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• An object reference is required for the non-static field, method, or property using global variable

  - by Jose Cardama

  Hello Iam working in a global int in which a variable will be used later. I've made the global variable like this: class Foo { public static int stream = Bass.BASS_StreamCreateFile(path1.Text, 0, 0, BASSFlag.BASS_DEFAULT); } which will be later called like this: Foo.stream and it can also contain more then 1 stream for example stream20,30,etc... The problem here is that it returns me this error: "An object reference is required for the non-static field, method, or property" where I call the text in path1.Text How do I fix this?

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• Security Resources Defining, Static/Dynamic

  - by mmontalvo

  I am implementing a simple(hopefully) security manager within an application. Is it better to have predefined(static) roles, custom roles(dynamic)? I am leaning more towards dynamic groups or roles only because then it would not require a redeploy to update the system. Also, what would be the best approach to define resources in general? The application has a database that can hold either the static or dynamic values.

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• Create a new instance in a static function of an abstract class

  - by arno

  abstract class db_table { static function get_all_rows() { ... while(...) { $rows[] = new self(); ... } return $rows; } } class user extends db_table { } $rows = user::get_all_rows(); I want to create instances of a class from a static method defined in the abstract parent class but PHP tells me "Fatal error: Cannot instantiate abstract class ..." How should I implement it correctly?

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• Invoking static methods containing Generic Parameters using Reflection.

  - by AJP

  While executing the following code i gets this error "Late bound operations cannot be performed on types or methods for which ContainsGenericParameters is true." class Program { static void Main(string[] args) { MethodInfo MI = typeof(MyClass).GetMethod("TestProc"); MI.MakeGenericMethod(new [] {typeof(string)}); MI.Invoke(null, new [] {"Hello"}); } } class MyClass { public static void TestProc<T>(T prefix) { Console.WriteLine("Hello"); } } Please help.

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• Java - public static void main()

  - by Gogi

  Should there be any specific order in which I should write the following : public static void main() ? In other words, can I re-shuffle public,static,void in any order ? Why or Why not ?

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• Static page routing in Sinatra (Ruby)

  - by JP

  You can serve static files with Sinatra by placing them in public/ (by default) -- I have an index.html in there at the moment, but how can I make the root point to that file without having to parse it as a template? To be clear, I can access /index.html successfully, and I'd like to route / to be the same static file, but without redirecting. Any idea how to do this?

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• Hibernate (JPA) Entity with Static collection as a member

  - by Kyle Partridge

  Is it possible to have a static collection as a member of a hibernate entity? Say I have an object Question: public class Question { private String category; ... } Would it be possible to populate a static Set<String> that is a distinct set of all categories in the Database? I know I could just query this, but I was wondering if there was a more elegant solution, as it seems like something that other people may have come across.

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• Static code Anaylysis tool for C and C++ [closed]

  - by Vaibhav

  Possible Duplicate: What open source C++ static analysis tools are available? I am Looking for a static code analysis tool for C and C++ on a Unix platform. Can you please recommend one for me, that you have used your self or know about.

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• Unable to create unmanaged object using new keyword in managed C++

  - by chair79

  Hi all, I've created a class with a boost::unordered_map as a member, Linkage.h #ifndef LINKAGE_H #define LINKAGE_H #include <boost/unordered_map.hpp> class Linkage { private: boost::unordered_map<int, int> m_IOMap; public: .... }; Linkage.cpp #include "stdafx.h" ... // methods and in the managed side of C++, I try to create the pointer of the obj: private: System::Void Form1_Load(System::Object^ sender, System::EventArgs^ e) { Linkage* m_pLink = new Linkage(); ..... } However this produces errors: Error 4 error LNK2005: "private: static unsigned int const boost::detail::type_with_alignment_imp<4>::found" (?found@?$type_with_alignment_imp@$03@detail@boost@@$$Q0IB) already defined in Proj_Test.obj Linkage.obj ..... Error 7 fatal error LNK1169: one or more multiply defined symbols found Could anyone explain to me pls? Thanks.

