partial classes - Page 417

JPA + EJB + JSF: how can design complicated query

- by Harry Pham

I am using netbean 6.8 btw. Let say that I have 4 different tables: Company, Facility, Project, and Document. So the relationship is this. A company can have multiple facilities. A facility can have multiple projects, and a project can have multiple documents. Company: +companyNum: PK +facilityNum: FK Facility: +facilityNum: PK +projectNum: FK Project: +projectNum: PK +drawingNum: FK So when I create Entity Class From Database in netbean 6.8, I have 4 entity classes that named after the above 4 tables. So if I want to see all the Document in the database, then it is easy. In my SessionBean, I would do this: @PersistenceContext private EntityManager em; List<Document> documents = em.createNamedQuery("Document.findAll").getResultList(); However, that is not all what I need. Let say that I want to know all the Document from a particular Company, or all the Document from a particular Project from a particular Facility from a particular Company. I am very new to JPA + EJB + JSF as a whole. Please help me out.

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Cast base class object to derived class

- by Popgalop

Lets say I have two classes, animal and dog like this. class Animal { }; class Dog : public Animal { }; And I have an animal object named animal, that is actually an instance of dog, how would I cast it back to dog? This may seem like an odd question, but I need it because I am writing a programming language interpreter, and on the stack everything is stored as a BaseObject, and all the other datatypes extend BaseObject. How would I cast the base object from the stack, to a specific data type? I have tried something like this Dog dog = static_cast<Dog>(animal); But it gives me an error 1>------ Build started: Project: StackTests, Configuration: Debug Win32 ------ 1> StackTests.cpp 1>c:\users\owner\documents\visual studio 2012\projects\stacktests\stacktests\stacktests.cpp(173): error C2440: 'static_cast' : cannot convert from 'Animal' to 'Dog' 1> No constructor could take the source type, or constructor overload resolution was ambiguous 1>c:\users\owner\documents\visual studio 2012\projects\stacktests\stacktests\stacktests.cpp(173): error C2512: 'Dog' : no appropriate default constructor available ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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Vertical line on HxW canvas of pixels

- by bobby williams

I searched and found nothing. I'm trying to draw lines (simple y=mx+b ones) on a canvas of black pixels. It works fine, but no line occurs when it is vertical. I'm not sure why. My first if statement checks if the denominator is zero, therefore m is undefined and no need for a line equation. My second and third if statement check how steep it is and based on that, calculate the points in between. I don't think there is a need for other classes, since I think there is a bug in my code or I'm just not translating the mathematics into code properly. If more is needed, I'll be happy to post more. /** * Returns an collection of points that connects p1 and p2 */ public ArrayList getPoints() { ArrayList points = new ArrayList(); // checks to see if denominator in m is zero. if zero, undefined. if ((p2.getX() - p1.getX()) == 0) { for (int y = p1.getY(); y<p2.getY(); y++) { points.add(new Point(p1.getX(), y, getColor())); } } double m = (double)(p2.getY()-p1.getY())/(double)(p2.getX()-p1.getX()); int b = (int)(p1.getY() - (m * p1.getX())); // checks to see if slope is steep. if (m > -1 || m < 1) { for (int x = p1.getX(); x<p2.getX(); x++) { int y = (int) ((m*x)+b); points.add(new Point(x, y, getColor())); } } // checks to see if slope is not steep. if (m <= -1 || m >= 1) { for (int y = p1.getY(); y<p2.getY(); y++) { int x = (int) ((y-b)/m); points.add(new Point(x, y, getColor())); } } return points; }

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Simple Fluent NHibernate Mapping Problem

