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• How do you update a secondary view?

  - by Troy Sartain

  Perhaps there's a better way to set this up so I'm open to suggestions. But here's what I'm doing. I have a main UIView. On top of that I have a UIImageView and another UIView. When the UIImageView changes, I want to change the second UIView. So I have a class for it and the IB object's type is set to the class. In the .m of that class is a drawRect method that draws some rectangles. Also in the .m is a NSMutableArray property that is synthesized. I created an instance of that class in the controller of the main view. The problem: despite the fact that the drawRect works fine when the app starts (as traced in the debugger,) when the UIImageView changes I call a "setNeedsDisplay" on the instance variable of the second view after updating the @synthesize'd array but the drawRect does not get called. I think it has to do with instances. I wouldn't think threading would be an issue here. I just want to draw in a separate area of the screen based on an image also displayed.

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• Same random numbers from instantiated class

  - by user1797202

  I'm learning C# and created a class within my program that holds a random number generator: class RandomNumberGenerator { Random RNG = new Random(); // A bunch of methods that use random numbers are in here } Inside this class are a few methods that use the RNG. Data gets sent here from other parts of the program, gets processed, then gets returned. One of the methods does the following: // Method works something like this int Value1 = RNG.Next(x, y); int Value2 = RNG.Next(x, y); int Value3 = RNG.Next(x, y); The x, y values are to be sent here from another class. So, I have to create an instance of the RandomNumberGenerator within that class so I can call its methods and pass the x and y values to it. class DoStuff { RandomNumberGenerator Randomizer = new RandomNumberGenerator // Here I call a bunch of Randomizer methods that give me values I need } The problem in the above method is that I get the same numbers every time for all three values. I'm not sure if it's because they're so close together and Randomizer's seed value hasn't had time to change or if I'm doing something wrong when I create a new instance of the RandomNumberGenerator class. I've gone through a bunch of answers on here already and typically problems like this are due to people creating many new Random objects when they run methods (thus setting the seed for all of them to the same value), but the only new Random object I create is within the RandomNumberGenerator class. I then instantiate that once within the other class so I can pass it data and use its methods. Why is this happening and how would I fix this?

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• Easy ways to investigate unknown Python APIs

  - by jedi_coder

  When studying a snippet of unknown Python code, I occasionally bump into the varName.methodName() pattern. To figure out what's this, I shall study the code more, find where varName was instantiated, find its type. So if varName proves to be an instance of ClassName class, I would knew that methodName() is a method of ClassName. Sometimes varName == self and methodName() is a method of this class, or a method inherited from some other class, if the current class is subclassing some other classes. Are there quick ways / tools that could take 'methodName' as input, scan over all installed Python modules and show which classes have methodName()? The closest thing related to this I know of is ipython. If I type a class name, then dot ('.') then TAB, it can show the class members. Instead of a class I could use a name of an object (which is an instance of a certain class) and it would work too. As soon as I choose a method name from the provided options, I can type '?' or '??' and get some help if there's a docstring. I wonder if ipython can do some intelligent scanning based only on 'methodName' string. If you know alternatives to ipython that could possibly help with this, please do suggest them.

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• Is it possible to have WAMP run httpd.exe as user [myself] instead of local SYSTEM?

  - by Olivier H

  Hello! I run a django application over apache with mod_wsgi, using WAMP. A certain URL allows me to stream the content of image files, the paths of which are stored in database. The files can be located whether on local machine or under network drive (\my\network\folder). With the development server (manage.py runserver), I have no trouble at all reading and streaming the files. With WAMP, and with network drive files, I get a IOError : obviously because the httpd instance does not have read permission on said drive. In the task manager, I see that httpd.exe is run by SYSTEM. I would like to tell WAMP to run the server as [myself] as I have read and write permissions on the shared folder. (eventually, the production server should be run by a 'www-admin' user having the permissions) Mapping the network shared folder on a drive letter (Z: for instance) does not solve this at all. The User/Group directives in httpd.conf do not seem to have any kind of influence on Apache's behaviour. I've also regedited : I tried to duplicate the HKLM[...]\wampapache registry key under HK_CURRENT_USER\ and rename the original key, but then the new key does not seem to be found when I cmd this > httpd.exe -n wampapache -k start or when I run WAMP. I've run out of ideas :) Has anybody ever had the same issue?

