Search Results

Search found 45316 results on 1813 pages for 'class literals'.

Page 530/1813 | < Previous Page | 526 527 528 529 530 531 532 533 534 535 536 537  | Next Page >

  • Dynamic access of classes of a given namespace

    - by user322383
    Hi! I'm writing an interface that will be implemented by a lot of classes, and I'm writing a class that will hold a collection of instances of these implementations. Every class will have a default constructor. So, is there a simple way (e.g. using some kind of reflection) to put an instance of each of these implementing classes to the collection? Besides doing it manually, which is simple, yes, but a lot of work and error prone (what if I missed an implementation while writing the method? What if a new implementation came and I forgot to update the given method?). So, what I would like is to be able to iterate through all classes of a given namespace or maybe through the list of all available classes. My method then would simply check, through reflection, if the given class implements the given interface, and if it does, puts it into the collection. Thank you.

    Read the article

  • Best way to manage a header navigation menu from within a template?

    - by Stefan Kendall
    I'm looking to put navigation in my GSP template, and I would like to set the active class on the navigation elements for each respective page. What's the best way to do this? I have several .gsp views merging with a single template that looks like this: <div id="bd" role="main"> <div role="navigation" class="yui-g"> <ul id="nav"><a href="index.gsp"><li class="active">Home</li></a><a href = "products.gsp"><li>Products</li></a><a href = "contacts.gsp"><li>Contact</li></a></ul> </div> <g:layoutBody/> </div>

    Read the article

  • Assign fixed IP address via DHCP by DNS lookup

    - by Janoszen
    Preface I'm building a virtualization environment with Ubuntu 14.04 and LXC. I don't want to write my own template since the upgrade from 12.04 to 14.04 has shown that backwards compatibility is not guaranteed. Therefore I'm deploying my virtual machines via lxc-create, using the default Ubuntu template. The DNS for the servers is provided by Amazon Route 53, so no local DNS server is needed. I also use Puppet to configure my servers, so I want to keep the manual effort on the deployment minimal. Now, the default Ubuntu template assigns IP addresses via DHCP. Therefore, I need a local DHCP server to assign IP addresses to the nodes, so I can SSH into them and get Puppet running. Since Puppet requires a proper DNS setup, assigning temporary IP addresses is not an option, the client needs to get the right hostname and IP address from the start. Question What DHCP server do I use and how do I get it to assign the IP address based only on the host-name DHCP option by performing a DNS lookup on that very host name? What I've tried I tried to make it work using the ISC DHCP server, however, the manual clearly states: Please be aware that only the dhcp-client-identifier option and the hardware address can be used to match a host declaration, or the host-identifier option parameter for DHCPv6 servers. For example, it is not possible to match a host declaration to a host-name option. This is because the host-name option cannot be guaranteed to be unique for any given client, whereas both the hardware address and dhcp-client-identifier option are at least theoretically guaranteed to be unique to a given client. I also tried to create a class that matches the hostname like this: class "my-client-name" { match if option host-name = "my-client-name"; fixed-address my-client-name.my-domain.com; } Unfortunately the fixed-address option is not allowed in class statements. I can replace it with a 1-size pool, which works as expected: subnet 10.103.0.0 netmask 255.255.0.0 { option routers 10.103.1.1; class "my-client-name" { match if option host-name = "my-client-name"; } pool { allow members of "my-client-name"; range 10.103.1.2 10.103.1.2; } } However, this would require me to administer the IP addresses in two places (Amazon Route53 and the DHCP server), which I would prefer not to do. About security Since this is only used in the bootstrapping phase on an internal network and is then replaced by a static network configuration by Puppet, this shouldn't be an issue from a security standpoint. I am, however, aware that the virtual machine bootstraps with "ubuntu:ubuntu" credentials, which I intend to fix once this is running.

    Read the article

  • "partial views" best practices for 'container' divs?

