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  • C++ vtable resolving with virtual inheritance

    - by Tomas Cokis
    I was curious about C++ and virtual inheritance - in particular, the way that vtable conflicts are resolved between bass and child classes. I won't pretend to understand the specifics on how they work, but what I've gleamed so far is that their is a small delay caused by using virtual functions due to that resolution. My question then is if the base class is blank - ie, its virtual functions are defined as: virtual void doStuff() = 0; Does this mean that the resolution is not necessary, because there's only one set of functions to pick from? Forgive me if this is an stupid question - as I said, I don't understand how vtables work so I don't really know any better.

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  • Rails table inheritance issue

    - by Tristan O'Neil
    I've setup some models in the table inheritance fashion and everything seems to be all fine and dandy. But, when I use a collection select field to select values from one of the models it saves it but it saves the ID of the data and not the actual value of the data. So when I try to display the value on the show view it just shows the corresponding ID and not the actual value. Here is my setup. I'm using formtastic as a side note. View <%= show_field "County", @company.county %> Form <%= f.input :county, :label => 'County', :as => :select, :collection => County.find(:all) %> Base Model class Tag < ActiveRecord::Base before_create :set_type before_update :set_type attr_accessible :type, :name, :category belongs_to :company def set_type self.type = self.category end end Inherited Model class County < Tag end

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  • Inheritance in kohana

    - by Binaryrespawn
    Hi all, I have recently started to use Kohana and I know inheritance is in infancy stages at the moment. The work around is using a $_has_one annotation on the child class model. In may case i have "page" as the parent of "article". I have something like, protected $_has_one = array('mypage'=>array('model'=>'page', 'foreign_key'=>'id')); In my controller, I have an action which queries the database. In this query I am trying to access fields form the parent of "article" which is the "page". $n->articles=ORM::factory('article')->where('expires','=',0) ->where('articledate','<',date('y-m-d')) ->where('expirydate','>',date('y-m-d')) ->where('mypage->status','=','PUBLISHED') ->order_by('articledate','desc') ->find_all(); The status column resides in the page table and my query is generating an error to the effect of "cannot find status", clearly because it belongs to the parent. Any ideas ?

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  • Inheritance vs specific types in Financial Modelling for cashflows

    - by BlueTrin
    Hello, I have to program some financial applications where I have to represent a schedule of flows. The flows can be of 3 types: - fee flow (just a lump payment at some date) - floating rate flow (the flow is dependant of an interest rate to be determined at a later date) - fixed rate flow (the flow is dependant of an interest rate determined when the deal is done) I need to keep the whole information and I need to represent a schedule of these flows. Originally I wanted to use inheritance and create three classes FeeFlow, FloatingFlow, FixedFlow all inheriting from ICashFlow and implement some method GetFlowType() returning an enum then I could dynamic_cast the object to the correct type. That would allow me to have only one vector to represent my schedule. What do you think of this design, should I rather use three vectors vector, vector and vector to avoid the dynamic casts ?

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  • Template inheritance: X is not a template

    - by user2923917
    I am trying to build a inheritance-structure which looks like: Base - template Grandpa - template Father class Base {}; template <int x> class Grandpa: public Base {}; template <int x> class Father: public Grandpa<x> {}; However, the compiler complains when compiling Father, that Grandpa is not a template. I guess it is just some synthatic issue, however everything I've tried so far led to even more compiler complaints ;) Any idea whats wrong?

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  • how to implement inheritance in hibernate ??

    - by user359057
    Hi guys i am working in a web application. I have a entities as BaseEntity --Which contains user login info like createdBy,createdTime,EditedBy,editedTime Employee -- which contains employee information like name,address,etc... RegularEmployee --which contains salary ,bonus tht kind of fields and ContactEmployee -- which contains HourlyRate,contactPeriod etc.... My inheritance structure is BaseEntity <--- Employee <---- RegularEmployee (i.e. Employee extends BaseEntity and RegularEmployee extends Employee ContractEmployee also extend Employee Class ). How to design database structure in this case considering all the tables have id and version fields (all tables should at least have these two fields).

