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  • Hibernate/JPA - annotating bean methods vs fields

    - by Benju
    I have a simple question about usage of Hibernate. I keep seeing people using JPA annotations in one of two ways by annotating the fields of a class and also by annotating the get method on the corresponding beans. My question is as follows: Is there a difference between annotating fields and bean methods with JPA annoations such as @Id. example: @Entity public class User { **@ID** private int id; public int getId(){ return this.id; } public void setId(int id){ this.id=id; } } -----------OR----------- @Entity public class User { private int id; **@ID** public int getId(){ return this.id; } public void setId(int id){ this.id=id; } }

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  • basics of c++ encapsulation

    - by sasquatch
    I have a task to create class Encapsulation, with fields in available encapsulation sections. Then I must create an application showing all allowed and forbidden methods of fields access. What are the encapsulations sections in c++ ? And what methods apart from object.field or *object-field are there anyway ?

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  • Synchronizing access to an inner object's methods?

    - by user291701
    Suppose I have the following: public class Foo { private ReadingList mReadingList = new ReadingList(); public ReadingList getReadingList() { synchronized (mReadingList) { return mReadingList; } } } If I try modifying the ReadingList object in two threads, the synchronization above won't help me, right?: // Thread 1 foo1.getReadingList().setName("aaa"); // Thread 2 foo2.getReadingList().setName("bbb"); do I have to wrap each method I want synchronized like so: public class Foo { private ReadingList mReadingList = new ReadingList(); public synchronized void setReadingListName(String name) { mReadingList.setName(name); } public synchronized void setReadingListAuthor(String author) { mReadingList.setAuthor(author); } ... and so on for each method of ReadingList I want exposed and synched? I'd end up just writing wrapper methods for each method of ReadingList. Thanks

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  • Static method,new thread performance question

    - by ylazez
    Hey guys i just have two questions about two methods used in many controllers/servlets in my app: 1-what is the difference between calling a static method in a util class or a non static method (like methods dealing with dates i.e getting current time,converting between timezones), which is better ? 2-what is the difference between calling a method(contain too many logic like sending emails) in the controller directly or running this method in a different thread ?

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  • Mistake in display and insert methods (double-ended queue)

    - by MANAL
    1) My problem when i make remove from right or left program will be remove true but when i call diplay method the content wrong like this I insert 12 43 65 23 and when make remove from left program will remove 12 but when call display method show like this 12 43 65 and when make remove from right program will remove 23 but when call display method show like this 12 43 Why ?????? ); and when i try to make insert after remove write this Can not insert right because the queue is full . first remove right and then u can insert right where is the problem ?? Please Help me please 2) My code FIRST CLASS class dqueue { private int fullsize; //number of all cells private int item_num; // number of busy cells only private int front,rear; public int j; private double [] dqarr; //========================================== public dqueue(int s) //constructor { fullsize = s; front = 0; rear = -1; item_num = 0; dqarr = new double[fullsize]; } //========================================== public void insert(double data) { if (rear == fullsize-1) rear = -1; rear++; dqarr[rear] = data; item_num++; } public double removeLeft() // take item from front of queue { double temp = dqarr[front++]; // get value and incr front if(front == fullsize) front = 0; item_num --; // one less item return temp; } public double removeRight() // take item from rear of queue { double temp = dqarr[rear--]; // get value and decr rear if(rear == -1) // rear = item_num -1; item_num --; // one less item return temp; } //========================================= public void display () //display items { for (int j=0;j<item_num;j++) // for every element System.out.print(dqarr[j] +" " ); // display it System.out.println(""); } //========================================= public int size() //number of items in queue { return item_num; } //========================================== public boolean isEmpty() // true if queue is empty { return (item_num ==0); } } SECOND CLASS import java.util.Scanner; class dqueuetest { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println(" ***** Welcome here***** "); System.out.println(" ***** Mind Of Programming Group***** "); System.out.println(" _____________________________________________ "); System.out.println("enter size of your dqueue"); int size = input.nextInt(); dqueue mydq = new dqueue(size); System.out.println(""); System.out.println("enter your itemes"); //===================================== for(int i = 0;i<=size-1;i++) { System.out.printf("item %d:",i+1); double item = input.nextDouble(); mydq.insert(item); System.out.println(""); } //===================================== int queue =size ; int c = 0 ; while (c != 6) { System.out.println(""); System.out.println("************************************************"); System.out.println(" MAIN MENUE"); System.out.println("1- INSERT RIGHT "); System.out.println("2- REMOVE LEFT"); System.out.println("3- REMOVE RIGHT"); System.out.println("4- DISPLAY"); System.out.println("5- SIZE"); System.out.println("6- EXIT"); System.out.println("************************************************"); System.out.println("choose your operation by number(1-6)"); c = input.nextInt(); switch (c) { case 1: if (queue == size) System.out.print("Can not insert right because the queue is full . first remove right and then u can insert right "); else { System.out.print("enter your item: "); double item = input.nextDouble(); mydq.insert(item);} break; case 2: System.out.println("REMOVE FROM REAR :"); if( !mydq.isEmpty() ) { double item = mydq.removeLeft(); System.out.print(item + "\t"); } // end while System.out.println(""); mydq.display(); break; case 3: System.out.println("REMOVE FROM FRONT :"); if( !mydq.isEmpty() ) { double item = mydq.removeRight(); System.out.print(item + "\t"); } // end while System.out.println(""); mydq.display(); break; case 4: System.out.println("The items in Queue are :"); mydq.display(); break; case 5: System.out.println("The Size of the Queue is :"+mydq.size()); break; case 6: System.out.println("Good Bye"); break; default: System.out.println("wrong chiose enter again"); } //end switch } //end while } // end main }//end class

