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  • Significant amount of the time, I can't think of a reason to have an object instead of a static class. Do objects have more benefits than I think?

    - by Prog
    I understand the concept of an object, and as a Java programmer I feel the OO paradigm comes rather naturally to me in practice. However recently I found myself thinking: Wait a second, what are actually the practical benefits of using an object over using a static class (with proper encapsulation and OO practices)? I could think of two benefits of using an object (both significant and powerful): Polymorphism: allows you to swap functionality dynamically and flexibly during runtime. Also allows to add new functionality 'parts' and alternatives to the system easily. For example if there's a Car class designed to work with Engine objects, and you want to add a new Engine to the system that the Car can use, you can create a new Engine subclass and simply pass an object of this class into the Car object, without having to change anything about Car. And you can decide to do so during runtime. Being able to 'pass functionality around': you can pass an object around the system dynamically. But are there any more advantages to objects over static classes? Often when I add new 'parts' to a system, I do so by creating a new class and instantiating objects from it. But recently when I stopped and thought about it, I realized that a static class would do just the same as an object, in a lot of the places where I normally use an object. For example, I'm working on adding a save/load-file mechanism to my app. With an object, the calling line of code will look like this: Thing thing = fileLoader.load(file); With a static class, it would look like this: Thing thing = FileLoader.load(file); What's the difference? Fairly often I just can't think of a reason to instantiate an object when a plain-old static-class would act just the same. But in OO systems, static classes are fairly rare. So I must be missing something. Are there any more advantages to objects other from the two that I listed? Please explain.

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  • iPhone SDK linking errors with static library

    - by Nico
    Hello all! I've built my own static library with components to be reused in my project, and recently had the need to update a bunch of classes. Specifically, some methods' signatures were changed due to the fact that some classes changed names. What happens now is that the library compiles fine on its own, but, when added to an app project, the project fails to link: Ld build/Sucursales.build/Debug-iphoneos/Sucursales.build/Objects-normal/armv6/Sucursales normal armv6 cd /Users/nameghino/src/Sucursales setenv IPHONEOS_DEPLOYMENT_TARGET 3.1 setenv PATH "/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin" /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc-4.2 -arch armv6 -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.2.sdk -L/Users/nameghino/src/Sucursales/build/Debug-iphoneos -L/Users/nameghino/src/Sucursales/../../Library/MyLibraries/MSSharedLibrary-1.0.0 -F/Users/nameghino/src/Sucursales/build/Debug-iphoneos -filelist /Users/nameghino/src/Sucursales/build/Sucursales.build/Debug-iphoneos/Sucursales.build/Objects-normal/armv6/Sucursales.LinkFileList -dead_strip -lxml2 -ObjC -all_load -miphoneos-version-min=3.1 -framework Foundation -framework UIKit -framework CoreGraphics -lsqlite3.0 -framework CoreLocation -framework MapKit -lxml2 /Users/nameghino/src/MSSharedComponents/Frameworks/MSSharedLibrary/build/Debug-iphoneos/libMSSharedLibrary.a -o /Users/nameghino/src/Sucursales/build/Sucursales.build/Debug-iphoneos/Sucursales.build/Objects-normal/armv6/Sucursales Undefined symbols: "_OBJC_CLASS_$_DataCatalogService_GetSingleRow", referenced from: objc-class-ref-to-DataCatalogService_GetSingleRow in libMSSharedLibrary.a(MSDataCatalogSpecification.o) **"_OBJC_CLASS_$_DataCatalogService_ArrayOfString", referenced from: objc-class-ref-to-DataCatalogService_ArrayOfString in libMSSharedLibrary.a(MSDataCatalogSpecification.o) "_OBJC_CLASS_$_DataCatalogService_GetSingleRowResponse", referenced from: objc-class-ref-to-DataCatalogService_GetSingleRowResponse in libMSSharedLibrary.a(MSSingleRowResultsParser.o) "_OBJC_CLASS_$_DataCatalogService_GetMultiRowResponse", referenced from: objc-class-ref-to-DataCatalogService_GetMultiRowResponse in libMSSharedLibrary.a(MSMultiRowResultsParser.o) "_OBJC_CLASS_$_DataCatalogService_GetMultiRow", referenced from: objc-class-ref-to-DataCatalogService_GetMultiRow in libMSSharedLibrary.a(MSDataCatalogSpecification.o) "_OBJC_CLASS_$_DataCatalogService_HelloWorldResponse", referenced from: objc-class-ref-to-DataCatalogService_HelloWorldResponse in libMSSharedLibrary.a(DataCatalogService.o) ld: symbol(s) not found collect2: ld returned 1 exit status** The curious thing is that after a lot of project cleanups (both in the app and the lib projects), I still get the same issue. Even after starting a new project, the problem is still there. I've also taken care to restart Xcode between a clean and a build a couple of times, but no good. Any ideas on where to look? Thanks in advance Nico

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  • Static libraries, dynamic libraries, DLLs, entry points, headers ... how to get out of this alive?

