Search Results

Search found 17487 results on 700 pages for 'static members'.

Page 38/700 | < Previous Page | 34 35 36 37 38 39 40 41 42 43 44 45  | Next Page >

• Using static mutex in a class

  - by Dmitry Yudakov

  I have a class that I can have many instances of. Inside it creates and initializes some members from a 3rd party library (that use some global variables) and is not thread-safe. I thought about using static boost::mutex, that would be locked in my class constructor and destructor. Thus creating and destroying instances among my threads would be safe for the 3rd party members. class MyClass { static boost::mutex mx; // 3rd party library members public: MyClass(); ~MyClass(); }; MyClass::MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // create and init 3rd party library stuff } MyClass::~MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // destroy 3rd party library stuff } I cannot link because I receive error: undefined reference to `MyClass::mx` Do I need some special initialization of such static member? Is the whole conception of static mutex wrong?

  Read the article

• C#: System.Lazy&lt;T&gt; and the Singleton Design Pattern

  - by James Michael Hare

  So we've all coded a Singleton at one time or another.  It's a really simple pattern and can be a slightly more elegant alternative to global variables.  Make no mistake, Singletons can be abused and are often over-used -- but occasionally you find a Singleton is the most elegant solution. For those of you not familiar with a Singleton, the basic Design Pattern is that a Singleton class is one where there is only ever one instance of the class created.  This means that constructors must be private to avoid users creating their own instances, and a static property (or method in languages without properties) is defined that returns a single static instance. 1: public class Singleton 2: { 3: // the single instance is defined in a static field 4: private static readonly Singleton _instance = new Singleton(); 5:  6: // constructor private so users can't instantiate on their own 7: private Singleton() 8: { 9: } 10:  11: // read-only property that returns the static field 12: public static Singleton Instance 13: { 14: get 15: { 16: return _instance; 17: } 18: } 19: } This is the most basic singleton, notice the key features: Static readonly field that contains the one and only instance. Constructor is private so it can only be called by the class itself. Static property that returns the single instance. Looks like it satisfies, right?  There's just one (potential) problem.  C# gives you no guarantee of when the static field _instance will be created.  This is because the C# standard simply states that classes (which are marked in the IL as BeforeFieldInit) can have their static fields initialized any time before the field is accessed.  This means that they may be initialized on first use, they may be initialized at some other time before, you can't be sure when. So what if you want to guarantee your instance is truly lazy.  That is, that it is only created on first call to Instance?  Well, there's a few ways to do this.  First we'll show the old ways, and then talk about how .Net 4.0's new System.Lazy<T> type can help make the lazy-Singleton cleaner. Obviously, we could take on the lazy construction ourselves, but being that our Singleton may be accessed by many different threads, we'd need to lock it down. 1: public class LazySingleton1 2: { 3: // lock for thread-safety laziness 4: private static readonly object _mutex = new object(); 5:  6: // static field to hold single instance 7: private static LazySingleton1 _instance = null; 8:  9: // property that does some locking and then creates on first call 10: public static LazySingleton1 Instance 11: { 12: get 13: { 14: if (_instance == null) 15: { 16: lock (_mutex) 17: { 18: if (_instance == null) 19: { 20: _instance = new LazySingleton1(); 21: } 22: } 23: } 24:  25: return _instance; 26: } 27: } 28:  29: private LazySingleton1() 30: { 31: } 32: } This is a standard double-check algorithm so that you don't lock if the instance has already been created.  However, because it's possible two threads can go through the first if at the same time the first time back in, you need to check again after the lock is acquired to avoid creating two instances. Pretty straightforward, but ugly as all heck.  Well, you could also take advantage of the C# standard's BeforeFieldInit and define your class with a static constructor.  It need not have a body, just the presence of the static constructor will remove the BeforeFieldInit attribute on the class and guarantee that no fields are initialized until the first static field, property, or method is called.   1: public class LazySingleton2 2: { 3: // because of the static constructor, this won't get created until first use 4: private static readonly LazySingleton2 _instance = new LazySingleton2(); 5:  6: // Returns the singleton instance using lazy-instantiation 7: public static LazySingleton2 Instance 8: { 9: get { return _instance; } 10: } 11:  12: // private to prevent direct instantiation 13: private LazySingleton2() 14: { 15: } 16:  17: // removes BeforeFieldInit on class so static fields not 18: // initialized before they are used 19: static LazySingleton2() 20: { 21: } 22: } Now, while this works perfectly, I hate it.  Why?  Because it's relying on a non-obvious trick of the IL to guarantee laziness.  Just looking at this code, you'd have no idea that it's doing what it's doing.  Worse yet, you may decide that the empty static constructor serves no purpose and delete it (which removes your lazy guarantee).  Worse-worse yet, they may alter the rules around BeforeFieldInit in the future which could change this. So, what do I propose instead?  .Net 4.0 adds the System.Lazy type which guarantees thread-safe lazy-construction.  Using System.Lazy<T>, we get: 1: public class LazySingleton3 2: { 3: // static holder for instance, need to use lambda to construct since constructor private 4: private static readonly Lazy<LazySingleton3> _instance 5: = new Lazy<LazySingleton3>(() => new LazySingleton3()); 6:  7: // private to prevent direct instantiation. 8: private LazySingleton3() 9: { 10: } 11:  12: // accessor for instance 13: public static LazySingleton3 Instance 14: { 15: get 16: { 17: return _instance.Value; 18: } 19: } 20: } Note, you need your lambda to call the private constructor as Lazy's default constructor can only call public constructors of the type passed in (which we can't have by definition of a Singleton).  But, because the lambda is defined inside our type, it has access to the private members so it's perfect. Note how the Lazy<T> makes it obvious what you're doing (lazy construction), instead of relying on an IL generation side-effect.  This way, it's more maintainable.  Lazy<T> has many other uses as well, obviously, but I really love how elegant and readable it makes the lazy Singleton.

