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• Saving Abstract and Sub classes to database

  - by bretddog

  Hi, I have an abstract class "StrategyBase", and a set of sub classes, StrategyA/B/C etc. The sub classes use some of the properties of the base class, and have some individual properties. My question is how to save this to a database. I'm currently using SqlCE, and Linq-To-Sql by creating entity classes automatically with SqlMetal.exe. I've seen there are three solutions shown in this question, but I'm not able to see how these solutions will work or not with SqlMetal/entity classes. Though it seems to me the "concrete table inheritance" would probably work without any manual modifying. What about the other two, would they be problematic? For "Single Table Inheritance" wouldn't all classes get all variables, even though they don't need them? And for the "Class table inheritance" solution I can't really see at all how that will map into the entity-classes for a useful purpose. I may note that I extend these partial entity classes for making the classes of my business objects. I may also consider moving to EntityFramework instead of SqlMetal/Linq2Sql, so would be nice also to know if that makes any difference to what schema is easy to implement. One likely important thing to note is that I will constantly be develop new strategies, which makes me have to modify the program code, and probably the database shcema; when adding a new strategy. Sorry the question is a bit "all over the place", but hopefully it's some clear advantages/disadvantages here that you may be able to advice. ? Cheers!

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• variables in abstract classes C++

  - by wyatt

  I have an abstract class CommandPath, and a number of derived classes as below: class CommandPath { public: virtual CommandResponse handleCommand(std::string) = 0; virtual CommandResponse execute() = 0; virtual ~CommandPath() {} }; class GetTimeCommandPath : public CommandPath { int stage; public: GetTimeCommandPath() : stage(0) {} CommandResponse handleCommand(std::string); CommandResponse execute(); }; All of the derived classes have the member variable 'stage'. I want to build a function into all of them which manipulates 'stage' in the same way, so rather than defining it many times I thought I'd build it into the parent class. I moved 'stage' from the private sections of all of the derived classes into the protected section of CommandPath, and added the function as follows: class CommandPath { protected: int stage; public: virtual CommandResponse handleCommand(std::string) = 0; virtual CommandResponse execute() = 0; std::string confirmCommand(std::string, int, int, std::string, std::string); virtual ~CommandPath() {} }; class GetTimeCommandPath : public CommandPath { public: GetTimeCommandPath() : stage(0) {} CommandResponse handleCommand(std::string); CommandResponse execute(); }; Now my compiler tells me for the constructor lines that none of the derived classes have a member 'stage'. I was under the impression that protected members are visible to derived classes? The constructor is the same in all classes, so I suppose I could move it to the parent class, but I'm more concerned about finding out why the derived classes aren't able to access the variable. Also, since previously I've only used the parent class for pure virtual functions, I wanted to confirm that this is the way to go about adding a function to be inherited by all derived classes.

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• SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – SQL and 10-11 May SharePoint

  - by pinaldave

  There were lots of request about providing more details for the blog post through email address specified in the article SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning. Here is the complete brochure of the course. There are two different courses are offered by Solid Quality Mentors 1) Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning – Pinal Dave Date: May 12-14, 2010 Price: Rs. 14,000/person for 3 days Discount Code: ‘SQLAuthority.com‘ Effective Price: Rs. 11,000/person for 3 days 2) SharePoint 2010 – Joy Rathnayake Date: May 10-11, 2010 Price: Rs. 11,000/person for 3 days Discount Code: ‘SQLAuthority.com’ Effective Price: Rs. 8,000/person for 3 days Download the complete PDF brochure. Additionally there is special program of SolidQ India Insider. I will provide the details for the same very soon. Please do send me email if you need any additional details. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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• SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – SQL and 10-11 May SharePoint

  - by pinaldave

  There were lots of request about providing more details for the blog post through email address specified in the article SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning. Here is the complete brochure of the course. There are two different courses are offered by Solid Quality Mentors 1) Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning – Pinal Dave Date: May 12-14, 2010 Price: Rs. 14,000/person for 3 days Discount Code: ‘SQLAuthority.com‘ Effective Price: Rs. 11,000/person for 3 days 2) SharePoint 2010 – Joy Rathnayake Date: May 10-11, 2010 Price: Rs. 11,000/person for 3 days Discount Code: ‘SQLAuthority.com’ Effective Price: Rs. 8,000/person for 3 days Download the complete PDF brochure. Additionally there is special program of SolidQ India Insider. I will provide the details for the same very soon. Please do send me email if you need any additional details. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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• Due to the Classes

  - by Ratman21

  Why does it seem that I am always saying sorry (or in Japanese Gomennasi)?  Well I am late again for blog as you can see. The CCNA class’s part 1 (also known as CCENT) was, well more intense than all of the certification classes before it.   The teacher was cramming as much as he could into us during the week and it was hard to come home and do much more than fall into bed (Well I was doing still doing my Job search and checking up on my web sites and groups).   But I didn’t have much left in the way of blogging (Which by the way is now in 3 different sites). Even though it was hard some times, I really liked the fact I was getting back to something like (and mean really like, in fact I like Cisco routers than some people I know). At the class, I got some software that allows me to simulate setting up and troubles shoot Lan’s or Wan’s.   When we weren’t getting facts for the test thrown at us, we were doing labs with this software. It was fun for me to be able to use the CISCO router commands and trouble shoot router issues. Even if it was just a sim. So now it is study, study, take practices tests and do the labs. I took the week end and more off after cram CCENT week but, now I am back at it.  Also I could not keep up with my Love Dare book during week of the class. No I did not stop or forget what I already learned. I just put the next dare on hold. Well the hold is off starting tomorrow and tonight I think I am going to write a new cover letter. Let’s see what else I can get done tonight. Hmm I think I will try to do a sim of my home wireless LAN and study for CCENT test in about 3 weeks.   So see you tomorrow (I hope).

