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  • Static Vs Non-Static Method Performance C#

    - by dotnetguts
    Hello All, I have few global methods declared in public class in my asp.net web application. I have habbit of declaring all global methods in public class in following format public static string MethodName(parameters) { } I want to know how it would impact on performance point of view? 1) Which one is Better? Static Method or Non-Static Method? 2) Reason why it is better? Following link shows Non-Static methods are good because, static methods are using locks to be Thread-safe. The always do internally a Monitor.Enter() and Monitor.exit() to ensure Thread-safety. http://bytes.com/topic/c-sharp/answers/231701-static-vs-non-static-function-performance And Following link shows Static Methods are good static methods are normally faster to invoke on the call stack than instance methods. There are several reasons for this in the C# programming language. Instance methods actually use the 'this' instance pointer as the first parameter, so an instance method will always have that overhead. Instance methods are also implemented with the callvirt instruction in the intermediate language, which imposes a slight overhead. Please note that changing your methods to static methods is unlikely to help much on ambitious performance goals, but it can help a tiny bit and possibly lead to further reductions. http://dotnetperls.com/static-method I am little confuse which one to use? Thanks

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  • netbeans autocompletion when using singleton to retrieve object instead of new operator?

    - by fayer
    when i use the 'new' operator to instantiate a class, netbeans has no problem to autocomplete the members of the object. $instance = new Singleton(); $instance-> // shows test() method but when i use a singleton to retrieve an object it cannot autocomplete the members in the object retrieved. the getInstance code looks like this: public function test() { echo "hello"; } public static function getInstance() { if ( ! is_object(self::$_instance)) { self::$_instance = new self(); self::$_instance->initialize(); } return self::$_instance; } so i use: $instance = Singleton::getInstance(); $instance-> // no autocompletion! does anyone have the same problem? how do i work around it? thanks!

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  • MySQL - Calculating fields on the fly vs storing calculated data

    - by Christian Varga
    Hi Everyone, I apologise if this has been asked before, but I can't seem to find an answer to a question that I have about calculating on the fly vs storing fields in a database. I read a few articles that suggested it was preferable to calculate when you can, but I would just like to know if that still applies to the following 2 examples. Example 1. Say you are storing data relating to a car. You store the fuel tank size in litres, and how many litres it uses per 100km. You also want to know how many KMs it can travel, which can be calculated from the tank size and economy. I see 2 ways of doing this: When a car is added or updated, calculate the amount of KMs and store this as a static field in the database. Every time a car is accessed, calculate the amount of KMs on the fly. Because the cars economy/tank size doesn't change (although it could be edited), the KMs is a pretty static value. I don't see why we would calculate it every single time the car is accessed. Wouldn't this waste cpu time as opposed to simply storing it in a separate field in the database and calculating only when a car is added or updated? My next example, which is almost an entirely different question (but on the same topic), relates to counting children. Let's say we have a app which has categories and items. We have a view where we display all the categories, and a count of all the items inside each category. Again, I'm wondering what's better. To perform a MySQL query to count all the items in each category every single time the page is accessed? Or store the count in a field in the categories table and update when an item is added / deleted? I know it is redundant to store anything that can be calculated, but I worry that calculating fields or counting records might be slow as opposed to storing the data in a field. If it's not then please let me know, I just want to learn about when to use either method. On a small scale I guess it wouldn't matter either way, but apps like Facebook, would they really count the amount of friends you have every time someone views your profile or would they just store it as a field? I'd appreciate any responses to both of these scenarios, and any resource that might explain the benefits of calculating vs storing. Thanks in advance, Christian

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  • Can silverlight detect or communicate across browser instances?

    - by isolatedIterator
    User starts up a silverlight application in their browser by navigating to a given URL. User then opens another browser and starts up the same silverlight application by navigating to the same URL. Can the second instance of the application detect that there is already an instance running on the same computer? Can it detect itself if both applications are running within the same browser instance? I would expect the answer to be 'no' but thought that i would ask it anyway. Otherwise i believe that i will have to setup a webservice and have each instance register itself and send requests to other instances from the same IP. does that sound reasonable?