- by user500038

I have the following tables I need to map: +-------------------------+ | Person | +-------------------------+ | PersonId | | FullName | +-------------------------+ +-------------------------+ | PersonAddress | +-------------------------+ | PersonId | | AddressId | | IsDefault | +-------------------------+ +-------------------------+ | Address | +-------------------------+ | AddressId | | State | +-------------------------+ And the following classes: public class Person { public virtual int Id { get; set; } public virtual string FullName { get; set; } } public class PersonAddress { public virtual Person Person { get; set; } public virtual Address Address { get; set; } public virtual bool IsDefault { get; set; } } public class Address { public virtual int Id { get; set; } public virtual string State { get; set; } } And finally the mappings: public class PersonMap : ClassMap<Person> { public PersonMap() { Id(x => x.Id, "PersonId"); } } public class PersonAddressMap : ClassMap<PersonAddress> { public PersonAddressMap() { CompositeId().KeyProperty(x => x.Person, "PersonID") .KeyProperty(x => x.Address, "AddressID"); } } public class AddressMap: ClassMap<Address> { public AddressMap() { Id(x => x.Id, "AddressId"); } } Assume I cannot alter the tables. If I take the mapping class (PersonAddress) out of the equation, everything works fine. If I put it back in I get: Could not determine type for: Person, Person, Version=1.0, Culture=neutral, PublicKeyToken=null, for columns: NHibernate.Mapping.Column(PersonId) What am I missing here? I'm sure this must be simple.

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c# Why can't open generic types be passed as parameters?

- by Rich Oliver

Why can't open generic types be passed as parameters. I frequently have classes like: public class Example<T> where T: BaseClass { public int a {get; set;} public List<T> mylist {get; set;} } Lets say BaseClass is as follows; public BaseClass { public int num; } I then want a method of say: public int MyArbitarySumMethod(Example example)//This won't compile Example not closed { int sum = 0; foreach(BaseClass i in example.myList)//myList being infered as an IEnumerable sum += i.num; sum = sum * example.a; return sum; } I then have to write an interface just to pass this one class as a parameter as follows: public interface IExample { public int a {get; set;} public IEnumerable<BaseClass> myIEnum {get;} } The generic class then has to be modified to: public class Example<T>: IExample where T: BaseClass { public int a {get; set;} public List<T> mylist {get; set;} public IEnumerable<BaseClass> myIEnum {get {return myList;} } } That's a lot of ceremony for what I would have thought the compiler could infer. Even if something can't be changed I find it psychologically very helpful if I know the reasons / justifications for the absence of Syntax short cuts.

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C++ and Dependency Injection in unit testing

- by lhumongous

Suppose I have a C++ class like so: class A { public: A() { } void SetNewB( const B& _b ) { m_B = _b; } private: B m_B; } In order to unit test something like this, I would have to break A's dependency on B. Since class A holds onto an actual object and not a pointer, I would have to refactor this code to take a pointer. Additionally, I would need to create a parent interface class for B so I can pass in my own fake of B when I test SetNewB. In this case, doesn't unit testing with dependency injection further complicate the existing code? If I make B a pointer, I'm now introducing heap allocation, and some piece of code is now responsible for cleaning it up (unless I use ref counted pointers). Additionally, if B is a rather trivial class with only a couple of member variables and functions, why introduce a whole new interface for it instead of just testing with an instance of B? I suppose you could make the argument that it would be easier to refactor A by using an interface. But are there some cases where two classes might need to be tightly coupled?

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C++ private inheritance and static members/types

- by WearyMonkey

I am trying to stop a class from being able to convert its 'this' pointer into a pointer of one of its interfaces. I do this by using private inheritance via a middle proxy class. The problem is that I find private inheritance makes all public static members and types of the base class inaccessible to all classes under the inheriting class in the hierarchy. class Base { public: enum Enum { value }; }; class Middle : private Base { }; class Child : public Middle { public: void Method() { Base::Enum e = Base::value; // doesn't compile BAD! Base* base = this; // doesn't compile GOOD! } }; I've tried this in both VS2008 (the required version) and VS2010, neither work. Can anyone think of a workaround? Or a different approach to stopping the conversion? Also I am curios of the behavior, is it just a side effect of the compiler implementation, or is it by design? If by design, then why? I always thought of private inheritance to mean that nobody knows Middle inherits from Base. However, the exhibited behavior implies private inheritance means a lot more than that, in-fact Child has less access to Base than any namespace not in the class hierarchy!

