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• What is a good practice for handling SQL connections within a WCF call?

  - by Rising Star

  Suppose I want to create a (stateless) WCF service with three methods exposed on an endpoint: performSqlOperationA(), performSqlOperationB(), and performSqlOperationC(). Each method inserts data into a SQL database. The way I've seen things done at my office, each method would begin with code to initialize a SqlConnection object. Each method would end with code to safely dispose it. What is a good practice for coding these WCF methods so that the SqlConnection object is initialized and disposed in each method without having to do these things in each method? I know that I can have the connection initialized in the constructor for the class for the WCF methods, but I don't know about disposing it... The calls cannot be wrapped in a using block. One solution I'm familiar with is PostSharp, which allows me to set an attribute which causes specific code to automatically run at the beginning and end of each method call, but it would be greatly preferable to do this with only the .net framework.

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• Linq to NHibernate - How to return a parent object with only certain child objects included

  - by vakman

  Given a simplified model like the following: public class Enquiry { public virtual DateTime Created { get; set; } public virtual Sender Sender { get; set; } } public class Sender { public virtual IList<Enquiry> Enquiries { get; set; } } How can you construct a Linq to Nhibernate query such that it gives you back a list of senders and their enquiries where the enquiries meet some criteria. I have tried something like this: return session.Linq<Enquiry>() .Where(enquiry => enquiry.Created < DateTime.Now) .Select(enquiry => enquiry.Sender) In this case I get an InvalidCastException saying you can't cast type Sender to type Enquiry. Any pointers on how I can do this without using HQL?

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• Optional parens in Ruby for method with uppercase start letter?

  - by RasmusKL

  I just started out using IronRuby (but the behaviour seems consistent when I tested it in plain Ruby) for a DSL in my .NET application - and as part of this I'm defining methods to be called from the DSL via define_method. However, I've run into an issue regarding optional parens when calling methods starting with an uppercase letter. Given the following program: class DemoClass define_method :test do puts "output from test" end define_method :Test do puts "output from Test" end def run puts "Calling 'test'" test() puts "Calling 'test'" test puts "Calling 'Test()'" Test() puts "Calling 'Test'" Test end end demo = DemoClass.new demo.run Running this code in a console (using plain ruby) yields the following output: ruby .\test.rb Calling 'test' output from test Calling 'test' output from test Calling 'Test()' output from Test Calling 'Test' ./test.rb:13:in `run': uninitialized constant DemoClass::Test (NameError) from ./test.rb:19:in `<main>' I realize that the Ruby convention is that constants start with an uppercase letter and that the general naming convention for methods in Ruby is lowercase. But the parens are really killing my DSL syntax at the moment. Is there any way around this issue?

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• How to synchronize static method in java.

  - by Summer_More_More_Tea

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

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• Java Interface Reflection Alternatives

  - by Phaedrus

  I am developing an application that makes use of the Java Interface as more than a Java interface, i.e., During runtime, the user should be able to list the available methods within the interface class, which may be anything: private Class<? extends BaseInterface> interfaceClass. At runtime, I would like to enum the available methods, and then based on what the user chooses, invoke some method. My question is: Does the Java "Interface" architecture provide any method for me to peek and invoke methods without using the Reflection API? I wish there were something like this (Maybe there is): private Interface<? extends BaseInterface> interfaceAPI; public void someMethod(){ interfaceAPI.listMethods(); interfaceAPI.getAnnotations(); } Maybe there is some way to use Type Generics to accomplish what I want? Thanks, Phaedrus

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• C++: Avoid .cpp files with only an empty (de)constructor

  - by Martijn Courteaux

  Hi, When I have a header file like this: #ifndef GAMEVIEW_H_ #define GAMEVIEW_H_ #include <SDL/SDL.h> class GameView { public: GameView(); virtual ~GameView(); virtual void Update() = 0; virtual void Render(SDL_Surface* buffer) = 0; }; #endif /* GAMEVIEW_H_ */ I need to create a .cpp file like this: #include "GameView.h" GameView::~GameView() { } GameView::GameView() { } This is a bit stupid. Just a .cpp file for an empty constructor and deconstructor. I want to implement that method simply in the header file. That is much cleaner. How to do this?