  Read the article

• Enabling Http caching and compression in IIS 7 for asp.net websites

  - by anil.kasalanati

  Caching – There are 2 ways to set Http caching 1-      Use Max age property 2-      Expires header. Doing the changes via IIS Console – 1.       Select the website for which you want to enable caching and then select Http Responses in the features tab       2.       Select the Expires webcontent and on changing the After setting you can generate the max age property for the cache control    3.       Following is the screenshot of the headers   Then you can use some tool like fiddler and see 302 response coming from the server. Doing it web.config way – We can add static content section in the system.webserver section <system.webServer>   <staticContent>             <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="365.00:00:00" />   </staticContent> Compression - By default static compression is enabled on IIS 7.0 but the only thing which falls under that category is CSS but this is not enough for most of the websites using lots of javascript.  If you just thought by enabling dynamic compression would fix this then you are wrong so please follow following steps –   In some machines the dynamic compression is not enabled and following are the steps to enable it – Open server manager Roles > Web Server (IIS) Role Services (scroll down) > Add Role Services Add desired role (Web Server > Performance > Dynamic Content Compression) Next, Install, Wait…Done!   ?  Roles > Web Server (IIS) ?  Role Services (scroll down) > Add Role Services     Add desired role (Web Server > Performance > Dynamic Content Compression)     Next, Install, Wait…Done!     Enable  - ?  Open server manager ?  Roles > Web Server (IIS) > Internet Information Services (IIS) Manager   Next pane: Sites > Default Web Site > Your Web Site Main pane: IIS > Compression         Then comes the custom configuration for encrypting javascript resources. The problem is that the compression in IIS 7 completely works on the mime types and by default there is a mismatch in the mime types Go to following location C:\Windows\System32\inetsrv\config Open applicationHost.config The mimemap is as follows  <mimeMap fileExtension=".js" mimeType="application/javascript" />   So the section in the staticTypes should be changed          <add mimeType="application/javascript" enabled="true" />     Doing the web.config way –   We can add following section in the system.webserver section <system.webServer> <urlCompression doDynamicCompression="false"  doStaticCompression="true"/> More Information/References – ·         http://weblogs.asp.net/owscott/archive/2009/02/22/iis-7-compression-good-bad-how-much.aspx ·         http://www.west-wind.com/weblog/posts/98538.aspx  

  Read the article

• What functionality does dynamic typing allow?