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  • Reflection: take values from an unknown running alpplication

    - by Dr.Lesh
    I'm writing an application that searchs for Semaphore types in the fields of unknown classes in unknown application (passed by user). I made it using Reflection and it worked. Now I want to fill up these semaphores with values, taking them from a running instance of this unknown application. So i took the class with "main" method of this unknown application, made a newInstance, and passed it when invoking the main method to start the application: Class mainClass = getItSomeWhere(); Object instance = mainClass.newInstance(); Method mainMethod = mainClass.getDeclaredMethod("main", new Class[]{String[].class}); mainMethod.invoke(instance, new Object[]{args}); and it worked fine. Now, how can I get the semaphore values, taking them from the classes of this running application, when I only have an instance of the main class? Many thanks for the answers.

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  • Grails design for domain class initialization from static data

    - by Allison Eer
    I have some data, stateNames, to instantiate an instance of the object Country. Right now, I will only have one Country but stateNames for each country should be different. What is the best way to instantiate the instance of Country with my data? I am new to grails and would appreciate any "best practices" or common designs. One solution I can think of is to use BootStrap to save the unitedStates instance of Country to the database. What are the cons of this approach? Another solution would be to save the data in a file (in xml?) under web-app folder. If I did this approach, should the unitedStates instance of Country be instantiated by a controller?

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  • Howto check if a object is connected to another in hibernate

    - by codevourer
    Imagine two domain object classes, A and B. A has a bidirectional one-to-many relationship to B. A is related to thousands of B. The relations must be unique, it's not possible to have a duplicate. To check if an instance of B is already connected to a given instance of A, we could perform an easy INNER JOIN but this will only ensure the already persisted relations. What about the current transient relations? class A { @OneToMany private List<B> listOfB; } If we access the listOfB and perform a check of contains() this will fetch all the connected instances of B lazy from the datasource. I only want to validate them by their primary-key. Is there an easy solution where I can do things like "Does this instance of A is connected with this instance of B?" Without loading all these data into memory and perform a based on collections?

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  • load balancing in Tomcat

    - by Alvin
    Hi All, I want to implement the load balancing in tomcat 6.0 so that we can create more than one instance of a tomcat and when any of the instance is down then other instance will run our application. so that our application will never be down even when the large number of concurrent request comes. But i have no idea to implement it. Please give your precious suggestions.

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  • Can XPath concatenate two nodeset values? (for use in XForms)

    - by iHeartGreek
    Hi! I am wanting to concatenate two nodeset values using XPath in XForms. I know that XPath has a concat(string, string) function, but how would I go about concatenating two nodeset values? BEGIN EDIT: I tried concat function.. I tried this.. and variations of it to make it work, but it doesn't <xf:value ref="concat(instance('param_choices')/choice/root, .)"/> END EDIT Below is a simplified code example of what I am trying to achieve. XForms model: <xf:instance id="param_choices" xmlns=""> <choices> <root label="Param Choices">/param</root> <choice label="Name">/@AAA</choice> <choice label="Value">/@BBB</choice> </choices> </xf:instance> XForms ui code that I currently have: <xf:select ref="instance('criteria_data')/criteria/criterion" appearance="full"> <xf:label>Param choices:</xf:label> <br/> <xf:itemset nodeset="instance('param_choices')/choice"> <xf:label ref="@label"></xf:label> <xf:value ref="."></xf:value> </xf:itemset> </xf:select> (if user selects "Name" checkbox..) the XML output is: <criterion>/@BBB</criterion> However! I want to combine the root nodeset value with the current choice nodeset value. Essentially: <xf:value ref="(instance('definition_choices')/choice/root) + ."/> to achieve the following XML output: <criterion>/param/@BBB</criterion> Any suggestions on how to do this? (I am fairly new to XPath and XForms) p.s. what I am asking makes sense to me when I typed it out, but if you have trouble figuring out what I'm asking, just let me know.. thanks!

