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  • C# property definition

    - by Sunny
    For C# properties, I can do this: public class Employee{ public string Name { get; private set; } public Employee(string name){ Name = name; } } which means that the Name property can be set within the class Employee & can be read publicly. But, if I want to restrict the set to only within the constructors of the Employee class, I need to do: public class Employee{ public readonly string Name = String.Empty; public Employee(string name){ Name = name; } } But, for this case, I had to change the property to a field. Is there any reason this is not possible/allowed in C#: public class Employee{ public string Name { get; private readonly set; } public Employee(string name){ Name = name; } } IMO this will allow us to have properties which can be set only in the constructor & does not require us to change properties to fields... Thanks!

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  • Hot to get generic type from object type

    - by Murat
    My Classes are; class BaseClass { } class DerivedClass1 : BaseClass { } class GenericClass<T> { } class DerivedClass2 : BaseClass { GenericClass<DerivedClass1> subItem; } I want to access all fields of DerivedClass2 class. I use System.Reflection and FieldInfo.GetValue() method; Bu I cant get subItem field. FieldInfo.GetValue() method return type is "object". And I cant cast to GenericClass<DerivedClass1> or I cant get DerivedClass1 type. I try this with BaseClass BaseClass instance = FieldInfo.Getvalue(this) as GenericClass<BaseClass>; but instance is null. How to get instance with type or how to get only type?

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  • Dajano admin site foreign key fields

    - by user292652
    hi i have the following models setup class Player(models.Model): #slug = models.slugField(max_length=200) Player_Name = models.CharField(max_length=100) Nick = models.CharField(max_length=100, blank=True) Jersy_Number = models.IntegerField() Team_id = models.ForeignKey('Team') Postion_Choices = ( ('M', 'Manager'), ('P', 'Player'), ) Poistion = models.CharField(max_length=1, blank=True, choices =Postion_Choices) Red_card = models.IntegerField( blank=True, null=True) Yellow_card = models.IntegerField(blank=True, null=True) Points = models.IntegerField(blank=True, null=True) #Pic = models.ImageField(upload_to=path/for/upload, height_field=height, width_field=width, max_length=100) class PlayerAdmin(admin.ModelAdmin): list_display = ('Player_Name',) search_fields = ['Player_Name',] admin.site.register(Player, PlayerAdmin) class Team(models.Model): """Model docstring""" #slug = models.slugField(max_length=200) Team_Name = models.CharField(max_length=100,) College = models.CharField(max_length=100,) Win = models.IntegerField(blank=True, null=True) Loss = models.IntegerField(blank=True, null=True) Draw = models.IntegerField(blank=True, null=True) #logo = models.ImageField(upload_to=path/for/upload, height_field=height, width_field=width, max_length=100) class Meta: pass #def __unicode__(self): # return Team_Name #def save(self, force_insert=False, force_update=False): # pass @models.permalink def get_absolute_url(self): return ('view_or_url_name') class TeamAdmin(admin.ModelAdmin): list_display = ('Team_Name',) search_fields = ['Team_Name',] admin.site.register(Team, TeamAdmin) my question is how do i get to the admin site to show Team_name in the add player form Team_ID field currently it is only showing up as Team object in the combo box

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  • C#: How to inherit constructors?

    - by Ian Boyd
    Imagine a base class with many constructors and a virtual method public class Foo { ... public Foo() {...} public Foo(int i) {...} ... public virtual void SomethingElse() {...} ... } and now I want to create a descendant class that overrides the virtual method: public class Bar : Foo { public override void SomethingElse() {...} } And another descendant that does some more stuff: public class Bah : Bar { public void DoMoreStuff() {...} } Do I really have to copy all constructors from Foo into Bar and Bah? And then if I change a constructor signature in Foo, do I have to update it in Bar and Bah? Is there no way to inherit constructors? Is there no way to encourage code reuse?

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  • Subterranean IL: The ThreadLocal type