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  • [C++] Simple inheritance question

    - by xbonez
    I was going over some sample questions for an upcoming test, and this question is totally confusing me. Any help would be appreciated. Consider the following code: class GraduateStudent : public Student { ... }; If the word "public" is omitted, GraduateStudent uses private inheritance, which means which of the following? GraduateStudent objects may not use methods of Student. GraduateStudent does not have access to private objects of Student. No method of GraduateStudent may call a method of Student. Only const methods of GraduateStudent can call methods of Student.

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  • Hadoop Hive web interface options

    - by Garethr
    I've been experimenting with Hive for some data mining activities and would like to make it easily available to less command line orientated colleagues. Hive does now ship with a web interface (http://wiki.apache.org/hadoop/Hive/HiveWebInterface) but it's very basic at this stage. My question is does a visually polished and fully featured interface (either desktop or preferably web based) to Hive exist yet? Are their any open source efforts outside the Hive project working on this?

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  • Using JAXB to unmarshal/marshal a List<String> - Inheritance

    - by gerry
    I've build the following case. An interface for all JAXBLists: public interface JaxbList<T> { public abstract List<T> getList(); } And an base implementation: @XmlRootElement(name="list") public class JaxbBaseList<T> implements JaxbList<T>{ protected List<T> list; public JaxbBaseList(){} public JaxbBaseList(List<T> list){ this.list=list; } @XmlElement(name="item" ) public List<T> getList(){ return list; } } As well as an implementation for a list of URIs: @XmlRootElement(name="uris") public class JaxbUriList2 extends JaxbBaseList<String> { public JaxbUriList2() { super(); } public JaxbUriList2(List<String> list){ super(list); } @Override @XmlElement(name="uri") public List<String> getList() { return list; } } And I'm using the List in the following way: public JaxbList<String> init(@QueryParam("amount") int amount){ List<String> entityList = new Vector<String>(); ... enityList.add("http://uri"); ... return new JaxbUriList2(entityList); } I thought the output should be: <uris> <uri> http://uri </uri> ... </uris> But it is something like this: <uris> <item xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:string"> http://uri </item> ... <uri> http://uri </uri> ... </uris> I think it has something to do with the inheritance, but I don't get it... What's the problem? - How can I fix it? Thanks in advance!

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  • What is the IServiceLocator interface?

    - by stiank81
    From what I understand IServiceLocator is an interface to abstract the actual IoC container away? I'm asking with relation to Prism where I'm trying to replace Unity with Prism, and I see Prism-classes relying on IServiceLocator. Could someone please clarify the role of the interface and when it is used? And also; what is the Common Service Locator, and will this be helpful when working with IServiceLocator?

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  • Solaris: Programmatic interface to ifconfig?

    - by David Citron
    I'm looking for a programmatic interface to the Solaris ifconfig(1M) command. Apparently Linux has the getifaddrs(3) command, but as far as I can tell this has not been ported to Solaris. Short of attempting to use the code at the link above, is there any way to determine ifconfig(1M)-type data (network interface presence, state, etc.) without forking the system command and parsing the output?

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  • How one extends JNA interface mappings? (Java)

    - by rukoche
    User32 interface (platform library) is missing some WinAPI functions, so I tried extending it: package myapp import com.sun.jna.platform.win32.W32API public interface User32 extends com.sun.jna.platform.win32.User32 { myapp.User32 INSTANCE boolean IsWindow(W32API.HWND hWnd) } But then calling myapp.User32.INSTANCE.FindWindow(..) results in java.lang.NullPointerException: Cannot invoke method FindWindow() on null object

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  • iTunes COM interface on OS/X

    - by jldupont
    Is the iTunes COM interface available on Mac OS/X? From the documentation I could find, it seems much more extensive than the Applescript interface I could expose through the Automator program. Disclaimer: absolute OS/X newbie here.