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• Writing cross-platforms Types, Interfaces and Classes/Methods in C++

  - by user827992

  I'm looking for the best solution to write cross-platform software, aka code that I write and that I have to interface with different libraries and platforms each time. What I consider the easiest part, correct me if I'm wrong, is the definition of new types, all I have to do is to write an hpp file with a list of typedefs, I can keep the same names for each new type across the different platforms so my codebase can be shared without any problem. typedefs also helps me to redefine a better scope for my types in my code. I will probably end up having something like this: include |-windows | |-types.hpp |-linux | |-types.hpp |-mac |-types.hpp For the interfaces I'm thinking about the same solution used for the types, a series of hpp files, probably I will write all the interfaces only once since they rely on the types and all "cross-platform portability" is ensured by the work done on the types. include | |-interfaces.hpp | |-windows | |-types.hpp |-linux | |-types.hpp |-mac | |-types.hpp For classes and methods I do not have a real answer, I would like to avoid 2 things: the explicit use of pointers the use of templates I want to avoid the use of the pointers because they can make the code less readable for someone and I want to avoid templates just because if I write them, I can't separate the interface from the definition. What is the best option to hide the use of the pointers? I would also like some words about macros and how to implement some OS-specifics calls and definitions.

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• The problems with Avoiding Smurf Naming classes with namespaces

  - by Daniel Koverman

  I pulled the term smurf naming from here (number 21). To save anyone not familiar the trouble, Smurf naming is the act of prefixing a bunch of related classes, variables, etc with a common prefix so you end up with "a SmurfAccountView passes a SmurfAccountDTO to the SmurfAccountController", etc. The solution I've generally heard to this is to make a smurf namespace and drop the smurf prefixes. This has generally served me well, but I'm running into two problems. I'm working with a library with a Configuration class. It could have been called WartmongerConfiguration but it's in the Wartmonger namespace, so it's just called Configuration. I likewise have a Configuration class which could be called SmurfConfiguration, but it is in the Smurf namespace so that would be redundant. There are places in my code where Smurf.Configuration appears alongside Wartmonger.Configuration and typing out fully qualified names is clunky and makes the code less readable. It would be nicer to deal with a SmurfConfiguration and (if it was my code and not a library) WartmongerConfiguration. I have a class called Service in my Smurf namespace which could have been called SmurfService. Service is a facade on top of a complex Smurf library which runs Smurf jobs. SmurfService seems like a better name because Service without the Smurf prefix is so incredibly generic. I can accept that SmurfService was already a generic, useless name and taking away smurf merely made this more apparent. But it could have been named Runner, Launcher, etc and it would still "feel better" to me as SmurfLauncher because I don't know what a Launcher does, but I know what a SmurfLauncher does. You could argue that what a Smurf.Launcher does should be just as apparent as a Smurf.SmurfLauncher, but I could see `Smurf.Launcher being some kind of class related to setup rather than a class that launches smurfs. If there is an open and shut way to deal with either of these that would be great. If not, what are some common practices to mitigate their annoyance?

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• Moving my sprite in XNA using classes

  - by Tom

  Hey, im a newbie at this programming lark and its really frustrating me. I'm trying to move a snake in all directions while using classes. Ive created a vector2 for speed and ive attempted creating a method which moves the snake within the snake class. Now I'm confused and not sure what to do next. Appreciate any help. Thanks :D This is what i've done in terms of the method... public Vector2 direction() { Vector2 inputDirection = Vector2.Zero; if (Keyboard.GetState().IsKeyDown(Keys.Left)) inputDirection.X -= -1; if (Keyboard.GetState().IsKeyDown(Keys.Right)) inputDirection.X += 1; if (Keyboard.GetState().IsKeyDown(Keys.Up)) inputDirection.Y -= -1; if (Keyboard.GetState().IsKeyDown(Keys.Down)) inputDirection.Y += 1; return inputDirection * snakeSpeed; } Appreciate any help. Thanks :D EDIT: Well let me make everything clear. Im making a small basic game for an assignment. The game is similar to the old snake game on the old Nokia phones. I've created a snake class (even though I'm not sure whether this is needed because im only going to be having one moving sprite within the game). After I written the code above (in the snake class), the game ran with no errors but I couldn't actually move the image :( EDIT2: Thanks so much for everyones responses!!