    - by Simon Cooper
    I came across ThreadLocal<T> while I was researching ConcurrentBag. To look at it, it doesn't really make much sense. What's all those extra Cn classes doing in there? Why is there a GenericHolder<T,U,V,W> class? What's going on? However, digging deeper, it's a rather ingenious solution to a tricky problem. Thread statics Declaring that a variable is thread static, that is, values assigned and read from the field is specific to the thread doing the reading, is quite easy in .NET: [ThreadStatic] private static string s_ThreadStaticField; ThreadStaticAttribute is not a pseudo-custom attribute; it is compiled as a normal attribute, but the CLR has in-built magic, activated by that attribute, to redirect accesses to the field based on the executing thread's identity. TheadStaticAttribute provides a simple solution when you want to use a single field as thread-static. What if you want to create an arbitary number of thread static variables at runtime? Thread-static fields can only be declared, and are fixed, at compile time. Prior to .NET 4, you only had one solution - thread local data slots. This is a lesser-known function of Thread that has existed since .NET 1.1: LocalDataStoreSlot threadSlot = Thread.AllocateNamedDataSlot("slot1"); string value = "foo"; Thread.SetData(threadSlot, value); string gettedValue = (string)Thread.GetData(threadSlot); Each instance of LocalStoreDataSlot mediates access to a single slot, and each slot acts like a separate thread-static field. As you can see, using thread data slots is quite cumbersome. You need to keep track of LocalDataStoreSlot objects, it's not obvious how instances of LocalDataStoreSlot correspond to individual thread-static variables, and it's not type safe. It's also relatively slow and complicated; the internal implementation consists of a whole series of classes hanging off a single thread-static field in Thread itself, using various arrays, lists, and locks for synchronization. ThreadLocal<T> is far simpler and easier to use. ThreadLocal ThreadLocal provides an abstraction around thread-static fields that allows it to be used just like any other class; it can be used as a replacement for a thread-static field, it can be used in a List<ThreadLocal<T>>, you can create as many as you need at runtime. So what does it do? It can't just have an instance-specific thread-static field, because thread-static fields have to be declared as static, and so shared between all instances of the declaring type. There's something else going on here. The values stored in instances of ThreadLocal<T> are stored in instantiations of the GenericHolder<T,U,V,W> class, which contains a single ThreadStatic field (s_value) to store the actual value. This class is then instantiated with various combinations of the Cn types for generic arguments. In .NET, each separate instantiation of a generic type has its own static state. For example, GenericHolder<int,C0,C1,C2> has a completely separate s_value field to GenericHolder<int,C1,C14,C1>. This feature is (ab)used by ThreadLocal to emulate instance thread-static fields. Every time an instance of ThreadLocal is constructed, it is assigned a unique number from the static s_currentTypeId field using Interlocked.Increment, in the FindNextTypeIndex method. The hexadecimal representation of that number then defines the specific Cn types that instantiates the GenericHolder class. That instantiation is therefore 'owned' by that instance of ThreadLocal. This gives each instance of ThreadLocal its own ThreadStatic field through a specific unique instantiation of the GenericHolder class. Although GenericHolder has four type variables, the first one is always instantiated to the type stored in the ThreadLocal<T>. This gives three free type variables, each of which can be instantiated to one of 16 types (C0 to C15). This puts an upper limit of 4096 (163) on the number of ThreadLocal<T> instances that can be created for each value of T. That is, there can be a maximum of 4096 instances of ThreadLocal<string>, and separately a maximum of 4096 instances of ThreadLocal<object>, etc. However, there is an upper limit of 16384 enforced on the total number of ThreadLocal instances in the AppDomain. This is to stop too much memory being used by thousands of instantiations of GenericHolder<T,U,V,W>, as once a type is loaded into an AppDomain it cannot be unloaded, and will continue to sit there taking up memory until the AppDomain is unloaded. The total number of ThreadLocal instances created is tracked by the ThreadLocalGlobalCounter class. So what happens when either limit is reached? Firstly, to try and stop this limit being reached, it recycles GenericHolder type indexes of ThreadLocal instances that get disposed using the s_availableIndices concurrent stack. This allows GenericHolder instantiations of disposed ThreadLocal instances to be re-used. But if there aren't any available instantiations, then ThreadLocal falls back on a standard thread local slot using TLSHolder. This makes it very important to dispose of your ThreadLocal instances if you'll be using lots of them, so the type instantiations can be recycled. The previous way of creating arbitary thread-static variables, thread data slots, was slow, clunky, and hard to use. In comparison, ThreadLocal can be used just like any other type, and each instance appears from the outside to be a non-static thread-static variable. It does this by using the CLR type system to assign each instance of ThreadLocal its own instantiated type containing a thread-static field, and so delegating a lot of the bookkeeping that thread data slots had to do to the CLR type system itself! That's a very clever use of the CLR type system.