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• Why would one want to use the public constructors on Boolean and similar immutable classes?

  - by Robert J. Walker

  (For the purposes of this question, let us assume that one is intentionally not using auto(un)boxing, either because one is writing pre-Java 1.5 code, or because one feels that autounboxing makes it too easy to create NullPointerExceptions.) Take Boolean, for example. The documentation for the Boolean(boolean) constructor says: Note: It is rarely appropriate to use this constructor. Unless a new instance is required, the static factory valueOf(boolean) is generally a better choice. It is likely to yield significantly better space and time performance. My question is, why would you ever want to get a new instance in the first place? It seems like things would be simpler if constructors like that were private. For example, if they were, you could write this with no danger (even if myBoolean were null): if (myBoolean == Boolean.TRUE) It'd be safe because all true Booleans would be references to Boolean.TRUE and all false Booleans would be references to Boolean.FALSE. But because the constructors are public, someone may have used them, which means that you have to write this instead: if (Boolean.TRUE.equals(myBoolean)) But where it really gets bad is when you want to check two Booleans for equality. Something like this: if (myBooleanA == myBooleanB) ...becomes this: if ( (myBooleanA == null && myBooleanB == null) || (myBooleanA == null && myBooleanA.equals(myBooleanB)) ) I can't think of any reason to have separate instances of these objects which is more compelling than not having to do the nonsense above. What say you?

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• dynamic inheritance without touching classes

  - by Jasper

  I feel like the answer to this question is really simple, but I really am having trouble finding it. So here goes: Suppose you have the following classes: class Base; class Child : public Base; class Displayer { public: Displayer(Base* element); Displayer(Child* element); } Additionally, I have a Base* object which might point to either an instance of the class Base or an instance of the class Child. Now I want to create a Displayer based on the element pointed to by object, however, I want to pick the right version of the constructor. As I currently have it, this would accomplish just that (I am being a bit fuzzy with my C++ here, but I think this the clearest way) object->createDisplayer(); virtual void Base::createDisplayer() { new Displayer(this); } virtual void Child::createDisplayer() { new Displayer(this); } This works, however, there is a problem with this: Base and Child are part of the application system, while Displayer is part of the GUI system. I want to build the GUI system independently of the Application system, so that it is easy to replace the GUI. This means that Base and Child should not know about Displayer. However, I do not know how I can achieve this without letting the Application classes know about the GUI. Am I missing something very obvious or am I trying something that is not possible?

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• Using an unencoded key vs a real Key, benefits?

  - by user246114

  Hi, I am reading the docs for Key generation in app engine. I'm not sure what effect using a simple String key has over a real Key. For example, when my users sign up, they must supply a unique username: class User { /** Key type = unencoded string. */ @PrimaryKey private String name; } now if I understand the docs correctly, I should still be able to generate named keys and entity groups using this, right?: // Find an instance of this entity: User user = pm.findObjectById(User.class, "myusername"); // Create a new obj and put it in same entity group: Key key = new KeyFactory.Builder( User.class.getSimpleName(), "myusername") .addChild(Goat.class.getSimpleName(), "baa").getKey(); Goat goat = new Goat(); goat.setKey(key); pm.makePersistent(goat); the Goat instance should now be in the same entity group as that User, right? I mean there's no problem with leaving the User's primary key as just the raw String? Is there a performance benefit to using a Key though? Should I update to: class User { /** Key type = unencoded string. */ @PrimaryKey private Key key; } // Generate like: Key key = KeyFactory.createKey( User.class.getSimpleName(), "myusername"); user.setKey(key); it's almost the same thing, I'd still just be generating the Key using the unique username anyway, Thanks

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• CodeModel help needed for right-hand singleton.getinstance() assignment.