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• htaccess hotlinking problem

  - by DesperateWebDev

  Hi! Iam fighting following problem with little success. I want to block hotlinking to images in static folder from other domains than my_domain.com htaccess looks like this: RewriteEngine on RewriteCond %{HTTP_REFERER} !^$ RewriteCond %{HTTP_REFERER} !^http://(www\.)?my_domain\.com [NC] RewriteRule \.(gif|jpe?g|js|css)$ - [F,NC,L] RewriteRule ^(favicon\.ico)$ static/$1 [L] RewriteCond $1 !^(index\.php|static|robots\.txt|7e3b7a5bafcb0fa8e8dfe3ea6aca9186\.txt) RewriteRule ^(.*)$ /index.php/$1 [L] Page is on CodeIgniter and it have static folder so images can be loaded for ex: http://www.mydomain.com/static/somepic.jpg but users are linking from other sites and eat my bandwidth fast. Presented above htaccess doesnt work and I have NO idea why :( Please help!

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• the use of private keyword

  - by LAT

  Hi everyone I am new to programming. I am learning Java now, there is something I am not really sure, that the use of private. Why programmer set the variable as private then write , getter and setter to access it. Why not put everything in public since we use it anyway. public class BadOO { public int size; public int weight; ... } public class ExploitBadOO { public static void main (String [] args) { BadOO b = new BadOO(); b.size = -5; // Legal but bad!! } } I found some code like this, and i saw the comment legal but bad. I don't understand why, please explain me.

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• Difference between :: and -> in PHP

  - by vrode

  I always see people in serious projects use :: everywhere, and - only occasionally in local environment. I only use - myself and never end up in situations when I need a static value outside of a class. Am I a bad person? As I understand, the only situation when -> won't work is when I try following: class StaticDemo { private static $static } $staticDemo = new StaticDemo( ); $staticDemo->static; // wrong $staticDemo::static; // right But am I missing out on some programming correctness when I don't call simple public methods by :: ? Or is it just so that I can call a method without creating an instance?

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• Source Control Checkin Comments at Top Of Source Files

  - by James Wiseman

  I've noticed a discrepancy with some source files in our system whereby some contain source-control checkin comments, and some do not. These comments are added automatically to the top of the file when it is checked in: * $Log: //vm1/Projects/Morpheus/Sleep.bdy-arc $ -- -- Rev 1.14 Apr 14 2009 15:32:52 John Smith --Fixed bugs 2292 and 2230. This seems to have been quite prevelant in all the compainies with which I have worked, but I must confess that I struggle to see the point. Generally the comments aren't that good, are ofen left by people who have long since departed, and even when they are of a high standard it is difficult to tie them to physical code changes. It also strikes me, that you are physically changing the file that you are checking in. Now, this may not be such a problem with files that will be compiled, but could be a disaster with others, e.g. JavaScript files. So really, my query is what was the motivation in concept behind providing this functionality in the first instance? Does anyone actually find these comments useful? Also, I would be curious to know if this was feature that is commonly supported within Source Control systems. I am aware of it with PVCS, VSS and Subversion (Subversion Keyword Substitution), however I wonder if it is also available in some of the more popular DVCSs. Your help, as always is much appreciated.

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• Reference-type conversion operators: asking for trouble?

  - by Ben

  When I compile the following code using g++ class A {}; void foo(A&) {} int main() { foo(A()); return 0; } I get the following error messages: > g++ test.cpp -o test test.cpp: In function ‘int main()’: test.cpp:10: error: invalid initialization of non-const reference of type ‘A&’ from a temporary of type ‘A’ test.cpp:6: error: in passing argument 1 of ‘void foo(A&)’ After some reflection, these errors make plenty of sense to me. A() is just a temporary value, not an assignable location on the stack, so it wouldn't seem to have an address. If it doesn't have an address, then I can't hold a reference to it. Okay, fine. But wait! If I add the following conversion operator to the class A class A { public: operator A&() { return *this; } }; then all is well! My question is whether this even remotely safe. What exactly does this point to when A() is constructed as a temporary value? I am given some confidence by the fact that void foo(const A&) {} can accept temporary values according to g++ and all other compilers I've used. The const keyword can always be cast away, so it would surprise me if there were any actual semantic differences between a const A& parameter and an A& parameter. So I guess that's another way of asking my question: why is a const reference to a temporary value considered safe by the compiler whereas a non-const reference is not?

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• Is using YIELD a read-only way to return a collection?