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jtable update data not visible

- by Thomas n

I am running into a problem similar to what I have read here about inserted data and added data not showing up on jtable. I have tried repaint() and revalidate(), but to no avail. Basically, I have two classes say A and B. A calls a function in class B to add a row of data to the table. Here is the code.(By the way I am using Netbeans 7.1.2 to add a table and then add some code to handle the update.) public void callUpdateTable(){ DefaultTableModel myModel = (DefaultTableModel)jTable1.getModel(); DateFormat dateFormate = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss"); Object[] str = new Object[3]; Date date = new Date(); str[0] = dateFormate.format(date); str[1] = "Robot"; str[2] = "hello"; // myModel.addRow(str); myModel.insertRow(1, str); myModel.setValueAt("Hello", 1, 2); System.out.println("count = " + myModel.getValueAt(1, 2)); jTable1.repaint(); } The funny thing is on system print it prints out the value at the cell(1,2) I set the value, but doesn't show up on the table. Thank you for your help.

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What would be a better implementation of shared variable among subclass

- by Churk

So currently I have a spring unit testing application. And it requires me to get a session cookie from a foreign authentication source. Problem what that is, this authentication process is fairly expensive and time consuming, and I am trying to create a structure where I am authenticate once, by any subclass, and any subsequent subclass is created, it will reuse this session cookie without hitting the authentication process again. My problem right now is, the static cookie is null each time another subclass is created. And I been reading that using static as a global variable is a bad idea, but I couldn't think of another way to do this because of Spring framework setting things during run time and how I would set the cookie so that all other classes can use it. Another piece of information. The variable is being use, but is change able during run time. It is not a single user being signed in and used across the board. But more like a Sub1 would call login, and we have a cookie. Then multiple test will be using that login until SubX will come in and say, I am using different credential, so I need to login as something else. And repeats. Here is a outline of my code: public class Parent implements InitializingBean { protected static String BASE_URL; public static Cookie cookie; ... All default InitializingBean methods ... afterPropertiesSet() { cookie = // login process returns a cookie } } public class Sub1 extends Parent { @resource public String baseURL; @PostConstruct public void init() { // set parents with my baseURL; BASE_URL = baseURL; } public void doSomething() { // Do something with cookie, because it should have been set by parent class } } public class Sub2 extends Parent { @resource public String baseURL; @PostConstruct public void init() { // set parents with my baseURL; BASE_URL = baseURL; } public void doSomethingElse() { // Do something with cookie, because it should have been set by parent class } }

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problem with "select new Object ... join ... where"

- by jacob

Hi, I'm having a problem with an HQL query Three classes ClassOne is my BusinessObject public class ClassOne { private int id; private int status; private Set<ClassTwo> classTwos; + other fields/getters/setters/constructor etc } ClassTwo is referenced in a set of ClassOne and is kind of the history of an object of ClassOne public class ClassTwo { private int id; private int oldStatus; private int newStatus; private String message; //+ getters/setters/constructor etc } ClassThree is my DTO/VO with just one classTwo (not the whole history) public class ClassThree { private int id; private int status; private ClassTwo classTwo; public ClassThree(int pId, int pStatus, ClassTwo pClassTwo) { id=pId; status=pStatus; classTwo=pClassTwo; } //+ getters/setters etc } Now I'd like to create an HQL query like this: I'd like to get all objects of ClassThree with a certain status and if it exists the newest ClassTwo with a certain newStatus. For example: I'd like to get all the DTOs (ClassThree) of ClassOne whose status is now 1, but earlier in their history it has been 2 and I'd like to have the latest ClassTwo object which has 2 as newStatus. SELECT new ClassThree(c1.id, c1.status, c2) FROM ClassOne c1 LEFT JOIN c1.classtwos c2 (...) and (...) is where I don't know what to do, I'm not even sure if it's a join / join fetch Looked around and tried quite a lot already, but no clue. Especially with the join fetch I get some Hibernate errors like org.hibernate.QueryException: query specified join fetching, but the owner of the fetched association was not present in the select list. Fetching the BusinessObject like that is no problem SELECT distinct(c1) FROM ClassOne c1 LEFT OUTER JOIN FETCH c1.classtwos c2 and I get the ClassTwos as my field. Thanks in advance, Jacob P.S.: One thing might be important, ClassTwo has no reference to ClassOne!!