  - by Justin984

  I've been using python for a few days now and I think I understand the difference between dynamic and static typing. What I don't understand is under what circumstances it would be preferred. It is flexible and readable, but at the expense of more runtime checks and additional required unit testing. Aside from non-functional criteria like flexibility and readability, what reasons are there to choose dynamic typing? What can I do with dynamic typing that isn't possible otherwise? What specific code example can you think of that illustrates a concrete advantage of dynamic typing?

  Read the article

• Are there any empirical studies on the effect of different languages on software quality?

  - by jgre

  The proponents of functional programming languages assert that functional programming makes it easier to reason about code. Those in favor of statically typed languages say that their compilers catch enough errors to make up for the additional complexity of type systems. But everything I read on these topics is based on rational argument, not on empirical data. Are there any empirical studies on what effects the different categories of programming languages have on defect rates or other quality metrics? (The answers to this question seem to indicate that there are no such studies, at least not for the dynamic vs. static debate)

  Read the article

• best practice for last-modified and created dates

  - by drewbenn

  I have a website with a handful (currently 3; I anticipate about a dozen when it's complete) of static html pages. I'd like to include "created" and "last-modified" dates in the pages for the benefit of visitors who arrive a week or a month or a few years from now. I expect anyone who cares to be viewing the source, so I could do: <!-- created yyyy-mm-dd, last-modified yyyy-mm-dd --> but I'd like to use something more standard (and elegant). I've found one reference to last modified (but only a mention in the text, not an actual code reference, so I'm not positive how to properly implement it) but not created. Is there a proper way to display both (or at least one) of these dates?

  Read the article

• Internal class and access to external members.

  - by Knowing me knowing you

  I always thought that internal class has access to all data in its external class but having code: template<class T> class Vector { template<class T> friend std::ostream& operator<<(std::ostream& out, const Vector<T>& obj); private: T** myData_; std::size_t myIndex_; std::size_t mySize_; public: Vector():myData_(nullptr), myIndex_(0), mySize_(0) { } Vector(const Vector<T>& pattern); void insert(const T&); Vector<T> makeUnion(const Vector<T>&)const; Vector<T> makeIntersection(const Vector<T>&)const; class Iterator : public std::iterator<std::bidirectional_iterator_tag,T> { private: T** itData_; public: Iterator()//<<<<<<<<<<<<<------------COMMENT { /*HERE I'M TRYING TO USE ANY MEMBER FROM Vector<T> AND I'M GETTING ERR SAYING: ILLEGAL CALL OF NON-STATIC MEMBER FUNCTION*/} Iterator(T** ty) { itData_ = ty; } Iterator operator++() { return ++itData_; } T operator*() { return *itData_[0]; } bool operator==(const Iterator& obj) { return *itData_ == *obj.itData_; } bool operator!=(const Iterator& obj) { return *itData_ != *obj.itData_; } bool operator<(const Iterator& obj) { return *itData_ < *obj.itData_; } }; typedef Iterator iterator; iterator begin()const { assert(mySize_ > 0); return myData_; } iterator end()const { return myData_ + myIndex_; } }; See line marked as COMMENT. So can I or I can't use members from external class while in internal class? Don't bother about naming, it's not a Vector it's a Set. Thank you.