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  • How to synchronize static method in java.

    - by Summer_More_More_Tea
    Hi there: I come up with this question when implementing singleton pattern in Java. Even though the example listed blow is not my real code, yet very similar to the original one. public class ConnectionFactory{ private static ConnectionFactory instance; public static synchronized ConnectionFactory getInstance(){ if( instance == null ){ instance = new ConnectionFactory(); } return instance; } private ConnectionFactory(){ // private constructor implementation } } Because I'm not quite sure about the behavior of a static synchronized method, I get some suggestion from google -- do not have (or as less as possible) multiple static synchronized methods in the same class. I guess when implementing static synchronized method, a lock belongs to Class object is used so that multiple static synchronized methods may degrade performance of the system. Am I right? or JVM use other mechanism to implement static synchronized method? What's the best practice if I have to implement multiple static synchronized methods in a class? Thank you all! Kind regards!

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  • when to make a method static

    - by Don
    Hi, I'd like to know how people decide whether to define a method as static. I'm aware that a method can only be defined as static if it doesn't require access to instance fields. So lets say we have a method that does not access instance fields, do you always define such a method as static, or only if you need to call it statically (without a reference to an instance). Perhaps another way of asking the same question, is whether you use static or non-static as the default? Thanks, Don

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  • SQLiteOpenHelper getWritableDatabse() fails with no Exception

    - by Michal K
    I have a very strange problem. It only shows from time to time, on several devices. Can't seem to reproduce it when I want, but had it so many times, that I think I know where I get it. So I have a Loader which connects to sqlite through a singleton SQLiteOpenHelper: try{ Log.i(TAG, "Get details offline / db helper: "+DatabaseHelper.getInstance(getContext())); SQLiteDatabase db=DatabaseHelper.getInstance(this.getContext()).getWritableDatabase(); Log.i(TAG, "Get details offline / db: "+db); //doing some work on the db //... } catch(SQLiteException e){ e.printStackTrace(); return null; } catch(Exception e){ e.printStackTrace(); return null; //trying everything to grab some exception or whatever } My SQLIteOpenHelper looks something like this: public class DatabaseHelper extends SQLiteOpenHelper { private static DatabaseHelper mInstance = null; private static Context mCxt; public static DatabaseHelper getInstance(Context cxt) { //using app context ass suggested by CommonsWare Log.i("DBHELPER1", "cxt"+mCxt+" / instance: "+mInstance); if (mInstance == null) { mInstance = new DatabaseHelper(cxt.getApplicationContext()); } Log.i("DBHELPER2", "cxt"+mCxt+" / instance: "+mInstance); mCxt = cxt; return mInstance; } //private constructor private DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); this.mCxt = context; } @Override public void onCreate(SQLiteDatabase db) { //some tables created here } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { //upgrade code here } It really works great in most cases. But from time to time I get a log similar to this: 06-10 23:49:59.621: I/DBHELPER1(26499): cxtcom.bananout.Bananout@407152c8 / instance: com.bananout.helpers.DatabaseHelper@40827560 06-10 23:49:59.631: I/DBHELPER2(26499): cxtcom.bananout.Bananout@407152c8 / instance: com.bananout.helpers.DatabaseHelper@40827560 06-10 23:49:59.631: I/DetailsLoader(26499): Get event details offline / db helper: com.bananout.helpers.DatabaseHelper@40827560 06-10 23:49:59.631: I/DBHELPER1(26499): cxtcom.bananout.Bananout@407152c8 / instance: com.bananout.helpers.DatabaseHelper@40827560 06-10 23:49:59.651: I/DBHELPER2(26499): cxtcom.bananout.Bananout@407152c8 / instance: com.bananout.helpers.DatabaseHelper@40827560 This line Log.i(TAG, "Get details offline / db: "+db); never gets called! No Exceptions, silence. Plus, the thread with the Loader is not running anymore. So nothing past this line SQLiteDatabase db=DatabaseHelper.getInstance(this.getContext()).getWritableDatabase(); gets executed. What can possibly go wrong on this line?