    - by ropstah
    What is the 'best' way to handle the html markup for partial views? (which are also refreshed using AJAX) The biggest issue I run into is where to place the 'container' div... Consider having a masterpage and a partial view. (class="" could be interchanged with id="" depending if the partial is guaranteed to be unique, however this isn't really important to the issue i think) Masterpage: <div id="place1" class="placeholder"> <!-- render partial --> </div> Partial: <div id="partial1" class="partial"> <!-- content --> </div> I feel that something isn't being done right. However I cannot remove the div in the masterpage, because I need that to 'encapsulate' the response from AJAX partial updates. And also I cannot move the div in the partial to the masterpage, because that would require to move 'partial' info to the masterpage... How do you handle this?

    Read the article

  • Service injection into Controller (Spring MVC)

    - by ThaSaleni
    Hi I have a Spring web application, I have built it up to the controller stage and I could inject my Daos, into my Services fine. Now when I want to inject my Service into my controller i get an error for dependency with the Dao and further down the sessionFactory. I don't want to inject these again cause this will ultimately lead me to eventually create a data source but I have my Daos for data access and they already know about sessionFactory. Am I missing something here? here's the sample code snippets My Service: @Service("productService") @Transactional public class ProductServiceImpl implements ProductService { private ProductDao productDao; @Autowired public void setDao(ProductDao productDao) { this.productDao = productDao; } My Controller @Controller @WebServlet(name="controllerServlet", loadOnStartup= urlPatterns=...}) public class ControllerServlet extends HttpServlet { boolean isUserLogedIn =false; @Autowired private ProductService productService; public void setProductService(ProductService productService){ this.productService = productService; } Servlet-context Stack trace javax.servlet.ServletException: Servlet.init() for servlet mvcServlet threw exception org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java: 565) org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1812) java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) java.lang.Thread.run(Thread.java:662) root cause org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'controllerServlet': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.phumzile.acme.services.ProductService com.phumzile.acme.client.web.controller.ControllerServlet.productService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.phumzile.acme.services.ProductService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.p ostProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:287) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) SERVLET-CONTEXT <context:component-scan base-package="com.phumzile.acme.client" /> <!-- Enables the Spring MVC @Controller programming model --> <mvc:annotation-driven /> </beans> APP-CONFIG <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <list> <value>configuration.properties</value> </list> </property> </bean> <context:annotation-config/> <context:component-scan base-package="com.phumzile.acme" /> <import resource="db-config.xml" /> </beans> DB-CONFIG <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <property name="idleConnectionTestPeriod" value="10800"/> <property name="maxIdleTime" value="21600"/> <property name="driverClass"> <value>${jdbc.driver.className}</value> </property> <property name="jdbcUrl"> <value>${jdbc.url}</value> </property> <property name="user"> <value>${jdbc.username}</value> </property> <property name="password"> <value>${jdbc.password}</value> </property> </bean> <bean id="sessionFactory" class="org.springframework.orm.hibernate3.a nnotation.AnnotationSessionFactoryBean"> <property name="dataSource"> <ref bean="dataSource" /> </property> <property name="annotatedClasses"> <list> <!-- Entities --> <value>com.phumzile.acme.model.User</value> <value>com.phumzile.acme.model.Person</value> <value>com.phumzile.acme.model.Company</value> <value>com.phumzile.acme.model.Product</value> <value>com.phumzile.acme.model.Game</value> <value>com.phumzile.acme.model.Book</value> <!-- Entities --> </list> </property> <property name="packagesToScan" value="com.phumzile.acme" /> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">${jdbc.hibernate.dialect </prop> <prop key="hibernate.hbm2ddl.auto">validate</prop> <prop key="hibernate.show_sql">true</prop> </props> </property> </bean> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory"> <ref bean="sessionFactory" /> </property> </bean> <tx:annotation-driven /> </beans> CONFIGURATION.PROPERTIES jdbc.driver.className=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/mydb jdbc.username=root jdbc.password=root jdbc.hibernate.dialect=org.hibernate.dialect.MySQLDialect

    Read the article

  • Why is the C# SerializedAttribute is sealed?