  Read the article

• An Object reference is required for the non-static field

  - by Muhammad Akhtar

  I have make my existing method to static method to get access in javascript, like.. [WebMethod(EnableSession = true), ScriptMethod()] public static void Build(String ID) { Control releaseControl = LoadControl("~/Controls/MyControl.ascx"); //An Object reference is required for the non-static field, mthod or property // 'System.Web.UI.TemplateControl.LoadControl(string)' plc.Controls.Add(releaseControl); // where plc is place holder control //object reference is required for the nonstatic field, method, or property '_Default.pl' } When I build I am getting error and I have posted these in comments below each line before converted it to static method, it working perfectly. Please suggest me the solution of my issue. Thanks

  Read the article

• Static factory pattern with EJB3/JBoss

  - by purecharger

  I'm fairly new to EJBs and full blown application servers like JBoss, having written and worked with special purpose standalone Java applications for most of my career, with limited use of JEE. I'm wondering about the best way to adapt a commonly used design pattern to EJB3 and JBoss: the static factory pattern. In fact this is Item #1 in Joshua Bloch's Effective Java book (2nd edition) I'm currently working with the following factory: public class CredentialsProcessorFactory { private static final Log log = LogFactory.getLog(CredentialsProcessorFactory.class); private static Map<CredentialsType, CredentialsProcessor> PROCESSORS = new HashMap<CredentialsType, CredentialsProcessor>(); static { PROCESSORS.put(CredentialsType.CSV, new CSVCredentialsProcessor()); } private CredentialsProcessorFactory() {} public static CredentialsProcessor getProcessor(CredentialsType type) { CredentialsProcessor p = PROCESSORS.get(type); if(p == null) throw new IllegalArgumentException("No CredentialsProcessor registered for type " + type.toString()); return p; } However, in the implementation classes of CredentialsProcessor, I require injected resources such as a PersistenceContext, so I have made the CredentialsProcessor interface a @Local interface, and each of the impl's marked with @Stateless. Now I can look them up in JNDI and use the injected resources. But now I have a disconnect because I am not using the factory anymore. My first thought was to change the getProcessor(CredentialsType) method to do a JNDI lookup and return the SLSB instance that is required, but then I need to configure and pass the proper qualified JNDI name. Before I go down that path, I wanted to do more research on accepted practices. How is this design pattern treated in EJB3 / JEE?

  Read the article

• Can't define static abstract string property

  - by goombaloon

  I've run into an interesting problem and am looking for some suggestions on how best to handle this... I have an abstract class that contains a static method that accepts a static string that I would like to define as an abstract property. Problem is that C# doesn't doesn't support the following (see the ConfigurationSectionName and Current properties): public abstract class ProviderConfiguration : ConfigurationSection { private const string _defaultProviderPropertyName = "defaultProvider"; private const string _providersPropertyName = "providers"; protected static string ConfigurationSectionName { get; } public static Configuration Current { get { return Configuration)ConfigurationManager.GetSection(ConfigurationSectionName); } } } I suppose one way to handle this would be to make ConfigurationSectionName NOT abstract and then create a new definition of ConfigurationSectionName in the derived classes, but that feels pretty hackish. Any suggestions would be most welcome. Gratias!!!

  Read the article

• Java (Tomcat): how to configure a cookieless subdomain to serve static content

  - by Webinator

  One of the tip given by both Google and Yahoo! to speed up webpages loading is to configure a cookieless subdomain to server static content. How do you configure a "cookieless subdomain" using Tomcat in standalone mode (this question is not about how to use Apache to serve static content in a cookieless-way, but about how to do it in Tomcat-standalone mode)? Note that I don't care about filters supporting If-Modified-Since nor care about filters supporting gzipping: the static content I'm serving is forever cacheable (or its name will change) and it is already compressed data (so gzip would only slow down the transfer). Do I need two different Tomcat webapps? (one "cookiefull" and one "cookieless") Do I need two different servlets? (as of now I've got only one dispatcher/controller servlet). Why would a "regular" link to, say, a static image be called in a cookiefull way when it would be on the same domain as the main webapp and then be called in a "cookie-less" way when it is on a subdomain? I don't understand exactly what is going on: is it the browser that decides to append or not cookies to the query? If so, why would it not append the cookies to a static query on a "cookieless" subdomain. Any example as to what is going on behind the scene is most welcome :)