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Rate my C# code (~300 SLOC) using GDI+/Backgroundworker

- by sebastianlarsson

Hi, I want to get some feedback on my code! Below is some background info. I am taking a pre-certification course in C# (Sweden, 15 ECTS). The focus of the course is theoretical and only limited practical work. I dont find the assignments very hard at all to tell you the truth, but since I only have very limited work experience as a developer (I have worked 15h/week at Ericsson since November) I think I would benefit from having the certificate (70-536 and more probably). I am currently reading Martin Fowler's "Refactoring: Improving the design of existing code" and I tried to apply his techniques to my latest lab in the course. I have been on the lookout for a website which have the idea of providing feedback on code, but so far I have yet to discover any. Please take a look on my code and tell me what you think. It is only roughly 300 lines of code divided into a couple of classes. GDI+, backgroundworker and user controls are what the lab is about. I reckon you may have to spend as little as a couple of minutes on looking on the solution. Link to solution: http://www.filefactory.com/file/b18h7d5/n/Lab4_Lab5_SebastianLarsson.zip Regards and thank you, Sebastian

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What database options do I have for the Blackberry?

- by peeping-jane

I notice most of the discussions about Blackberry database options are old, and generally not too informative. As of today, March 31st, 2010, what is the best, most universally supported, free database option available for Blackberry developers? I heard SQLite is available for JDE v5, but last I checked, that was still in beta, and I didn't want to commit to developing on a system that is not supported by most of the phones in service. Thing is, I don't see any dates on these claims. For all I know, the announcements I am reading are from 2008. So, I am still on v 4.7. I need to use a relational DB for the app I am developing, but there aren't many resources for DB handling available - or at least resources that are useful to me. I find a lot of "tutorials" that assume you know everything there is to know about Blackberry development, or Java. But no complete classes or anything. Many of these examples don't even work. Eclipse gives warnings and errors from code copied and pasted from other people's examples. I can answer any questions that may assist in this case. Hopefully, this thread will help many BB developers in the future.

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What do you call a generalized (non-GUI-related) "Model-View-Controller" architecture?

- by dcuccia

I am currently refactoring code that coordinates multiple hardware components for data acquisition, and feeling a bit like I'm recreating the wheel. In particular, an MVC-like pattern seems to be emerging. Except, this has nothing to do with a GUI and I'm worried that I'm forcing this particular pattern where another might be more appropriate. Here's my scenario: Individual hardware "component" classes obey interface contracts for each hardware type. Previously, component instances were orchestrated by a single monolithic InstrumentController class, which relied heavily on configuration + branching logic for executing a specific acquisition sequence. After an iteration, I have a separate controller for each component, with these controllers all managed by a small InstrumentControllerBase (or its derivatives). The composite system will receive "input" either programmatically or via inter-hardware component triggering - in either case these interactions are routed to, and handled by, the appropriate controller. So, I have something that feels MVC-esque, but I don't know if that's because I'm forcing the point. With little direct MVC experience in application development, it's hard to know if I'm just trying to make my scenario fit MVC, where another pattern might be a good alternative or complimentary. My problem is, search results and wiki documentation of these family of patterns seems to immediately drop me into GUI-specific discussions. I understand "M means Model data and the V means View" - but do you call the superset pattern? Component-Commander-Controller? Whence can I exhume examples exemplary?

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How should I handle header files in a bundle?

- by ldiqual

I want to develop a program that relies on plugins (here: loadable bundles) to work. Multiple plugins are asked to use the same AFNetworking ressource to make network requests. However, I don't know where to put AFNetworking and CustomPluginProtocol headers. Here is how my program structure looks like for now: MyApp.xcodeproj - AFNetworking - Header.h - Plugins - Plugin1.xcodeproj - PrincipalClass.m - Plugin2.xcodeproj - PrincipalClass.m - Classes - CustomPluginProtocol.h - MainClass.m Of course, every principalClass from PluginN complies to the CustomPluginProtocol. Do the headers have to be copied in each bundle ? Can I just include the main program AFNetworking headers from my plugins ? If so (and that's what I do for now), I don't have any completion. How can I get it ? Edit Ok, so maybe I wasn't clear in my question. I want my plugins to use sources from the main application, let's say CommonClass.m and CommonClass.h. Do the plugins need CommonClass.h in their bundle, and if not, how do I enable completion when I'm in the plugin scope ?

