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• Override bits of a CSS class while inline?

  - by larryq

  I have an html img that is being styled by a CSS class. I would like to override the width and height values used in that class under some circumstances. I'm building this img tag using something called a TagBuilder class, provided by Microsoft for the .Net system, which allows developers to assign attributes to an html element. In this case a CSS class has been assigned to the img tag, and I can assign width and height attributes individually, but they're not taking precedence over the values set in the CSS class. My tag looks like this currently: <img alt="my link" class="static" height="240" id="StaticImage" src="http://imageserver.com/myImage.jpg" width="240"> The static CSS class has width and height values of 300 each, and as you can see I'm trying to override them with 240. It's not working in this instance but can I do it without a second CSS class?

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• python class attribute

  - by chnet

  Hi, i have a question about class attribute in python. class base : def __init__ (self): pass derived_val = 1 t1 = base() t2 = base () t2.derived_val +=1 t2.__class__.derived_val +=2 print t2.derived_val # its value is 2 print t2.__class__.derived_val # its value is 3 The results are different. I also use id() function to find t2.derived_val and t2.class.derived_val have different memory address. My problem is derived_val is class attribute. Why it is different in above example? Is it because the instance of class copy its own derived_val beside the class attribute?

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• Python Class inherit from all submodules

  - by Dhruv Govil

  I'm currently writing a wrapper in python for a lot of custom company tools. I'm basically going to break each tool into its own py file with a class containing the call to the tool as a method. These will all be contained in a package. Then there'll be a master class that will import all from the package, then inherit from each and every class, so as to appear as one cohesive class. masterClass.py pyPackage - __ init__.py - module1.py --class Module1 ---method tool1 - module2.py --class Module2 ---method tool2 etc Right now, I'm autogenerating the master class file to inherit from the packages modules, but I was wondering if there was a more elegant way to do it? ie from package import * class MasterClass(package.all): pass

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• cast operator to base class within a thin wrapper derived class

  - by miked

  I have a derived class that's a very thin wrapper around a base class. Basically, I have a class that has two ways that it can be compared depending on how you interpret it so I created a new class that derives from the base class and only has new constructors (that just delegate to the base class) and a new operator==. What I'd like to do is overload the operator Base&() in the Derived class so in cases where I need to interpret it as the Base. For example: class Base { Base(stuff); Base(const Base& that); bool operator==(Base& rhs); //typical equality test }; class Derived : public Base { Derived(stuff) : Base(stuff) {}; Derived(const Base& that) : Base(that) {}; Derived(const Derived& that) : Base(that) {}; bool operator==(Derived& rhs); //special case equality test operator Base&() { return (Base&)*this; //Is this OK? It seems wrong to me. } }; If you want a simple example of what I'm trying to do, pretend I had a String class and String==String is the typical character by character comparison. But I created a new class CaseInsensitiveString that did a case insensitive compare on CaseInsensitiveString==CaseInsensitiveString but in all other cases just behaved like a String. it doesn't even have any new data members, just an overloaded operator==. (Please, don't tell me to use std::string, this is just an example!) Am I going about this right? Something seems fishy, but I can't put my finger on it.

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• Getting the name of a child class in the parent class (static context)

  - by Benoit Myard

  Hi everybody, I'm building an ORM library with reuse and simplicity in mind; everything goes fine except that I got stuck by a stupid inheritance limitation. Please consider the code below: class BaseModel { /* * Return an instance of a Model from the database. */ static public function get (/* varargs */) { // 1. Notice we want an instance of User $class = get_class(parent); // value: bool(false) $class = get_class(self); // value: bool(false) $class = get_class(); // value: string(9) "BaseModel" $class = __CLASS__; // value: string(9) "BaseModel" // 2. Query the database with id $row = get_row_from_db_as_array(func_get_args()); // 3. Return the filled instance $obj = new $class(); $obj->data = $row; return $obj; } } class User extends BaseModel { protected $table = 'users'; protected $fields = array('id', 'name'); protected $primary_keys = array('id'); } class Section extends BaseModel { // [...] } $my_user = User::get(3); $my_user->name = 'Jean'; $other_user = User::get(24); $other_user->name = 'Paul'; $my_user->save(); $other_user->save(); $my_section = Section::get('apropos'); $my_section->delete(); Obviously, this is not the behavior I was expecting (although the actual behavior also makes sense).. So my question is if you guys know of a mean to get, in the parent class, the name of child class.