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• Data classes: getters and setters or different method design

  - by Frog

  I've been trying to design an interface for a data class I'm writing. This class stores styles for characters, for example whether the character is bold, italic or underlined. But also the font-size and the font-family. So it has different types of member variables. The easiest way to implement this would be to add getters and setters for every member variable, but this just feels wrong to me. It feels way more logical (and more OOP) to call style.format(BOLD, true) instead of style.setBold(true). So to use logical methods insteads of getters/setters. But I am facing two problems while implementing these methods: I would need a big switch statement with all member variables, since you can't access a variable by the contents of a string in C++. Moreover, you can't overload by return type, which means you can't write one getter like style.getFormatting(BOLD) (I know there are some tricks to do this, but these don't allow for parameters, which I would obviously need). However, if I would implement getters and setters, there are also issues. I would have to duplicate quite some code because styles can also have a parent styles, which means the getters have to look not only at the member variables of this style, but also at the variables of the parent styles. Because I wasn't able to figure out how to do this, I decided to ask a question a couple of weeks ago. See Object Oriented Programming: getters/setters or logical names. But in that question I didn't stress it would be just a data object and that I'm not making a text rendering engine, which was the reason one of the people that answered suggested I ask another question while making that clear (because his solution, the decorator pattern, isn't suitable for my problem). So please note that I'm not creating my own text rendering engine, I just use these classes to store data. Because I still haven't been able to find a solution to this problem I'd like to ask this question again: how would you design a styles class like this? And why would you do that? Thanks on forehand!

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• Breaking up classes and methods into smaller units

  - by micahhoover

  During code reviews a couple devs have recommended I break up my methods into smaller methods. Their justification was (1) increased readability and (2) the back trace that comes back from production showing the method name is more specific to the line of code that failed. There may have also been some colorful words about functional programming. Additionally I think I may have failed an interview a while back because I didn't give an acceptable answer about when to break things up. My inclination is that when I see a bunch of methods in a class or across a bunch of files, it isn't clear to me how they flow together, and how many times each one gets called. I don't really have a good feel for the linearity of it as quickly just by eye-balling it. The other thing is a lot of people seem to place a premium of organization over content (e.g. 'Look at how organized my sock drawer is!' Me: 'Overall, I think I can get to my socks faster if you count the time it took to organize them'). Our business requirements are not very stable. I'm afraid that if the classes/methods are very granular it will take longer to refactor to requirement changes. I'm not sure how much of a factor this should be. Anyway, computer science is part art / part science, but I'm not sure how much this applies to this issue.

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• 7 drived classes with one common base class

  - by user144905

  i have written the following code, //main.cpp #include<iostream> #include<string> #include"human.h" #include"computer.h" #include"referee.h" #include"RandomComputer.h" #include"Avalanche.h" #include"Bureaucrat.h" #include"Toolbox.h" #include"Crescendo.h" #include"PaperDoll.h" #include"FistfullODollors.h" using namespace std; int main() { Avalanche pla1; Avalanche pla2; referee f; pla1.disp(); for (int i=0;i<5;i++) { cout<<pla2.mov[i]; } return 0; } in this program all included classes except referee.h and human.h are drived from computer.h. each drived calls has a char array variable which is initialized when a member of a drived class is declared. the problem is that when i declare tow diffrent drived class memebers lets say Avalache and ToolBox. upon printing the char array for one of them using for loop it prints nothing. However if i declare only one of them in main.cpp the it works properly. and the file for computer.h is as such: #ifndef COMPUTER_H #define COMPUTER_H class computer { public: int nump; char mov[]; void disp(); }; #endif ToolBox.h is like this: #ifndef TOOLBOX_H #define TOOLBOX_H #include"computer.h" class Toolbox: public computer { public: Toolbox(); }; #endif finally Avalanche.h is as following: #ifndef AVALANCHE_H #define AVALANCHE_H #include"computer.h" class Avalanche: public computer { public: Avalanche(); }; #endif

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• Help with design structure choice: Using classes or library of functions

  - by roverred

  So I have GUI Class that will call another class called ImageProcessor that contains a bunch functions that will perform image processing algorithms like edgeDetection, gaussianblur, contourfinding, contour map generations, etc. The GUI passes an image to ImageProcessor, which performs one of those algorithm on it and it returns the image back to the GUI to display. So essentially ImageProcessor is a library of independent image processing functions right now. It is called in the GUI like so Image image = ImageProcessor.EdgeDetection(oldImage); Some of the algorithms procedures require many functions, and some can be done in a single function or even one line. All these functions for the algorithms jam packed into ImageProcessor can be pretty messy, and ImageProcessor doesn't sound it should be a library. So I was thinking about making every algorithm be a class with a shared interface say IAlgorithm. Then I pass the IAlgorithm interface from the GUI to the ImageProcessor. public interface IAlgorithm{ public Image Process(); } public class ImageProcessor{ public Image Process(IAlgorithm TheAlgorithm){ return IAlgorithm.Process(); } } Calling in the GUI like so Image image = ImageProcessor.Process(new EdgeDetection(oldImage)); I think it makes sense in an object point of view, but the problem is I'll end up with some classes that are just one function. What do you think is a better design, or are they both crap and you have a much better idea? Thanks!