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  • Override generic methods in c#

    - by Pascal
    I thought I can not override generic methods of a derived class. http://my.safaribooksonline.com/book/programming/csharp/9780071741163/generics/ch18lev1sec13 The code in this link runs fine. The overriden method is called although the instance type of the base class is used and not the instance of the derived type. Now I am confused because a former question of mine Type parameter declaration must be identifier not a type is about calling the overriding generic method with the instance of base type which did NOT work!

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  • Who needs singletons?

    - by sexyprout
    Imagine you access your MySQL database via PDO. You got some functions, and in these functions, you need to access the database. The first thing I thought of is global, like: $db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'root', 'pwd'); function some_function() { global $db; $db->query('...'); } But it's considered as a bad practice. So, after a little search, I ended up with the Singleton pattern, which "applies to situations in which there needs to be a single instance of a class." According to the example of the manual, we should do this: class Database { private static $instance, $db; private function __construct(){} static function singleton() { if(!isset(self::$instance)) self::$instance = new __CLASS__; return self:$instance; } function get() { if(!isset(self::$db)) self::$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'user', 'pwd') return self::$db; } } function some_function() { $db = Database::singleton(); $db->get()->query('...'); } some_function(); But I just can't understand why you need that big class when you can do it merely with: class Database { private static $db; private function __construct(){} static function get() { if(!isset(self::$rand)) self::$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'user', 'pwd'); return self::$db; } } function some_function() { Database::get()->query('...'); } some_function(); This last one works perfectly and I don't need to worry about $db anymore. But maybe I'm forgetting something. So, who's wrong, who's right?

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  • Maximize application in system tray?

    - by Nicros
    I wrote a little WPF app that when 'closed' minimizes to the system tray (customer requirement). Double clicking pops it back up, or right click gives a context menu to exit. But if the app is minimized, and the users navigate to Start-All Programs-The Application it starts a new instance. What (in C#) do I need to do to get the app to maximize the running instance if the user does this rather than fire up a new instance? Thanks!

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  • Insert Registration Data in MySQL using PHP

    - by J M 4
    I may not be asking this in the best way possible but i will try my hardest. Thank you ahead of time for your help: I am creating an enrollment website which allows an individual OR manager to enroll for medical testing services for professional athletes. I will NOT be using the site as a query DB which anybody can view information stored within the database. The information is instead simply stored, and passed along in a CSV format to our network provider so they can use as needed after the fact. There are two possible scenarios: Scenario 1 - Individual Enrollment If an individual athlete chooses to enroll him/herself, they enter their personal information, submit their payment information (credit/bank account) for processing, and their information is stored in an online database as Athlete1. Scenario 2 - Manager Enrollment If a manager chooses to enroll several athletes he manages/ promotes for, he enters his personal information, then enters the personal information for each athlete he wishes to pay for (name, address, ssn, dob, etc), then submits payment information for ALL athletes he is enrolling. This number can range from 1 single athlete, up to 20 athletes per single enrollment (he can return and complete a follow up enrollment for additional athletes). Initially, I was building the database to house ALL information regardless of enrollment type in a single table which housed over 400 columns (think 20 athletes with over 10 fields per athlete such as name, dob, ssn, etc). Now that I think about it more, I believe create multiple tables (manager(s), athlete(s)) may be a better idea here but still not quite sure how to go about it for the following very important reasons: Issue 1 If I list the manager as the parent table, I am afraid the individual enrolling athlete will not show up in the primary table and will not be included in the overall registration file which needs to be sent on to the network providers. Issue 2 All athletes being enrolled by a manager are being stored in SESSION as F1FirstName, F2FirstName where F1 and F2 relate to the id of the fighter. I am not sure technically speaking how to store multiple pieces of information within the same table under separate rows using PHP. For example, all athleteswill have a first name. The very basic theory of what i am trying to do is: If number_of_athletes 1, store F1FirstName in row 1, column 1 of Table "Athletes"; store F1LastName in row 1, column 2 of Table "Athletes"; store F2FirstName in row 2, column 1 of Table "Athletes"; store F2LastName in row 2, column 2 of table "Athletes"; Does this make sense? I know this question is very long and probably difficult so i appreciate the guidance.