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• Class initialization and synchronized class method

  - by nybon

  Hi there, In my application, there is a class like below: public class Client { public synchronized static print() { System.out.println("hello"); } static { doSomething(); // which will take some time to complete } } This class will be used in a multi thread environment, many threads may call the Client.print() method simultaneously. I wonder if there is any chance that thread-1 triggers the class initialization, and before the class initialization complete, thread-2 enters into print method and print out the "hello" string? I see this behavior in a production system (64 bit JVM + Windows 2008R2), however, I cannot reproduce this behavior with a simple program in any environments. In Java language spec, section 12.4.1 (http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html), it says: A class or interface type T will be initialized immediately before the first occurrence of any one of the following: T is a class and an instance of T is created. T is a class and a static method declared by T is invoked. A static field declared by T is assigned. A static field declared by T is used and the reference to the field is not a compile-time constant (§15.28). References to compile-time constants must be resolved at compile time to a copy of the compile-time constant value, so uses of such a field never cause initialization. According to this paragraph, the class initialization will take place before the invocation of the static method, however, it is not clear if the class initialization need to be completed before the invocation of the static method. JVM should mandate the completion of class initialization before entering its static method according to my intuition, and some of my experiment supports my guess. However, I did see the opposite behavior in another environment. Can someone shed me some light on this? Any help is appreciated, thanks.

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• Handles Comparison: empty classes vs. undefined classes vs. void*

  - by Nawaz

  Microsoft's GDI+ defines many empty classes to be treated as handles internally. For example, (source GdiPlusGpStubs.h) //Approach 1 class GpGraphics {}; class GpBrush {}; class GpTexture : public GpBrush {}; class GpSolidFill : public GpBrush {}; class GpLineGradient : public GpBrush {}; class GpPathGradient : public GpBrush {}; class GpHatch : public GpBrush {}; class GpPen {}; class GpCustomLineCap {}; There are other two ways to define handles. They're, //Approach 2 class BOOK; //no need to define it! typedef BOOK *PBOOK; typedef PBOOK HBOOK; //handle to be used internally //Approach 3 typedef void* PVOID; typedef PVOID HBOOK; //handle to be used internally I just want to know the advantages and disadvantages of each of these approaches. One advantage with Microsoft's approach is that, they can define type-safe hierarchy of handles using empty classes, which (I think) is not possible with the other two approaches. What else? EDIT: One advantage with the second approach (i.e using incomplete classes) is that we can prevent clients from dereferencing the handles (that means, this approach appears to support encapsulation strongly, I suppose). The code would not even compile if one attempts to dereference handles. What else?

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• How to get the line non-empty of a file using tail ? Bash

  - by debugger

  Do you have an idea how to get the last line non-empty using tail in bash ? For example my_file.txt will be as following: hello hola bonjour (empty line) (empty line) Obviously if i do tail -n 1 my_file.txt i will get an empty line. In my case i want to get bonjour Any clues? Thanks Debugger

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• How do I get the last non-empty line of a file using tail in Bash?

  - by debugger

  How do I get the last non-empty line using tail under Bash shell? For example, my_file.txt looks like this: hello hola bonjour (empty line) (empty line) Obviously, if I do tail -n 1 my_file.txt I will get an empty line. In my case I want to get bonjour. How do I do that?