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  • SpringMvc java.lang.NullPointerException When Posting Form To Server [closed]

    - by dev_darin
    I have a form with a user name field on it when i tab out of the field i use a RESTFUL Web Service that makes a call to a handler method in the controller. The method makes a call to a DAO class that checks the database if the user name exists. This works fine, however when the form is posted to the server i call the same exact function i would call in the handler method however i get a java.lang.NullPointerException when it accesses the class that makes a call to the DAO object. So it does not even access the DAO object the second time. I have exception handlers around the calls in all my classes that makes calls. Any ideas as to whats happening here why i would get the java.lang.NullPointerException the second time the function is called.Does this have anything to do with Spring instantiating DAO classes using a Singleton method or something to that effect? What can be done to resolve this? This is what happens the First Time The Method is called using the Web Service(this is suppose to happen): 13011 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - Inside jdbcOfficersDAO 13031 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL query 13034 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL statement [SELECT userName FROM crimetrack.tblofficers WHERE userName = ?] 13071 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource 13496 [http-8084-2] DEBUG org.springframework.jdbc.core.StatementCreatorUtils - Setting SQL statement parameter value: column index 1, parameter value [adminz], value class [java.lang.String], SQL type unknown 13534 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource 13537 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - No username was found in exception 13537 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz does NOT exist The Second time When The Form Is 'Post' and a validation method handles the form and calls the same method the web service would call: 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - Inside Do UserNameExist about to validate with username : adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz EXCEPTION OCCURED java.lang.NullPointerException ValidateUserNameManager.java public class ValidateUserNameManager implements ValidateUserNameIFace { private OfficersDAO officerDao; private final Logger logger = Logger.getLogger(getClass()); public boolean DoesUserNameExist(String userName) throws Exception { logger.info("Inside Do UserNameExist about to validate with username : " + userName); try{ if(officerDao.OfficerExist(userName) == true){ logger.info("UserName :" + userName + " does exist"); return true; }else{ logger.info("UserName :" + userName + " does NOT exist"); return false; } }catch(Exception e){ logger.info("UserName :" + userName + " EXCEPTION OCCURED " + e.toString()); return false; } } /** * @return the officerDao */ public OfficersDAO getOfficerDao() { return officerDao; } /** * @param officerdao the officerDao to set */ public void setOfficerDao(OfficersDAO officerDao) { this.officerDao = officerDao; } } JdbcOfficersDAO.java public boolean OfficerExist(String userName){ String dbUserName; try{ logger.info("Inside jdbcOfficersDAO"); String sql = "SELECT userName FROM crimetrack.tblofficers WHERE userName = ?"; try{ dbUserName = (String)getJdbcTemplate().queryForObject(sql, new Object[]{userName},String.class); logger.info("Just Returned from database"); }catch(Exception e){ logger.info("No username was found in exception"); return false; } if(dbUserName == null){ logger.info("Database did not find any matching records"); } logger.info("after JdbcTemplate"); if (dbUserName.equals(userName)) { logger.info("User Name Exists"); return true; }else{ logger.info("User Name Does NOT Exists"); return false; } }catch(Exception e){ logger.info("Exception Message in JdbcOfficersDAO is "+e.getMessage()); return false; } } OfficerRegistrationValidation.java public class OfficerRegistrationValidation implements Validator{ private final Logger logger = Logger.getLogger(getClass()); private ValidateUserNameManager validateUserNameManager; public boolean supports(Class<?> clazz) { return Officers.class.equals(clazz); } public void validate(Object target, Errors errors) { Officers officer = (Officers) target; if (officer.getUserName() == null){ errors.rejectValue("userName", "userName.required"); }else{ String userName = officer.getUserName(); logger.info("UserName is not null so going to check if its valid for :" + userName); try { logger.info("User Name in try.....catch block is " + userName); if (validateUserNameManager.DoesUserNameExist(userName)== true){ errors.rejectValue("userName", "userName.exist"); } } catch (Exception e) { logger.info("Error Occured When validating UserName"); errors.rejectValue("userName", "userName.error"); } } if(officer.getPassword()== null){ errors.rejectValue("password", "password.required"); } if(officer.getPassword2()== null){ errors.rejectValue("password2", "password2.required"); } if(officer.getfName() == null){ errors.rejectValue("fName","fName.required"); } if(officer.getlName() == null){ errors.rejectValue("lName", "lName.required"); } if (officer.getoName() == null){ errors.rejectValue("oName", "oName.required"); } if (officer.getEmailAdd() == null){ errors.rejectValue("emailAdd", "emailAdd.required"); } if (officer.getDob() == null){ errors.rejectValue("dob", "dob.required"); } if (officer.getGenderId().equals("A")){ errors.rejectValue("genderId","genderId.required"); } if(officer.getDivisionNo() == 1){ errors.rejectValue("divisionNo", "divisionNo.required"); } if(officer.getPositionId() == 1){ errors.rejectValue("positionId", "positionId.required"); } if (officer.getStartDate() == null){ errors.rejectValue("startDate","startDate.required"); } if(officer.getEndDate() == null){ errors.rejectValue("endDate","endDate.required"); } logger.info("The Gender ID is " + officer.getGenderId().toString()); if(officer.getPhoneNo() == null){ errors.rejectValue("phoneNo", "phoneNo.required"); } } /** * @return the validateUserNameManager */ public ValidateUserNameManager getValidateUserNameManager() { return validateUserNameManager; } /** * @param validateUserNameManager the validateUserNameManager to set */ public void setValidateUserNameManager( ValidateUserNameManager validateUserNameManager) { this.validateUserNameManager = validateUserNameManager; } } Update Error Log using Logger.Error("Message", e): 39024 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 39025 [http-8084-2] ERROR com.crimetrack.service.OfficerRegistrationValidation - Message java.lang.NullPointerException at com.crimetrack.service.OfficerRegistrationValidation.validate(OfficerRegistrationValidation.java:47) at org.springframework.validation.DataBinder.validate(DataBinder.java:725) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doBind(HandlerMethodInvoker.java:815) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:367) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:436) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:424) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - Error Occured When validating UserName