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• OOP Design: relationship between entity classes

  - by beginner_

  I have at first sight a simple issue but can't wrap my head around on how to solve. I have an abstract class Compound. A Compound is made up of Structures. Then there is also a Container which holds 1 Compound. A "special" implementation of Compound has Versions. For that type of Compound I want the Container to hold the Versionof the Compound and not the Compound itself. You could say "just create an interface Containable" and a Container holds 1 Containable. However that won't work. The reason is I'm creating a framework and the main part of that framework is to simplify storing and especially searching for special data type held by Structure objects. Hence to search for Containers which contain a Compound made up of a specific Structure requires that the "Path" from Containerto Structure is well defined (Number of relationships or joins). I hope this was understandable. My question is how to design the classes and relationships to be able to do what I outlined.

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• C#: Dynamically instantiate different classes in the same statement?

  - by C. Griffin

  Here is a simplified version of what I'm trying to do: Without having multiple if..else clauses and switch blocks, can I mimic the behavior of Javascript's eval() shudder to instantiate a class in C#? // Determine report orientation -- Portrait or Landscape // There are 2 differently styled reports (beyond paper orientation) string reportType = "Portrait"; GenericReport report; report = new eval(reportType + "Report()"); // Resolves to PortraitReport() The need stems from the fact that I have 6 types of Crystal Reports (that do the same thing, but look drastically different) for 50 states. There are 3 styles each, rather than entertain the notion of a giant switch block with nested if..else statements determining which of 900 reports to use, I was hoping for an eval-like solution.

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• C# - Which is more efficient and thread safe? static or instant classes?

  - by Soni Ali

  Consider the following two scenarios: //Data Contract public class MyValue { } Scenario 1: Using a static helper class. public class Broker { private string[] _userRoles; public Broker(string[] userRoles) { this._userRoles = userRoles; } public MyValue[] GetValues() { return BrokerHelper.GetValues(this._userRoles); } } static class BrokerHelper { static Dictionary<string, MyValue> _values = new Dictionary<string, MyValue>(); public static MyValue[] GetValues(string[] rolesAllowed) { return FilterForRoles(_values, rolesAllowed); } } Scenario 2: Using an instance class. public class Broker { private BrokerService _service; public Broker(params string[] userRoles) { this._service = new BrokerService(userRoles); } public MyValue[] GetValues() { return _service.GetValues(); } } class BrokerService { private Dictionary<string, MyValue> _values; private string[] _userRoles; public BrokerService(string[] userRoles) { this._userRoles = userRoles; this._values = new Dictionary<string, MyValue>(); } public MyValue[] GetValues() { return FilterForRoles(_values, _userRoles); } } Which of the [Broker] scenarios will scale best if used in a web environment with about 100 different roles and over a thousand users. NOTE: Feel free to sugest any alternative approach.

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• How many times can classes be nested within a class?

  - by Kushal Paudyal

  I came across this questions on one of the online Java Tests. The options were 4,5,8 and any number of times. I have only used one inner class, but have never tried multiple ones. I was wondering if anyone knows the answer.

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• How do I avoid web method parameters using proxy classes?

  - by Alex Angas

  I have a serializable POCO called DataUnification.ClientData.ClientInfo in a .NET class library project A. It's used in a parameter for a web service defined in project B: public XmlDocument CreateNewClient(ClientInfo ci, string system) I now wish to call this web method from project C and use the original DataUnification.ClientData.ClientInfo type in the parameter. However due to the generated proxy class it has now become a different type: WebServices.ClientDataUnification.DataUnificationWebService.ClientInfo. As far as .NET is concerned these are not the same types. How can I get around this?

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• I'm new to OOP/PHP. What's the practicality of visibility and extensibility in classes?

  - by marcdev

  I'm obviously brand new to these concepts. I just don't understand why you would limit access to properties or methods. It seems that you would just write the code according to intended results. Why would you create a private method instead of simply not calling that method? Is it for iterative object creation (if I'm stating that correctly), a multiple developer situation (don't mess up other people's work), or just so you don't mess up your own work accidentally?

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• Getting a seg fault, having trouble with classes and variables.

  - by celestialorb

  Ok, so I'm still learning the ropes of C++ here so I apologize if this is a simple mistake. I have this class: class RunFrame : public wxFrame { public: RunFrame(); void OnKey(wxKeyEvent& keyEvent); private: // Configuration variables. const wxString *title; const wxPoint *origin; const wxSize *size; const wxColour *background; const wxColour *foreground; const wxString *placeholder; // Control variables. wxTextCtrl *command; // Event table. DECLARE_EVENT_TABLE() }; ...then in the OnKey method I have this code: void RunFrame::OnKey(wxKeyEvent& keyEvent) { // Take the key and process it. if(WXK_RETURN == keyEvent.GetKeyCode()) { bool empty = command -> IsEmpty(); } // Propogate the event through. keyEvent.Skip(); } ...but my program keeps seg faulting when it reaches the line where I attempt to call the IsEmpty method from the command variable. My question is, "Why?" In the constructor of the RunFrame class I can seemingly call methods for the command variable in the same way I'm doing so in the OnKey method...and it compiles correctly, it just seg faults on me when it attempts to execute that line. Here is the code for the constructor if necessary: RunFrame::RunFrame() : wxFrame(NULL, wxID_ANY, wxT("DEFAULT"), wxDefaultPosition, wxDefaultSize, wxBORDER_NONE) { // Create the styling constants. title = new wxString(wxT("RUN")); origin = new wxPoint(0, 0); size = new wxSize(250, 25); background = new wxColour(33, 33, 33); foreground = new wxColour(255, 255, 255); placeholder = new wxString(wxT("command")); // Set the styling for the frame. this -> SetTitle(*title); this -> SetSize(*size); // Create the panel and attach the TextControl to it. wxPanel *panel = new wxPanel(this, wxID_ANY, *origin, *size, wxBORDER_NONE); // Create the text control and attach it to the panel. command = new wxTextCtrl(panel, wxID_ANY, *placeholder, *origin, *size); // Set the styling for the text control. command -> SetBackgroundColour(*background); command -> SetForegroundColour(*foreground); // Connect the key event to the text control. command -> Connect(wxEVT_CHAR, wxKeyEventHandler(RunFrame::OnKey)); // Set the focus to the command box. command -> SetFocus(); } Thanks in advance for any help you can give! Regards, celestialorb