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• Breaking through the class sealing

  - by Jason Crease

  Do you understand 'sealing' in C#?  Somewhat?  Anyway, here's the lowdown. I've done this article from a C# perspective, but I've occasionally referenced .NET when appropriate. What is sealing a class? By sealing a class in C#, you ensure that you ensure that no class can be derived from that class.  You do this by simply adding the word 'sealed' to a class definition: public sealed class Dog {} Now writing something like " public sealed class Hamster: Dog {} " you'll get a compile error like this: 'Hamster: cannot derive from sealed type 'Dog' If you look in an IL disassembler, you'll see a definition like this: .class public auto ansi sealed beforefieldinit Dog extends [mscorlib]System.Object Note the addition of the word 'sealed'. What about sealing methods? You can also seal overriding methods.  By adding the word 'sealed', you ensure that the method cannot be overridden in a derived class.  Consider the following code: public class Dog : Mammal { public sealed override void Go() { } } public class Mammal { public virtual void Go() { } } In this code, the method 'Go' in Dog is sealed.  It cannot be overridden in a subclass.  Writing this would cause a compile error: public class Dachshund : Dog { public override void Go() { } } However, we can 'new' a method with the same name.  This is essentially a new method; distinct from the 'Go' in the subclass: public class Terrier : Dog { public new void Go() { } } Sealing properties? You can also seal seal properties.  You add 'sealed' to the property definition, like so: public sealed override string Name {     get { return m_Name; }     set { m_Name = value; } } In C#, you can only seal a property, not the underlying setters/getters.  This is because C# offers no override syntax for setters or getters.  However, in underlying IL you seal the setter and getter methods individually - a property is just metadata. Why bother sealing? There are a few traditional reasons to seal: Invariance. Other people may want to derive from your class, even though your implementation may make successful derivation near-impossible.  There may be twisted, hacky logic that could never be second-guessed by another developer.  By sealing your class, you're protecting them from wasting their time.  The CLR team has sealed most of the framework classes, and I assume they did this for this reason. Security.  By deriving from your type, an attacker may gain access to functionality that enables him to hack your system.  I consider this a very weak security precaution. Speed.  If a class is sealed, then .NET doesn't need to consult the virtual-function-call table to find the actual type, since it knows that no derived type can exist.  Therefore, it could emit a 'call' instead of 'callvirt' or at least optimise the machine code, thus producing a performance benefit.  But I've done trials, and have been unable to demonstrate this If you have an example, please share! All in all, I'm not convinced that sealing is interesting or important.  Anyway, moving-on... What is automatically sealed? Value types and structs.  If they were not always sealed, all sorts of things would go wrong.  For instance, structs are laid-out inline within a class.  But what if you assigned a substruct to a struct field of that class?  There may be too many fields to fit. Static classes.  Static classes exist in C# but not .NET.  The C# compiler compiles a static class into an 'abstract sealed' class.  So static classes are already sealed in C#. Enumerations.  The CLR does not track the types of enumerations - it treats them as simple value types.  Hence, polymorphism would not work. What cannot be sealed? Interfaces.  Interfaces exist to be implemented, so sealing to prevent implementation is dumb.  But what if you could prevent interfaces from being extended (i.e. ban declarations like "public interface IMyInterface : ISealedInterface")?  There is no good reason to seal an interface like this.  Sealing finalizes behaviour, but interfaces have no intrinsic behaviour to finalize Abstract classes.  In IL you can create an abstract sealed class.  But C# syntax for this already exists - declaring a class as a 'static', so it forces you to declare it as such. Non-override methods.  If a method isn't declared as override it cannot be overridden, so sealing would make no difference.  Note this is stated from a C# perspective - the words are opposite in IL.  In IL, you have four choices in total: no declaration (which actually seals the method), 'virtual' (called 'override' in C#), 'sealed virtual' ('sealed override' in C#) and 'newslot virtual' ('new virtual' or 'virtual' in C#, depending on whether the method already exists in a base class). Methods that implement interface methods.  Methods that implement an interface method must be virtual, so cannot be sealed. Fields.  A field cannot be overridden, only hidden (using the 'new' keyword in C#), so sealing would make no sense.

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• In .NET, Why Can I Access Private Members of a Class Instance within the Class?