    - by ahmet alp balkan
    I was trying to create an attribute that implies [Serializable] but I noticed that this SerializableAttribute class is sealed. In Java it was possible to create an interface (say, MyInterface) that is inherited from Serializable interface and so all the subclasses of MyInterface would also be serializable, even its sub-sub classes would be so. Let's say I am creating an ORM and I want customers to annotate their entity classes as [DatabaseEntity] but in order to make sure that entities are serializable, I also need to ask them to attribute their classes with extra [Serializable] which does not look quite compact and neat. I am wondering why SerializableAttribute class is sealed and why has Inherited=false which implies that subclasses of serializable class will not be serializable unless it is explicitly stated. What motives are behind these design choices?

    Read the article

  • Apply Alloy UI 1.5 datepicker to multiple instances

    - by MyTitle
    I want to create Alloy UI datapickers on multiple form fields: <div id="date_1_wrapper"> <input type="text" class="datepick" id="date_1" /> </div> <div id="date_2_wrapper"> <input type="text" class="datepick" id="date_2" /> </div> Using JQuery I can do it using following code: $('.datepick').each(function(){ $(this).datepicker(); }); But how to achieve same functionality in Alloy UI? For now I use following code, but this code apply DatePickers by ID, not by CSS class in loop: AUI().use( 'aui-datepicker', function(A) { new A.DatePicker ( { calendar: { dateFormat: '%d/%m/%Y' }, trigger: '#date_1' } ).render('#date_1_wrapper'); new A.DatePicker( { calendar: { dateFormat: '%d/%m/% }, trigger: '#date_2' } ).render('#date_2_wrapper'); } ); I think it this code can be used in beginning, but how to deal with input's and div's ID's? (A.all('.datepcik').each(function() {)

    Read the article

  • Simple Windows.Forms binding is failing using framework 4.0.

    - by jyoung
    This works under the .net framework 3.5 client. This fails under the .net framework 4.0 client. Was I doing something that was illegal under 3.5 but just happened to work, or is this a bug? Note that in my project 'PropInt' does not raise change events so using ctx[obj1.PropObj2, "PropInt"] is not an option. public class Obj1 { public Obj2 PropObj2 { get; set; } public Obj1() { PropObj2 = new Obj2(); } } public class Obj2 { public int PropInt { get; set; } } static class Program { [STAThread] static void Main() { var ctx = new BindingContext(); var obj1 = new Obj1(); var x1 = ctx[obj1, "PropObj2.PropInt"]; } }

    Read the article

  • How does git-diff generate hunk descriptions?

    - by RobM
    (git version 1.6.5.7) When I run git diff the output has a nice scope hint after the line numbers for my Python scripts, e.g.: diff --git a/file.py b/file.py index 024f5bb..c3b5c56 100644 --- a/file.py +++ b/file.py @@ -14,6 +14,8 @@ TITF: Test Infrastructure Tags Format ... @@ -1507,13 +1533,16 @@ class Tags( object ): ... Note that the line numbers are followed by TITF: Test Infrastructure Tags Format and class Tags( object ):. The first patch applies to module scope and the description TITF: Test Infrastructure Tags Format is the module's description. The second patch applies to a method of the Tags class. How does git generate these descriptions? How can I tweak them to show the method name that the patch applies to?

    Read the article

  • C# listbox,params

    - by Oyeme
    As Andrew Hare suggested in his answer: Create a field to store all the ListBox instances and then change the constructor to accept an arbitrary number of them: by I tried the following class scaner { readonly IEnumerable<ListBox> listBoxes; public IEnumerable<ListBox> ListBoxes { get { return this.listBoxes; } } public scaner(params ListBox[] listBoxes) { this.listBoxes = listBoxes; } } This will allow you to do this: scaner Comp = new scaner(listBox1, listBox2); How can i access listbox1? In class scaner i'm trying to call this.listBoxes. (I need to call the listbox1 in scaner class.How can i do/call it? Thanks for answers.

    Read the article

  • Are all public read/write members serialized with XmlSerializer?

    - by David
    I have a handful of public read/write members that are not being serialized and I can't figure out why. Reviewing some code, and my root class is marked serializable: [Serializable] public class MyClass I have a default constructor that initializes 10-15 string members. There are about 50 public read/write string members in MyClass with get and set--no explicit serialization attributes are set on any of these. Serialization looks like this: XmlSerializer x = new XmlSerializer(typeof(MyClass)); TextWriter twWriter = new StreamWriter(sFileName); x.Serialize(twWriter, this); twWriter.Close(); only a handful (20-30) of these members are actually seralized to my xml file. what am i missing or misunderstanding about the XmlSerializer class?