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  • choosing an image locally from http url and serving that image without a server round trip

    - by serverman
    Hi folks I am a complete novice to Flash (never created anything in flash). I am quite familiar with web applications (J2EE based) and have a reasonable expertise in Javascript. Here is my requirement. I want the user to select (via an html form) an image. Normally in the post, this image would be sent to server and may be stored there to be served later. I do not want that. I want to store this image locally and then serve it via HTTP to the user. So, the flow is: 1. Go to the "select image url":mywebsite.com/selectImage Browse the image and select the image This would transfer control locally to some code running on the client (Javascript or flash), which would then store the image locally at some place on the client machine. Go to the "show image url": mywebsite.com/showImage This would eventually result in some client code running on the browser that retrieves the image and renders it (without any server round trips.) I considered the following options: Use HTML5 local storage. Since I am a complete novice to flash, I looked into this. I found that it is fairly straightforward to store and retrieve images in javascript (only strings are allowed but I am hoping storing base64 encoded strings would work at least for small images). However, how do I serve the image via http url that points to my server without a server round trip? I saw the interesting article at http://hacks.mozilla.org/category/fileapi/ but that would work only in firefox and I need to work on all latest browsers (at least the ones supporting HTML5 local storage) Use flash SharedObjects. OK, this would have been good - the only thing is I am not sure where to start. Snippets of actionscripts to do this are scattered everywhere but I do not know how to use those scripts in an actual html page:) I do not need to create any movies or anything - just need to store an image and serve it locally. If I go this route, I would also use it to store other "strings" locally. If you suggest this, please give me the exact steps (could be pointers to other web sites) on how to do this. I would like to avoid paying for any flash development environment software ideally:) Thank you!

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  • unable to add objects to saved collection in GAE

    - by Jeffrey Chee
    I have a ClassA containing an ArrayList of another ClassB I can save a new instance of ClassA with ClassB instances also saved using JDO. However, When I retrieve the instance of Class A, I try to do like the below: ClassA instance = PMF.get().getPersistenceManager().GetObjectByID( someid ); instance.GetClassBArrayList().add( new ClassB(...) ); I get an Exception like the below: Uncaught exception from servlet com.google.appengine.api.datastore.DatastoreNeedIndexException: no matching index found.. So I was wondering, Is it possible to add a new item to the previously saved collection? Or was it something I missed out. Best Regards

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  • Is there a simpler way to redirect using a route while adding paramters in Kohana?

    - by Darryl Hein
    I find myself doing the following or similar quite often: Request::instance()->redirect(Route::get('route')->uri(array('action' => 'action'))); Or: Request::instance()->redirect(Route::get(Route::name(Request::instance()->route))->uri(array('action' => 'action'))); I'm wondering if there's any short, easier, simpler way of doing this. I love the Route functionality, but it makes for some long lines of PHP.

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  • Typeclass instances for unnamed types in Scala

    - by ncreep
    How would one encode the following constraint in Scala (pseudocode)? def foo(x: T forSome { type T has a Numeric[T] instance in scope }) = { val n= implicitly[...] // obtain the Numeric instance for x n.negate(x) // and use it with x } In words: I need a type class instance for my input argument, but I don't care about the argument's type, I just need to obtain the instance and use it on my argument. It doesn't have to be an existential type, but I need to avoid type parameters in the def's signature. Thanks.