  - by AMissico

  While cleaning some code today written by someone else, I changed the access modifier from Public to Private on a class variable/member/field. I expected a long list of compiler errors that I use to "refactor/rework/review" the code that used this variable. Imagine my surprise when I didn't get any errors. After reviewing, it turns out that another instance of the Class can access the private members of another instance declared within the Class. Totally unexcepted. Is this normal? I been coding in .NET since the beginning and never ran into this issue, nor read about it. I may have stumbled onto it before, but only "vaguely noticed" and move on. Can anyone explain this behavoir to me? I would like to know the "why" I can do this. Please explain, don't just tell me the rule. Am I doing something wrong? I found this behavior in both C# and VB.NET. The code seems to take advantage of the ability to access private variables. Sincerely, Totally Confused Class Jack Private _int As Integer End Class Class Foo Public Property Value() As Integer Get Return _int End Get Set(ByVal value As Integer) _int = value * 2 End Set End Property Private _int As Integer Private _foo As Foo Private _jack As Jack Private _fred As Fred Public Sub SetPrivate() _foo = New Foo _foo.Value = 4 'what you would expect to do because _int is private _foo._int = 3 'TOTALLY UNEXPECTED _jack = New Jack '_jack._int = 3 'expected compile error _fred = New Fred '_fred._int = 3 'expected compile error End Sub Private Class Fred Private _int As Integer End Class End Class

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• Java: Generics, Class.isaAssignableFrom, and type casting

  - by bguiz

  This method that uses method-level generics, that parses the values from a custom POJO, JXlistOfKeyValuePairs (which is exactly that). The only thing is that both the keys and values in JXlistOfKeyValuePairs are Strings. This method wants to taken in, in addition to the JXlistOfKeyValuePairs instance, a Class<T> that defines which data type to convert the values to (assume that only Boolean, Integer and Float are possible). It then outputs a HashMap with the specified type for the values in its entries. This is the code that I have got, and it is obviously broken. private <T extends Object> Map<String, T> fromListOfKeyValuePairs(JXlistOfKeyValuePairs jxval, Class<T> clasz) { Map<String, T> val = new HashMap<String, T>(); List<Entry> jxents = jxval.getEntry(); T value; String str; for (Entry jxent : jxents) { str = jxent.getValue(); value = null; if (clasz.isAssignableFrom(Boolean.class)) { value = (T)(Boolean.parseBoolean(str)); } else if (clasz.isAssignableFrom(Integer.class)) { value = (T)(Integer.parseInt(str)); } else if (clasz.isAssignableFrom(Float.class)) { value = (T)(Float.parseFloat(str)); } else { logger.warn("Unsupporteded value type encountered in key-value pairs, continuing anyway: " + clasz.getName()); } val.put(jxent.getKey(), value); } return val; } This is the bit that I want to solve: if (clasz.isAssignableFrom(Boolean.class)) { value = (T)(Boolean.parseBoolean(str)); } else if (clasz.isAssignableFrom(Integer.class)) { value = (T)(Integer.parseInt(str)); } I get: Inconvertible types required: T found: Boolean Also, if possible, I would like to be able to do this with more elegant code, avoiding Class#isAssignableFrom. Any suggestions? Sample method invocation: Map<String, Boolean> foo = fromListOfKeyValuePairs(bar, Boolean.class);

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• Generic Class Vb.net

  - by KoolKabin

  hi guys, I am stuck with a problem about generic classes. I am confused how I call the constructor with parameters. My interface: Public Interface IDBObject Sub [Get](ByRef DataRow As DataRow) Property UIN() As Integer End Interface My Child Class: Public Class User Implements IDBObject Public Sub [Get](ByRef DataRow As System.Data.DataRow) Implements IDBObject.Get End Sub Public Property UIN() As Integer Implements IDBObject.UIN Get End Get Set(ByVal value As Integer) End Set End Property End Class My Next Class: Public Class Users Inherits DBLayer(Of User) #Region " Standard Methods " #End Region End Class My DBObject Class: Public Class DBLayer(Of DBObject As {New, IDBObject}) Public Shared Function GetData() As List(Of DBObject) Dim QueryString As String = "SELECT * ***;" Dim Dataset As DataSet = New DataSet() Dim DataList As List(Of DBObject) = New List(Of DBObject) Try Dataset = Query(QueryString) For Each DataRow As DataRow In Dataset.Tables(0).Rows **DataList.Add(New DBObject(DataRow))** Next Catch ex As Exception DataList = Nothing End Try Return DataList End Function End Class I get error in the starred area of the DBLayer Object. What might be the possible reason? what can I do to fix it? I even want to add New(byval someval as datatype) in IDBObject interface for overloading construction. but it also gives an error? how can i do it? Adding Sub New(ByVal DataRow As DataRow) in IDBObject producess following error 'Sub New' cannot be declared in an interface. Error Produced in DBLayer Object line: DataList.Add(New DBObject(DataRow)) Msg: Arguments cannot be passed to a 'New' used on a type parameter.