    Read the article

  • Service locator for generics

    - by vittore
    Hi everyone, I have say a dozen types T which inherit from EntityObject and IDataObject. I have generic the following interface IDataManager<T> where T : EntityObject, IDataObject ... I have also base class for data managers BaseDataManager<T> : IDataManager<T> where T : EntityObject, IDataObject .... And i have particular classes public class Result : EntityObject, IDataObject .... public class ResultDataManager : BaseDataManager<Result> ... I want to implement service locator, which will return instance of IDataManager<T> for T But I stucked how to implement it in a neat way without a lot of castings. Any ideas?

    Read the article

  • Implementing sub fields in a PropertyGrid

    - by evolve
    Alright so my terminology when it comes to C# isn't great, so I'll attempt to explain this with a small example. If you create a class which you are using within a PropertyGrid and you have the following values: class Test { public Point example { get; set; } } This will produce a PropertyGrid which has an expandable object "example" which has fields X and Y in order to create a "Point". I'm attempting to create an object "name" which has fields "firstname" and "lastname", so I have: class Test { public Name example { get; set; } } public struct Name { public string firstname { get; set; } public string lastname { get; set; } } This however isn't working as intended. I think I need to override some method(s) in order to get this working, however since I don't really have the terminology down for PropertyGrids it is difficult for me to find a solution. Any help would be great.

    Read the article

  • Remapping design issue

    - by Sirupsen
    Hello, I'm currently developing a Ruby Gem and I'm a bit lost on the design currently. Basically, I'm remapping some APIs, so my skeleton is something like this: module MyApp module SomeApi class Function > Base::Function ... end class Function2 > Base::Function2 ... end ... end module SomeApi2 ... end class RemappedFunction def initalize # set some values and stuf ... end def remapped_method # Problem: # How would I know, if I should take contact to # SomeApi, or SomeApi2? end end def interact_with(api) # What would be the best way of letting RemappedFunction # know which API to use? end end someapi2 = MyApp.interact_with(:someapi2) someapi2.remapped_method Any ideas?

    Read the article

  • Uses for static generic classes?

    - by Hightechrider
    What are the key uses of a Static Generic Class in C#? When should they be used? What examples best illustrate their usage? e.g. public static class Example<T> { public static ... } Since you can't define extension methods in them they appear to be somewhat limited in their utility. Web references on the topic are scarce so clearly there aren't a lot of people using them. Here's a couple:- http://ayende.com/Blog/archive/2005/10/05/StaticGenericClass.aspx http://stackoverflow.com/questions/686630/static-generic-class-as-dictionary

    Read the article

  • Using Fortran to call C++ Functions

    - by Dane Larsen
    I'm trying to get some FORTRAN code to call a couple c++ functions that I wrote (c_tabs_ being one of them). Linking and everything works just fine, as long as I'm calling functions that don't belong to a class. My problem is that the functions I want the FORTRAN code to call belong to a class. I looked at the symbol table using nm and the function name is something ugly like this: 00000000 T _ZN9Interface7c_tabs_Ev FORTRAN won't allow me to call a function by that name, because of the underscore at the beginning, so I'm at a loss. The symbol for c_tabs when it's not in a class is quite simple, and FORTRAN has no problems with it: 00000030 T c_tabs_ Any suggestions? Thanks in advance.

    Read the article

  • JavaScript socket vs. Flash socket?