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  • Rails - Paperclip, getting width and height of image in model

    - by Corey Tenold
    Trying to get the width and height of the uploaded image while still in the model on the initial save. Any way to do this? Here's the snippet of code I've been testing with from my model. Of course it fails on "instance.photo_width". has_attached_file :photo, :styles => { :original => "634x471>", :thumb => Proc.new { |instance| ratio = instance.photo_width/instance.photo_height min_width = 142 min_height = 119 if ratio > 1 final_height = min_height final_width = final_height * ratio else final_width = min_width final_height = final_width * ratio end "#{final_width}x#{final_height}" } }, :storage => :s3, :s3_credentials => "#{RAILS_ROOT}/config/s3.yml", :path => ":attachment/:id/:style.:extension", :bucket => 'foo_bucket' So I'm basically trying to do this to get a custom thumbnail width and height based on the initial image dimensions. Any ideas?

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  • Problem when trying to define Show for my Point3D type in Haskell

    - by devoured elysium
    I am trying to define Show for my Point3D type: type Point3D = (Integer, Integer, Integer) instance Show Point3D where show (x,y,z) = "<" ++ (show x) ++ "," ++ (show y) ++ "," ++ (show z) ++ ">" yet I must be missing something in the sintax, as I am always getting an error: Illegal instance declaration for `Show Point3D' (All instance types must be of the form (T t1 ... tn) where T is not a synonym. Use -XTypeSynonymInstances if you want to disable this.) In the instance declaration for `Show Point3D' What am I doing wrong?

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  • Add console.profile statements to JavaScript/jQuery code on the fly.

    - by novogeek
    Hi folks, We have a thick client app using jQuery heavily and want to profile the performance of the code using firebug's console.profile API. The problem is, I don't want to change the code to write the profile statements. Take this example: var search=function(){ this.init=function(){ console.log('init'); } this.ajax=function(){ console.log('ajax'); //make ajax call using $.ajax and do some DOM manipulations here.. } this.cache=function(){ console.log('cache'); } } var instance=new search(); instance.ajax(); I want to profile my instance.ajax method, but I dont want to add profile statements in the code, as that makes it difficult to maintain the code. I'm trying to override the methods using closures, like this: http://www.novogeek.com/post/2010/02/27/Overriding-jQueryJavaScript-functions-using-closures.aspx but am not very sure how I can achieve. Any pointers on this? I think this would help many big projects to profile the code easily without a big change in code. Here is the idea. Just run the below code in firebug console, to know what I'm trying to achieve. var search=function(){ this.init=function(){ console.log('init'); } this.ajax=function(){ console.log('ajax'); //make ajax call using $.ajax and do some DOM manipulations here.. } this.cache=function(){ console.log('cache'); } } var instance=new search(); $.each(instance, function(functionName, functionBody){ (function(){ var dup=functionBody functionBody=function(){ console.log('modifying the old function: ',functionName); console.profile(functionName); dup.apply(this,arguments); console.profileEnd(functionName); } })(); console.log(functionName, '::', functionBody()); }); Now what I need is, if i say instance.ajax(), I want the new ajax() method to be called, along with the console.profile statements. Hope I'm clear with the requirement. Please improvise the above code. Regards, Krishna, http://www.novogeek.com

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  • Thread-safe use of a singleton's members

    - by Anthony Mastrean
    I have a C# singleton class that multiple classes use. Is access through Instance to the Toggle() method thread-safe? If yes, by what assumptions, rules, etc. If no, why and how can I fix it? public class MyClass { private static readonly MyClass instance = new MyClass(); public static MyClass Instance { get { return instance; } } private int value = 0; public int Toggle() { if(value == 0) { value = 1; } else if(value == 1) { value = 0; } return value; } }

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  • PHP troubleshooting unexpected T_PUBLIC error

    - by jasondavis
    PHP is driving me insane right now, please help me, I must be missing something. In this VERY BASIC example below I get this error... Parse error:syntax error, unexpected T_PUBLIC in C:\filename here on line 12 On this line.... public static function getInstance(){ The code... <?PHP class Session{ private static $instance; function __construct() { { session_start(); echo 'Session object created<BR><BR>'; } public static function getInstance(){ if (!self::$instance) { self::$instance = new Session(); } return self::$instance; } }

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