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  • What was your "aha moment" in understanding delegates?

    - by CM90
    Considering the use of delegates in C#, does anyone know if there is a performance advantage or if it is a convenience to the programmer? If we are creating an object that holds a method, it sounds as if that object would be a constant in memory to be called on, instead of loading the method every time it is called. For example, if we look at the following Unity3D-based code: public delegate H MixedTypeDelegate<G, H>(G g) public class MainParent : MonoBehaviour // Most Unity classes inherit from M.B. { public static Vector3 getPosition(GameObject g) { /* GameObject is a Unity class, and Vector3 is a struct from M.B. The "position" component of a GameObject is a Vector3. This method takes the GameObject I pass to it & returns its position. */ return g.transform.position; } public static MixedTypeDelegate<GameObject, Vector3> PositionOf; void Awake( ) // Awake is the first method called in Unity, always. { PositionOf = MixedTypeDelegate<GameObject, Vector3>(getPosition); } } public class GameScript : MainParent { GameObject g = new GameObject( ); Vector3 whereAmI; void Update( ) { // Now I can say: whereAmI = PositionOf(g); // Instead of: whereAmI = getPosition(g); } } . . . But that seems like an extra step - unless there's that extra little thing that it helps. I suppose the most succinct way to ask a second question would be to say: When you had your aha moment in understanding delegates, what was the context/scenario/source? Thank you!

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  • Java threads problem

    - by MyNameIs
    Hi! I have a problem with java threads: public class MyClass{ public void Core(){ runTools(); //here I would like to call runTools() method } public void runTools(){ final String run_tool ="cmd.exe /C sources.exe"; Runnable doRun = new Runnable() { public void run() { try { Process tool_proc = Runtime.getRuntime().exec(run_tool); } catch (IOException e) { e.printStackTrace(); } } }; Thread th = new Thread(doRun); th.start(); } } If I do this, then I don't know why, but the thread doesn't work. Please give me some ideas to create a thread. I have already been seen lots of examples, but I should some code such as my example here. Thanks!

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  • How to use Transaction in Entity FrameWork?

    - by programmerist
    How to use Transaction in Entity FrameWork? i read some links on Stackoverflow : http://stackoverflow.com/questions/815586/entity-framework-using-transactions-or-savechangesfalse-and-acceptallchanges BUT; i have 3 table so i have 3 entities: CREATE TABLE Personel (PersonelID integer PRIMARY KEY identity not null, Ad varchar(30), Soyad varchar(30), Meslek varchar(100), DogumTarihi datetime, DogumYeri nvarchar(100), PirimToplami float); Go create TABLE Prim (PrimID integer PRIMARY KEY identity not null, PersonelID integer Foreign KEY references Personel(PersonelID), SatisTutari int, Prim float, SatisTarihi Datetime); Go CREATE TABLE Finans (ID integer PRIMARY KEY identity not null, Tutar float); Personel, Prim,Finans my tables. if you look Prim table you can see Prim value float value if i write a textbox not float value my transaction must run. using (TestEntities testCtx = new TestEntities()) { using (TransactionScope scope = new TransactionScope()) { // do someyihng... testCtx.Personel.SaveChanges(); // do someyihng... testCtx.Prim.SaveChanges(); // do someyihng... testCtx.Finans.SaveChanges(); scope .Complete(); success = true; } } How can i do that?

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  • Need a refresher course on property access...