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  • why does my C# client that uses Library A need to have a using statement for Library B (which A uses

    - by Greg
    Hi, I have: Main Program Class - uses Library A Library A - has partial classes which mix in methods from Library B Library B - mix in methods & interfaces So in Library B when I include a partial Node class which implements INode (defined in Library B) I suddenly get an error in my main class where it uses Node from Library A. The error tells me in the Main Class I have to have a using statement to Library B. Any ideas?

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  • C++ privately contructed class

    - by Nona Urbiz
    How can I call a function and keep my constructor private? If I make the class static, I need to declare an object name which the compiler uses to call the constructor, which it cannot if the constructor is private (also the object would be extraneous). Here is the code I am attempting to use (it is not compilable): I want to keep the constructor private because I will later be doing a lot of checks before adding an object, modifying previous objects when all submitted variables are not unique rather than creating new objects. #include <iostream> #include <fstream> #include <regex> #include <string> #include <list> #include <map> using namespace std; using namespace tr1; class Referral { public: string url; map<string, int> keywords; static bool submit(string url, string keyword, int occurrences) { //if(Referrals.all.size == 0){ // Referral(url, keyword, occurrences); //} } private: list<string> urls; Referral(string url, string keyword, int occurrences) { url = url; keywords[keyword] = occurrences; Referrals.all.push_back(this); } }; struct All { list<Referral> all; }Referrals; int main() { Referral.submit("url", "keyword", 1); }

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  • Array structure returned by Yii's model