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• C++ HW - defining classes - objects that have objects of other class problem in header file (out of

  - by kitfuntastik

  This is my first time with much of this code. With this instancepool.h file below I get errors saying I can't use vector (line 14) or have instance& as a return type (line 20). It seems it can't use the instance objects despite the fact that I have included them. #ifndef _INSTANCEPOOL_H #define _INSTANCEPOOL_H #include "instance.h" #include <iostream> #include <string> #include <vector> #include <stdlib.h> using namespace std; class InstancePool { private: unsigned instances;//total number of instance objects vector<instance> ipp;//the collection of instance objects, held in a vector public: InstancePool();//Default constructor. Creates an InstancePool object that contains no Instance objects InstancePool(const InstancePool& original);//Copy constructor. After copying, changes to original should not affect the copy that was created. ~InstancePool();//Destructor unsigned getNumberOfInstances() const;//Returns the number of Instance objects the the InstancePool contains. const instance& operator[](unsigned index) const; InstancePool& operator=(const InstancePool& right);//Overloading the assignment operator for InstancePool. friend istream& operator>>(istream& in, InstancePool& ip);//Overloading of the >> operator. friend ostream& operator<<(ostream& out, const InstancePool& ip);//Overloading of the << operator. }; #endif Here is the instance.h : #ifndef _INSTANCE_H #define _INSTANCE_H ///////////////////////////////#include "instancepool.h" #include <iostream> #include <string> #include <stdlib.h> using namespace std; class Instance { private: string filenamee; bool categoryy; unsigned featuress; unsigned* featureIDD; unsigned* frequencyy; string* featuree; public: Instance (unsigned features = 0);//default constructor unsigned getNumberOfFeatures() const; //Returns the number of the keywords that the calling Instance object can store. Instance(const Instance& original);//Copy constructor. After copying, changes to the original should not affect the copy that was created. ~Instance() { delete []featureIDD; delete []frequencyy; delete []featuree;}//Destructor. void setCategory(bool category){categoryy = category;}//Sets the category of the message. Spam messages are represented with true and and legit messages with false.//easy bool getCategory() const;//Returns the category of the message. void setFileName(const string& filename){filenamee = filename;}//Stores the name of the file (i.e. “spam/spamsga1.txt”, like in 1st assignment) in which the message was initially stored.//const string& trick? string getFileName() const;//Returns the name of the file in which the message was initially stored. void setFeature(unsigned i, const string& feature, unsigned featureID,unsigned frequency) {//i for array positions featuree[i] = feature; featureIDD[i] = featureID; frequencyy[i] = frequency; } string getFeature(unsigned i) const;//Returns the keyword which is located in the ith position.//const string unsigned getFeatureID(unsigned i) const;//Returns the code of the keyword which is located in the ith position. unsigned getFrequency(unsigned i) const;//Returns the frequency Instance& operator=(const Instance& right);//Overloading of the assignment operator for Instance. friend ostream& operator<<(ostream& out, const Instance& inst);//Overloading of the << operator for Instance. friend istream& operator>>(istream& in, Instance& inst);//Overloading of the >> operator for Instance. }; #endif Also, if it is helpful here is instance.cpp: // Here we implement the functions of the class apart from the inline ones #include "instance.h" #include <iostream> #include <string> #include <stdlib.h> using namespace std; Instance::Instance(unsigned features) { //Constructor that can be used as the default constructor. featuress = features; if (features == 0) return; featuree = new string[featuress]; // Dynamic memory allocation. featureIDD = new unsigned[featuress]; frequencyy = new unsigned[featuress]; return; } unsigned Instance::getNumberOfFeatures() const {//Returns the number of the keywords that the calling Instance object can store. return featuress;} Instance::Instance(const Instance& original) {//Copy constructor. filenamee = original.filenamee; categoryy = original.categoryy; featuress = original.featuress; featuree = new string[featuress]; for(unsigned i = 0; i < featuress; i++) { featuree[i] = original.featuree[i]; } featureIDD = new unsigned[featuress]; for(unsigned i = 0; i < featuress; i++) { featureIDD[i] = original.featureIDD[i]; } frequencyy = new unsigned[featuress]; for(unsigned i = 0; i < featuress; i++) { frequencyy[i] = original.frequencyy[i];} } bool Instance::getCategory() const { //Returns the category of the message. return categoryy;} string Instance::getFileName() const { //Returns the name of the file in which the message was initially stored. return filenamee;} string Instance::getFeature(unsigned i) const { //Returns the keyword which is located in the ith position.