    - by Code Sherpa
    Hi. I need help with accessing class properties within a given class. For example, take the below class: public partial class Account { private Profile _profile; private Email _email; private HostInfo _hostInfo; public Profile Profile { get { return _profile; } set { _profile = value; } } public Email Email { get { return _email; } set { _email = value; } } public HostInfo HostInfo { get { return _hostInfo; } set { _hostInfo = value; } } In the class "Account" exists a bunch of class properties such as Email or Profile. Now, when I want to access those properties at run-time, I do something like this (for Email): _accountRepository = ObjectFactory.GetInstance<IAccountRepository>(); string username = Cryptography.Decrypt(_webContext.UserNameToVerify, "verify"); Account account = _accountRepository.GetAccountByUserName(username); if(account != null) { account.Email.IsConfirmed = true; But, I get "Object reference not set..." for account.Email... Why is that? How do I access Account such that account.Email, account.Profile, and so on returns the correct data for a given AccountId or UserName. Here is a method that returns Account: public Account GetAccountByUserName(string userName) { Account account = null; using (MyDataContext dc = _conn.GetContext()) { try { account = (from a in dc.Accounts where a.UserName == userName select a).FirstOrDefault(); } catch { //oops } } return account; } The above works but when I try: account = (from a in dc.Accounts join em in dc.Emails on a.AccountId equals em.AccountId join p in dc.Profiles on em.AccountId equals p.AccountId where a.UserName == userName select a).FirstOrDefault(); I am still getting object reference exceptions for my Email and Profile properties. Is this simply a SQL problem or is there something else I need to be doing to be able to fully access all the properties within my Account class? Thanks!

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  • Java homework help, Error <identifier> expected

    - by user2900126
    Help with java homework this is my assignment that I have, this assignment code I've tried. But when I try to compile it I keep getting errors which I cant seem to find soloutions too: Error says <identifier> expected for Line 67 public static void () Assignment brief To write a simple java classMobile that models a mobile phone. Details the information stored about each mobile phone will include • Its type e.g. “Sony ericsson x90” or “Samsung Galaxy S”; • Its screen size in inches; You may assume that this a whole number from the scale 3 to 5 inclusive. • Its memory card capacity in gigabytes You may assume that this a whole number • The name of its present service provider You may assume this is a single line of text. • The type of contract with service provider You may assume this is a single line of text. • Its camera resolution in megapixels; You should not assume that this a whole number; • The percentage of charge left on the phone e.g. a fully charged phone will have a charge of 100. You may assume that this a whole number • Whether the phone has GPS or not. Your class will have fields corresponding to these attributes . Start by opening BlueJ, creating a new project called myMobile which has a classMobile and set up the fields that you need, Next you will need to write a Constructor for the class. Assume that each phone is manufactured by creating an object and specifying its type, its screen size, its memory card capacity, its camera resolution and whether it has GPS or not. Therefore you will need a constructor that allows you to pass arguments to initialise these five attributes. Other fields should be set to appropriate default values. You may assume that a new phone comes fully charged. When the phone is sold to its owner, you will need to set the service provider and type of contract with that provider so you will need mutator methods • setProvider () - - to set service provider. • setContractType - - to set the type of contract These methods will be used when the phones provider is changed. You should also write a mutator method ChargeUp () which simulates fully charging the phone. To obtain information about your mobile object you should write • accessor methods corresponding to four of its fields: • getType () – which returns the type of mobile; • getProvider () – which returns the present service provider; • getContractType () – which returns its type of contract; • getCharge () – which returns its remaining charge. An accessor method to printDetails () to print, to the terminal window, a report about the phone e.g. This mobile phone is a sony Erricsson X90 with Service provider BigAl and type of contract PAYG. At present it has 30% of its battery charge remaining. Check that the new method works correctly by for example, • creating a Mobile object and setting its fields; • calling printDetails () and t=checking the report corresponds to the details you have just given the mobile; • changing the service provider and contract type by calling setprovider () and setContractType (); • calling printDetails () and checking the report now prints out the new details. Challenging excercises • write a mutator methodswitchedOnFor () =which simulates using the phone for a specified period. You may assume the phone loses 1% of its charge for each hour that it is switched on . • write an accessor method checkcharge () whichg checks the phone remaing charge. If this charge has a value less than 25%, then this method returns a string containg the message Be aware that you will soon need to re-charge your phone, otherwise it returns a string your phone charge is sufficient. • Write a method changeProvider () which simulates changing the provider (and presumably also the type of service contract). Finally you may add up to four additional fields, with appropriate methods, that might be required in a more detailed model. above is my assignment that I have, this assignment code I've tried. But when I try to oompile it I keep getting errors which I cant seem to find soloutions too: Error says <identifier> expected for Line 67 public static void () /** * to write a simple java class Mobile that models a mobile phone. * * @author (Lewis Burte-Clarke) * @version (14/10/13) */ public class Mobile { // type of phone private String phonetype; // size of screen in inches private int screensize; // menory card capacity private int memorycardcapacity; // name of present service provider private String serviceprovider; // type of contract with service provider private int typeofcontract; // camera resolution in megapixels private int cameraresolution; // the percentage of charge left on the phone private int checkcharge; // wether the phone has GPS or not private String GPS; // instance variables - replace the example below with your own private int x; // The constructor method public Mobile(String mobilephonetype, int mobilescreensize, int mobilememorycardcapacity,int mobilecameraresolution,String mobileGPS, String newserviceprovider) { this.phonetype = mobilephonetype; this.screensize = mobilescreensize; this.memorycardcapacity = mobilememorycardcapacity; this.cameraresolution = mobilecameraresolution; this.GPS = mobileGPS; // you do not use this ones during instantiation,you can remove them if you do not need or assign them some default values //this.serviceprovider = newserviceprovider; //this.typeofcontract = 12; //this.checkcharge = checkcharge; Mobile samsungPhone = new Mobile("Samsung", "1024", "2", "verizon", "8", "GPS"); 1024 = screensize; 2 = memorycardcapacity; 8 = resolution; GPS = gps; "verizon"=serviceprovider; //typeofcontract = 12; //checkcharge = checkcharge; } // A method to display the state of the object to the screen public void displayMobileDetails() { System.out.println("phonetype: " + phonetype); System.out.println("screensize: " + screensize); System.out.println("memorycardcapacity: " + memorycardcapacity); System.out.println("cameraresolution: " + cameraresolution); System.out.println("GPS: " + GPS); System.out.println("serviceprovider: " + serviceprovider); System.out.println("typeofcontract: " + typeofcontract); } /** * The mymobile class implements an application that * simply displays "new Mobile!" to the standard output. */ public class mymobile { public static void main(String[] args) { System.out.println("new Mobile!"); //Display the string. } } public static void buildPhones(){ Mobile Samsung = new Mobile("Samsung", "3.0", "4gb", "8mega pixels", "GPS"); Mobile Blackberry = new Mobile("Blackberry", "3.0", "4gb", "8mega pixels", "GPS"); Samsung.displayMobileDetails(); Blackberry.displayMobileDetails(); } public static void main(String[] args) { buildPhones(); } } any answers.replies and help would be greatly appreciated as I really lost!