  - by antarti

  I've been able to generate 99% of what I need with the CodeModel API, but I am stumped here... Using the various "directXX" methods does not add import statements to the generated code, and I can work without the "directXXX" type of methods except for one place in a generated class. Suppose I desire a generated method like: /** * Copies data from this Value-Obj instance, to the returned PERSON instance. * * @return PERSON * */ public PERSON mapVOToPERSON() throws MappingException { Mapper mapper = (com.blah.util.MapperSingleton.getMapperInstance()); return mapper.map(this, PERSON.class); } You can see the right hand of the Mapper assignment in parens. Emitting the entire package+class was the only way I could find to just declare "SomeSingleton.someMethod()" on the right hand side and have the generated code compile. Without the MapperSingleton being added to the object model, there is no import generated... Questions: 1) Is there a way to force an import to be generated? 2) How to declare an expression that gives me the right side of the Mapper assignment within the object model (so that an import of MapperSingleton gets generated. Any help appreciated...

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• C#: Any faster way of copying arrays?

  - by Yang

  I have three arrays that need to be combined in one three-dimension array. The following code shows slow performance in Performance Explorer. Is there a faster solution? for (int i = 0; i < sortedIndex.Length; i++) { if (i < num_in_left) { // add instance to the left child leftnode[i, 0] = sortedIndex[i]; leftnode[i, 1] = sortedInstances[i]; leftnode[i, 2] = sortedLabels[i]; } else { // add instance to the right child rightnode[i-num_in_left, 0] = sortedIndex[i]; rightnode[i-num_in_left, 1] = sortedInstances[i]; rightnode[i-num_in_left, 2] = sortedLabels[i]; } } Update: I'm actually trying to do the following: //given three 1d arrays double[] sortedIndex, sortedInstances, sortedLabels; // copy them over to a 3d array (forget about the rightnode for now) double[] leftnode = new double[sortedIndex.Length, 3]; // some magic happens here so that leftnode = {sortedIndex, sortedInstances, sortedLabels};

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• pass a pointer of a class

  - by small_potato

  Say I have Class1 and Class2 and I want a shallow copy constructor for Class1. Class1 has a member variable, which is a pointer pointing to a Class2 instance. Also I have to be able to change the Class2 ptr is pointing at. in header file: class Class1 { Class2* ptr; ... } in source file: Class1::Class1() { ptr = new Class2(); } ...... Class2* Class1::Exchange(Class2* newClass2) { Class2* temp; ptr = newClass2; return temp; } ...... Now say Class1 original; Class1 shallowCopy(original); Class2* newClass2 = new Class2(); Class2* oldClass2; oldClass2 = orignal.Exchange(newClass2); delete oldClass2; now I want is associate original.ptr with shallowCopy.ptr, when I implement the shallow copy constructor, how do I make sure these two pointer always point at the same Class2? I mean in the class above, the oldClass2 is deleted, so ptr of shallowCopy is pointing at nothing. If I don't delete oldClass2, ptrs of original and shallowCopy are pointing at different Class2 instance.

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• How can I avoid encoding mixups of strings in a C/C++ API?