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• mapping 'value object' collection in (Fluent) NHibernate

  - by adrin

  I have the following entity public class Employee { public virtual int Id {get;set;} public virtual ISet<Hour> XboxBreakHours{get;set} public virtual ISet<Hour> CoffeeBreakHours {get;set} } public class Hour { public DateTime Time {get;set;} } (What I want to do here is store information that employee A plays Xbox everyday let's say at 9:00 13:30 and has a coffee break everyday at 7:00 12:30 18:00) - I am not sure if my approach is valid at all here. The question is how should my (ideally fluent) mappings look like here? It is not necessary (from my point of view) for Hour class to have Id or be accessible from some kind of repository.

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• c struct map to ruby using SWIG

  - by pierr

  Hi, Is there any body can confirm the description here is true? My experience is that I can not use Example::Vector.new at all. C/C++ structs are wrapped as Ruby classes, with accessor methods (i.e. "getters" and "setters") for all of the struct members. For example, this struct declaration: struct Vector { double x, y; }; gets wrapped as a Vector class, with Ruby instance methods x, x=, y and y=. These methods can be used to access structure data from Ruby as follows: $ irb irb(main):001:0> require 'Example' true irb(main):002:0> f = Example::Vector.new #<Example::Vector:0x4020b268> irb(main):003:0> f.x = 10 nil irb(main):004:0> f.x 10.0

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• Multiple interfaces inhertience. Casting from one to another

  - by yossi1981

  Consider the following set of classes/Interfaces: class IFish{ public: virtual void eat() = 0; } class IFriendly{ public: virtual void protect() = 0; } class IAggresive{ public: virtual void attack(Point inDest) = 0; } class CDolphin : public IFish, IFriendly{ eat... protect.... } class CShark : public IFish, IAggresive{ eat.... attack... } Now I am having the following class void CDiver { Void shouldRunAway(IFish* fish) { //??? } } My question is , can "shouldRunAway" extract from the fish argument whether it is an IAggresive or IFreindly (if it is any of these at all...) is there some kind of casting that can help out?

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• Should I separate RESTful API controllers from "regular" controllers?

  - by keithjgrant

  This seems like an elementary question, but after a lot of searching around I can't seem to find a straightforward explanation: If I'm building a web application that is going to be accessed largely through a web browser, but that will also support some API requests in a RESTful way, should there be a large degree of separation between the two? On one hand, it seems a large amount of the functionality is the same, with identical data presented in different views (HTML vs. XML/JSON). But on the other hand, there are certain things I need to present to the browser that doesn't quite fit a RESTful approach: how to get an empty form to create a new instance of a resource and how to get a pre-populated form to edit an existing resource. Should these two different methods of accessing the system by funneled through different controllers? Different methods in the same controller? The exact same methods with a switch for view type?

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• New replicaset resident memory is larger than the existing sets

  - by eded

  From the mongodb tutorial of how to resync a set, I wipe all the files in /data/db and restart the mongod process to resync the data. Everything looks ok, I get the same number of documents as the existing two sets(primary and one secondary). However, when I check the memory on MMS. it shows me my new resynced set/mongod process has a different memory status value than the other two. For existing twos using db.serverStatus.mem shows like the following: "mem" : { "bits" : 64, "resident" : 239, "virtual" : 66348, "supported" : true, "mapped" : 32865, "mappedWithJournal" : 65730 } however, the new resynced set shows like: "mem" : { "bits" : 64, "resident" : 1239, "virtual" : 52447, "supported" : true, "mapped" : 25700, "mappedWithJournal" : 51400 } the resynced resident memory is 6-10 times more than the existing ones. I wouder if it is normal because all data comes in suddenly during the resyncing?? and even virtual and mapped value are different too. Can anyone explain?? thanks

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• Does C++ require a destructor call for each placement new?