    - by tunnuz
    Hello, I recently had to program C++ under Windows for an University project, and I'm pretty confused about static and dynamic libraries system, what the compiler needs, what the linker needs, how to build a library ... is there any good document about this out there? I'm pretty confused about the *nix library system as well (so, dylibs, the ar tool, how to compile them ...), can you point a review document about the current library techniques on the various architectures? Note: due to my poor knowledge this message could contain wrong concepts, feel free to edit it. Thank you Feel free to add more reference, I will add them to the summary. References Since most of you posted *nix or Windows specific references I will summarize here the best ones, I will mark as accepted answer the Wikipedia one, because is a good start point (and has references inside too) to get introduced to this stuff. Program Library Howto (Unix) Dynamic-Link Libraries (from MSDN) (Windows) DLL Information (StackOverflow) (Windows) Programming in C (Unix) An Overview of Compiling and Linking (Windows)

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  • Static route works on one computer, not the other

    - by Dan
    I have been struggling with this for a couple days now, maybe I just need some people with a fresh perspective to figure out what the issue is. Basically I have a bunch of computers that are being routed through a specific gateway in order to access a web page that is hosted internally on a separate subnet. I set up static routes on all of the computers, and they all work... except one. Here's what a route print -4 looks like for a working computer (Windows 7): =========================================================================== Interface List 14...xx xx xx xx xx xx ......Broadcom 802.11n Network Adapter 11...xx xx xx xx xx xx ......Realtek PCIe GBE Family Controller 1...........................Software Loopback Interface 1 12...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter 13...00 00 00 00 00 00 00 e0 Microsoft 6to4 Adapter 17...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface =========================================================================== IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 10.xxx.xxx.230 10.xxx.xxx.94 20 10.zzz.zzz.0 255.255.255.0 10.xxx.xxx.147 10.xxx.xxx.94 21 10.xxx.xxx.0 255.255.255.0 On-link 10.xxx.xxx.94 276 10.xxx.xxx.94 255.255.255.255 On-link 10.xxx.xxx.94 276 10.xxx.xxx.255 255.255.255.255 On-link 10.xxx.xxx.94 276 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 10.xxx.xxx.94 276 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306 255.255.255.255 255.255.255.255 On-link 10.xxx.xxx.94 276 =========================================================================== Persistent Routes: Network Address Netmask Gateway Address Metric 10.zzz.zzz.0 255.255.255.0 10.xxx.xxx.147 1 =========================================================================== And here's a route print -4 from the station that doesn't work (also Windows 7): =========================================================================== Interface List 10...xx xx xx xx xx xx ......Realtek PCIe GBE Family Controller 1...........................Software Loopback Interface 1 12...00 00 00 00 00 00 00 e0 Microsoft 6to4 Adapter 14...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2 16...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface =========================================================================== IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 10.xxx.xxx.230 10.xxx.xxx.132 276 10.zzz.zzz.0 255.255.255.0 10.xxx.xxx.147 10.xxx.xxx.132 21 10.xxx.xxx.0 255.255.255.0 On-link 10.xxx.xxx.132 276 10.xxx.xxx.132 255.255.255.255 On-link 10.xxx.xxx.132 276 10.xxx.xxx.255 255.255.255.255 On-link 10.xxx.xxx.132 276 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 10.xxx.xxx.132 276 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306 255.255.255.255 255.255.255.255 On-link 10.xxx.xxx.132 276 =========================================================================== Persistent Routes: Network Address Netmask Gateway Address Metric 10.zzz.zzz.0 255.255.255.0 10.xxx.xxx.147 1 =========================================================================== Both of these stations are running Windows 7. So essentially what I am trying to do here is route all traffic to the 10.zzz.zzz.0 subnet through the 10.xxx.xxx.147 gateway. Everything else should go through the 10.xxx.xxx.230 gateway. This is the intended behavior, and again it is working everywhere but that one station. I noticed that the Active Route metric costs differ between the two stations, but I am new to the routing table and I am not sure how that is impacting the behavior. I hope I have been able to explain the situation clearly. Any help would be much appreciated. I can provide any additional information if needed!