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  • Is there a way to achieve covariance of generic types in C# 3.0?

    - by nullDev
    This has been introduced in C# 4.0, but is there a way to achieve this in c# 3.0? For e.g., consider the following code: class Base { } class Derived1 : Base { } class Derived2 : Base { } class User<T> where T : Base { } class User1 : User<Derived1> { } Now, I would like to have a list of User<T>, in which I can store User<Derived1> as well as User<Derived2>, but the following code fails to compile in C# 3.0: List<User<Base>> users = new List<User<Base>>(); users.Add(new User1()); Any ideas?

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  • Placement of a call to the parent method

    - by Alejandro
    I have a class that has a method. That class has a child class that overrides that method. The child's method has to call the parent's method. In all OO that I've seen or written calls to the parent's version of the same method were on the first line of the method. On a project that I am working on circumstances call for placing that method call at the end of a method. Should I be worried? Is that a code smell? Is this code inherently bad? class Parent { function work() { // stuff } } class Child { function work() { // do thing 1 // do thing 2 parent::work(); // is this a bad practice? // should I call the parent's work() method before // I do anything in this method? } }

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  • Inheritance domain classes in Grails

    - by Tomáš
    Hi gurus how can I get Collection of specific Class? I use inheriance: On Planet live Human. Humans are dividing to Men and Women. class Planet{ String name static hasMany = [ humans : Human ] } class Human{ String name static belongsTo = [Planet] } class Man extends Human{ int countOfCar } class Woman extends Human{ int coutOfChildren } now a neet to get only Collection of Man or Collection of Woman: get all humans on planet is simple all = Planet.get(1).humans but what can I get only woman or men? womenLivedOnMars = Planet.get(1).getOnlyWoman menLivedOnJupiter = Planet.get(2).getOnlyMan Thanks for your help Tom

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  • Can you cast an object to one that implements an interface? (JAVA)

    - by DDP
    Can you cast an object to one that implements an interface? Right now, I'm building a GUI, and I don't want to rewrite the Confirm/Cancel code (A confirmation pop-up) over and over again. So, what I'm trying to do is write a class that gets passed the class it's used in and tells the class whether or not the user pressed Confirm or Cancel. The class always implements a certain interface. Code: class ConfirmFrame extends JFrame implements ActionListener { JButton confirm = new JButton("Confirm"); JButton cancel = new JButton("Cancel"); Object o; public ConfirmFrame(Object o) { // Irrelevant code here add(confirm); add(cancel); this.o = (/*What goes here?*/)o; } public void actionPerformed( ActionEvent evt) { o.actionPerformed(evt); } } I realize that I'm probably over-complicating things, but now that I've run across this, I really want to know if you can cast an object to another object that implements a certain interface.

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  • Android; Confused by views?

    - by javano
    I have created a class (InputControl) which extends the view of my main class (Main), and takes focus of the screen. I have a button on the main xml layout which calls control() and sets up my InputControl view, from there I capture user input. How can I return back to the xml layout from the InputControl view class? public class Main extends Activity { public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); InputControl = new InputControl(this); } //......SNIP! public void control(){ setContentView(InputControl); InputControl.requestFocus(); } } public class InputControl extends View implements OnTouchListener { public InputControl(Context context) { super(context); setFocusable(true); setFocusableInTouchMode(true); this.setOnTouchListener(this); } public boolean onTouch(View view, MotionEvent event) { //...I AM CAPTURING USER TOUCH EVENTS HERE } }

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  • Google App Engine : PolyModel + SelfReferenceProperty