    - by user1104955
    I am a Yii beginner and am running into a bit of a wall and hope someone will be able to help me get back onto track. I think this might be a fairly straight forward question to the seasoned Yii user. So here goes... In the controller, let's say I run the following call to the model- $variable = Post::model()->findAll(); All works fine and I pass the variable into the view. Here's where I get pretty stuck. The array that is returned in the above query is far more complex than I anticipated and I'm struggling to make sense of it. Here's a sample- print_r($variable); gives- Array ( [0] => Post Object ( [_md:CActiveRecord:private] => CActiveRecordMetaData Object ( [tableSchema] => CMysqlTableSchema Object ( [schemaName] => [name] => tbl_post [rawName] => `tbl_post` [primaryKey] => id [sequenceName] => [foreignKeys] => Array ( ) [columns] => Array ( [id] => CMysqlColumnSchema Object ( [name] => id [rawName] => `id` [allowNull] => [dbType] => int(11) [type] => integer [defaultValue] => [size] => 11 [precision] => 11 [scale] => [isPrimaryKey] => 1 [isForeignKey] => [autoIncrement] => 1 [_e:CComponent:private] => [_m:CComponent:private] => ) [post] => CMysqlColumnSchema Object ( [name] => post [rawName] => `post` [allowNull] => [dbType] => text [type] => string [defaultValue] => [size] => [precision] => [scale] => [isPrimaryKey] => [isForeignKey] => [autoIncrement] => [_e:CComponent:private] => [_m:CComponent:private] => ) ) [_e:CComponent:private] => [_m:CComponent:private] => ) [columns] => Array ( [id] => CMysqlColumnSchema Object ( [name] => id [rawName] => `id` [allowNull] => [dbType] => int(11) [type] => integer [defaultValue] => [size] => 11 [precision] => 11 [scale] => [isPrimaryKey] => 1 [isForeignKey] => [autoIncrement] => 1 [_e:CComponent:private] => [_m:CComponent:private] => ) [post] => CMysqlColumnSchema Object ( [name] => post [rawName] => `post` [allowNull] => [dbType] => text [type] => string [defaultValue] => [size] => [precision] => [scale] => [isPrimaryKey] => [isForeignKey] => [autoIncrement] => [_e:CComponent:private] => [_m:CComponent:private] => ) ) [relations] => Array ( [responses] => CHasManyRelation Object ( [limit] => -1 [offset] => -1 [index] => [through] => [joinType] => LEFT OUTER JOIN [on] => [alias] => [with] => Array ( ) [together] => [scopes] => [name] => responses [className] => Response [foreignKey] => post_id [select] => * [condition] => [params] => Array ( ) [group] => [join] => [having] => [order] => [_e:CComponent:private] => [_m:CComponent:private] => ) ) [attributeDefaults] => Array ( ) [_model:CActiveRecordMetaData:private] => Post Object ( [_md:CActiveRecord:private] => CActiveRecordMetaData Object *RECURSION* [_new:CActiveRecord:private] => [_attributes:CActiveRecord:private] => Array ( ) [_related:CActiveRecord:private] => Array ( ) [_c:CActiveRecord:private] => [_pk:CActiveRecord:private] => [_alias:CActiveRecord:private] => t [_errors:CModel:private] => Array ( ) [_validators:CModel:private] => [_scenario:CModel:private] => [_e:CComponent:private] => [_m:CComponent:private] => ) ) [_new:CActiveRecord:private] => [_attributes:CActiveRecord:private] => Array ( [id] => 1 [post] => User Post ) [_related:CActiveRecord:private] => Array ( ) [_c:CActiveRecord:private] => [_pk:CActiveRecord:private] => 1 [_alias:CActiveRecord:private] => t [_errors:CModel:private] => Array ( ) [_validators:CModel:private] => [_scenario:CModel:private] => update [_e:CComponent:private] => [_m:CComponent:private] => ) ) [sorry if there's an easier way to show this array, I'm not aware of it] Can anyone explain to me why the model returns such a complex array? It doesn't seem to matter what tables or columns or relations are used in your application, they all seem to me to return this format. Also, can someone explain the structure to me so that I can isolate the variables that I want to recover? Many thanks in advance, Nick

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  • C# Extension Methods - To Extend or Not To Extend...