  Read the article

• PowerMock Mockito static methods

  - by anergy

  Do we need to mock all static methods of a class when using PowerMock (with Mockito)? I mean, suppose we have: class MockMe { public static MockMe getInstance(){ //return new Instance via complex process; } public static List<X> anotherStaticMethod(){ // does xyz } } My question, if I need to mock getInstance method, is it necessary to mock "anotherStaticMethod" as well? PowerMock version:1.3, Mockito version:1.8

  Read the article

• defining asmx webservice class objects as static

  - by Usama Khalil

  Hi, is it better to declare Webservice class object instances as static as the .asmx webservice classes have only static methods. what i want is that i declare and instantiate webservice asmx class as static in aspx Page Behind Class. and on every event call on that page i could perform operation against webservice methods. is it beneficial in terms of performance? Thanks Usama

  Read the article

• C# Generic Static Constructor

  - by Seattle Leonard

  Will a static constructor on a generic class be run for every type you pass into the generic parameter such as this: class SomeGenericClass<T> { static List<T> _someList; static SomeGenericClass() { _someList = new List<T>(); } } Are there any draw backs to using this approach?

  Read the article

• Using singleton instead of a global static instance

  - by Farstucker

  I ran into a problem today and a friend recommended I use a global static instance or more elegantly a singleton pattern. I spent a few hours reading about singletons but a few things still escape me. Background: What Im trying to accomplish is creating an instance of an API and use this one instance in all my classes (as opposed to making a new connection, etc). There seems to be about 100 ways of creating a singleton but with some help from yoda I found some thread safe examples. ..so given the following code: public sealed class Singleton { public static Singleton Instance { get; private set; } private Singleton() { APIClass api = new APIClass(); //Can this be done? } static Singleton() { Instance = new Singleton(); } } How/Where would you instantiate the this new class and how should it be called from a separate class? EDIT: I realize the Singleton class can be called with something like Singleton obj1 = Singleton.Instance(); but would I be able to access the methods within the APIs Class (ie. obj1.Start)? (not that I need to, just asking) EDIT #2: I might have been a bit premature in checking the answer but I do have one small thing that is still causing me problems. The API is launching just fine, unfortunately Im able to launch two instances? New Code public sealed class SingletonAPI { public static SingletonAPI Instance { get; private set; } private SingletonAPI() {} static SingletonAPI() { Instance = new SingletonAPI(); } // API method: public void Start() { API myAPI = new API();} } but if I try to do something like this... SingletonAPI api = SingletonAPI.Instance; api.Start(); SingletonAPI api2 = SingletonAPI.Instance; // This was just for testing. api2.Start(); I get an error saying that I cannot start more than one instance.

  Read the article

• Ruby on Rails - Static page as start page

  - by meetraghu28

  Hello! I am developing an app in RoR which has static and dynamic parts. The static portion is placed in the public/ folder of the app. Now if i have an index.html in my public folder then i will not be able to use the routes configured in my routes.rb The default configurations like map.connect /:controller/:action will not be usable if i have an index.html. So i removed the index html. Now i have a static page startpage.html in my public/ folder which has to be the starting page of the app. And the i have links in it for other static/dynamic pages. The RoR app is hosted in apache and i tried to configure the Virtual Host configuration by adding the DirectoryIndex param so that when ever a request comes for the site it will direct it to the startpage.html but still it takes me to the default controller that i have specified in routes.rb with map.root I dont want to add a dummy controller and action and create a view which has the startpage and configure routes.rb to use it as the root. What i am looking to do here is Basically startpage.html should be my first page in the app served as a static page from the public/ folder. This will then have links to other pages and controllers/actions Here i am not able to apache to redirect to the html page instead of passing on the control to rails application. Directory listing is also enabled by using Options Indexes but still no change. Any pointers anyone?