//const string return featuree[i];} unsigned Instance::getFeatureID(unsigned i) const { //Returns the code of the keyword which is located in the ith position. return featureIDD[i];} unsigned Instance::getFrequency(unsigned i) const { //Returns the frequency return frequencyy[i];} Instance& Instance::operator=(const Instance& right) { //Overloading of the assignment operator for Instance. if(this == &right) return *this; delete []featureIDD; delete []frequencyy; delete []featuree; filenamee = right.filenamee; categoryy = right.categoryy; featuress = right.featuress; featureIDD = new unsigned[featuress]; frequencyy = new unsigned[featuress]; featuree = new string[featuress]; for(unsigned i = 0; i < featuress; i++) { featureIDD[i] = right.featureIDD[i]; } for(unsigned i = 0; i < featuress; i++) { frequencyy[i] = right.frequencyy[i]; } for(unsigned i = 0; i < featuress; i++) { featuree[i] = right.featuree[i]; } return *this; } ostream& operator<<(ostream& out, const Instance& inst) {//Overloading of the << operator for Instance. out << endl << "<message file=" << '"' << inst.filenamee << '"' << " category="; if (inst.categoryy == 0) out << '"' << "legit" << '"'; else out << '"' << "spam" << '"'; out << " features=" << '"' << inst.featuress << '"' << ">" <<endl; for (int i = 0; i < inst.featuress; i++) { out << "<feature id=" << '"' << inst.featureIDD[i] << '"' << " freq=" << '"' << inst.frequencyy[i] << '"' << "> " << inst.featuree[i] << " </feature>"<< endl; } out << "</message>" << endl; return out; } istream& operator>>(istream& in, Instance& inst) { //Overloading of the >> operator for Instance. string word; string numbers = ""; string filenamee2 = ""; bool categoryy2 = 0; unsigned featuress2; string featuree2; unsigned featureIDD2; unsigned frequencyy2; unsigned i; unsigned y; while(in >> word) { if (word == "<message") {//if at beginning of message in >> word;//grab filename word for (y=6; word[y]!='"'; y++) {//pull out filename from between quotes filenamee2 += word[y];} in >> word;//grab category word if (word[10] == 's') categoryy2 = 1; in >> word;//grab features word for (y=10; word[y]!='"'; y++) { numbers += word[y];} featuress2 = atoi(numbers.c_str());//convert string of numbers to integer Instance tempp2(featuress2);//make a temporary Instance object to hold values read in tempp2.setFileName(filenamee2);//set temp object to filename read in tempp2.setCategory(categoryy2); for (i=0; i<featuress2; i++) {//loop reading in feature reports for message in >> word >> word >> word;//skip two words numbers = "";//reset numbers string for (int y=4; word[y]!='"'; y++) {//grab feature ID numbers += word[y];} featureIDD2 = atoi(numbers.c_str()); in >> word;// numbers = ""; for (int y=6; word[y]!='"'; y++) {//grab frequency numbers += word[y];} frequencyy2 = atoi(numbers.c_str()); in >> word;//grab actual feature string featuree2 = word; tempp2.setFeature(i, featuree2, featureIDD2, frequencyy2); }//all done reading in and setting features in >> word;//read in last part of message : </message> inst = tempp2;//set inst (reference) to tempp2 (tempp2 will be destroyed at end of function call) return in; } } } and instancepool.cpp: // Here we implement the functions of the class apart from the inline ones #include "instancepool.h" #include "instance.h" #include <iostream> #include <string> #include <vector> #include <stdlib.h> using namespace std; InstancePool::InstancePool()//Default constructor. Creates an InstancePool object that contains no Instance objects { instances = 0; ipp.clear(); } InstancePool::~InstancePool() { ipp.clear();} InstancePool::InstancePool(const InstancePool& original) {//Copy constructor. instances = original.instances; for (int i = 0; i<instances; i++) { ipp.push_back(original.ipp[i]); } } unsigned InstancePool::getNumberOfInstances() const {//Returns the number of Instance objects the the InstancePool contains. return instances;} const Instance& InstancePool::operator[](unsigned index) const {//Overloading of the [] operator for InstancePool. return ipp[index];} InstancePool& InstancePool::operator=(const InstancePool& right) {//Overloading the assignment operator for InstancePool. if(this == &right) return *this; ipp.clear(); instances = right.instances; for(unsigned i = 0; i < instances; i++) { ipp.push_back(right.ipp[i]); } return *this; } istream& operator>>(istream& in, InstancePool& ip) {//Overloading of the >> operator. ip.ipp.clear(); string word; string numbers; int total;//int to hold total number of messages in collection while(in >> word) { if (word == "<messagecollection"){ in >> word;//reads in total number of all messages for (int y=10; word[y]!='"'; y++){ numbers = ""; numbers += word[y]; } total = atoi(numbers.c_str()); for (int x = 0; x<total; x++) {//do loop for each message in collection in >> ip.ipp[x];//use instance friend function and [] operator to fill in values and create Instance objects and read them intot he vector } } } } ostream& operator<<(ostream& out, const InstancePool& ip) {//Overloading of the << operator. out << "<messagecollection messages=" << '"' << '>' << ip.instances << '"'<< endl << endl; for (int z=0; z<ip.instances; z++) { out << ip[z];} out << endl<<"</messagecollection>\n"; } This code is currently not writing to files correctly either at least, I'm sure it has many problems. I hope my posting of so much is not too much, and any help would be very much appreciated. Thanks!