    - by James Michael Hare
    I've been thinking a lot about extension methods lately, and I must admit I both love them and hate them. They are a lot like sugar, they taste so nice and sweet, but they'll rot your teeth if you eat them too much.   I can't deny that they aren't useful and very handy. One of the major components of the Shared Component library where I work is a set of useful extension methods. But, I also can't deny that they tend to be overused and abused to willy-nilly extend every living type.   So what constitutes a good extension method? Obviously, you can write an extension method for nearly anything whether it is a good idea or not. Many times, in fact, an idea seems like a good extension method but in retrospect really doesn't fit.   So what's the litmus test? To me, an extension method should be like in the movies when a person runs into their twin, separated at birth. You just know you're related. Obviously, that's hard to quantify, so let's try to put a few rules-of-thumb around them.   A good extension method should:     Apply to any possible instance of the type it extends.     Simplify logic and improve readability/maintainability.     Apply to the most specific type or interface applicable.     Be isolated in a namespace so that it does not pollute IntelliSense.     So let's look at a few examples in relation to these rules.   The first rule, to me, is the most important of all. Once again, it bears repeating, a good extension method should apply to all possible instances of the type it extends. It should feel like the long lost relative that should have been included in the original class but somehow was missing from the family tree.    Take this nifty little int extension, I saw this once in a blog and at first I really thought it was pretty cool, but then I started noticing a code smell I couldn't quite put my finger on. So let's look:       public static class IntExtensinos     {         public static int Seconds(int num)         {             return num * 1000;         }           public static int Minutes(int num)         {             return num * 60000;         }     }     This is so you could do things like:       ...     Thread.Sleep(5.Seconds());     ...     proxy.Timeout = 1.Minutes();     ...     Awww, you say, that's cute! Well, that's the problem, it's kitschy and it doesn't always apply (and incidentally you could achieve the same thing with TimeStamp.FromSeconds(5)). It's syntactical candy that looks cool, but tends to rot and pollute the code. It would allow things like:       total += numberOfTodaysOrders.Seconds();     which makes no sense and should never be allowed. The problem is you're applying an extension method to a logical domain, not a type domain. That is, the extension method Seconds() doesn't really apply to ALL ints, it applies to ints that are representative of time that you want to convert to milliseconds.    Do you see what I mean? The two problems, in a nutshell, are that a) Seconds() called off a non-time value makes no sense and b) calling Seconds() off something to pass to something that does not take milliseconds will be off by a factor of 1000 or worse.   Thus, in my mind, you should only ever have an extension method that applies to the whole domain of that type.   For example, this is one of my personal favorites:       public static bool IsBetween<T>(this T value, T low, T high)         where T : IComparable<T>     {         return value.CompareTo(low) >= 0 && value.CompareTo(high) <= 0;     }   This allows you to check if any IComparable<T> is within an upper and lower bound. Think of how many times you type something like:       if (response.Employee.Address.YearsAt >= 2         && response.Employee.Address.YearsAt <= 10)     {     ...     }     Now, you can instead type:       if(response.Employee.Address.YearsAt.IsBetween(2, 10))     {     ...     }     Note that this applies to all IComparable<T> -- that's ints, chars, strings, DateTime, etc -- and does not depend on any logical domain. In addition, it satisfies the second point and actually makes the code more readable and maintainable.   Let's look at the third point. In it we said that an extension method should fit the most specific interface or type possible. Now, I'm not saying if you have something that applies to enumerables, you create an extension for List, Array, Dictionary, etc (though you may have reasons for doing so), but that you should beware of making things TOO general.   For example, let's say we had an extension method like this:       public static T ConvertTo<T>(this object value)     {         return (T)Convert.ChangeType(value, typeof(T));     }         This lets you do more fluent conversions like:       double d = "5.0".ConvertTo<double>();     However, if you dig into Reflector (LOVE that tool) you will see that if the type you are calling on does not implement IConvertible, what you convert to MUST be the exact type or it will throw an InvalidCastException. Now this may or may not be what you want in this situation, and I leave that up to you. Things like this would fail:       object value = new Employee();     ...     // class cast exception because typeof(IEmployee) != typeof(Employee)     IEmployee emp = value.ConvertTo<IEmployee>();       Yes, that's a downfall of working with Convertible in general, but if you wanted your fluent interface to be more type-safe so that ConvertTo were only callable on IConvertibles (and let casting be a manual task), you could easily make it:         public static T ConvertTo<T>(this IConvertible value)     {         return (T)Convert.ChangeType(value, typeof(T));     }         This is what I mean by choosing the best type to extend. Consider that if we used the previous (object) version, every time we typed a dot ('.') on an instance we'd pull up ConvertTo() whether it was applicable or not. By filtering our extension method down to only valid types (those that implement IConvertible) we greatly reduce our IntelliSense pollution and apply a good level of compile-time correctness.   Now my fourth rule is just my general rule-of-thumb. Obviously, you can make extension methods as in-your-face as you want. I included all mine in my work libraries in its own sub-namespace, something akin to:       namespace Shared.Core.Extensions { ... }     This is in a library called Shared.Core, so just referencing the Core library doesn't pollute your IntelliSense, you have to actually do a using on Shared.Core.Extensions to bring the methods in. This is very similar to the way Microsoft puts its extension methods in System.Linq. This way, if you want 'em, you use the appropriate namespace. If you don't want 'em, they won't pollute your namespace.   To really make this work, however, that namespace should only include extension methods and subordinate types those extensions themselves may use. If you plant other useful classes in those namespaces, once a user includes it, they get all the extensions too.   Also, just as a personal preference, extension methods that aren't simply syntactical shortcuts, I like to put in a static utility class and then have extension methods for syntactical candy. For instance, I think it imaginable that any object could be converted to XML:       namespace Shared.Core     {         // A collection of XML Utility classes         public static class XmlUtility         {             ...             // Serialize an object into an xml string             public static string ToXml(object input)             {                 var xs = new XmlSerializer(input.GetType());                   // use new UTF8Encoding here, not Encoding.UTF8. The later includes                 // the BOM which screws up subsequent reads, the former does not.                 using (var memoryStream = new MemoryStream())                 using (var xmlTextWriter = new XmlTextWriter(memoryStream, new UTF8Encoding()))                 {                     xs.Serialize(xmlTextWriter, input);                     return Encoding.UTF8.GetString(memoryStream.ToArray());                 }             }             ...         }     }   I also wanted to be able to call this from an object like:       value.ToXml();     But here's the problem, if i made this an extension method from the start with that one little keyword "this", it would pop into IntelliSense for all objects which could be very polluting. Instead, I put the logic into a utility class so that users have the choice of whether or not they want to use it as just a class and not pollute IntelliSense, then in my extensions namespace, I add the syntactical candy:       namespace Shared.Core.Extensions     {         public static class XmlExtensions         {             public static string ToXml(this object value)             {                 return XmlUtility.ToXml(value);             }         }     }   So now it's the best of both worlds. On one hand, they can use the utility class if they don't want to pollute IntelliSense, and on the other hand they can include the Extensions namespace and use as an extension if they want. The neat thing is it also adheres to the Single Responsibility Principle. The XmlUtility is responsible for converting objects to XML, and the XmlExtensions is responsible for extending object's interface for ToXml().