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• Python: Inheritance of a class attribute (list)

  - by Sano98

  Hi everyone, inheriting a class attribute from a super class and later changing the value for the subclass works fine: class Unit(object): value = 10 class Archer(Unit): pass print Unit.value print Archer.value Archer.value = 5 print Unit.value print Archer.value leads to the output: 10 10 10 5 which is just fine: Archer inherits the value from Unit, but when I change Archer's value, Unit's value remains untouched. Now, if the inherited value is a list, the shallow copy effect strikes and the value of the superclass is also affected: class Unit(object): listvalue = [10] class Archer(Unit): pass print Unit.listvalue print Archer.listvalue Archer.listvalue[0] = 5 print Unit.listvalue print Archer.listvalue Output: 10 10 5 5 Is there a way to "deep copy" a list when inheriting it from the super class? Many thanks Sano

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• gcc returns error with nested class

  - by Nate

  Howdy, I am attempting to use the fully qualified name of my nested class as below, but the compiler is balking! template <class T> class Apple { //constructors, members, whatevers, etc... public: class Banana { public: Banana() { //etc... } //other constructors, members, etc... }; }; template <class K> class Carrot{ public: //etc... void problemFunction() { Apple<int>::Banana freshBanana = someVar.returnsABanana(); //line 85 giveMonkey(freshBanana); //line 86 } }; My issue is, the compiler says: Carrot.h:85: error: expected ';' before 'freshBanana' Carrot.h:86: error: 'freshBanana' was not declared in this scope I had thought that using the fully qualified name permitted me to access this nested class? It's probably going to smack me in the face, but what on earth am I not seeing here??

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• Why can't my main class see the array in my calender class