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How do i implement tag searching with lucene?

- by acidzombie24

I havent used lucene. Last time i ask (many months ago, maybe a year) people suggested lucene. As am example say there are 3 items tag like this apples carrots apples carrots apple banana if a user search apples i dont care if there is any preference from 1,2 and 4. However i seen many forums do this which i hated is when a user search apple carrots 2 and 3 are get high results while 1 is hard to find even though it matches my search more closely. I HATED this in forums. Also i would like the ability to do search carrots -apples which will only get me 3. I am not sure what should happen if i search carrots banana but anyways as long as more 2 and 3 results are lower priority then 1 when i search apples carrots i'll be happy. Can lucene do this? and where do i start? i see a lot of classes and many of them talk about docs. What should i use for tagging?

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How do I use the Enum value from a class in another part of code?

- by ChiggenWingz

Coming from a C# background from a night course at a local college, I've sort of started my way in C++. Having a lot pain getting use to the syntax. I'm also still very green when it comes to coding techniques. From my WinMain function, I want to be able to access a variable which is using an enum I declared in another class. (inside core.h) class Core { public: enum GAME_MODE { INIT, MENUS, GAMEPLAY }; GAME_MODE gameMode; Core(); ~Core(); ...OtherFunctions(); }; (inside main.cpp) Core core; int WINAPI WinMain(...) { ... startup code here... core.gameMode = Core.GAME_MODE.INIT; ...etc... } Basically I want to set that gameMode to the enum value of Init or something like that from my WinMain function. I want to also be able to read it from other areas. I get the error... expected primary-expression before '.' token If I try to use core.gameMode = Core::GAME_MODE.INIT;, then I get the same error. I'm not fussed about best practices, as I'm just trying to get the basic understanding of passing around variables in C++ between files. I'll be making sure variables are protected and neatly tucked away later on once I am use to the flexibility of the syntax. If I remember correctly, C# allowed me to use Enums from other classes, and all I had to do was something like Core.ENUMNAME.ENUMVALUE. I hope what I'm wanting to do is clear :\ As I have no idea what a lot of the correct terminology is.

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Are workflows good for web service business logic?

- by JL

I have a series of complex web services that are getting used in my SOA application. I am generally happy with the overall design of the application, but as the complexity grows, I was wondering if Windows Workflow might be the way to go. My motivations for this are that you can get a graphic representation of the applications functionality, so it would be easier to maintain the code by its business function, rather than what I have now ( a standard 3 tier class library structure). My concerns are: I would be inducing an abstraction in my code, and I don't want to spend time having to deal with possible WF quirks or bugs. I've never worked with WF, is it a solid technology? I don't want to hit any WF limitations that prevent me from developing my solution. Is a WF even the right solution for the task? Simply put I am considering writing my next web service in this app to call a WF, and in this work flow manage the tasks the web service needs to carry out. I think it will be much neater and easier to maintain than a regular c# class library (maintainable by namespaces, classes ). Do you think this is the right thing to do? I'm hoping for positive feedback on WF (.net 4), but brutal honestly at the end of the day would help more. Thanks

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Convert SVG to PDF

- by Adrian Smith

How would one go about converting a SVG file to a PDF programatically? (I need to alter the SVG in certain respects before generating the PDF so simply pre-converting it using a tool won't be sufficient.) Ideally using Java but Perl or PHP would be fine too. Obviously I am basically considering Apache FOP and Batik with Java. However no matter how long I search I cannot find a simple introduction on how to do it. Things like SVGConverter have descriptions like "Defines the interface for classes that are able to convert part or all of a GraphicContext", but I don't really know what that means. I have this feeling there must be an API to do this quite simply, provided by FOP or Batik, but I'm just not able to find it at the moment (or perhaps it really doesn't exist.) In terms of the supported SVG features I need, the file has some paths which are filled with some linear gradients. Ideally if I could pass the SVG in as a DOM Document that would be ideal; then I would load my template SVG file, change it as specified by the user, and then generate the PDF.