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  • google maps api v3 - loop through overlays - overlayview methods

    - by user317005
    what's wrong with the code below? when i execute it, the map doesn't even show up. but when i put the overlayview methods outside the for-loop and manually assign a lat/lng then it magically works?! but does anyone know how i can loop through an array of lats/lngs (=items) using the overlayview methods? i hope this makes sense, just don't know how else to explain it. and unfortunately, i run my code on my localhost var overlay; OverlayTest.prototype = new google.maps.OverlayView(); [taken out: options] var map = new google.maps.Map(document.getElementById('map_canvas'), options); var items = [ ['lat','lng'],['lat','lng'] ]; for (var i = 0; i < items.length; i++) { var latlng = new google.maps.LatLng(items[i][0], items[i][1]); var bounds = new google.maps.LatLngBounds(latlng); overlay = new OverlayTest(map, bounds); function OverlayTest(map, bounds) { [taken out: not important] this.setMap(map); } OverlayTest.prototype.onAdd = function() { [taken out: not important] } OverlayTest.prototype.draw = function() { [taken out: not important] } }

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  • Design by contract: predict methods needed, discipline yourself and deal with code that comes to min

    - by fireeyedboy
    I like the idea of designing by contract a lot (at least, as far as I understand the principal). I believe it means you define intefaces first before you start implementing actual code, right? However, from my limited experience (3 OOP years now) I usually can't resist the urge to start coding pretty early, for several reasons: because my limited experience has shown me I am unable to predict what methods I will be needing in the interface, so I might as well start coding right away. or because I am simply too impatient to write out the whole interfaces first. or when I do try it, I still wind up implementing bits of code already, because I fear I might forget this or that imporant bit of code, that springs to mind when I am designing the interfaces. As you see, especially with the last two points, this leads to a very disorderly way of doing thing. Tasks get mixed up. I should draw a clear line between designing interfaces and actual coding. If you, unlike me, are a good/disciplined planner, as intended above, how do you: ...know the majority of methods you will be needing up front so well? Especially if it's components that implement stuff you are not familiar with yet. ...keep yourself from resisting the urge to start coding right away? ...deal with code that comes to mind when you are designing the intefaces?

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  • TDD test data loading methods

    - by Dave Hanson
    I am a TDD newb and I would like to figure out how to test the following code. I am trying to write my tests first, but I am having trouble for creating a test that touches my DataAccessor. I can't figure out how to fake it. I've done the extend the shipment class and override the Load() method; to continue testing the object. I feel as though I end up unit testing my Mock objects/stubs and not my real objects. I thought in TDD the unit tests were supposed to hit ALL of the methods on the object; however I can never seem to test that Load() code only the overriden Mock Load My tests were write an object that contains a list of orders based off of shipment number. I have an object that loads itself from the database. public class Shipment { //member variables protected List<string> _listOfOrders = new List<string>(); protected string _id = "" //public properties public List<string> ListOrders { get{ return _listOfOrders; } } public Shipment(string id) { _id = id; Load(); } //PROBLEM METHOD // whenever I write code that needs this Shipment object, this method tries // to hit the DB and fubars my tests // the only way to get around is to have all my tests run on a fake Shipment object. protected void Load() { _listOfOrders = DataAccessor.GetOrders(_id); } } I create my fake shipment class to test the rest of the classes methods .I can't ever test the Real load method without having an actual DB connection public class FakeShipment : Shipment { protected new void Load() { _listOfOrders = new List<string>(); } } Any thoughts? Please advise. Dave

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  • Correct Interactive Website System Design Concepts / Methods?