  - by Frerich Raabe

  I'm working on implementing different APIs in C and C++ and wondered what techniques are available for avoiding that clients get the encoding wrong when receiving strings from the framework or passing them back. For instance, imagine a simple plugin API in C++ which customers can implement to influence translations. It might feature a function like this: const char *getTranslatedWord( const char *englishWord ); Now, let's say that I'd like to enforce that all strings are passed as UTF-8. Of course I'd document this requirement, but I'd like the compiler to enforce the right encoding, maybe by using dedicated types. For instance, something like this: class Word { public: static Word fromUtf8( const char *data ) { return Word( data ); } const char *toUtf8() { return m_data; } private: Word( const char *data ) : m_data( data ) { } const char *m_data; }; I could now use this specialized type in the API: Word getTranslatedWord( const Word &englishWord ); Unfortunately, it's easy to make this very inefficient. The Word class lacks proper copy constructors, assignment operators etc.. and I'd like to avoid unnecessary copying of data as much as possible. Also, I see the danger that Word gets extended with more and more utility functions (like length or fromLatin1 or substr etc.) and I'd rather not write Yet Another String Class. I just want a little container which avoids accidental encoding mixups. I wonder whether anybody else has some experience with this and can share some useful techniques. EDIT: In my particular case, the API is used on Windows and Linux using MSVC 6 - MSVC 10 on Windows and gcc 3 & 4 on Linux.

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• open a text file only if not opened alread (open in NotePad)

  - by Mr_Green

  In my project, I am trying to open a text file. Well the below code works but when the user click the button again and again, many files are being opened. (which I dont want) System.Diagnostics.Process.Start(filePath); I also tried Link , File.Open and File.OpenText which are not opening the text file and also not showing any error (tried with try catch block) File.Open(filePath); (or) File.OpenText(filePath); (or) FileStream fileStream = new FileStream(filePath, FileMode.Open); I also tried this: (ERROR : Cannot be accessed with instance reference qualify with a type name instead) System.Diagnostics.Process proc = new System.Diagnostics.Process(); proc.Start(filePath); /*red scribbles here*/ proc.WaitForExit(); How to show only one instance of the Text file(.txt). am I doing something wrong in my attempts? please suggest. EDIT: I want to open other text files afterwards but not the same and also the application should be accessible after opening a text file(or many). I have only one form.

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• lists searches in SYB or uniplate haskell

  - by Chris

  I have been using uniplate and SYB and I am trying to transform a list For instance type Tree = [DataA] data DataA = DataA1 [DataB] | DataA2 String | DataA3 String [DataA] deriving Show data DataB = DataB1 [DataA] | DataB2 String | DataB3 String [DataB] deriving Show For instance, I would like to traverse my tree and append a value to all [DataB] So my first thought was to do this: changeDataB:: Tree -> Tree changeDataB = everywhere(mkT changeDataB') chanegDataB'::[DataB] -> [DataB] changeDataB' <add changes here> or if I was using uniplate changeDataB:: Tree -> Tree changeDataB = transformBi changeDataB' chanegDataB'::[DataB] -> [DataB] changeDataB' <add changes here> The problem is that I only want to search on the full list. Doing either of these searches will cause a search on the full list and all of the sub-lists (including the empty list) The other problem is that a value in [DataB] may generate a [DataB], so I don't know if this is the same kind of solution as not searching chars in a string. I could pattern match on DataA1 and DataB3, but in my real application there are a bunch of [DataB]. Pattern matching on the parents would be extensive. The other thought that I had was to create a data DataBs = [DataB] and use that to transform on. That seems kind of lame, there must be a better solution.

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• Binding the selected value from a combobox to a member of a class.

  - by CM

  I have a combobox that is bound to a an instance of a class. I need to get the user's selection ID of the combobox and set a class property equal to it. For example, here is the class: public class robot { private string _ID; private string _name; private string _configFile; [XmlElement("hardware")] public hardware[] hardware; public string ID { get { return _ID; } set { _ID = value; } } public string name { get { return _name; } set { _name = value; } } public string configFile { get { return _configFile; } set { _configFile = value; } } } Now here is the code to bind the combobox to an instance of that class. This display's the name of each robot in the array in the combobox. private void SetupDevicesComboBox() { robot[] robot = CommConfig.robot; cmbDevices.DataSource = robot; cmbDevices.DisplayMember = "name"; cmbDevices.ValueMember = "ID"; } But now I can't seem to take what the user selects and use it. How do I use the "ID" of what the user select's from the combobox? Settings.selectedRobotID = cmbDevices.ValueMember; //This just generates "ID" regardless of what is selected. I also tried Settings.selectedRobotID = cmbDevices.SelectedItem.ToString(); //This just generates "CommConfig.robot" Thanks

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• How does Haskell do pattern matching without us defining an Eq on our data types?