    - by Dr.Dredel
    Steve Jobs just posted this article on why Apple rejects Flash... http://www.apple.com/hotnews/thoughts-on-flash/ I agree that javascript and css can be used to replicate some of Flash's animation, though Flash does all sorts of scaling and tweening that is incredibly powerful, and I'm not sure that there's anything comparable in javascript, if there is, I certainly haven't seen it. However, my question is about the socket. Flash has an incredibly powerful openSocket class that allows you to connect to a server and have the server and the client talk back and forth to one another. As far as I know there is no equivalent class in Javascript. Am I mistaken? Is there some secret mystery Ajax class that replicates the openSocket? If not, then that feature alone makes Flash an invaluable tool. I'm interested in all answers though... and yes this IS a programming question! :)

    Read the article

  • Returning a collection of objects from a webmethod

    - by Narmatha Balasundaram
    How do I return a collection of objects from a webmethod? And can this collection of objects be of different types - say of these 3 classes, private class ClassA { int A1; int A2; } private class ClassB { int B1; } private class ClassC { int C1; } ClassA objA = new ClassA(...); ClassB objB = new ClassB(...); ClassC objC = new ClassC(...); How can I return the objects, objA, objB and objC from a method?

    Read the article

  • Working with the Objective-C/Cocoa flat namespace

    - by Stephen Blinkhorn
    I've not found anything that addresses my specific name space question as yet. I am working on some AudioUnit plug-ins featuring Cocoa based GUIs. The plug-ins use a common library of user interface classes (sliders, buttons etc) which are simply added to each Xcode project. When I recompile and distribute updates it is pretty much guaranteed that at least one user interface class will have been updated since the last release. If the user launches an older plug-in before an updated plug-in then the old Cocoa classes are already loaded into the run time and the plug-in attempts to use the older implementations - often resulting in a failure one way or another. I know frameworks are the intended solution but the overhead and backwards compatibility issues are not ideal. I prefix all class names where possible but what options do I have to ensure that each plug-in contains unique class names for the shared user interface classes?

    Read the article

  • How can i see if dealloc is being called on a uikit object, or any object not created by myself

    - by Gyozo Kudor
    I think i have an UIImage that has a higher retain count than it should have and i am probably leaking memory. I use this image as a thumbnail, to set a custom background to a uibutton. So the uibutton is holding a reference to it and so do i. But instead of 2, the retainCount is 3. Do i have to create a custom UIImage derived class and override dealloc if I want to place a log message there and then change the class used from UIImage to my class, or is there an easier way. Thanks in advance.

    Read the article

  • NullPointerException Java help

    - by KP65
    Hello guys. I've been tearing my hair out the past few hours trying to solve this problem. Every time I click on a JButton which should open a JFrame(And it does), i get a stacktrace saying I have a null point exception at these bits of code: In class A i have: aButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { B instanceofB = new B(userSession.getBalance()); }); and Class B super.getSomeBtn().setVisible(false); This is where the stacktrace says the errors are in the two above sections. I have a line exactly the same as the one above in Class B and it works fine? Really stuck here!

    Read the article

  • Android: Using MediaRecorder to crop an existing audio file?

    - by user141146
    Hi, I'd like to take an existing mp3 file located on an SD card and arbitrarily crop it (e.g. crop from 0:12 to 1:14 in a 3 minute song). The only class that I've seen that seems remotely relevant to do this is the MediaRecorder class. My 'hope' would be to "record" an existing file like this: MediaRecorder recorder = new MediaRecorder(); recorder.setAudioSource(###some magical way of specifying an existing file??###); But this obviously doesn't work (setAudioSource() takes an int and seems to default to the phone's microphone). Is there a class or an approach that can be used to crop audio on the phone itself? TKS!!

    Read the article

  • Singleton constructor question

    - by gillyb
    Hi, I created a Singleton class in c#, with a public property that I want to initialize when the Singleton is first called. This is the code I wrote : public class BL { private ISessionFactory _sessionFactory; public ISessionFactory SessionFactory { get { return _sessionFactory; } set { _sessionFactory = value; } } private BL() { SessionFactory = Dal.SessionFactory.CreateSessionFactory(); } private object thisLock = new object(); private BL _instance = null; public BL Instance { get { lock (thisLock) { if (_instance == null) { _instance = new BL(); } return _instance; } } } } As far as I know, when I address the Instance BL object in the BL class for the first time, it should load the constructor and that should initialize the SessionFactory object. But when I try : BL.Instance.SessionFactory.OpenSession(); I get a Null Reference Exception, and I see that SessionFactory is null... why?