    - by rvandervort
    Is a PolyModel-based class able to be used as a SelfReferenceProperty ? I have the below code : class BaseClass(polymodel.PolyModel): attribute1 = db.IntegerProperty() attribute2 = db.StringProperty() class ParentClass(BaseClass): attribute3 = db.StringProperty() class ChildClass(BaseClass): parent = SelfReferenceProperty(collection_name = 'children') p = ParentClass() p.attribute1 = 1 p.attribute2 = "Parent Description" p.attribute3 = "Parent additional data" p.put() c = ChildClass() c.attribute1 = 5 c.attribute2 = "Child Description" c.parent = p.key() c.put() I execute this code and check the datastore via the development server's admin interface. The parent instance is saved to the datastore class = 'BaseClass,ParentClass', but the child is not. There is no error output to the browser (debug is turned on) and nothing in the launcher's log for my app. Is this possible to do ?

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  • Grails Runtime Exception with Audit Logging Plugin

    - by Paul
    I've deployed my app to tomcat running on EC2 via Cloud Foundry. The application uses the Grails Audit Logging Plugin I'm getting the following runtime error: Error 500: Executing action [save] of controller [com.questern.aoms.CompanyController] caused exception: groovy.lang.MissingPropertyException: No such property: errors for class: org.codehaus.groovy.grails.plugins.orm.auditable.AuditLogEvent Servlet: grails URI: /aoms/grails/company/save.dispatch Exception Message: No such property: errors for class: org.codehaus.groovy.grails.plugins.orm.auditable.AuditLogEvent Caused by: No such property: errors for class: org.codehaus.groovy.grails.plugins.orm.auditable.AuditLogEvent Class: CompanyController At Line: [30] The exception is: groovy.lang.MissingPropertyException: No such property: errors for class: org.codehaus.groovy.grails.plugins.orm.auditable.AuditLogEvent at $Proxy10.saveOrUpdate(Unknown Source) at com.questern.aoms.CompanyController$_closure4.doCall(CompanyController.groovy:30) at com.questern.aoms.CompanyController$_closure4.doCall(CompanyController.groovy) I have added the import statement to the controller CompanyController, but to no avail. import org.codehaus.groovy.grails.plugins.orm.auditable.AuditLogEvent I checked the war file and the AuditLogEvent is include in: aoms-0.1.war\WEB-INF\classes\org\codehaus\groovy\grails\plugins\orm\auditable\ Any suggestions as to what the problem could be?

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  • Jpa subclass mapping

    - by Roy Chan
    I am making a POS like system. I wonder how to map subclass using JPA (this is for my DAO). Product class has product details and OrderProduct class has information about the Product and details about the order. @Entity @Table(name="products") public class Product implements Serializable{ @Id @Column(name="id") @GeneratedValue(strategy = GenerationType.AUTO public int getId(){ return id;} /** Other get/set methods */ } @Entity @Table(name="order_products") public class OrderProduct extends Product{ @Id @Column(name="id") @GeneratedValue(strategy = GenerationType.AUTO) public int getId(){ return id;} /** Other get/set methods */ } I got complain about duplicate @Id. But OrderProduct class really need another id than the product one. How should I map this? DB is something like this Table products id int name varchar(32) Table order_product id int quantity int productid int fk referencing product table Would @IdClass or @AttributeOverride help?

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  • Java/JAXB: Unmarshall Xml to specific subclass based on an attribute

    - by Frothy
    Is it possible to use JAXB to unmarshall xml to a specific Java class based on an attribute of the xml? <shapes> <shape type="square" points="4" square-specific-attribute="foo" /> <shape type="triangle" points="3" triangle-specific-attribute="bar" /> </shapes> I would like to have a List of Shape objects containing a triangle and a square, each with their own shape-specific attribute. IE: abstract class Shape { int points; //...etc } class Square extends Shape { String square-specific-attribute; //...etc } class Triangle extends Shape { String triangle-specific-attribute; //...etc } I'm currently just putting all attributes in one big "Shape" class and it's less than ideal. I could get this to work if the shapes were properly named xml elements, but unfortunately I don't have control of the xml I'm retrieving. Thanks!

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  • Copying a Polymorphic object in C++

    - by doron
    I have base-class Base from which is derived Derived1, Derived2 and Derived3. I have constructed an instance for one of the the derived classes which I store as Base* a. I now need to make a deep copy of the object which I will store as Base* b. As far as I know, the normal way of copying a class is to use copy constructors and to overload operator=. However since I don't know whether a is of type Derived1, Derived2 or Derived3, I cannot think of a way of using either the copy constructor or operator=. The only way I can think of to cleanly make this work is to implement something like: class Base { public: virtual Base* Clone() = 0; }; and the implement Clone in in the derived class as in: class Derivedn : public Base { public: Base* Clone() { Derived1* ret = new Derived1; copy all the data members } }; Java tends to use Clone quite a bit is there more of a C++ way of doing this?