  - by devoured elysium

  I have defined a binary tree: data Tree = Null | Node Tree Int Tree and have implemented a function that'll yield the sum of the values of all its nodes: sumOfValues :: Tree -> Int sumOfValues Null = 0 sumOfValues (Node Null v Null) = v sumOfValues (Node Null v t2) = v + (sumOfValues t2) sumOfValues (Node t1 v Null) = v + (sumOfValues t1) sumOfValues (Node t1 v t2) = v + (sumOfValues t1) + (sumOfValues t2) It works as expected. I had the idea of also trying to implement it using guards: sumOfValues2 :: Tree -> Int sumOfValues2 Null = 0 sumOfValues2 (Node t1 v t2) | t1 == Null && t2 == Null = v | t1 == Null = v + (sumOfValues2 t2) | t2 == Null = v + (sumOfValues2 t1) | otherwise = v + (sumOfValues2 t1) + (sumOfValues2 t2) but this one doesn't work because I haven't implemented Eq, I believe: No instance for (Eq Tree) arising from a use of `==' at zzz3.hs:13:3-12 Possible fix: add an instance declaration for (Eq Tree) In the first argument of `(&&)', namely `t1 == Null' In the expression: t1 == Null && t2 == Null In a stmt of a pattern guard for the definition of `sumOfValues2': t1 == Null && t2 == Null The question that has to be made, then, is how can Haskell make pattern matching without knowing when a passed argument matches, without resorting to Eq?

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• Changing pointer of self

  - by rob5408

  I have an object that I alloc/init like normal just to get a instance. Later in my application I want to load state from disk for that object. I figure I could unarchive my class (which conforms to NSCoding) and just swap where my instance points to. To this end I use this code... NSString* pathForDataFile = [self pathForDataFile]; if([[NSFileManager defaultManager] fileExistsAtPath:pathForDataFile] == YES) { NSLog(@"Save file exists"); NSData *data = [[NSMutableData alloc] initWithContentsOfFile:pathForDataFile]; NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; [data release]; Person *tempPerson = [unarchiver decodeObjectForKey:@"Person"]; [unarchiver finishDecoding]; [unarchiver release]; if (tempPerson) { [self release]; self = [tempPerson retain]; } } Now when I sprinkled some NSLogs throughout my application I noticed self.person: <Person: 0x3d01a10> (After I create the object with alloc/init) self: <Person: 0x3d01a10> (At the start of this method) tempPerson: <Person: 0x3b1b880> (When I create the tempPerson) self: <Person: 0x3b1b880> (after i point self to the location of the tempPerson) self.person: <Person: 0x3d01a10> (After the method back in the main program) What am I missing?

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• Rapid Opening and Closing System.IO.StreamWriter in C#

  - by ccomet

  Suppose you have a file that you are programmatically logging information into with regards to a process. Kinda like your typical debug Console.WriteLine, but due to the nature of the code you're testing, you don't have a console to write onto so you have to write it somewhere like a file. My current program uses System.IO.StreamWriter for this task. My question is about the approach to using the StreamWriter. Is it better to open just one StreamWriter instance, do all of the writes, and close it when the entire process is done? Or is it a better idea to open a new StreamWriter instance to write a line into the file, then immediately close it, and do this for every time something needs to be written in? In the latter approach, this would probably be facilitated by a method that would do just that for a given message, rather than bloating the main process code with excessive amounts of lines. But having a method to aid in that implementation doesn't necessarily make it the better choice. Are there significant advantages to picking one approach or the other? Or are they functionally equivalent, leaving the choice on the shoulders of the programmer?