  - by Rocky Celltick Eadie

  This is a homework problem. I'm already 5 days late and can't figure out what I'm doing wrong.. this is my 1st semester in Java and my first post on this site Here is the assignment.. Create a class called Calendar. The class should contain a variable called events that is a String array. The array should be created to hold 5 elements. Use a constant value to specify the array size. Do not hard code the array size. Initialize the array in the class constructor so that each element contains the string “ – No event planned – “. The class should contain a method called CreateEvent. This method should accept a String argument that contains a one-word user event and an integer argument that represents the day of the week. Monday should be represented by the number 1 and Friday should be represented by the number 5. Populate the events array with the event info passed into the method. Although the user will input one-word events, each event string should prepend the following string to each event: event_dayAppoinment: (where event_day is the day of the week) For example, if the user enters 1 and “doctor” , the first array element should read: Monday Appointment: doctor If the user enters 2 and “PTA” , the second array element should read: Tuesday Appointment: PTA Write a driver program (in a separate class) that creates and calls your Calendar class. Then use a loop to gather user input. Ask for the day (as an integer) and then ask for the event (as a one word string). Pass the integer and string to the Calendar object’s CreateEvent method. The user should be able enter 0 – 5 events. If the user enters -1, the loop should exit and your application should print out all the events in a tabular format. Your program should not allow the user to enter invalid values for the day of the week. Any input other than 1 – 5 or -1 for the day of the week would be considered invalid. Notes: When obtaining an integer from the user, you will need to use the nextInt() method on your Scanner object. When obtaining a string from a user, you will need to use the next() method on your Scanner object. Here is my code so far.. //DRIVER CLASS /** * * @author Rocky */ //imports scanner import java.util.Scanner; //begin class driver public class driver { /** * @paramargs the command line arguments */ //begin main method public static void main(String[] args) { //initiates scanner Scanner userInput = new Scanner (System.in); //declare variables int dayOfWeek; String userEvent; //creates object for calender class calendercalenderObject = new calender(); //user prompt System.out.println("Enter day of week for your event in the following format:"); System.out.println("Enter 1 for Monday"); System.out.println("Enter 2 for Tuesday"); System.out.println("Enter 3 for Wednsday"); System.out.println("Enter 4 for Thursday"); System.out.println("Enter 5 for Friday"); System.out.println("Enter -1 to quit"); //collect user input dayOfWeek = userInput.nextInt(); //user prompt System.out.println("Please type in the name of your event"); //collect user input userEvent = userInput.next(); //begin while loop while (dayOfWeek != -1) { //test for valid day of week if ((dayOfWeek>=1) && (dayOfWeek<=5)){ //calls createEvent method in calender class and passes 2 variables calenderObject.createEvent(userEvent,dayOfWeek); } else { //error message System.out.println("You have entered an invalid number"); //user prompts System.out.println("Press -1 to quit or enter another day"); System.out.println("Enter 1 for Monday"); System.out.println("Enter 2 for Tuesday"); System.out.println("Enter 3 for Wednsday"); System.out.println("Enter 4 for Thursday"); System.out.println("Enter 5 for Friday"); System.out.println("Enter -1 to quit"); //collect user input dayOfWeek = userInput.nextInt(); //end data validity test } //end while loop } //prints array to screen int i=0; for (i=0;i<events.length;i++){ System.out.println(events[i]); } //end main method } } /** * * @author Rocky */ //imports scanner import java.util.Scanner; //begin calender class public class calender { //creates events array String[] events = new String[5]; //begin calender class constructor public calender() { //Initializes array String[] events = {"-No event planned-","-No event planned-","-No event planned-","-No event planned-","-No event planned-"}; //end calender class constructor } //begin createEvent method public String[] createEvent (String userEvent, int dayOfWeek){ //Start switch test switch (dayOfWeek){ case 1: events[0] = ("Monday Appoinment:") + userEvent; break; case 2: events[1] = ("Tuesday Appoinment:") + userEvent; break; case 3: events[2] = ("WednsdayAppoinment:") + userEvent; break; case 4: events[3] = ("Thursday Appoinment:") + userEvent; break; case 5: events[4] = ("Friday Appoinment:") + userEvent; break; default: break; //End switch test } //returns events array return events; //end create event method } //end calender class }

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• Objective-C: Getting the True Class of Classes in Class Clusters

  - by TechZen

  Recently while trying to answer a questions here, I ran some test code to see how Xcode/gdb reported the class of instances in class clusters. (see below) In the past, I've expected to see something like: PrivateClusterClass:PublicSuperClass:NSObject Such as this (which still returns as expected): NSPathStore2:NSString:NSObject ... for a string created with +[NSString pathWithComponents:]. However, with NSSet and subclass the following code: - (void)applicationDidFinishLaunching:(UIApplication *)application { NSSet *s=[NSSet setWithObject:@"setWithObject"]; NSMutableSet *m=[NSMutableSet setWithCapacity:1]; [m addObject:@"Added String"]; NSMutableSet *n = [[NSMutableSet alloc] initWithCapacity:1]; [self showSuperClasses:s]; [self showSuperClasses:m]; [self showSuperClasses:n]; [self showSuperClasses:@"Steve"]; } - (void) showSuperClasses:(id) anObject{ Class cl = [anObject class]; NSString *classDescription = [cl description]; while ([cl superclass]) { cl = [cl superclass]; classDescription = [classDescription stringByAppendingFormat:@":%@", [cl description]]; } NSLog(@"%@ classes=%@",[anObject class], classDescription); } ... outputs: // NSSet *s NSCFSet classes=NSCFSet:NSMutableSet:NSSet:NSObject //NSMutableSet *m NSCFSet classes=NSCFSet:NSMutableSet:NSSet:NSObject //NSMutableSet *n NSCFSet classes=NSCFSet:NSMutableSet:NSSet:NSObject // NSString @"Steve" NSCFString classes=NSCFString:NSMutableString:NSString:NSObject The debugger shows the same class for all Set instances. I know that in the past the Set class cluster did not return like this. What has changed? (I suspect it is a change in the bridge from Core Foundation.) What class cluster report just a generic class e.g. NSCFSet and which report an actual subclass e.g. NSPathStore2? Most importantly, when debugging how do you determine the actual class of a NSSet cluster instance?