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  • How to capture a click on a href value using jQuery

    - by tonsils
    Hi, I have the following HTML code in the backend, ie. <div class="navi"> <a class="" href="0"></a> <a class="" href="1"></a> <a class="" href="2"></a> <a class="" href="3"></a> </div> Apologies for the basic question but I would like to use jQuery to capture the user's click when they only click on the href value of "0" Basically want to hide a div called "info" when the user clicks on the where the href="0" Unsure how to do? Thanks.

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  • wrapping the content of a span inside an li so it stays in its own column

    - by codergeek
    hello, I have a list, each li in it has this structure: <li> <img class="yes" src="..."> <img class="no" src="..."> <span class="a">...</span> <span class="b">...</span> </li> now if the content of class b is long, it will wrap around the image. I don't want it to wrap under the image, I want it to stay in its own column. If there is anyway to do this, please let me know as using tables to do it will be just wrong. Thanks! Nima

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  • Understanding the concept of inheritance in Java

    - by Nirmal
    Hello All.... I am just refreshing the oops features of the java. So, I have a little confusion regarding inheritance concept. For that I have a following sample code : class Super{ int index = 5; public void printVal(){ System.out.println("Super"); } } class Sub extends Super{ int index = 2; public void printVal(){ System.out.println("Sub"); } } public class Runner { public static void main(String args[]){ Super sup = new Sub(); System.out.println(sup.index+","); sup.printVal(); } } Now above code is giving me output as : 5,Sub. Here, we are overriding printVal() method, so that is understandable that it is accessing child class method only. But I could not understand why it's accessing the value of x from Super class... Thanks in advance....

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  • Extract Generic types from extended Generic

    - by Brigham
    I'm trying to refactor a class and set of subclasses where the M type does extend anything, even though we know it has to be a subclass of a certain type. That type is parametrized and I would like its parametrized types to be available to subclasses that already have values for M. Is there any way to define this class without having to include the redundant K and V generic types in the parameter list. I'd like to be able to have the compiler infer them from whatever M is mapped to by subclasses. public abstract class NewParametrized<K, V, M extends SomeParametrized<K, V>> { public void someMethodThatTakesKAndV(K k1, V v1) { } } In other words, I'd like the class declaration to look something like: public class NewParametrized<M extends SomeParametrized<K, V>> { And K and V's types would be inferred from the definition of M.

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  • super() in Python 2.x without args

    - by Slava Vishnyakov
    Trying to convert super(B, self).method() into a simple nice bubble() call. Did it, see below! Is it possible to get reference to class B in this example? class A(object): pass class B(A): def test(self): test2() class C(B): pass import inspect def test2(): frame = inspect.currentframe().f_back cls = frame.[?something here?] # cls here should == B (class) c = C() c.test() Basically, C is child of B, B is child of A. Then we create c of type C. Then the call to c.test() actually calls B.test() (via inheritance), which calls to test2(). test2() can get the parent frame frame; code reference to method via frame.f_code; self via frame.f_locals['self']; but type(frame.f_locals['self']) is C (of course), but not B, where method is defined. Any way to get B?

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  • C# generics method invocation

    - by Firat KÜÇÜK
    Hi, i have some polymorphic methods and i want to call via using an intermediate method. Following class is the simplified version of my program. class Program { public class A { } public class B { } public class C { } public void SomeMethod(A value) { Console.WriteLine("A value"); } public void SomeMethod(B value) { Console.WriteLine("B value"); } public void SomeMethod(C value) { Console.WriteLine("C value"); } static void Main(string[] args) { Program p = new Program(); // code block p.IntermediateMethod<A>(new A()); p.IntermediateMethod<B>(new B()); p.IntermediateMethod<C>(new C()); } public void IntermediateMethod<T>(T value) { // code block SomeMethod(value); // code block } }

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  • problem in adding image to the UIButton.