  - by Eric

  I'm writing an interface which has a collection property which I want to be read only. I don't want users of the interface to be able to modify the collection. The typical suggestion I've found for creating a read only collection property is to set the type of the property to IEnumerable like this: private List<string> _mylist; public IEnumerable<string> MyList { get { return this._mylist; } } Yet this does not prevent the user from casting the IEnumerable back to a List and modifying it. If I use a Yield keyword instead of returning _mylist directly would this prevent users of my interface from being able to modify the collection. I think so because then I'm only returning the objects one by one, and not the actual collection. private List<string> _mylist; public IEnumerable<string> MyList { get { foreach(string str in this._mylist) { yield return str; } } }

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• Adding click/double-click events to static group box controls

  - by omatai

  Having realised my own reasons were way too dubious, I've now gone about this a different way. But I'm still curious... For reasons of nostalgia, familiarity and laziness, I'm coding a UI with MFC. For dubious reasons (as if those were not enough), I wanted to add a (double-)click event to a group box. Naturally, the group box contains things - in fact, it contains another static item, to which I can successfully add a (double-)click event handler. Is there any reason I cannot get an event handler to work for clicks on my group box the same way I can do that for the simple text static item? No amount of clicking on, in or near the control fires the event. Note - I've read through http://www.codeproject.com/KB/static/staticctrl_tut.aspx and tried responding to both ON_STN_... events and ON_BN_... messages, setting the notify style (BS_NOTIFY appears in the rc file)... and still I'm missing something - what is it? Is it even possible? Most of what I've googled suggests it is... but without clear answers for C++/MFC. Since first posting this question, I've found reference to a WM_NCHITTEST message, and hints that you have to create a handler for this message to override the group box default behaviour of responding with HT_TRANSPARENT... despite having its transparent property in ClassWizard set to false. Hmmm. Can anyone confirm that this is indeed the key?

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• WinForms Load Event / Static Initialization Strangeness

  - by Eric J.

  Background I'm troubleshooting an WinForms 2.0 program that's already been burned to CD for distribution to an internet-challenged target audience. Some users are experiencing a fatal error that I can reproduce locally. Reproducing the Error I get the fatal error when I log into my Vista box using a standard user that I just created, even if I run the program as administrator. I do not get the fatal error when I log in as local administrator. I'm not sure that being administrator is necessarily the trigger (since runas did not help). I have reproduced this half a dozen times under each account with consistent results. The faulty code Base.cs (base class for several user controls, only one of which is shown on first screen) private void BaseWindow_Load(object sender, EventArgs e) { // This message shown once in both cases MessageBox.Show("BaseWindow_Load for " + this.GetType().FullName); SkinManager.ApplySkin(this); } SkinManager.cs private static Skin skin = null; public static void ApplySkin(UserControl applyTo) { if (skin == null) { skin = new Skin(SkinsDirectory, "Default"); } } Skin.cs internal Skin(string skinPath, string skinName) { config = SkinConfig.Load(path); } SkinConfig.cs public static SkinConfig Load(string path) { // This message shown only once running as Admin but twice running as standard user System.Windows.Forms.MessageBox.Show("@1"); // !!! LOCK path HERE !!! } A user control loads on the first form, which triggers a call to SkinManager.ApplySkin, which checks if skin is null and, if so assigns it (without thread synchronization or recursion protection), which ultimately causes a file to be opened. When logged in as local admin, that sequence completes just fine. When logged in as my test standard user, ApplySkin is always called a second time while skin is still null, causing a second attempt to load, causing the file to be locked on the second attempt. The error handling is draconian at this point and the program terminates. The Question While this code can be easily fixed, I would like to understand why the error is happening only in some cases.