    - by Xandel
    Hi all, I hope this question isn't too open ended, but a nudge in the right direction is all I need! I am currently building an online accounting system - the idea is that users can register, log in, and then create customers, generate invoices and other documents and eventually print / email those documents out. I am a Java programmer but unfortunately haven't had too much experience in web projects and their design concepts... This is what I have got thus far - A Tomcat web server which loads Spring. Spring handles my DAO's and required classes for the business logic. Tomcat serves JSP's containing the pages which make up the website. To make it interactive I have used JavaScript in the pages (jQuery and its AJAX calls) to send and receive JSON data (this is done by posting to a page which calls a handleAction() method in one of my classes). My question is, am I tackling this project in the right way? Am I using the right tools and methods? I understand there are literally countless ways of tackling any project but I would really love to get feedback with regards to tried and tested methods, general practices etc. Thanks in advance! Xandel

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  • How to refactor these generic methods?

    - by Steve Crane
    I have written two nearly identical generic extension methods and am trying to figure out how I might refactor them into a single method. They differ only in that one operates on List and the other on List, and the properties I'm interested in are AssetID for AssetDocument and PersonID for PersonDocument. Although AssetDocument and PersonDocument have the same base class the properties are defined in each class so I don't think that helps. I have tried public static string ToCSVList<T>(this T list) where T : List<PersonDocument>, List<AssetDocument> thinking I might then be able to test the type and act accordingly but this results in the syntax error Type parameter 'T' inherits conflicting constraints These are the methods that I would like to refactor into a single method but perhaps I am simply going overboard and they would besat be left as they are. I'd like to hear what you think. public static string ToCSVList<T>(this T list) where T : List<AssetDocument> { var sb = new StringBuilder(list.Count * 36 + list.Count); string delimiter = String.Empty; foreach (var document in list) { sb.Append(delimiter + document.AssetID.ToString()); delimiter = ","; } return sb.ToString(); } public static string ToCSVList<T>(this T list) where T : List<PersonDocument> { var sb = new StringBuilder(list.Count * 36 + list.Count); string delimiter = String.Empty; foreach (var document in list) { sb.Append(delimiter + document.PersonID.ToString()); delimiter = ","; } return sb.ToString(); }

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  • Why are virtual methods considered early bound?

    - by AspOnMyNet
    One definition of binding is that it is the act of replacing function names with memory addresses. a) Thus I assume early binding means function calls are replaced with memory addresses during compilation process, while with late binding this replacement happens during runtime? b) Why are virtual methods also considered early bound (thus the target method is found at compile time, and code is created that will call this method)? As far as I know, with virtual methods the call to actual method is resolved only during runtime and not compile time?! thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) v-table calls are neither early nor late bound. Instead there's an offset into a table of function pointers. The offset is fixed at compile time, but which table the function pointer is chosen from depends on the runtime type of the object (the object contains a hidden pointer to its v-table), so the final function address is found at runtime. But assuming the object of type T is created via reflection ( thus app doesn’t even know of existence of type T ), then how can at compile time exist an entry point for that type of object?

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  • Looking for detailed explanation of Hibernate UserType methods for mutable objects

    - by Tom
    I am creating a custom UserType class in Hibernate. The specific case is for an HL7v3 clinical document (I work in health IT). It is a mutable object and most of the documentation around the Hibernate UserType interface seems to center around immutable types. I want a better understanding of how and when the interface methods are used, specifically: assemble - why two parameters (one Serializable, one Object)? What is the use case for this method? disassemble - should I just implement this method to return a serializable form (e.g. String representation)? When and how is this method invoked? equals - is this for update? read? contention? dirty reads? What are the consequences of simply returning false in most cases? replace - I really don't understand where the three Object parameters come from, when this method is invoked, and what Hibernate expects to return, or how that return value is used. Any pointers would be appreciated. I've searched and read all I can find on the subject, but have not found much documentation at all explaining how these methods are used for mutable objects.