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Add file in ANT build (Tomcat server)

- by Shaded

Hey everyone, I have an ANT build that I need to setup so on deployment of the .war a certain file will be placed in a specific location. Currently my ant builds the war as follows... <target name="war" depends="jar"> <war destfile="${deploy}/file.war" webxml="${web-inf}/web.xml"> <fileset dir="${WebRoot}"> <include name="**/*.vm" /> <include name="**/*.js" /> <include name="**/*.jsp" /> <include name="**/*.html" /> <include name="**/*.css" /> <include name="**/*.gif" /> <include name="**/*.jpg" /> <include name="**/*.png" /> <include name="**/*.tld" /> <include name="**/applicationContext*.xml" /> <include name="**/jpivot/**" /> <include name="**/wcf/**" /> <include name="**/platform/**" /> <include name="**/Reports/**" /> </fileset> <lib dir="${web-inf.lib}" /> </war> </target> The file I need is called Scriptlet.class and it needs to be in WebRoot/WEB-INF/classes/ I've tried several things to get this to work and have yet to find one that works... if anyone can point me in the right direction I'd appreciate it!

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Which options do I have for Java process communication?

- by Dmitriy Matveev

We have a place in a code of such form: void processParam(Object param) { wrapperForComplexNativeObject result = jniCallWhichMayCrash(param); processResult(result); } processParam - method which is called with many different arguments. jniCallWhichMayCrash - a native method which is intended to do some complex processing of it's parameter and to create some complex object. It can crash in some cases. wrapperForComplexNativeObject - wrapper type generated by SWIG processResult - a method written in pure Java which processes it's parameter by creation of several kinds (by the kinds I'm not meaning classes, maybe some like hierarchies) of objects: 1 - Some non-unique objects which are referencing each other (from the same hierarchy), these objects can have duplicates created from the invocations of processParam() method with different parameter values. Since it's costly to keep all the duplicates it's necessary to cache them. 2 - Some unique objects which are referencing each other (from the same hierarchy) and some of the objects of 1st kind. After processParam is executed for each of the arguments from some set the data created in processResult will be processed together. The problem is in fact that jniCallWhichMayCrash method may crash the entire JVM and this will be very bad. The reason of crash may be such that it can happen for one argument value and not for the other. We've decided that it's better to ignore crashes inside of JVM and just skip some chunks of data when such crashes occur. In order to do this we should run processParam function inside of separate process and pass the result somehow (HOW? HOW?! This is a question) to the main process and in case of any crashes we will only lose some part of data (It's ok) without lose of everything else. So for now the main problem is implementation of transport between different processes. Which options do I have? I can think about serialization and transmitting of binary data by the streams, but serialization may be not very fast due to object complexity. Maybe I have some other options of implementing this?

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How can I get my business objects layer to use the management layer in their methods?

- by Tom Pickles

I have a solution in VS2010 with several projects, each making up a layer within my application. I have business entities which are currently objects with no methods, and I have a management layer which references the business entities layer in it's project. I now think I have designed my application poorly and would like to move methods from helper classes (which are in another layer) into methods I'll create within the business entities themselves. For example I have a VirtualMachine object, which uses a helper class to call a Reboot() method on it which passes the request to the management layer. The static manager class talks to an API that reboots the VM. I want to move the Reboot() method into the VirtualMachine object, but I will need to reference the management layer: public void Reboot() { VMManager.Reboot(this.Name); } So if I add a reference to my management project in my entities project, I get the circular dependency error, which is how it should be. How can I sort this situation out? Do I need to an yet another layer between the entity layer and the management layer? Or, should I just forget it and leave it as it is. The application works ok now, but I am concerned my design isn't particularly OOP centric and I would like to correct this.