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• SQLAuthority News – Public Training Classes In Hyderabad 12-14 May – Microsoft SQL Server 2005/2008

  - by pinaldave

  After successfully delivering many corporate trainings as well as the private training Solid Quality Mentors, India is launching the Public Training in Hyderabad for SQL Server 2008 and SharePoint 2010. This is going to be one of the most unique and one-of-a-kind events in India where Solid Quality Mentors are offering public classes. I will be leading the training on Microsoft SQL Server 2005/2008 Query Optimization & Performance Tuning. This intensive, 3-day course intends to give attendees an in-depth look at Query Optimization and Performance Tuning in SQL Server 2005 and 2008. Designed to prepare SQL Server developers and administrators for a transition into SQL Server 2005 or 2008, the course covers the best practices for a variety of essential tasks in order to maximize the performance. At the end of the course, there would be daily discussions about your real-world problems and find appropriate solutions. Note: Scroll down for course fees, discount, dates and location. Do not forget to take advantage of Discount code ‘SQLAuthority‘. The training premises are very well-equipped as they will be having 1:1 computers. Every participant will be provided with printed course materials. I will pick up your entire lunch tab and we will have lots of SQL talk together. The best participant will receive a special gift at the end of the course. Even though the quality of the material to be delivered together with the course will be of extremely high standard, the course fees are set at a very moderate rate. The fee for the course is INR 14,000/person for the whole 3-day convention. At the rate of 1 USD = 44 INR, this fee converts to less than USD 300. At this rate, it is totally possible to fly from anywhere from the world to India and take the training and still save handsome pocket money. It would be even better if you register using the discount code “SQLAuthority“, for you will instantly get an INR 3000 discount, reducing the total cost of the training to INR 11,000/person for whole 3 days course. This is a onetime offer and will not be available in the future. Please note that there will be a 10.3% service tax on course fees. To register, either send an email to [email protected] or call +91 95940 43399. Feel free to drop me an email at [email protected] for any additional information and clarification. Training Date and Time: May 12-14, 2010 10 AM- 6 PM. Training Venue: Abridge Solutions, #90/B/C/3/1, Ganesh GHR & MSY Plaza, Vittalrao Nagar, Near Image Hospital, Madhapur, Hyderabad – 500 081. The details of the course is as listed below. Day 1 : Strengthen the basics along with SQL Server 2005/2008 New Features Module 01: Subqueries, Ranking Functions, Joins and Set Operations Module 02: Table Expressions Module 03: TOP and APPLY Module 04: SQL Server 2008 Enhancements Day 2: Query Optimization & Performance Tuning 1 Module 05: Logical Query Processing Module 06: Query Tuning Module 07:  Introduction to the Query Processor Module 08:  Review of common query coding which causes poor performance Day 3: Query Optimization & Performance Tuning 2 Module 09:  SQL Server Indexing and index maintenance Module 10:  Plan Guides, query hints, UDFs, and Computed Columns Module 11:  Understanding SQL Server Execution Plans Module 12: Real World Index and Optimization Tips Download the complete PDF brochure. We are also going to have SharePoint 2010 training by Joy Rathnayake on 10-11 May. All the details for discount applies to the same as well. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Technology

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• Override ToString() in your Classes

  - by psheriff

  One of the reasons I love teaching is because of the questions that I get from attendees. I was giving a presentation at DevConnections and was showing a collection of Product objects. When I hovered over the variable that contained the collection, it looked like Figure 2. As you can see in the collection, I have actual product names of my videos from www.pdsa.com/videos being displayed. To get your data to appear in the data tips you must override the ToString() method in your class. To illustrate this, take the following simple Product class shown below: public class Product{  public string ProductName { get; set; }  public int ProductId { get; set; }} This class does not have an override of the ToString() method so if you create a collection of Product objects you will end up with data tips that look like Figure 1. Below is the code I used to create a collection of Product objects. I have shortened the code in this blog, but you can get the full source code for this sample by following the instructions at the bottom of this blog entry. List<Product> coll = new List<Product>();Product prod; prod = new Product()  { ProductName = "From Zero to HTML 5 in 60 Minutes",     ProductId = 1 };coll.Add(prod);prod = new Product()   { ProductName = "Architecting Applications …",     ProductId = 2 };coll.Add(prod);prod = new Product()  { ProductName = "Introduction to Windows Phone Development",    ProductId = 3 };coll.Add(prod);prod = new Product()   { ProductName = "Architecting a Business  …",     ProductId = 4 };coll.Add(prod);......   Figure 1: Class without overriding ToString() Now, go back to the Product class and add an override of the ToString() method as shown in the code listed below: public class Product{  public string ProductName { get; set; }  public int ProductId { get; set; }   public override string ToString()  {    return ProductName;  }} In this simple sample, I am just returning the ProductName property. However, you can create a whole string of information if you wish to display more data in your data tips. Just concatenate any properties you want from your class and return that string. When you now run the application and hover over the collection object you will now see something that looks like Figure 2. Figure 2: Overriding ToString() in your Class Another place the ToString() override comes in handy is if you forget to use a DisplayMemberPath in your ListBox or ComboBox. The ToString() method is called automatically when a class is bound to a list control. Summary You should always override the ToString() method in your classes as this will help you when debugging your application. Seeing relevant data immediately in the data tip without having to drill down one more layer and maybe scroll through a complete list of properties should help speed up your development process. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “Override ToString” from the drop down list.  