  Read the article

• Java: Cipher package (encrypt and decrypt). invalid key error

  - by noinflection

  Hello folks, i am doing a class with static methods to encrypt and decrypt a message using javax.crypto. I have 2 static methods that use ecipher and dcipher in order to do what they are supossed to do i need to initialize some variables (which are static also). But when i try to use it i get InvalidKeyException with the parameters i give to ecipher.init(...). I can't find why. Here is the code: private static byte[] raw = {-31, 17, 7, -34, 59, -61, -60, -16, 26, 87, -35, 114, 0, -53, 99, -116, -82, -122, 68, 47, -3, -17, -21, -82, -50, 126, 119, -106, -119, -5, 109, 98}; private static SecretKeySpec skeySpec; private static Cipher ecipher; private static Cipher dcipher; static { try { skeySpec = new SecretKeySpec(raw, "AES"); // Instantiate the cipher ecipher = Cipher.getInstance("AES"); dcipher = Cipher.getInstance("AES"); ecipher.init(Cipher.ENCRYPT_MODE, skeySpec); dcipher.init(Cipher.DECRYPT_MODE, skeySpec); } catch (NoSuchAlgorithmException e) { throw new UnhandledException("No existe el algoritmo deseado", e); } catch (NoSuchPaddingException e) { throw new UnhandledException("No existe el padding deseado", e); } catch (InvalidKeyException e) { throw new UnhandledException("Clave invalida", e); } }

  Read the article

• Java Static Methods

  - by KP65

  Hello, I am wondering when to use static methods? Say If i have a class with a few getters and setters, a method or two, and i want those methods only to be invokable on an instance object of the class. Does this mean i should use a static method? e.g Obj x = new Obj(); x.someMethod or Obj.someMethod (is this the static way?) I'm rather confused!

  Read the article

• C# 4.0: casting dynamic to static

  - by Kevin Won

  This is an offshoot question that's related to another I asked here. I'm splitting it off because it's really a sub-question: I'm having difficulties casting an object of type dynamic to another (known) static type. I have an ironPython script that is doing this: import clr clr.AddReference("System") from System import * def GetBclUri(): return Uri("http://google.com") note that it's simply newing up a BCL System.Uri type and returning it. So I know the static type of the returned object. now over in C# land, I'm newing up the script hosting stuff and calling this getter to return the Uri object: dynamic uri = scriptEngine.GetBclUri(); System.Uri u = uri as System.Uri; // casts the dynamic to static fine Works no problem. I now can use the strongly typed Uri object as if it was originally instantiated statically. however.... Now I want to define my own C# class that will be newed up in dynamic-land just like I did with the Uri. My simple C# class: namespace Entity { public class TestPy // stupid simple test class of my own { public string DoSomething(string something) { return something; } } } Now in Python, new up an object of this type and return it: sys.path.append(r'C:..path here...') clr.AddReferenceToFile("entity.dll") import Entity.TestPy def GetTest(): return Entity.TestPy(); // the C# class then in C# call the getter: dynamic test = scriptEngine.GetTest(); Entity.TestPy t = test as Entity.TestPy; // t==null!!! here, the cast does not work. Note that the 'test' object (dynamic) is valid--I can call the DoSomething()--it just won't cast to the known static type string s = test.DoSomething("asdf"); // dynamic object works fine so I'm perplexed. the BCL type System.Uri will cast from a dynamic type to the correct static one, but my own type won't. There's obviously something I'm not getting about this...