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  • non-static method setPrzechowaj(java.lang.String) cannot be referenced froma a static context

    - by bigbluedragon
    hey i have problem with JDialogForm. I have created it using netbeans 6.8. That JDialogForm have textfield and button below it. and here is some code... private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { String sciezka = jTextField1.getText(); if (sciezka.length() > 0) { Zmienne_pomocnicze.setPrzechowaj(sciezka); } } Now i want to copy that string "sciezka" to my main window but if I do it like this public class Zmienne_pomocnicze { public String n; public void setPrzechowaj (String neew) { n = neew; } public String getPrzechowaj () { return n; } } i get error in jButton1: non-static method setPrzechowaj(java.lang.String) cannot be referenced froma a static context any ideas?

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  • Third Party Libraries and Technologies very Java Programmer must be aware of?

    - by kunjaan
    I agree that this is a very subjective question but as a student of Java , I get suggested good libraries and technologies for Java by my mentors at work. For example, I was not aware of Google Guice for Dependency Injection, awesomeness of Java Reflection APIs, ORMs like Hibernate or stuffs you could do with libraries like Hadoop. I want to collect and share some of the libraries that exemplifies good java programming (so that beginners like me could code walk and emulate the coding practice), teach unique concepts to Java (for example Dependency Injections or ORM) and/or are really interesting libraries that a student like me would get to do interesting projects on (eg. Hadoop). I redited this question 3 times to make it more specific : ). I am sorry if I am really not clear in my intentions. But some kind of a list of good concepts and third party libraries for Java could really help some of my intern friends here at work. Thank you.

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  • Third Party Libraries and Technologies every Java Programmer must be aware of?

    - by kunjaan
    I agree that this is a very subjective question but as a student of Java , I get suggested good libraries and technologies for Java by my mentors at work. For example, I was not aware of Google Guice for Dependency Injection, awesomeness of Java Reflection APIs, ORMs like Hibernate or stuffs you could do with libraries like Hadoop. I want to collect and share some of the libraries that exemplifies good java programming (so that beginners like me could code walk and emulate the coding practice), teach unique concepts to Java (for example Dependency Injections or ORM) and/or are really interesting libraries that a student like me would get to do interesting projects on (eg. Hadoop). I redited this question 3 times to make it more specific : ). I am sorry if I am really not clear in my intentions. But some kind of a list of good concepts and third party libraries for Java could really help some of my intern friends here at work. Thank you.

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  • C# "Enum" Serialization - Deserialization to Static Instance

    - by Walt W
    Suppose you have the following class: class Test : ISerializable { public static Test Instance1 = new Test { Value1 = "Hello" ,Value2 = 86 }; public static Test Instance2 = new Test { Value1 = "World" ,Value2 = 26 }; public String Value1 { get; private set; } public int Value2 { get; private set; } public void GetObjectData(SerializationInfo info, StreamingContext context) { //Serialize an indicator of which instance we are - Currently //I am using the FieldInfo for the static reference. } } I was wondering if it is possible / elegant to deserialize to the static instances of the class? Since the deserialization routines (I'm using BinaryFormatter, though I'd imagine others would be similar) look for a constructor with the same argument list as GetObjectData(), it seems like this can't be done directly . . Which I would presume means that the most elegant solution would be to actually use an enum, and then provide some sort of translation mechanism for turning an enum value into an instance reference. How might one go about this?

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  • Why doesn't Visual Studio show an exception message when my exception occurs in a static constructor

    - by Tim Goodman
    I'm running this C# code in Visual Studio in debug mode: public class MyHandlerFactory : IHttpHandlerFactory { private static Dictionary<string, bool> myDictionary = new Dictionary<string, bool>(); static MyHandlerFactory() { myDictionary.Add("someKey",true); myDictionary.Add("someKey",true); // fails due to duplicate key } } Outside of the static constructor, when I get to the line with the error Visual Studio highlights it and pops up a message about the exception. But in the static constructor I get no such message. I am stepping through line-by-line, so I know that I'm getting to that line and no further. Why is this? (I have no idea if that fact that my class implements IHttpHandlerFactory matters, but I included it just in case.) This is VS2005, .Net 2.0

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  • Static analysis tool customization for any language

    - by Sam
    Hi, We are using a Tool in our project. This tool has its own language which is similar to Java. I am looking for a static analysis tool which can be applied to the new language. Are there any static analysis tools which can be customized to any languages? or Is there any document or any reference on how to develop the static analysis tool for our own languages? Thanks.

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  • Why static fields are not initialized in time?