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  • Fluently setting C# properties and chaining methods

    - by John Feminella
    I'm using .NET 3.5. We have some complex third-party classes which are automatically generated and out of my control, but which we must work with for testing purposes. I see my team doing a lot of deeply-nested property getting/setting in our test code, and it's getting pretty cumbersome. To remedy the problem, I'd like to make a fluent interface for setting properties on the various objects in the hierarchical tree. There are a large number of properties and classes in this third-party library, and it would be too tedious to map everything manually. My initial thought was to just use object initializers. Red, Blue, and Green are properties, and Mix() is a method that sets a fourth property Color to the closest RGB-safe color with that mixed color. Paints must be homogenized with Stir() before they can be used. Bucket b = new Bucket() { Paint = new Paint() { Red = 0.4; Blue = 0.2; Green = 0.1; } }; That works to initialize the Paint, but I need to chain Mix() and other methods to it. Next attempt: Create<Bucket>(Create<Paint>() .SetRed(0.4) .SetBlue(0.2) .SetGreen(0.1) .Mix().Stir() ) But that doesn't scale well, because I'd have to define a method for each property I want to set, and there are hundreds of different properties in all the classes. Also, C# doesn't have a way to dynamically define methods prior to C# 4, so I don't think I can hook into things to do this automatically in some way. Third attempt: Create<Bucket>(Create<Paint>().Set(p => { p.Red = 0.4; p.Blue = 0.2; p.Green = 0.1; }).Mix().Stir() ) That doesn't look too bad, and seems like it'd be feasible. Is this an advisable approach? Is it possible to write a Set method that works this way? Or should I be pursuing an alternate strategy?

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  • topic-comment naming of functions/methods

    - by Daniel
    I was looking at American Sign Language the other day... and I noticed that the construction of the language was topic-comment. As in "Weather is good". That got me to thinking about why we name methods/functions in the manner of: function getName() { ... } function setName(v) { ... } If we think about naming in a topic-comment function, the function names would be function nameGet() { ... } function nameSet() { ... } This might be better for a class had multiple purposes. IE: class events { function ListAdd(); function ListDelete(); function ListGet(); function EventAdd(); function EventDelete(); function EventGet(); } This way the functions are grouped by "topic". Where as the former naming, functions are grouped Action-Noun, but are sorted by Noun. I thought this was an interesting POV, what do other people think about naming functions/methods Topic-Comment? Obviously, mixing naming conventions up in the same project would be weird, but overall? -daniel

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  • JQuery methods and DOM properties

    - by Bob Smith
    I am confused as to when I can use the DOM properties and when I could use the Jquery methods on a Jquery object. Say, I use a selector var $elemSel = $('#myDiv').find('[id *= \'select\']') At this point, $elemSel is a jquery object which I understand to be a wrapper around the array of DOM elements. I could get a reference to the DOM elements by iterating through the $elemSel object/array (Correct?) My questions: 1. Is there a way to convert this $elemSel into a non JQuery regular array of DOM elements? 2. Can I combine DOM properties and JQuery methods at the same time (something like this) $elemSel.children('td').nodeName (nodeName is DOM related, children is JQuery related) EDIT: What's wrong with this? $elemSel.get(0).is(':checked') EDIT 2: Thanks for the responses. I understand now that I can use the get(0) to get a DOM element. Additional questions: How would I convert a DOM element to a JQuery object? If I assign "this" to a variable, is that new var DOM or JQuery? If it's JQuery, how can I convert this to a DOM element? (Since I can't use get(0)) var $elemTd = $(this); When I do a assignment like the one above, I have seen some code samples not include the $ sign for the variable name. Why? And as for my original question, can I combine the DOM properties and JQuery functions at the same time on a JQuery object? $elemSel.children('td').nodeName

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  • Scope of "library" methods

    - by JS
    Hello, I'm apparently laboring under a poor understanding of Python scoping. Perhaps you can help. Background: I'm using the 'if name in "main"' construct to perform "self-tests" in my module(s). Each self test makes calls to the various public methods and prints their results for visual checking as I develop the modules. To keep things "purdy" and manageable, I've created a small method to simplify the testing of method calls: def pprint_vars(var_in): print("%s = '%s'" % (var_in, eval(var_in))) Calling pprint_vars with: pprint_vars('some_variable_name') prints: some_variable_name = 'foo' All fine and good. Problem statement: Not happy to just KISS, I had the brain-drizzle to move my handy-dandy 'pprint_vars' method into a separate file named 'debug_tools.py' and simply import 'debug_tools' whenever I wanted access to 'pprint_vars'. Here's where things fall apart. I would expect import debug_tools foo = bar debug_tools.pprint_vars('foo') to continue working its magic and print: foo = 'bar' Instead, it greets me with: NameError: name 'some_var' is not defined Irrational belief: I believed (apparently mistakenly) that import puts imported methods (more or less) "inline" with the code, and thus the variable scoping rules would remain similar to if the method were defined inline. Plea for help: Can someone please correct my (mis)understanding of scoping regards imports? Thanks, JS