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• Purpose of singletons in programming

  - by thecoshman

  This is admittedly a rather loose question. My current understanding of singletons is that they are a class that you set up in such a way that only one instance is ever created. This sounds a lot like a static class to me. The main differnce being that with a static class you don't / can't instance it, you just use it such as Math.pi(). With a singletong class, you would still need to do something like singleton mySingleton = new singleton(); mysingleton.set_name("foo"); singleton otherSingleton = new singleton(); // correct me if i am wrong, but mysingleton == othersingleton right now, yes? // this the following should happen? otherSingleston.set_name("bar"); mysingleton.report_name(); // will output "bar" won't it? Please note, I am asking this language independently, more about the concept. So I am not so worried about actually how to coed such a class, but more why you would wan't to and what thing you would need to consider.

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• "assignment makes integer from pointer without a cast " warning in c

  - by mekasperasky

  #include<stdio.h> /* this is a lexer which recognizes constants , variables ,symbols, identifiers , functions , comments and also header files . It stores the lexemes in 3 different files . One file contains all the headers and the comments . Another file will contain all the variables , another will contain all the symbols. */ int main() { int i=0,j; char a,b[20],c[30]; FILE *fp1,*fp2; c[0]='"if"; c[1]="then"; c[2]="else"; c[3]="switch"; c[4]="printf"; c[5]="scanf"; c[6]="NULL"; c[7]="int"; c[8]="char"; c[9]="float"; c[10]="long"; c[11]="double"; c[12]="char"; c[13]="const"; c[14]="continue"; c[15]="break"; c[16]="for"; c[17]="size of"; c[18]="register"; c[19]="short"; c[20]="auto"; c[21]="while"; c[22]="do"; c[23]="case"; fp1=fopen("source.txt","r"); //the source file is opened in read only mode which will passed through the lexer fp2=fopen("lext.txt","w"); //now lets remove all the white spaces and store the rest of the words in a file if(fp1==NULL) { perror("failed to open source.txt"); //return EXIT_FAILURE; } i=0; while(!feof(fp1)) { a=fgetc(fp1); if(a!=' ') { b[i]=a; } else { for (j=0;j<23;j++) { if(c[j]==b) { fprintf(fp2, "%.20s\n", c[j]); continue ; } b[i]='\0'; fprintf(fp2, "%.20s\n", b); i=0; continue; } //else if //{ i=i+1; /*Switch(a) { case EOF :return eof; case '+':sym=sym+1; case '-':sym=sym+1; case '*':sym=sym+1; case '/':sym=sym+1; case '%':sym=sym+1; case ' */ } fclose(fp1); fclose(fp2); return 0; } This is my c code for lexical analysis .. its giving warnings and also not writing anything into the lext file ..

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• Laravel check if id exists?

  - by devt204

  I've two columns in contents tables 1. id 2. content now this is what i'm trying to do Route::post('save', function() { $editor_content=Input::get('editor_content'); $rules = array('editor_content' => 'required'); $validator= Validator::make(Input::all(), $rules); if($validator->passes()) { //1. check if id is submitted? //2. if id exists update content table //3. else insert new content //create new instance $content= new Content; // insert the content to content column $content->content = $editor_content; //save the content $content->save(); // check if content has id $id=$content->id; return Response::json(array('success' => 'sucessfully saved', 'id' => $id)); } if($validator->fails()) { return $validator->messages() ; } }); i wanted to check if id has been already submit or checked i'm processing the request via ajax, and if id exists i wanted update the content column and if it doesn't i wanted to create new instance how do i do it ?

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• how are association, aggregation and composition written?

  - by ajsie

  i have read some posts about the differences between these 3 relationships and i think i get the point. i just wonder, are all these written the same when coding? question 1: all 3 are just a value of the object type in a instance variable? class A { public $b = '' public function __construct($object) { $this->b = $object // <-- could be a association, aggregation or a composition relation? } } question 2: does it have to be an instance variable or can it be a static one? class A { public static $b = '' // <-- nothing changed? public function __construct($object) { $this->b = $object } } question 3: is there a difference in where the object is created? i tend to think that composition object is created inside the object: class A { public $b = '' public function __construct() { $this->b = new Object // is created inside the object } } and aggregation/association is passed through a constructor or another method: class A { public $b = '' public function __construct($object) { // passed through a method $this->b = $object } } question 4: why/when is this important to know. do i have to comment an object inside another what relation its about or do you do it in an UML diagram? could someone shed a light on these questions. thanks!