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  • What is the best way to "override" enums?

    - by Tyler
    I have a number of classes which extend an abstract class. The abstract parent class defines an enum with a set of values. Some of the subclasses inherit the parent class's enum values, but some of the subclasses need the enum values to be different. Is there any way to somehow override the enum for these particular subclasses, and if not, what is a good way to achieve what I'm describing? class ParentClass { private MyEnum m_EnumVal; public virtual MyEnum EnumVal { get { return m_EnumVal; } set { m_EnumVal = value; } } public enum MyEnum { a, b, c }; } class ChildClass : ParentClass { private MyEnum m_EnumVal; public virtual MyEnum EnumVal { get { return m_EnumVal; } set { m_EnumVal = value; } } public enum MyEnum { d, e, f }; }

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  • .Net Inherited Control Property Default

    - by Yisman
    Hello fellows Im trying to make a simple "ButtonPlus" control. the main idea is to inherit from the button control and add some default property values (such as font,color,padding...) No matter how i try, the WinForm always generates (or "serializes") the property value in the client forms the whole point is to have minimal and clean code, not that every instance of the buttonPlus should have 5 lines of init code. I want that the form designer should not generate any code for theses properties and be able to control them from the ButtonPlus code. In other words, if I change the ForeColor from red to blue only 1 single bingle line of code in the app should change. heres my code so far. as you can see, ive tried using defaultvalue, reset , shouldserialize.... anything i was able to find on the web! Public Class ButtonPlus Inherits Button Sub New() 'AutoSize = True AutoSizeMode = Windows.Forms.AutoSizeMode.GrowAndShrink Font = New System.Drawing.Font("Arial", 11.0!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(177, Byte)) Padding = New System.Windows.Forms.Padding(3) Anchor = AnchorStyles.Left + AnchorStyles.Right + AnchorStyles.Top ForeColor = Color.Aqua End Sub ' _ 'Public Overrides Property AutoSize() As Boolean ' Get ' Return MyBase.AutoSize ' End Get ' Set(ByVal value As Boolean) ' MyBase.AutoSize = value ' End Set 'End Property Public Function ShouldSerializeAutoSize() As Boolean Return False ' Not AutoSize = True End Function Public Function ShouldSerializeForeColor() As Boolean Return False 'Not ForeColor = Color.Aqua End Function Public Overrides Sub ResetForeColor() ForeColor = Color.Aqua End Sub End Class Thank you very much for taking the time to look this over and answer all the best