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  • PHP OOP: Avoid Singleton/Static Methods in Domain Model Pattern

    - by sunwukung
    I understand the importance of Dependency Injection and its role in Unit testing, which is why the following issue is giving me pause: One area where I struggle not to use the Singleton is the Identity Map/Unit of Work pattern (Which keeps tabs on Domain Object state). //Not actual code, but it should demonstrate the point class Monitor{//singleton construction omitted for brevity static $members = array();//keeps record of all objects static $dirty = array();//keeps record of all modified objects static $clean = array();//keeps record of all clean objects } class Mapper{//queries database, maps values to object fields public function find($id){ if(isset(Monitor::members[$id]){ return Monitor::members[$id]; } $values = $this->selectStmt($id); //field mapping process omitted for brevity $Object = new Object($values); Monitor::new[$id]=$Object return $Object; } $User = $UserMapper->find(1);//domain object is registered in Id Map $User->changePropertyX();//object is marked "dirty" in UoW // at this point, I can save by passing the Domain Object back to the Mapper $UserMapper->save($User);//object is marked clean in UoW //but a nicer API would be something like this $User->save(); //but if I want to do this - it has to make a call to the mapper/db somehow $User->getBlogPosts(); //or else have to generate specific collection/object graphing methods in the mapper $UserPosts = $UserMapper->getBlogPosts(); $User->setPosts($UserPosts); Any advice on how you might handle this situation? I would be loathe to pass/generate instances of the mapper/database access into the Domain Object itself to satisfy DI - At the same time, avoiding that results in lots of calls within the Domain Object to external static methods. Although I guess if I want "save" to be part of its behaviour then a facility to do so is required in its construction. Perhaps it's a problem with responsibility, the Domain Object shouldn't be burdened with saving. It's just quite a neat feature from the Active Record pattern - it would be nice to implement it in some way.

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  • Memory management of objects returned by methods (iOS / Objective-C)

    - by iOSNewb
    I am learning Objective-C and iOS programming through the terrific iTunesU course posted by Stanford (http://www.stanford.edu/class/cs193p/cgi-bin/drupal/) Assignment 2 is to create a calculator with variable buttons. The chain of commands (e.g. 3+x-y) is stored in a NSMutableArray as "anExpression", and then we sub in random values for x and y based on an NSDictionary to get a solution. This part of the assignment is tripping me up: The final two [methods] “convert” anExpression to/from a property list: + (id)propertyListForExpression:(id)anExpression; + (id)expressionForPropertyList:(id)propertyList; You’ll remember from lecture that a property list is just any combination of NSArray, NSDictionary, NSString, NSNumber, etc., so why do we even need this method since anExpression is already a property list? (Since the expressions we build are NSMutableArrays that contain only NSString and NSNumber objects, they are, indeed, already property lists.) Well, because the caller of our API has no idea that anExpression is a property list. That’s an internal implementation detail we have chosen not to expose to callers. Even so, you may think, the implementation of these two methods is easy because anExpression is already a property list so we can just return the argument right back, right? Well, yes and no. The memory management on this one is a bit tricky. We’ll leave it up to you to figure out. Give it your best shot. Obviously, I am missing something with respect to memory management because I don't see why I can't just return the passed arguments right back. Thanks in advance for any answers!

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  • Putting all methods in class definition

    - by Amnon
    When I use the pimpl idiom, is it a good idea to put all the methods definitions inside the class definition? For example: // in A.h class A { class impl; boost::scoped_ptr<impl> pimpl; public: A(); int foo(); } // in A.cpp class A::impl { // method defined in class int foo() { return 42; } // as opposed to only declaring the method, and defining elsewhere: float bar(); }; A::A() : pimpl(new impl) { } int A::foo() { return pimpl->foo(); } As far as I know, the only problems with putting a method definition inside a class definition is that (1) the implementation is visible in files that include the class definition, and (2) the compiler may make the method inline. These are not problems in this case since the class is defined in a private file, and inlining has no effect since the methods are called in only one place. The advantage of putting the definition inside the class is that you don't have to repeat the method signature. So, is this OK? Are there any other issues to be aware of?

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