  - by Josh Haberman

  I understand that placement new calls are usually matched with explicit calls to the destructor. My question is: if I have no need for a destructor (no code to put there, and no member variables that have destructors) can I safely skip the explicit destructor call? Here is my use case: I want to write C++ bindings for a C API. In the C API many objects are accessible only by pointer. Instead of creating a wrapper object that contains a single pointer (which is wasteful and semantically confusing). I want to use placement new to construct an object at the address of the C object. The C++ object will do nothing in its constructor or destructor, and its methods will do nothing but delegate to the C methods. The C++ object will contain no virtual methods. I have two parts to this question. Is there any reason why this idea will not work in practice on any production compiler? Does this technically violate the C++ language spec?

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• In Java how instance of and type cast(i.e (ClassName)) works on proxy object ?

  - by learner

  Java generates a proxy class for a given interface and provides the instance of the proxy class. But when we type cast the proxy object to our specific Object, how java handles this internally? Is this treated as special scenario? For example I have class 'OriginalClass' and it implements 'OriginalInterface', when I create proxy object by passing 'OriginalInterface' interface java created proxy class 'ProxyClass' using methods in the provided interface and provides object of this class(i.e ProxyClass). If my understanding is correct then can you please answer following queries 1) When I type cast object of ProxyClass to my class OriginalClass this works, but how java is allowing this? Same in case of instace of? 2) As my knowledge java creates a proxy class only with the methods, but what happen when I try to access attributes on this object? 3) Only interface methods are getting implemented in Proxy, but what happens when I try to access a method which not in interface and only mentioned in the class? Thanks, Student

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• non-scalar type requested

  - by lego69

  can somebody please help me with an error conversion from `A' to non-scalar type `B' requested I have class A and derived from it B, but I have problems with these rows: A a(1); A *pb = new B(a); B b = *pb; //here I have an error thanks in advance for any help class A { protected: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); virtual ~A(){}; virtual void foo(); void foo() const; operator int(); }; class B: public A { public: B(int initPlayer): A(initPlayer){}; ~B(){}; virtual void foo(); };

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• Can I use the decorator pattern to wrap a method body?

  - by mgroves

  I have a bunch of methods with varying signatures. These methods interact with a fragile data connection, so we often use a helper class to perform retries/reconnects, etc. Like so: MyHelper.PerformCall( () => { doStuffWithData(parameters...) }); And this works fine, but it can make the code a little cluttery. What I would prefer to do is decorate the methods that interact with the data connection like so: [InteractsWithData] protected string doStuffWithData(parameters...) { // do stuff... } And then essentially, whenever doStuffWithData is called, the body of that method would be passed in as an Action to MyHelper.PerformCall(). How do I do this?

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• Select from parent table return ID = 0 column values for child objects

  - by SaD

  Entities: public class Person { public Person(){} public virtual long ID { get; set; } } public class Employee : Person { public Employee(){} public virtual long ID { get; set; } public virtual string Appointment { get; set; } } Mappings: public class PersonMap : ClassMap<Person> { public PersonMap() { Id(x => x.ID) .GeneratedBy.Identity(); } } public class EmployeeMap : SubclassMap<Employee> { public EmployeeMap() { KeyColumn("ID"); Map(x => x.Appointment) .Not.Nullable() .Length(50); } } 2 items in Person table 1 item in Employee table (1 in base class, 1 in child class) Query:var list = Session.CreateQuery("from Person").List<Person>(); Return: 0 | ID = 1 1 | ID = 0, Appointment = "SomeAppointment"

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• Refactoring method that was previously injected with implement

  - by ryber

  Greetings, I'm trying to override or extend the Element.show() and .hide() methods in mootools in order to add some WAI-Aria toggling. I was trying to use the Class.Refactor() method like this: Element = Class.refactor(Element, { show: function(displayString) { result = this.previous(displayString); // Do my thing return result; }, hide: function() { result = this.previous(); // Do my thing return result; } }); however, this is not working, previous is null and I think the reason is that Mootools injects those methods through Element.implement. So the methods are not native? I have figured out how to completely replace .show and .hide but I would like to retain all of their existing functionality and just add to it. Any ideas?

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• Examples of both beautiful and ugly java code?