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• Use of base class object by child class reference - java

  - by JavaUser

  Hi, What is the use of creating base class object using child class reference in Java

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• Interface and base class mix, the right way to implement this

  - by Lerxst

  I have some user controls which I want to specify properties and methods for. They inherit from a base class, because they all have properties such as "Foo" and "Bar", and the reason I used a base class is so that I dont have to manually implement all of these properties in each derived class. However, I want to have a method that is only in the derived classes, not in the base class, as the base class doesn't know how to "do" the method, so I am thinking of using an interface for this. If i put it in the base class, I have to define some body to return a value (which would be invalid), and always make sure that the overriding method is not calling the base. method Is the right way to go about this to use both the base class and an interface to expose the method? It seems very round-about, but every way i think about doing it seems wrong... Let me know if the question is not clear, it's probably a dumb question but I want to do this right.

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• Can a main() method of class be invoked in another class in java

  - by sa

  Can a main() method of class be invoked in another class in java

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• How to make some functions of a class as private for third level of inheritance.

  - by Shantanu Gupta

  I have created a class say A which has some functions defined as protected. Now Class B inherits A and class C inherits B. Class A has private default constructor and protected parameterized constructor. I want Class B to be able to access all the protected functions defined in Class A but class C can have access on some of the functions only not all the functions and class C is inheriting class B. How can I restrict access to some of the functions of Class A from Class C ? Class A { private A(){} protected A(int ){} protected calc(){} protected allow(){} } Class B : A {} // calc() and allow() should be accessible here CLass C:B { // calc() should not be accessible here but allow() should be accessible here. }

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• calling members of class to another class

  - by Hussain

  hii every one I m using Applets i ve three classes ie three applets and I need some members(variables) of one class into another class when i m trying to access variables from one class to another class by creating of object of called class in to calling class then it doesnt give wright output it access those variables but gives null or zero values

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• Having a base class function depend on its child class C#

  - by Junk Junk

  I have a Base class with a method that a child class will almost always override. However, instead of replacing the base class' method entirely, I would like for whatever is derived in the child class to be added to what is already in the base class. For Example: class BaseClass public string str() { var string = "Hello my name is" ; } class ChildClass : BaseClass public override string str(){ var string = "Sam"; } The point is that if I want to access the str() method by creating an instance of the ChildClass, the string will print out as "Hello, my name is Sam". I've been looking around and all I have been finding is that this should NOT happen, as the base class shouldn't even know that it is being inherited. So, if the design is false, how would I go about doing this? Keep in mind that there will be multiple child classes inheriting from BaseClass. Thank you

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• choose the best class if 2 class have same P (c|d), naive bayes

  - by ryandi

  Hello I have some question about naive bayes classifier . In my project I have to classify a text into a class from 4 available class. In naive bayes we have formula like cmap=argmax.P(d|c).P(c) I have standarize the amount of training document of each class, so I got a same P(c) value for each class (0.25). Here's my question: What if a testing document token doesn't have any token which belong to any of those 4 class(in document training)? Resulted to all of the class have same value of P(d|c).P(c). Which class should i pick? What if the token exist, and 2 class or more have same value of P(d|c).P(c) what should I do? Thank you..

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• defining information out of class

  - by calccrypto

  is there a way to define a value within a class in the __init__ part, send it to some variable outside of the class without calling another function within the class? like class c: def __init__(self, a): self.a = a b = 4 # do something like this so that outside of class c, # b is set to 4 automatically when i use class c def function(self): ... # whatever. this doesnt matter i have multiple classes that have different values for b. i could just make a list that tells the computer to change b, but i would rather set b within each class

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