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• syntax help required on templated static member function

  - by omatai

  I have a bunch of containers of object pointers that I want to iterate through in different contexts to produce diagnostics for them. I'm struggling with the syntax required to define the functions... which, on account of these objects filtering through diverse parts of my application, seem best encapsulated in a dedicated diagnostics class thus: // Code sketch only - detail fleshed out below... class ObjectListDiagnoser { public: static void GenerateDiagnostics( /* help required here! */ ); }; ... // Elsewhere in the system... ObjectListDiagnoser::GenerateDiagnostics( /* help required here! */ ); What I'd like to be able to do (in places across my application) is at least this: std::vector<MyObject *> objGroup1; std::list<MyObject *> objGroup2; ObjectListDiagnoser::GenerateDiagnostics( objGroup1.begin(), objGroup1.end() ); ObjectListDiagnoser::GenerateDiagnostics( objGroup2.begin(), objGroup2.end() ); ObjectListDiagnoser::GenerateDiagnostics( objGroup1.rbegin(), objGroup1.rend() ); I have tried to template my function in two ways, with no success: class ObjectListDiagnoser { public: // 1 - nope. template <class ObjIter> static void GenerateDiagnostics( ObjIter first, ObjIter last ); // 2. - nope. template <class Container, class ObjIter> static void GenerateDiagnostics( Container<MyObject *>::ObjIter first, Container<MyObject *>::ObjIter last ); }; Can someone provide the correct syntax for this? The container type will vary, and the direction of iteration will vary, but always for the same type of object.

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• PHP syntax for referencing self with late static binding

  - by Chris

  When I learned PHP it was pretty much in procedural form, more recently I've been trying to adapt to the OOP way of doing things. Hoever the tutorials I've been following were produced before PHP 5.3 when late static binding was introduced. What I want to know is how do I reference self when calling a function from a parent class. For example these two methods were written for a User class which is a child of DatabaseObject. Right now they're sitting inside the User class, but, as they're used in other child classes of DatabaseObject I'd like to promote them to be included inside DatabaseObject. public static function find_all() { global $database; $result_set = self::find_by_sql("select * from ".self::$table_name); return $result_set; } and: protected function cleaned_attributes() { global $database; $clean_attributes = array(); foreach($this->attributes() as $key => $value) { $clean_attributes[$key] = $database->escape_value($value); } return $clean_attributes; } So I have three questions: 1) How do I change the self:: reference when I move it to the parent. Is it static:: or something similar? 2) When calling the function from my code do I call it in the same way, as a function of the child class eg User::find_all() or is there a change there also? 3) Is there anything else I need to know before I start chopping bits up?

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• Adding exclusive filter for <static initializer> in findbugs

  - by MilanAleksic

  Hi all, I want my findbugs report not show the following error: DM_NUMBER_CTOR: Method invokes inefficient Number constructor; use static valueOf instead The problem is that this happens in groovy-generated code files, so I can't control the source code - that is why I want to exclude it and add it to my exclude filter. I do not want to add explicitly class (since I make API that many tools will use, I want my filter to be generic). I would not like to completely remove this bug from the report by type, I would really like to only exclude this bug from appearing if it happenned in "static initializer" methods. Any idea? I tried the filter below but no luck, maybe somebody has better idea? <Match> <Method name="~.*static initializer.*" /> <Bug pattern="DM_NUMBER_CTOR" /> </Match> Here is the "stacktrace" of FindBugs in that case: In class net.milanaleksic.cuc.tools.sound.SoundPlayerTool In method net.milanaleksic.cuc.tools.sound.SoundPlayerTool.() Called method new Long(long) Should call Long.valueOf(long) instead In SoundPlayerTool.groovy

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• using volatile keyword

  - by sap

  As i understand, if we declare a variable as volatile, then it will not be stored in the local cache. Whenever thread are updating the values, it is updated to the main memory. So, other threads can access the updated value. But in the following program both volatile and non-volatile variables are displaying same value. The volatile variable is not updated for the second thread. Can anybody plz explain this why testValue is not changed. class ExampleThread extends Thread { private int testValue1; private volatile int testValue; public ExampleThread(String str){ super(str); } public void run() { if (getName().equals("Thread 1 ")) { testValue = 10; testValue1= 10; System.out.println( "Thread 1 testValue1 : " + testValue1); System.out.println( "Thread 1 testValue : " + testValue); } if (getName().equals("Thread 2 ")) { System.out.println( "Thread 2 testValue1 : " + testValue1); System.out.println( "Thread 2 testValue : " + testValue); } } } public class VolatileExample { public static void main(String args[]) { new ExampleThread("Thread 1 ").start(); new ExampleThread("Thread 2 ").start(); } } output: Thread 1 testValue1 : 10 Thread 1 testValue : 10 Thread 2 testValue1 : 0 Thread 2 testValue : 0