  - by tputkonen

  I would like to demonstrate how difficult it is for a layman to identify high quality code from flawed code. I'm thinking of doing this with the help of two java methods. Both of the methods should look like they do the same, pretty simple thing. However one of them should have several kind of flaws, for example: iteration with array off by one error string concatenations causing lots of objects to be created (as opposed to StringBuffer in the "good" code, which looks more complicated) possibly null pointer exception (but it should not be trivial to spot) Those are just some examples, all kinds of other issues including bugs and performance related structures are highly appreciated. Methods should be around 10-20 lines of length, and the task they do should be something simple - preferably printing something in an iteration.

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• Active Record's SessionScope in BL or DL ?

  - by StupidDeveloper

  Imagine that I have 3 projects: DL, BL and WS. DL contains Active Record implementation with all the mappings, BL has some logic (calling various DL methods) and finally WebService project exposes some BL methods (using some DTO mappings). The questions are: Should I put all data related methods in DL or is it allowed to use SessionScope in BL ? There are some complicated stuff that is right now done on BL. Should/can BL operate on classes-mappings of the Active record? The question is where should be the translation to DTO be made (at the BL level? ) ?

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• Is there a design pattern for this ?

  - by ytrewq

  I have a component that needs to call a specific service depending on the input it receives. So my component has to look at the input and based on a configuration that says "for this input call this service with this data" needs to call the proper service. The services have a common signature method and a specific one (each). I thought about an abstract class that includes the signatures for all three methods. The implementation for the two services will override all three methods (throwing NotImplementedException for the methods that are not supported by current service). A component that could be initialized with a map (that for each input type will have the type of the service to be called) will also be defined. Do you have a better approach to cope this scenario ?

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• Make sure base method gets called in C#

  - by Fnatte

  Can I somehow force a derived class to always call the overridden methods base? public class BaseClass { public virtual void Update() { if(condition) { throw new Exception("..."); // Prevent derived method to be called } } } And then in a derived class : public override void Update() { base.Update(); // Forced call // Do any work } I've searched and found a suggestion to use a non-virtual Update() but also a protected virtual UpdateEx(). It just doesn't feel very neat, isn't there any better way? I hope you get the question and I am sorry for any bad English.

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• c++: strange syntax in what() method of std::exception

  - by Patrick Oscity

  When i am inheriting from std::exception in order to define my own exception type, i need to override the what() method, which has the following signature: virtual const char* what() const throw(); This definitely looks strange to me, like if there were two method names in the signature. Is this some very specific syntax, like with pure virtual methods, e.g.: virtual int method() const = 0; or is this a feature, that could somehow be used in another context, too? And if so, for what could it be used?

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• Using a part of a class in multiple projects

  - by Axarydax

  I have a set of methods that do some utility work over SQL connection, and until now these have been copied over from project to project. But as time goes on, project numbers have grown and I need to keep these methods in sync in case I find a bug or need to update it. I have managed to get it to the state that SQL access class is a partial class, one part is specific for project and contains wrappers for a specific database. The second part is the common one and contains methods that are used in all project-specific databases. The problem is that now I would have the "utility" class copied over 8 projects, with the same content, but in different namespaces. In C/C++ it would have been simple, because I would just have #included the contents of the file wherever needed. What should I do in C#?

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• Const Functions and Interfaces in C++

  - by 58gh1z

  I'll use the following (trivial) interface as an example: struct IObject { virtual ~IObject() {} virtual std::string GetName() const = 0; virtual void ChangeState() = 0; }; Logic dictates that GetName should be a const member function while ChangeState shouldn't. All code that I've seen so far doesn't follow this logic, though. That is, GetName in the example above wouldn't be marked as a const member function. Is this laziness/carelessness or is there a legitimate reason for this? What are the major cons of me forcing my clients to implement const member functions when they are logically called for?

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• Merging and splitting overlapping rectangles to produce non-overlapping ones

  - by uj

  I am looking for an algorithm as follows: Given a set of possibly overlapping rectangles (All of which are "not rotated", can be uniformly represented as (left,top,right,bottom) tuplets, etc...), it returns a minimal set of (non-rotated) non-overlapping rectangles, that occupy the same area. It seems simple enough at first glance, but prooves to be tricky (at least to be done efficiently). Are there some known methods for this/ideas/pointers? Methods for not necessarily minimal, but heuristicly small, sets, are interesting as well, so are methods that produce any valid output set at all.

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