent loading of the child objects be circumventing the data access layer? For consistency, shouldn't all the BookDescription objects be loaded and persisted via some BookDescriptionDao object (or BookDao.loadDescription method)? Yet refactoring in that way would make manipulating the model needlessly complicated. So my question is, what's wrong with calling JDO (or Hibernate, or whatever ORM you fancy) directly in the business layer? Its syntax is already quite concise, and it is datastore-agnostic. What is the advantage, if any, of encapsulating it in Data Access Objects?

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  • C# Delegate Invoke Required Issue

    - by Goober
    Scenario I have a C# windows forms application that has a number of processes. These processes run on separate threads and all communicate back to the Main Form class with updates to a log window and a progress bar. I'm using the following code below, which up until now has worked fine, however, I have a few questions. Code delegate void SetTextCallback(string mxID, string text); public void UpdateLog(string mxID, string text) { if (txtOutput.InvokeRequired) { SetTextCallback d = new SetTextCallback(UpdateLog); this.BeginInvoke(d, new object[] { mxID, text }); } else { UpdateProgressBar(text); } } Question Will, calling the above code about 10 times a second, repeatedly, give me errors, exceptions or generally issues?.....Or more to the point, should it give me any of these problems? Occasionally I get OutofMemory Exceptions and the program always seems to crash around this bit of code......

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  • iPhone: Sharing protocol/delegate code

    - by pion
    I have the following code protocol snippets: @protocol FooDelegate; @interface Foo : UIViewController { id delegate; } ... @protocol FooDelegate ... // method 1 ... // method 2 ... @end Also, the following code which implements FooDelegate: @interface Bar1 : UIViewController { ... } @interface Bar2 : UITableViewController { ... } It turns out the implementation of FooDelegate is the same on both Bar1 and Bar2 classes. I currently just copy FooDelegate implementation code from Bar1 to Bar2. How do I structure/implement in such a way that Bar1 and Bar2 share the same code in a single code base (not as currently with 2 copies) since they are the same? Thanks in advance for your help.

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  • Traditional loop versus Action delegate in C#

    - by emddudley
    After learning about the Action delegate in C# I've been looking for ways I can best use it in my code. I came up with this pattern: Action<string> DoSomething = (lSomething) => { // Do something }; DoSomething("somebody"); DoSomething("someone"); DoSomething("somewhere"); If I were to have used a traditional loop, it would look something like this: List<string> lSomeList = new List<string>(); lSomeList.Add("somebody"); lSomeList.Add("someone"); lSomeList.Add("somewhere"); foreach (string lSomething in lSomeList) { // Do something } Are there any appreciable differences between the two? To me they look equally easy to understand and maintain, but are there some other criteria I might use to distinguish when one might be preferred over the other?

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  • SKProductsRequest delegate methods are never called.

    - by coneybeare
    This used to work for me but is now not working anymore and I can't figure out why. I have in-app purchase setup in my app. I confirmed that I have a correct set of product identifiers, matched by corresponding in-app purchase items in itunesconnect. The call goes out to Apple view [productRequest start], but I never get a response back, despite setting the delegate to myself. What am I missing? NSLog(@"productIdentifiersSet: %@", productIdentifiersSet); if ([productIdentifiersSet count]) { SKProductsRequest *productRequest = [[SKProductsRequest alloc] initWithProductIdentifiers:productIdentifiersSet]; [productRequest setDelegate:self]; [productRequest start]; } ……… - (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response { <never called> } - (void)requestDidFinish:(SKRequest *)request { <never called> } - (void)request:(SKRequest *)request didFailWithError:(NSError *)error { <never called> }

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  • C#: Delegate syntax?

    - by Rosarch
    I'm developing a game. I want to have game entities each have their own Damage() function. When called, they will calculate how much damage they want to do: public class CombatantGameModel : GameObjectModel { public int Health { get; set; } /// <summary> /// If the attack hits, how much damage does it do? /// </summary> /// <param name="randomSample">A random value from [0 .. 1]. Use to introduce randomness in the attack's damage.</param> /// <returns>The amount of damage the attack does</returns> public delegate int Damage(float randomSample); public CombatantGameModel(GameObjectController controller) : base(controller) {} } public class CombatantGameObject : GameObjectController { private new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } public CombatantGameObject() { model = new CombatantGameModel(this); } } However, when I try to call that method, I get a compiler error: /// <summary> /// Calculates the results of an attack, and directly updates the GameObjects involved. /// </summary> /// <param name="attacker">The aggressor GameObject</param> /// <param name="victim">The GameObject under assault</param> public void ComputeAttackUpdate(CombatantGameObject attacker, CombatantGameObject victim) { if (worldQuery.IsColliding(attacker, victim, false)) { victim.Model.Health -= attacker.Model.Damage((float) rand.NextDouble()); // error here Debug.WriteLine(String.Format("{0} hits {1} for {2} damage", attacker, victim, attackTraits.Damage)); } } The error is: 'Damage': cannot reference a type through an expression; try 'HWAlphaRelease.GameObject.CombatantGameModel.Damage' instead What am I doing wrong?

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  • Moving delegate-related function to a different thread

    - by Chris
    Hello everybody. We are developing a library in C# that communicates with the serial port. We have a function that is given to a delegate. The problem is that we want it to be run in a different thread. We tried creating a new thread (called DatafromBot) but keep using it as follows (first line): comPort.DataReceived += new SerialDataReceivedEventHandler(comPort_DataReceived); DatafromBot = new Thread(comPort_DataReceived); DatafromBot.Start(); comPort_DataReceived is defined as: Thread DatafromBot; public void comPort_DataReceived(object sender, SerialDataReceivedEventArgs e) { ... } The following errors occur: Error 3 The best overloaded method match for 'System.Threading.Thread.Thread(System.Threading.ThreadStart)' has some invalid arguments C:...\IR52cLow\CommunicationManager.cs 180 27 IR52cLow Error 4 Argument '1': cannot convert from 'method group' to 'System.Threading.ThreadStart' C:...\IR52cLow\CommunicationManager.cs 180 38 IR52cLow Any ideas of how we should convert this to get it to compile? Please note that comPort.DataReceived (pay attention to "." instead of "_") lies within a system library and cannot be modified. Thanks for your time! Chris

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  • Web Frameworks caring about persistence?

    - by Mik378
    I have noticed that Play! Framework encompasses persistence strategy (like JPA etc...) Why would a web framework care about persistence ?! Indeed, this would be the job of the server-sides components (like EJB etc...), wouldn't this? Otherwise, client would be too coupled with server's business logic. UPDATE: One answer would be : it's more likely used for simple application including itself the whole business logics. However, for large applications with well-designed layers(services, domain, DAO's etc..), persistence is not recommended within web client layer since there would be several different web(or not) clients.

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