    - by monish
    Hi friends, I got an another problem in my application and I am wasting so much of time on that. Does pls anyone can help with this problem. Actually I had an Event and I should give rating for that event for that I wrote the code as: In CellForRowAtIndexPath......I had the code as: - (UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MasterViewIdentifier"]; //UITableViewCell *cell = nil; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:@"MasterViewIdentifier"] autorelease]; cell.selectionStyle = UITableViewCellSelectionStyleNone; UIView* elementView = [[UIView alloc] initWithFrame:CGRectMake(20,170,320,280)]; elementView.tag = 0; elementView.backgroundColor=[UIColor clearColor]; [cell.contentView addSubview:elementView]; [elementView release]; } UIView* elementView = [cell.contentView viewWithTag:0]; elementView.backgroundColor=[UIColor clearColor]; for(UIView* subView in elementView.subviews) { [subView removeFromSuperview]; } if(indexPath.section == 8) { UIImage *whiteImg = [UIImage imageNamed:@"white_star.png"] ; UIImage *yellowImg = [UIImage imageNamed:@"yellow_Star.png"] ; UIButton *button1 = [[UIButton alloc]initWithFrame:CGRectMake(159, 15, 25, 20)]; [button1 addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside]; button1.tag = 1; UIButton *button2 = [[UIButton alloc]initWithFrame:CGRectMake(185, 15, 25, 20)]; [button2 addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside]; button2.tag = 2; UIButton *button3 = [[UIButton alloc]initWithFrame:CGRectMake(211, 15, 25, 20)]; [button3 addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside]; button3.tag = 3; UIButton *button4 = [[UIButton alloc]initWithFrame:CGRectMake(237, 15, 25, 20)]; [button4 addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside]; button4.tag = 4; UIButton *button5 = [[UIButton alloc]initWithFrame:CGRectMake(263, 15, 25, 20)]; [button5 addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside]; button5.tag = 5; if(event.eventRatings == 1) { [button1 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button2 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button3 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button4 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button5 setBackgroundImage:whiteImg forState:UIControlStateNormal]; } else if(event.eventRatings == 2) { [button1 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button2 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button3 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button4 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button5 setBackgroundImage:whiteImg forState:UIControlStateNormal]; } else if(event.eventRatings == 3) { [button1 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button2 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button3 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button4 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button5 setBackgroundImage:whiteImg forState:UIControlStateNormal]; } else if(event.eventRatings == 4) { [button1 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button2 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button3 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button4 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button5 setBackgroundImage:whiteImg forState:UIControlStateNormal]; } else if(event.eventRatings == 5) { [button1 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button2 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button3 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button4 setBackgroundImage:yellowImg forState:UIControlStateNormal]; [button5 setBackgroundImage:yellowImg forState:UIControlStateNormal]; } else { [button1 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button2 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button3 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button4 setBackgroundImage:whiteImg forState:UIControlStateNormal]; [button5 setBackgroundImage:whiteImg forState:UIControlStateNormal]; } [elementView addSubview:button1]; [button1 release]; [elementView addSubview:button2]; [button2 release]; [elementView addSubview:button3]; [button3 release]; [elementView addSubview:button4]; [button4 release]; [elementView addSubview:button5]; [button5 release]; if(isRightButton == YES) { button1.enabled = NO; button2.enabled = NO; button3.enabled = NO; button4.enabled = NO; button5.enabled = NO; } else if(isRightButton == NO) { button1.enabled = YES; button2.enabled = YES; button3.enabled = YES; button4.enabled = YES; button5.enabled = YES; } [elementView addSubview:ratingsTitleLabel]; cell.accessoryType = UITableViewCellAccessoryNone; } return cell; } And the action of the button is written as: -(void)buttonAction:(id)sender { rating = [sender tag]; printf("\n Ratig Value inside Button Action~~~~~~~~~~~~~~~~%d",rating); event.eventRatings = rating; [tableView reloadData]; } When I build the application in simlator of 3.1.2 O.S its working fine by displaying the star images. My porblem is when I build it in 3.1.2 O.S Device the images are not displaying.I checked the code for casesensitivity in file name and its gud but Im not gettig the images to display. Guys help me to solve this. Thank you, Monish Kumar.

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  • Optimizing drawing of cubes