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  • inconsistency between Sun JRE javac and Eclipse java compiler?

    - by Jason S
    This confuses me. The following compiles fine under Eclipse. package com.example.gotchas; public class GenericHelper1 { static <T> T fail() throws UnsupportedOperationException { throw new UnsupportedOperationException(); } /** * just calls fail() * @return something maybe */ public boolean argh() { return fail(); } public static void main(String[] args) { // TODO Auto-generated method stub } } But if I try to do a clean build with ant, or at the command line with javac, I get this: src\com\example\gotchas\GenericHelper1.java:14: type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds boolean,java.lang.Object public boolean argh() { return fail(); } ^ 1 error what gives, and how do I fix it?

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  • c# template member functions

    - by user3730583
    How can I define a template member function in C# For instance I will fill any collection which supports an Add(...) member function, please check out the sample code below public class CInternalCollection { public static void ExternalCollectionTryOne<T<int>>(ref T<int> ext_col, int para_selection = 0) { foreach (int int_value in m_int_col) { if (int_value > para_selection) ext_col.Add(int_value); } } public static void ExternalCollectionTryTwo<T>(ref T ext_col, int para_selection = 0) { foreach (int int_value in m_int_col) { if (int_value > para_selection) ext_col.Add(int_value); } } static int[] m_int_col = { 0, -1, -3, 5, 7, -8 }; } The ExternalCollectionTryOne<...(...) would be the preferred kind, because the int type can be explicit defined, but results in an error: Type parameter declaration must be an identifier not a type The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?) The ExternalCollectionTryTwo<...(...) results in an error: 'T' does not contain a definition for 'Add' and no extension method 'Add' accepting a first argument of type 'T' could be found (are you missing a using directive or an assembly reference?)... I hope the problem is clear – any suggestions? ----------------------------- edit -------------------------- The answers with the interface ICollection<.. without a template member works fine and thanks all for this hint, but I still cannot define successfully a member template(generic) function So a more simpler example ... how can I define this public class CAddCollectionValues { public static void AddInt<T>(ref T number, int selection) { T new_T = new T(); //this line is just an easy demonstration to get a compile error with type T foreach (int i_value in m_int_col) { if (i_value > selection) number += i_value; //again the type T cannot be used } } static int[] m_int_col = { 0, -1, -3, 5, 7, -8 }; }

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  • Pattern for version-specific implementations of a Java class

    - by Mike Monkiewicz
    So here's my conundrum. I am programming a tool that needs to work on old versions of our application. I have the code to the application, but can not alter any of the classes. To pull information out of our database, I have a DTO of sorts that is populated by Hibernate. It consumes a data object for version 1.0 of our app, cleverly named DataObject. Below is the DTO class. public class MyDTO { private MyWrapperClass wrapper; public MyDTO(DataObject data) { wrapper = new MyWrapperClass(data); } } The DTO is instantiated through a Hibernate query as follows: select new com.foo.bar.MyDTO(t1.data) from mytable t1 Now, a little logic is needed on top of the data object, so I made a wrapper class for it. Note the DTO stores an instance of the wrapper class, not the original data object. public class MyWrapperClass { private DataObject data; public MyWrapperClass(DataObject data) { this.data = data; } public String doSomethingImportant() { ... version-specific logic ... } } This works well until I need to work on version 2.0 of our application. Now DataObject in the two versions are very similar, but not the same. This resulted in different sub classes of MyWrapperClass, which implement their own version-specific doSomethingImportant(). Still doing okay. But how does myDTO instantiate the appropriate version-specific MyWrapperClass? Hibernate is in turn instantiating MyDTO, so it's not like I can @Autowire a dependency in Spring. I would love to reuse MyDTO (and my dozens of other DTOs) for both versions of the tool, without having to duplicate the class. Don't repeat yourself, and all that. I'm sure there's a very simple pattern I'm missing that would help this. Any suggestions?