  Read the article

• How to have struct members accessible in different ways

  - by Paul J. Lucas

  I want to have a structure token that has start/end pairs for position, sentence, and paragraph information. I also want the members to be accessible in two different ways: as a start/end pair and individually. Given: struct token { struct start_end { int start; int end; }; start_end pos; start_end sent; start_end para; typedef start_end token::*start_end_ptr; }; I can write a function, say distance(), that computes the distance between any of the three start/end pairs like: int distance( token const &i, token const &j, token::start_end_ptr mbr ) { return (j.*mbr).start - (i.*mbr).end; } and call it like: token i, j; int d = distance( i, j, &token::pos ); that will return the distance of the pos pair. But I can also pass &token::sent or &token::para and it does what I want. Hence, the function is flexible. However, now I also want to write a function, say max(), that computes the maximum value of all the pos.start or all the pos.end or all the sent.start, etc. If I add: typedef int token::start_end::*int_ptr; I can write the function like: int max( list<token> const &l, token::int_ptr p ) { int m = numeric_limits<int>::min(); for ( list<token>::const_iterator i = l.begin(); i != l.end(); ++i ) { int n = (*i).pos.*p; // NOT WHAT I WANT: It hard-codes 'pos' if ( n > m ) m = n; } return m; } and call it like: list<token> l; l.push_back( i ); l.push_back( j ); int m = max( l, &token::start_end::start ); However, as indicated in the comment above, I do not want to hard-code pos. I want the flexibility of accessible the start or end of any of pos, sent, or para that will be passed as a parameter to max(). I've tried several things to get this to work (tried using unions, anonymous unions, etc.) but I can't come up with a data structure that allows the flexibility both ways while having each value stored only once. Any ideas how to organize the token struct so I can have what I want? Attempt at clarification Given struct of pairs of integers, I want to be able to "slice" the data in two distinct ways: By passing a pointer-to-member of a particular start/end pair so that the called function operates on any pair without knowing which pair. The caller decides which pair. By passing a pointer-to-member of a particular int (i.e., only one int of any pair) so that the called function operates on any int without knowing either which int or which pair said int is from. The caller decides which int of which pair. Another example for the latter would be to sum, say, all para.end or all sent.start. Also, and importantly: for #2 above, I'd ideally like to pass only a single pointer-to-member to reduce the burden on the caller. Hence, me trying to figure something out using unions.

  Read the article

• Why aren't static const floats allowed?

  - by Jon Cage

  I have a class which is essentially just holds a bunch of constant definitions used through my application. For some reason though, longs compile but floats do not: class MY_CONSTS { public : static const long LONG_CONST = 1; // Compiles static const float FLOAT_CONST = 0.001f; // C2864 }; Gives the following error: 1>c:\projects\myproject\Constant_definitions.h(71) : error C2864: 'MY_CONSTS::FLOAT_CONST' : only static const integral data members can be initialized within a class Am I missing something?

  Read the article

• Calling method on category included from iPhone static library causes NSInvalidArgumentException

  - by Corey Floyd

  I have created a static library to house some of my code like categories. I have a category for UIViews in "UIView-Extensions.h" named Extensions. In this category I have a method called: - (void)fadeOutWithDelay:(CGFloat)delay duration:(CGFloat)duration; Calling this method works fine on the simulator on Debug configuration. However, if try to run the app on the device I get a NSInvalidArgumentException: [UIView fadeOutWithDelay:duration:]: unrecognized selector sent to instance 0x1912b0 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIView fadeOutWithDelay:duration:]: unrecognized selector sent to instance 0x1912b0 It seems for some reason UIView-Extensions.h is not being included in the device builds. What I have checked/tried I did try to include another category for NSString, and had the same issue. Other files, like whole classes and functions work fine. It is an issue that only happens with categories. I did a clean all targets, which did not fix the problem. I checked the static library project, the categories are included in the target's "copy headers" and "compile sources" groups. The static library is included in the main projects "link binary with library" group. Another project I have added the static library to works just fine. I deleted and re-added the static library with no luck -ObjC linker flag is set Any ideas? nm output libFJSCodeDebug.a(UIView-Extensions.o): 000004d4 t -[UIView(Extensions) changeColor:withDelay:duration:] 00000000 t -[UIView(Extensions) fadeInWithDelay:duration:] 000000dc t -[UIView(Extensions) fadeOutWithDelay:duration:] 00000abc t -[UIView(Extensions) firstResponder] 000006b0 t -[UIView(Extensions) hasSubviewOfClass:] 00000870 t -[UIView(Extensions) hasSubviewOfClass:thatContainsPoint:] 000005cc t -[UIView(Extensions) rotate:] 000002d8 t -[UIView(Extensions) shrinkToSize:withDelay:duration:] 000001b8 t -[UIView(Extensions) translateToFrame:delay:duration:] U _CGAffineTransformRotate 000004a8 t _CGPointMake U _CGRectContainsPoint U _NSLog U _OBJC_CLASS_$_UIColor U _OBJC_CLASS_$_UIView U ___CFConstantStringClassReference U ___addsf3vfp U ___divdf3vfp U ___divsf3vfp U ___extendsfdf2vfp U ___muldf3vfp U ___truncdfsf2vfp U _objc_enumerationMutation U _objc_msgSend U _objc_msgSend_stret U dyld_stub_binding_helper

  Read the article

• Does Java have dynamic variables for class members?