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• calling a function from a set of overloads depending on the dynamic type of an object

  - by Jasper

  I feel like the answer to this question is really simple, but I really am having trouble finding it. So here goes: Suppose you have the following classes: class Base; class Child : public Base; class Displayer { public: Displayer(Base* element); Displayer(Child* element); } Additionally, I have a Base* object which might point to either an instance of the class Base or an instance of the class Child. Now I want to create a Displayer based on the element pointed to by object, however, I want to pick the right version of the constructor. As I currently have it, this would accomplish just that (I am being a bit fuzzy with my C++ here, but I think this the clearest way) object->createDisplayer(); virtual void Base::createDisplayer() { new Displayer(this); } virtual void Child::createDisplayer() { new Displayer(this); } This works, however, there is a problem with this: Base and Child are part of the application system, while Displayer is part of the GUI system. I want to build the GUI system independently of the Application system, so that it is easy to replace the GUI. This means that Base and Child should not know about Displayer. However, I do not know how I can achieve this without letting the Application classes know about the GUI. Am I missing something very obvious or am I trying something that is not possible?

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• Do the 'up to date' guarantees provided by final field in Java's memory model extend to indirect ref

  - by mattbh

  The Java language spec defines semantics of final fields in section 17.5: The usage model for final fields is a simple one. Set the final fields for an object in that object's constructor. Do not write a reference to the object being constructed in a place where another thread can see it before the object's constructor is finished. If this is followed, then when the object is seen by another thread, that thread will always see the correctly constructed version of that object's final fields. It will also see versions of any object or array referenced by those final fields that are at least as up-to-date as the final fields are. My question is - does the 'up-to-date' guarantee extend to the contents of nested arrays, and nested objects? An example scenario: Thread A constructs a HashMap of ArrayLists, then assigns the HashMap to final field 'myFinal' in an instance of class 'MyClass' Thread B sees a (non-synchronized) reference to the MyClass instance and reads 'myFinal', and accesses and reads the contents of one of the ArrayLists In this scenario, are the members of the ArrayList as seen by Thread B guaranteed to be at least as up to date as they were when MyClass's constructor completed?

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• Get class constant names in php?

  - by user151841

  I have a php class with some class constants that indicate the status of an instance. When I'm using the class, after I run some methods on it, I do some checks to make sure that the status is what I expect it to be. For instance, after calling some methods, I expect the status to be MEANINGFUL_STATUS_NAME. $objInstance->method1(); $objInstance->method2(); if ( $objInstance->status !== class::MEANINGFUL_STATUS_NAME ) { throw new Exception("Status is wrong, should not be " . class::MEANINGFUL_STATUS_NAME . "."); } However, this gives me the exception message "Status is wrong, should not be 2" when what I really want to see is "Status is wrong, should not be MEANINGFUL_STATUS_NAME" So I've lost the meaningfulness of the constant name. I was thinking of making an 'translation table' array, so I can take the constant values and translate them back into their name, but this seems cumbersome. How should I translate this back, so I get an error message that gives me a better idea of what went wrong?

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• What is and what is not replicated in a glassfish cluster with a mod_jk load balancer?

  - by Navigateur

  I have a Glassfish (3.1.2) cluster over 2 computers as nodes, with a mod_jk load balancer. Are servlet instance variables replicated perfectly? If not, how do I make sure it is? Are all actions, including method calls and disk writes, replicated perfectly? If not, how do I make sure they are? These may seem like stupid questions, but I'm not seeking "load balancing" as much as I am seeking exact replication to enable future upgrading without any service interruption. How do I achieve this if it is not already the case?

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