    Read the article

  • C++0x rvalue references - lvalues-rvalue binding

    - by Doug
    This is a follow-on question to http://stackoverflow.com/questions/2748866/c0x-rvalue-references-and-temporaries In the previous question, I asked how this code should work: void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } It seems that the move overload should probably be called because of the implicit temporary, and this happens in GCC but not MSVC (or the EDG front-end used in MSVC's Intellisense). What about this code? void f(std::string &&); //NB: No const string & overload supplied void g1(const char * arg) { f(arg); } void g2(const std::string & arg) { f(arg); } It seems that, based on the answers to my previous question that function g1 is legal (and is accepted by GCC 4.3-4.5, but not by MSVC). However, GCC and MSVC both reject g2 because of clause 13.3.3.1.4/3, which prohibits lvalues from binding to rvalue ref arguments. I understand the rationale behind this - it is explained in N2831 "Fixing a safety problem with rvalue references". I also think that GCC is probably implementing this clause as intended by the authors of that paper, because the original patch to GCC was written by one of the authors (Doug Gregor). However, I don't this is quite intuitive. To me, (a) a const string & is conceptually closer to a string && than a const char *, and (b) the compiler could create a temporary string in g2, as if it were written like this: void g2(const std::string & arg) { f(std::string(arg)); } Indeed, sometimes the copy constructor is considered to be an implicit conversion operator. Syntactically, this is suggested by the form of a copy constructor, and the standard even mentions this specifically in clause 13.3.3.1.2/4, where the copy constructor for derived-base conversions is given a higher conversion rank than other implicit conversions: A conversion of an expression of class type to the same class type is given Exact Match rank, and a conversion of an expression of class type to a base class of that type is given Conversion rank, in spite of the fact that a copy/move constructor (i.e., a user-defined conversion function) is called for those cases. (I assume this is used when passing a derived class to a function like void h(Base), which takes a base class by value.) Motivation My motivation for asking this is something like the question asked in http://stackoverflow.com/questions/2696156/how-to-reduce-redundant-code-when-adding-new-c0x-rvalue-reference-operator-over ("How to reduce redundant code when adding new c++0x rvalue reference operator overloads"). If you have a function that accepts a number of potentially-moveable arguments, and would move them if it can (e.g. a factory function/constructor: Object create_object(string, vector<string>, string) or the like), and want to move or copy each argument as appropriate, you quickly start writing a lot of code. If the argument types are movable, then one could just write one version that accepts the arguments by value, as above. But if the arguments are (legacy) non-movable-but-swappable classes a la C++03, and you can't change them, then writing rvalue reference overloads is more efficient. So if lvalues did bind to rvalues via an implicit copy, then you could write just one overload like create_object(legacy_string &&, legacy_vector<legacy_string> &&, legacy_string &&) and it would more or less work like providing all the combinations of rvalue/lvalue reference overloads - actual arguments that were lvalues would get copied and then bound to the arguments, actual arguments that were rvalues would get directly bound. Questions My questions are then: Is this a valid interpretation of the standard? It seems that it's not the conventional or intended one, at any rate. Does it make intuitive sense? Is there a problem with this idea that I"m not seeing? It seems like you could get copies being quietly created when that's not exactly expected, but that's the status quo in places in C++03 anyway. Also, it would make some overloads viable when they're currently not, but I don't see it being a problem in practice. Is this a significant enough improvement that it would be worth making e.g. an experimental patch for GCC?

    Read the article

  • Java generics: Illegal forward reference

    - by Arian
    Given a generic interface interface Foo<A, B> { } I want to write an implementation that requires A to be a subclass of B. So I want to do class Bar<A, B super A> implements Foo<A, B> { } // --> Syntax error or class Bar<A extends B, B> implements Foo<A, B> { } // --> illegal forward reference But the only solution that seems to work is this: class Bar<B, A extends B> implements Foo<A, B> { } which is kind of ugly, because it reverses the order of the generic parameters. Are there any solutions or workarounds to this problem?

    Read the article

< Previous Page | 526 527 528 529 530 531 532 533 534 535 536 537  | Next Page >