    - by Christian Frantz
    After googling for hours I've come to a few conclusions, I need to either rewrite my whole cube class, or figure out how to use hardware instancing. I can draw up to 2500 cubes with little lag, but after that my fps drops. Is there a way I can use my class for hardware instancing? Or would I be better off rewriting my class for optimization? public class Cube { public GraphicsDevice device; public VertexBuffer cubeVertexBuffer; public Cube(GraphicsDevice graphicsDevice) { device = graphicsDevice; var vertices = new List<VertexPositionTexture>(); BuildFace(vertices, new Vector3(0, 0, 0), new Vector3(0, 1, 1)); BuildFace(vertices, new Vector3(0, 0, 1), new Vector3(1, 1, 1)); BuildFace(vertices, new Vector3(1, 0, 1), new Vector3(1, 1, 0)); BuildFace(vertices, new Vector3(1, 0, 0), new Vector3(0, 1, 0)); BuildFaceHorizontal(vertices, new Vector3(0, 1, 0), new Vector3(1, 1, 1)); BuildFaceHorizontal(vertices, new Vector3(0, 0, 1), new Vector3(1, 0, 0)); cubeVertexBuffer = new VertexBuffer(device, VertexPositionTexture.VertexDeclaration, vertices.Count, BufferUsage.WriteOnly); cubeVertexBuffer.SetData<VertexPositionTexture>(vertices.ToArray()); } private void BuildFace(List<VertexPositionTexture> vertices, Vector3 p1, Vector3 p2) { vertices.Add(BuildVertex(p1.X, p1.Y, p1.Z, 1, 0)); vertices.Add(BuildVertex(p1.X, p2.Y, p1.Z, 1, 1)); vertices.Add(BuildVertex(p2.X, p2.Y, p2.Z, 0, 1)); vertices.Add(BuildVertex(p2.X, p2.Y, p2.Z, 0, 1)); vertices.Add(BuildVertex(p2.X, p1.Y, p2.Z, 0, 0)); vertices.Add(BuildVertex(p1.X, p1.Y, p1.Z, 1, 0)); } private void BuildFaceHorizontal(List<VertexPositionTexture> vertices, Vector3 p1, Vector3 p2) { vertices.Add(BuildVertex(p1.X, p1.Y, p1.Z, 0, 1)); vertices.Add(BuildVertex(p2.X, p1.Y, p1.Z, 1, 1)); vertices.Add(BuildVertex(p2.X, p2.Y, p2.Z, 1, 0)); vertices.Add(BuildVertex(p1.X, p1.Y, p1.Z, 0, 1)); vertices.Add(BuildVertex(p2.X, p2.Y, p2.Z, 1, 0)); vertices.Add(BuildVertex(p1.X, p1.Y, p2.Z, 0, 0)); } private VertexPositionTexture BuildVertex(float x, float y, float z, float u, float v) { return new VertexPositionTexture(new Vector3(x, y, z), new Vector2(u, v)); } public void Draw(BasicEffect effect) { foreach (EffectPass pass in effect.CurrentTechnique.Passes) { pass.Apply(); device.SetVertexBuffer(cubeVertexBuffer); device.DrawPrimitives(PrimitiveType.TriangleList, 0, cubeVertexBuffer.VertexCount / 3); } } } The following class is a list that draws the cubes. public class DrawableList<T> : DrawableGameComponent { private BasicEffect effect; private ThirdPersonCam camera; private class Entity { public Vector3 Position { get; set; } public Matrix Orientation { get; set; } public Texture2D Texture { get; set; } } private Cube cube; private List<Entity> entities = new List<Entity>(); public DrawableList(Game game, ThirdPersonCam camera, BasicEffect effect) : base(game) { this.effect = effect; cube = new Cube(game.GraphicsDevice); this.camera = camera; } public void Add(Vector3 position, Matrix orientation, Texture2D texture) { entities.Add(new Entity() { Position = position, Orientation = orientation, Texture = texture }); } public override void Draw(GameTime gameTime) { foreach (var item in entities) { effect.VertexColorEnabled = false; effect.TextureEnabled = true; effect.Texture = item.Texture; Matrix center = Matrix.CreateTranslation(new Vector3(-0.5f, -0.5f, -0.5f)); Matrix scale = Matrix.CreateScale(1f); Matrix translate = Matrix.CreateTranslation(item.Position); effect.World = center * scale * translate; effect.View = camera.view; effect.Projection = camera.proj; effect.FogEnabled = true; effect.FogColor = Color.CornflowerBlue.ToVector3(); effect.FogStart = 1.0f; effect.FogEnd = 50.0f; cube.Draw(effect); } base.Draw(gameTime); } } } There are probably many reasons that my fps is so slow, but I can't seem to figure out how to fix it. I've looked at techcraft as well, but what I have is too specific to what I want the outcome to be to just rewrite everything from scratch

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  • Is there a way to achieve covariance of generic types in C# 3.5?

    - by nullDev
    This has been introduced in C# 4.0, but is there a way to achieve this in c# 3.5? For e.g., consider the following code: class Base { } class Derived1 : Base { } class Derived2 : Base { } class User<T> where T : Base { } class User1 : User<Derived1> { } Now, I would like to have a list of User<T>, in which I can store User<Derived1> as well as User<Derived2>, but the following code fails to compile in C# 3.5: List<User<Base>> users = new List<User<Base>>(); users.Add(new User1()); Any ideas?

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