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• ct.sym steals the ASM class

  - by Geertjan

  Some mild consternation on the Twittersphere yesterday. Marcus Lagergren not being able to find the ASM classes in JDK 8 in NetBeans IDE: And there's no such problem in Eclipse (and apparently in IntelliJ IDEA). Help, does NetBeans (despite being incredibly awesome) suck, after all? The truth of the matter is that there's something called "ct.sym" in the JDK. When javac is compiling code, it doesn't link against rt.jar. Instead, it uses a special symbol file lib/ct.sym with class stubs. Internal JDK classes are not put in that symbol file, since those are internal classes. You shouldn't want to use them, at all. However, what if you're Marcus Lagergren who DOES need these classes? I.e., he's working on the internal JDK classes and hence needs to have access to them. Fair enough that the general Java population can't access those classes, since they're internal implementation classes that could be changed anytime and one wouldn't want all unknown clients of those classes to start breaking once changes are made to the implementation, i.e., this is the rt.jar's internal class protection mechanism. But, again, we're now Marcus Lagergen and not the general Java population. For the solution, read Jan Lahoda, NetBeans Java Editor guru, here: https://netbeans.org/bugzilla/show_bug.cgi?id=186120 In particular, take note of this: AFAIK, the ct.sym is new in JDK6. It contains stubs for all classes that existed in JDK5 (for compatibility with existing programs that would use private JDK classes), but does not contain implementation classes that were introduced in JDK6 (only API classes). This is to prevent application developers to accidentally use JDK's private classes (as such applications would be unportable and may not run on future versions of JDK). Note that this is not really a NB thing - this is the behavior of javac from the JDK. I do not know about any way to disable this except deleting ct.sym or the option mentioned above. Regarding loading the classes: JVM uses two classpath's: classpath and bootclasspath. rt.jar is on the bootclasspath and has precedence over anything on the "custom" classpath, which is used by the application. The usual way to override classes on bootclasspath is to start the JVM with "-Xbootclasspath/p:" option, which prepends the given jars (and presumably also directories) to bootclasspath. Hence, let's take the first option, the simpler one, and simply delete the "ct.sym" file. Again, only because we need to work with those internal classes as developers of the JDK, not because we want to hack our way around "ct.sym", which would mean you'd not have portable code at the end of the day. Go to the JDK 8 lib folder and you'll find the file: Delete it. Start NetBeans IDE again, either on JDK 7 or JDK 8, doesn't make a difference for these purposes, create a new Java application (or use an existing one), make sure you have set the JDK above as the JDK of the application, and hey presto: The above obviously assumes you have a build of JDK 8 that actually includes the ASM package. And below you can see that not only are the classes found but my build succeeded, even though I'm using internal JDK classes. The yellow markings in the sidebar mean that the classes are imported but not used in the code, where normally, if I hadn't removed "ct.sym", I would have seen red error marking instead, and the code wouldn't have compiled. Note: I've tried setting "-XDignore.symbol.file" in "netbeans.conf" and in other places, but so far haven't got that to work. Simply deleting the "ct.sym" file (or back it up somewhere and put it back when needed) is quite clearly the most straightforward solution. Ultimately, if you want to be able to use those internal classes while still having portable code, do you know what you need to do? You need to create a JDK bug report stating that you need an internal class to be added to "ct.sym". Probably you'll get a motivation back stating WHY that internal class isn't supposed to be used externally. There must be a reason why those classes aren't available for external usage, otherwise they would have been added to "ct.sym". So, now the only remaining question is why the Eclipse compiler doesn't hide the internal JDK classes. Apparently the Eclipse compiler ignores the "ct.sym" file. In other words, at the end of the day, far from being a bug in NetBeans... we have now found a (pretty enormous, I reckon) bug in Eclipse. The Eclipse compiler does not protect you from using internal JDK classes and the code that you create in Eclipse may not work with future releases of the JDK, since the JDK team is simply going to be changing those classes that are not found in the "ct.sym" file while assuming (correctly, thanks to the presence of "ct.sym" mechanism) that no code in the world, other than JDK code, is tied to those classes.

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• Implementing Runnable vs. extending Thread

  - by abson

  Why is implementing Runnable a better option than extending from Thread class?

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• Java - Get a list of all Classes loaded in the JVM

  - by Walter White

  Hi all, I would like to get a list of all the classes loaded in the JVM at a particular point in time. The classes are in a particular package and are accessible via /WEB-INF/classes and not through a jar file in /WEB-INF/lib. How would I get a list of classes? Would I simply get the classpath, list all the files, then look for the names? Walter

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