    - by Tom Brito
    Somebody tell me: class MyClass { private static MyClass myClass = new MyClass(); private static final Object obj = new Object(); public MyClass() { System.out.println(obj); // will print null once } } I wonder, isn't this a bug? Why static objects are not initialized before the constructor runs?

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  • Best Static Website Generator

    - by Nick Retallack
    In the age of dynamic websites built with layouts and templates, nobody wants to write plain old repetitive static html anymore. But now that you can outsource dynamic features to services like Disqus, and you could get slashdotted/dugg/reddited at any moment, sometimes a static website is best for scalability. There are quite a few static website generators out there that let you use templates, layouts, alternative markup languages, and other new age stuff. So this question is a bit of a survey. Which do you think is the best, and why? Here are a few examples to start us off: WebGen StaticMatic Static

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  • Is it safe to lock a static variable in a non-static class?

    - by Dario Solera
    I've got a class that manages a shared resource. Now, since access to the resource depends on many parameters, this class is instantiated and disposed several times during the normal execution of the program. The shared resource does not support concurrency, so some kind of locking is needed. The first thing that came into my mind is having a static instance in the class, and acquire locks on it, like this: // This thing is static! static readonly object MyLock = new object(); // This thing is NOT static! MyResource _resource = ...; public DoSomeWork() { lock(MyLock) { _resource.Access(); } } Does that make sense, or would you use another approach?

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  • Advantage of using a static member function instead of an equivalent non-static member function?

    - by jonathanasdf
    I was wondering whether there's any advantages to using a static member function when there is a non-static equivalent. Will it result in faster execution (because of not having to care about all of the member variables), or maybe less use of memory (because of not being included in all instances)? Basically, the function I'm looking at is an utility function to rotate an integer array representing pixel colours an arbitrary number of degrees around an arbitrary centre point. It is placed in my abstract Bullet base class, since only the bullets will be using it and I didn't want the overhead of calling it in some utility class. It's a bit too long and used in every single derived bullet class, making it probably not a good idea to inline. How would you suggest I define this function? As a static member function of Bullet, of a non-static member function of Bullet, or maybe not as a member of Bullet but defined outside of the class in Bullet.h? What are the advantages and disadvantages of each?

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  • Why can't I inherit static classes?

    - by User
    I have several classes that do not really need any state. From the organizational point of view, I would like to put them into hierarchy. But it seems I can't declare inheritance for static classes. Something like that: public static class Base { } public static class Inherited : Base { } will not work. Why have the designers of the language closed that possibility?

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  • Static variables in Java for a test oObject creator

    - by stevebot
    Hey, I have something like the following TestObjectCreator{ private static Person person; private static Company company; static { person = new Person() person.setName("Joe"); company = new Company(); company.setName("Apple"); } public Person createTestPerson(){ return person; } public Person createTestCompany(){ return company; } } By applying static{} what am I gaining? I assume the objects are singletons as a result. However, if I did the following: Person person = TestObjectCreator.createTestPerson(); person.setName("Jill"); Person person2 = TestObjectCreator.createTestPerson(); would person2 be named Jill or Joe?

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  • How to return Current Object in a Static function in PHP

    - by streetparade
    I neet access to current object in a static method. Code: protected static $name; public static function name($modulename) { self::$name = $modulename; } public function __call($name, $arguments) { $me = new test(self::$name); return $me->$name($arguments); } I want to be able to call method log in Log class. Like this echo Mods::name("Log")->log("test"); How do i do that?

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  • Where to put constant strings in C++: static class members or anonymous namespaces

    - by stone
    I need to define some constant strings that will be used only by one class. It looks like I have three options: Embed the strings directly into locations where they are used. Define them as private static constant members of the class: //A.h class A { private: static const std::string f1; static const std::string f2; static const std::string f3; }; //A.cpp const std::string f1 = "filename1"; const std::string f2 = "filename2"; const std::string f3 = "filename3"; //strings are used in this file Define them in an anonymous namespace in the cpp file: //A.cpp namespace { const std::string f1 = "filename1"; const std::string f2 = "filename2"; const std::string f3 = "filename3"; } //strings are used in this file Given these options, which one would you recommend and why? Thanks.

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  • Best practise for overriding static classes

    - by maxp
    As it is not possible to override a static class in c#, if i want to override a method I generally define a delegate matching the signature of the static method, then modify the method along the lines of: public static void foo(int bar) { if (delegatename!=null) { delegatename.Invoke(bar); } else { //execute previous code as normal } } I feel a twinge of guilt, knowing this is a bit messy. Can anyone suggest a neater solution to this problem (other than rewriting the original structure)

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