  - by Arvanem

  Hi folks, I am wondering whether it is possible to make dynamic variables in Java. In other words, variables that change depending on my instructions. FYI, I am making a trading program. A given merchant will have an array of items for sale for various prices. The dynamism I am calling for comes in because each category of items for sale has its own properties. For example, a book item has two properties: int pages, and boolean hardCover. In contrast, a bookmark item has one property, String pattern. Here are skeleton snippets of code so you can see what I am trying to do: public class Merchants extends /* certain parent class */ { // only 10 items for sale to begin with Stock[] itemsForSale = new Stock[10]; // Array holding Merchants public static Merchants[] merchantsArray = new Merchants[maxArrayLength]; // method to fill array of stock goes here } and public class Stock { int stockPrice; int stockQuantity; String stockType; // e.g. book and bookmark // Dynamic variables here, but they should only be invoked depending on stockType int pages; boolean hardCover; String pattern; }

  Read the article

• Issue with deserialization of a static property in .Net

  - by Punit Singhi

  I have a class called Test which has four public properties and one of them is static. the problem is after deserialization the static property contains null value. i have debugged the code and found that at server side it contains the value which is a collection , but at client side it becomes null after deserialization. i know static members doesn't serialize and deserialize so obviously it should contain the value.

  Read the article

• NullPointerException with static variables

  - by tomekK

  I just hit very strange (to me) behaviour of java. I have following classes: public abstract class Unit { public static final Unit KM = KMUnit.INSTANCE; public static final Unit METERS = MeterUnit.INSTANCE; protected Unit() { } public abstract double getValueInUnit(double value, Unit unit); protected abstract double getValueInMeters(double value); } And: public class KMUnit extends Unit { public static final Unit INSTANCE = new KMUnit(); private KMUnit() { } //here are abstract methods overriden } public class MeterUnit extends Unit { public static final Unit INSTANCE = new MeterUnit(); private MeterUnit() { } ///abstract methods overriden } And my test case: public class TestMetricUnits extends TestCase { @Test public void testConversion() { System.out.println("Unit.METERS: " + Unit.METERS); System.out.println("Unit.KM: " + Unit.KM); double meters = Unit.KM.getValueInUnit(102.11, Unit.METERS); assertEquals(0.10211, meters, 0.00001); } } 1) MKUnit and MeterUnit are both singletons initialized statically, so during class loading. Constructors are private, so they can't be initialized anywhere else. 2) Unit class contains static final references to MKUnit.INSTANCE and MeterUnit.INSTANCE I would expect that: KMUnit class is loaded and instance is created. MeterUnit class is loaded and instance is created. Unit class is loaded and both KM and METERS variable are initialized, they are final so they cant be changed. But when I run my test case in console with maven my result is: T E S T S Running de.audi.echargingstations.tests.TestMetricUnits Unit.METERS: m Unit.KM: null Tests run: 3, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.089 sec <<< FAILURE! - in de.audi.echargingstations.tests.TestMetricUnits testConversion(de.audi.echargingstations.tests.TestMetricUnits) Time elapsed: 0.011 sec <<< ERROR! java.lang.NullPointerException: null at de.audi.echargingstations.tests.TestMetricUnits.testConversion(TestMetricUnits.java:29) Results : Tests in error: TestMetricUnits.testConversion:29 NullPointer And the funny part is that, when I run this test from eclipse via JUnit runner everything is fine, I have no NullPointerException and in console I have: Unit.METERS: m Unit.KM: km So the question is: what can be the reason that KM variable in Unit is null (and in the same time METERS is not null)

  Read the article

< Previous Page | 34 35 36 37 38 39 40 41 42 43 44 45  | Next Page >