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  • How to read pair in freemarker

    - by Lukasz Rys
    Ok i'm having little trouble with reading pair. So I'm creating my pair private Pair<Integer, Integer> count(somethink) { int c1 = 2; int c2 = 4; return new Pair<Integer, Integer>(c1, c2); } And 'sending' it to ftl via java mv.addObject("counted", count(somethink)); I won't write everythink how it sends because I dont think it really matters with my issue. So i'm recieving it in "ftl". Then i was trying to 'read' it <#list counted?keys as key> <a href="#offerOrderTab"><@spring.message "someMsg"/>(${key}/${counted[key]})</a> </#list> After then i'm getting error Expecting a string, date or number here, Expression x is instead a freemarker.ext.beans.SimpleMethodModel As i suppose you dont iterate pairs (or I'm wrong?) i know its pair that contains only one key and one value but still i have to do send it that way and I thought its goin be to similar to iterating through map, in java i would use pair.first() and pair.second() but it doesn't work in ftl (ye i know it shouldnt work). I also tried to cast it to String by using ?string but it didnt work too

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  • How do I alias the scala setter method 'myvar_$(myval)' to something more pleasing when in java?

    - by feydr
    I've been converting some code from java to scala lately trying to tech myself the language. Suppose we have this scala class: class Person() { var name:String = "joebob" } Now I want to access it from java so I can't use dot-notation like I would if I was in scala. So I can get my var's contents by issuing: person = Person.new(); System.out.println(person.name()); and set it via: person = Person.new(); person.name_$eq("sallysue"); System.out.println(person.name()); This holds true cause our Person Class looks like this in javap: Compiled from "Person.scala" public class Person extends java.lang.Object implements scala.ScalaObject{ public Person(); public void name_$eq(java.lang.String); public java.lang.String name(); public int $tag() throws java.rmi.RemoteException; } Yes, I could write my own getters/setters but I hate filling classes up with that and it doesn't make a ton of sense considering I already have them -- I just want to alias the _$eq method better. (This actually gets worse when you are dealing with stuff like antlr because then you have to escape it and it ends up looking like person.name_\$eq("newname"); Note: I'd much rather have to put up with this rather than fill my classes with more setter methods. So what would you do in this situation?

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  • Are static delegates thread-safe?

    - by leypascua
    Consider this code snippet: public static class ApplicationContext { private static Func<TService> Uninitialized<TService>() { throw new InvalidOperationException(); } public static Func<IAuthenticationProvider> AuthenticationProvider = Uninitialized<IAuthenticationProvider>(); public static Func<IUnitOfWorkFactory> UnitOfWorkFactory = Uninitialized<IUnitOfWorkFactory>(); } //can also be in global.asax if used in a web app. public static void Main(string[] args) { ApplicationContext.AuthenticationProvider = () => new LdapAuthenticationProvider(); ApplicationContext.UnitOfWorkFactory = () => new EFUnitOfWorkFactory(); } //somewhere in the code.. say an ASP.NET MVC controller ApplicationContext.AuthenticationProvider().SignIn(username, true); Are delegates in the static class ApplicationContext thread-safe in the sense that multiple-threads can invoke them? What potential problems will I face if I pursue this approach?

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  • Trying to edit an entity with data from dropdowns in MVC...