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Hibernate many-to-one - bad usage?

- by DaveA

Just trying out Hibernate (with Annotations) and I'm having problems with my mappings. I have two entity classes, AudioCD and Artist. @Entity public class AudioCD implements CatalogItem { @Id @GeneratedValue(strategy = GenerationType.AUTO) private int id; private String title; @ManyToOne(cascade = { CascadeType.ALL }, optional = false) private Artist artist; .... } @Entity @Table(uniqueConstraints = { @UniqueConstraint(columnNames = { "name" }) }) public class Artist { @Id @GeneratedValue(strategy = GenerationType.AUTO) private int id; @Column(nullable = false) private String name; ..... } I get AudioCD objects from an external source. When I try to persist the AudioCD the Artist gets persisted as well, just like I want to happen. If I try persisting another different CD, but Artist already exists I get errors due to constraint violations. I want Hibernate to recognise that the Artist already exists and shouldn't be inserted again. Can this be done via annotations? Or do I have to manage the persistence of the AudioCD and Artist seperately?

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Unable to delete inherited entity class in EF4

- by Coding Gorilla

I have two entities in an EF4 model (using Model First), let's call them EntityA and EntityB. EntityA is marked as abstract, and EntityB inherits from EntityA. They are similar to the following: public class EntityA { public Guid Id; public string Name; public string Uri; } public class EntityB : EntityA { public string AnotherProperty; } The generated database tables look as I would expect them, with EntityA as on table, and then another table like: EntityA_EntityB Id (PK, FK, uniqueidentifier) AnotherProperty (varchar) There is a foreign key constraint on EntityA_EntityB that references EntityA's Id property, no cascades are configured (although I did try changing these myself). The problem is that when I attempt to do something like: Context.DeleteObject(EntityA_EntityB); EF attempts to delete the EntityA_EntityB table record before deleting the EntityA table record, which of course violates the foreign key constraint on EntityA_EntityB table. Using EFProfiler I see the following commands being sent to the database: delete [dbo].[EntityA_EntityB] where (([Id] = '5c02899f-09ea-2ed9-d44b-01aef80f6b64' /* @0 */) followed by delete [dbo].[EntityA] where ([Id] = '5c02899f-09ea-2ed9-d44b-01aef80f6b64' /* @0 */) I'm completely stumped as to how to get around this problem. I would think the EF should know that it needs to delete the base class first, before deleting the inherited class. I know I could do some triggers or other database type solutions, but I'd rather avoid doing that if I can. All my classes are POCO built using some customized T4 templates. I don't want to paste in a lot of extraneous code, but if you need more information I'll provide what I can.

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Creating simple calculator with bison & flex in C++ (not C)

- by ak91

Hey, I would like to create simple C++ calculator using bison and flex. Please note I'm new to the creating parsers. I already found few examples in bison/flex but they were all written in C. My goal is to create C++ code, where classes would contain nodes of values, operations, funcs - to create AST (evaluation would be done just after creating whole AST - starting from the root and going forward). For example: my_var = sqrt(9 ** 2 - 32) + 4 - 20 / 5 my_var * 3 Would be parsed as: = / \ my_var + / \ sqrt - | / \ - 4 / / \ / \ ** 32 20 5 / \ 9 2 and the second AST would look like: * / \ my_var 3 Then following pseudocode reflects AST: ast_root = create_node('=', new_variable("my_var"), exp) where exp is: exp = create_node(OPERATOR, val1, val2) but NOT like this: $$ = $1 OPERATOR $3 because this way I directly get value of operation instead of creation the Node. I believe the Node should contain type (of operation), val1 (Node), val2 (Node). In some cases val2 would be NULL, like above mentioned sqrt which takes in the end one argument. Right? It will be nice if you can propose me C++ skeleton (without evaluation) for above described problem (including *.y file creating AST) to help me understand the way of creating/holding Nodes in AST. Code can be snipped, just to let me get the idea. I'll also be grateful if you point me to an existing (possibly simple) example if you know any. Thank you all for your time and assistance!

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Password value on click is not changing the text to 'Password'

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