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• Jsp static import

  - by folone

  I've created a Spring Roo project. Everything looks fine. Now I want to add a form with a text input and a button to my index.jspx. This form will change a static field currentUser in my ToDo class. So I'm adding: <form> <%@ page import="static com.mypack.domain.ToDo.*" %> <label for="_username_id">My name is:</label> <% currentUser = request.getParameter("username"); %> <input type="text" id="username" name="username" maxlength="30" path="username" size="0" value="<%= currentUser %>"/> <input type="submit"/> </form> somewhere in the middle of it. And now it won't work: This page contains the following errors: error on line 6 at column 20: StartTag: invalid element name Below is a rendering of the page up to the first error. function readCookie(name) { var nameEQ = name + '='; var ca = document.cookie.split(';'); for(var i=0;i If I comment the lines above, it works just fine. What is wrong? Is there a way to write a value to a static field of a class from a jsp page? How do I work around this?

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• Static Variables somehow maintaining state?

  - by gfoley

  I am working on an existing project, setup by another coder. I'm having some trouble understanding how state is being maintained between pages. There is a Class library which has some helper objects. Mostly these objects are just used for there static methods and rarely instantiated or inherited. This is an example class I'm testing with. public sealed class Application { public static string Test; } Now when i run something like the following in the base class of my page, I would expect the result to be "1: 2:Test" all the time (note that "1" is empty), but strangly its only this way the first time it is run. Then every time afterwards its "1:Test 2:Test". Somehow its maintaining the state of the static variable between pages and being refreshed?? Response.Write("1:" + SharedLibrary.Application.Test); SharedLibrary.Application.Test = "Test"; Response.Write(" 2:" + SharedLibrary.Application.Test); I need to create more classes like this, but want to understand why this is occurring in the first place. Many Thanks

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• Building static (but complicated) lookup table using templates.

  - by MarkD

  I am currently in the process of optimizing a numerical analysis code. Within the code, there is a 200x150 element lookup table (currently a static std::vector < std::vector < double ) that is constructed at the beginning of every run. The construction of the lookup table is actually quite complex- the values in the lookup table are constructed using an iterative secant method on a complicated set of equations. Currently, for a simulation, the construction of the lookup table is 20% of the run time (run times are on the order of 25 second, lookup table construction takes 5 seconds). While 5-seconds might not seem to be a lot, when running our MC simulations, where we are running 50k+ simulations, it suddenly becomes a big chunk of time. Along with some other ideas, one thing that has been floated- can we construct this lookup table using templates at compile time? The table itself never changes. Hard-coding a large array isn't a maintainable solution (the equations that go into generating the table are constantly being tweaked), but it seems that if the table can be generated at compile time, it would give us the best of both worlds (easily maintainable, no overhead during runtime). So, I propose the following (much simplified) scenario. Lets say you wanted to generate a static array (use whatever container suits you best- 2D c array, vector of vectors, etc..) at compile time. You have a function defined- double f(int row, int col); where the return value is the entry in the table, row is the lookup table row, and col is the lookup table column. Is it possible to generate this static array at compile time using templates, and how?

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• Java Class<T> static method forName() IncompatibleClassChangeError

  - by matt

  Hi, i have this code: private static Importable getRightInstance(String s) throws Exception { Class<? extends Importable> c = Class.forName(s).asSubclass(Importable.class); Importable i = c.newInstance(); return i; } which i can also write private static Importable getRightInstance(String s) throws Exception { Class<? extends Importable> c = (Class<? extends Importable>)Class.forName(s); Importable i = c.newInstance(); return i; } or private static Importable getRightInstance(String s) throws Exception { Class<?> c = Class.forName(s); Importable i = (Importable)c.newInstance(); return i; } where Importable is an interface and s is a string representing an implementing class. Well, in any case it gives the following: Exception in thread "main" java.lang.IncompatibleClassChangeError: class C1 has interface Importable as super class Here is the last snippet of the stack trace: at java.lang.Class.forName(Class.java:169) at Importer.getRightImportable(Importer.java:33) at Importer.importAll(Importer.java:44) at Test.main(Test.java:16) Now, class C1 actually implemens Importable and i totally don't understand why it complaints. Thanks in advance.

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