    - by user598352
    Hello! I'm having trouble getting my head around sending multiple models to a view in mvc. My problem is the following. Using EF4 I have a table with attributes organised by category. Couldn't post an image :-( [Have a table called attributes (AttributeTitle, AttributeName, CategoryID) connected to a table called Category (CategoryTitle).] What I want to do is be able to edit an attribute entity and have a dropdown of categories to choose from. I tried to make a custom viewmodel public class AttributeViewModel { public AttributeViewModel() { } public Attribute Attribute { get; set; } public IQueryable<Category> AllCategories { get; set; } } But it just ended up being a mess. <div class="editor-field"> <%: Html.DropDownList("Category", new SelectList((IEnumerable)Model.AllCategories, "CategoryID", "CategoryName")) %> </div> I was getting it back to the controller... [HttpPost] public ActionResult Edit(int AttributeID, FormCollection formcollection) { var _attribute = ProfileDB.GetAttribute(AttributeID); int _selcategory = Convert.ToInt32(formcollection["Category"]); _attribute.CategoryID = (int)_selcategory; try { UpdateModel(_attribute); (<---Error here) ProfileDB.SaveChanges(); return RedirectToAction("Index"); } catch (Exception e) { return View(_attribute); } } I've debugged the code and my _attribute looks correct and _attribute.CategoryID = (int)_selcategory updates the model, but then I get the error. Somewhere here I thought that there should be a cleaner way to do this, and that if I could only send two models to the view instead of having to make a custom viewmodel. To sum it up: I want to edit my attribute and have a dropdown of all of the available categories. Any help much appreciated!

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  • FindBugs and CheckForNull on classes vs. interfaces

    - by ndn
    Is there any way to let FindBugs check and warn me if a CheckForNull annotation is present on the implementation of a method in a class, but not on the declaration of the method in the interface? import javax.annotation.CheckForNull; interface Foo { public String getBar(); } class FooImpl implements Foo { @CheckForNull @Override public String getBar() { return null; } } public class FindBugsDemo { public static void main(String[] args) { Foo foo = new FooImpl(); System.out.println(foo.getBar().length()); } } I just discovered a bug in my application due to a missing null check that was not spotted by FindBugs because CheckForNull was only present on FooImpl, but not on Foo, and I don't want to spot all other locations of this problem manually.

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  • Does Qt support virtual pure slots ?

    - by ereOn
    Hi, My GUI project in Qt has a lot of "configuration pages" classes which all inherit directly from QWidget. Recently, I realized that all these classes share 2 commons slots (loadSettings() and saveSettings()). Regarding this, I have two questions: Does it make sense to write a intermediate base abstract class (lets name it BaseConfigurationPage) with these two slots as virtual pure methods ? (Every possible configuration page will always have these two methods, so I would say "yes") Before I do the heavy change in my code (if I have to) : does Qt support virtual pure slots ? Is there anything I should be aware of ? Here is a code example describing everything: class BaseConfigurationPage : public QWidget { // Some constructor and other methods, irrelevant here. public slots: virtual void loadSettings() = 0; virtual void saveSettings() = 0; }; class GeneralConfigurationPage : public BaseConfigurationPage { // Some constructor and other methods, irrelevant here. public slots: void loadSettings(); void saveSettings(); };

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  • Conditional Required Attribute for validation

    - by jeriley
    We're trying to get a conditional attribute to work, case in point, there's a boolean (checkbox) that if checked, its related text is required. So, ideally we'd have something like ... public bool Provision { get; set; } [ConditionalRequirement(IsNeededWhenTrue = Provision)] public string ProvisionText { get; set; } Is this even possible? Alternate idea (not as elegant?) public bool Provision2 { get; set; } [PropertyRequired(RequiredBooleanPropertyName = "Provision2")] public string Provision2Text { get; set; } I'd hate to use the magic string method ... but any other ideas?

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  • How do I access the enumerated item with an indexer and assign array string to it for display?