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  • Spring AOP pointcut that matches annotation on interface

    - by seanizer
    Hello, this is my first post here, so I apologize in advance for any stupidity on my side. I have a service class implemented in Java 6 / Spring 3 that needs an annotation to restrict access by role. I have defined an annotation called RequiredPermission that has as its value attribute one or more values from an enum called OperationType: public @interface RequiredPermission { /** * One or more {@link OperationType}s that map to the permissions required * to execute this method. * * @return */ OperationType[] value();} public enum OperationType { TYPE1, TYPE2; } package com.mycompany.myservice; public interface MyService{ @RequiredPermission(OperationType.TYPE1) void myMethod( MyParameterObject obj ); } package com.mycompany.myserviceimpl; public class MyServiceImpl implements MyService{ public myMethod( MyParameterObject obj ){ // do stuff here } } I also have the following aspect definition: /** * Security advice around methods that are annotated with * {@link RequiredPermission}. * * @param pjp * @param param * @param requiredPermission * @return * @throws Throwable */ @Around(value = "execution(public *" + " com.mycompany.myserviceimpl.*(..))" + " && args(param)" + // parameter object " && @annotation( requiredPermission )" // permission annotation , argNames = "param,requiredPermission") public Object processRequest(final ProceedingJoinPoint pjp, final MyParameterObject param, final RequiredPermission requiredPermission) throws Throwable { if(userService.userHasRoles(param.getUsername(),requiredPermission.values()){ return pjp.proceed(); }else{ throw new SorryButYouAreNotAllowedToDoThatException( param.getUsername(),requiredPermission.value()); } } The parameter object contains a user name and I want to look up the required role for the user before allowing access to the method. When I put the annotation on the method in MyServiceImpl, everything works just fine, the pointcut is matched and the aspect kicks in. However, I believe the annotation is part of the service contract and should be published with the interface in a separate API package. And obviously, I would not like to put the annotation on both service definition and implementation (DRY). I know there are cases in Spring AOP where aspects are triggered by annotations one interface methods (e.g. Transactional). Is there a special syntax here or is it just plain impossible out of the box. PS: I have not posted my spring config, as it seems to be working just fine. And no, those are neither my original class nor method names. Thanks in advance, Sean PPS: Actually, here is the relevant part of my spring config: <aop:aspectj-autoproxy proxy-target-class="false" /> <bean class="com.mycompany.aspect.MyAspect"> <property name="userService" ref="userService" /> </bean>

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  • Passing an Object as an Interface

    - by Christopher Chase
    This should be a simple answer, i believe its going to be a no, but taken from a larger project, i have an interface and the procedure iMyUnknown= interface(IInterface) ['..GUID..'] end; procedure WorkObject(iObj :iMyUnknown); i know this works var MyUnknown : iMyUnknown; begin if supports(obj, iMyUnknown, MyUnknown) then WorkObject(MyUnknown); But is it possible to do something like this? if supports(obj, iMyUnknown) then WorkObject(obj as iMyUnknown);

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  • C# - Dynamic Keyword and Interface Implementations

    - by Adam Driscoll
    I'm assuming this isn't possible but before digging further is there a way to do something like this: public void ProcessInterface(ISomeInterface obj) {} //... dynamic myDyn = GetDynamic<ISomeInterface>() ProcessInterface(myDyn); I've seen a post arguing for it but it sounds like it wasn't included. A little context: .Net assembly exposed through COM - Silverlight app consuming interface-implementing classes. Would be nice to refer to the objects by interface. I really don't expect that this was what was intended...

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  • What is the minimum interface that has the Count property in .Net

    - by SoMoS
    Hello, I need to change a method that has one parameter that takes a serie of objects. I need to find the lowest Interface (in inheritance tree) that has the Count property. Until now I was using the IEnumerable but as this has not Count I need to change it to the wider interface possible so the method can work with the biggest number of types of series (collections, lists, arrays, etc). Thanks in advance.

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  • real time scenario between interface/abstract class ?

    - by JavaUser
    Hi , Please give me a real time simple example for the below questions : Where to use interface rather abstract class Where to use abstract class rather interface I need code snippet for both . Which takes low memory and which performs well . Do I need to consider the design aspect also? What is the conceptual difference not the syntactical difference .

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