    - by g00p3k
    EDITED: Updated 3/23/09. See rest of post at bottom. I'm still having trouble with the indexer. Anymore help or examples would really help me out. Write a class, MyCourses, that contains an enumeration of all the courses that you are currently taking. This enum should be nested inside of your class MyCourses. Your class should also have an array field that provides a short description (as a String) of each of your courses. Write an indexer that takes one of your enumerated courses as an index and returns the String description of the course. Write a class MyFriends that contains an indexer that provides access to the names of your friends. namespace IT274_Unit4Project { public class MyCourses { // enumeration that contains an enumeration of all the courses that // student is currently enrolled in public enum CourseName {IT274= 0,CS210 = 1} // array field that provides short description for each of classes, // returns string description of the course private String[] courseDescription = {"Intermediate C#: Teaches intermediate elements of C# programming and software design", "Career Development Strategies: Teaches principles for career progression, resume preparation, and overall self anaylsis"}; // indexer that takes one of the enumerated courses as an index // and returns the String description of the course public String this[CourseName index] { get { if (index == 1) return courseDescription[0]; else return courseDescription[1]; } set { if (index == 1) courseDescription[0] = value; else courseDescription[1] = value; } } } }//end public class MyCourses I'm working on this homework project and having trouble understanding the text explaining how to correctly take the accessed value of the enumeration and then apply the string array value to it. Can you please help me understand this? The text we are using is very difficult and poorly written for a beginner to understand, so I'm kind of on my own here. I've got the first parts written, but need some help on the accessing of the enumeration value and assigning, i think i'm close, but don't understand how to properly get and set the values on this. Please do not provide me with direct code answers, unless a MSDN style explanation that is generalized and not specific to my project. ie: public class MyClass { string field1; string field2; //properties public string Value1 get etc... Thanks!

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  • C# Inherited member variables behaving undexpectedly

    - by Nilbert
    If I have a class like this: class A { public string fe = "A"; } And a class that inherits from it like so: class B : A { public string fe = "B"; } Visual C++ will tell me that B.fe hides A.fe so I should use the new keyword. So I change class B to look like: class B : A { public new string fe = "B"; } And then I have a function that takes an A (but, by virtue of inheritance, will also take a B) like this: class D { public static void blah(A anAObject) { Console.Writeline(A.fe); } } Even when I pass it an instance of a B object, which it will take without question, it will print "A"! Why is this, and how can I make it work how I want without setting the variable in the constructor?

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  • Set a default value to a property

    - by BrunoLM
    Is it possible to set a default value without the body of a property? Maybe through annotations? [SetTheDefaultValueTo(true)] public bool IsTrue { get; set; } [SetTheDefaultValueTo(false)] public bool IsFalse { get; set; } public void Something() { var isTrue = this.IsTrue; var isFalse = this.IsFalse; }

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  • Help Optimizing MySQL Table (~ 500,000 records) and PHP Code.

    - by Pyrite
    I have a MySQL table that collects player data from various game servers (Urban Terror). The bot that collects the data runs 24/7, and currently the table is up to about 475,000+ records. Because of this, querying this table from PHP has become quite slow. I wonder what I can do on the database side of things to make it as optomized as possible, then I can focus on the application to query the database. The table is as follows: CREATE TABLE IF NOT EXISTS `people` ( `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(40) NOT NULL, `ip` int(4) unsigned NOT NULL, `guid` varchar(32) NOT NULL, `server` int(4) unsigned NOT NULL, `date` int(11) NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `Person` (`name`,`ip`,`guid`), KEY `server` (`server`), KEY `date` (`date`), KEY `PlayerName` (`name`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COMMENT='People that Play on Servers' AUTO_INCREMENT=475843 ; I'm storying the IPv4 (ip and server) as 4 byte integers, and using the MySQL functions NTOA(), etc to encode and decode, I heard that this way is faster, rather than varchar(15). The guid is a md5sum, 32 char hex. Date is stored as unix timestamp. I have a unique key on name, ip and guid, as to avoid duplicates of the same player. Do I have my keys setup right? Is the way I'm storing data efficient? Here is the code to query this table. You search for a name, ip, or guid, and it grabs the results of the query and cross references other records that match the name, ip, or guid from the results of the first query, and does it for each field. This is kind of hard to explain. But basically, if I search for one player by name, I'll see every other name he has used, every IP he has used and every GUID he has used. <form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post"> Search: <input type="text" name="query" id="query" /><input type="submit" name="btnSubmit" value="Submit" /> </form> <?php if (!empty($_POST['query'])) { ?> <table cellspacing="1" id="1up_people" class="tablesorter" width="300"> <thead> <tr> <th>ID</th> <th>Player Name</th> <th>Player IP</th> <th>Player GUID</th> <th>Server</th> <th>Date</th> </tr> </thead> <tbody> <?php function super_unique($array) { $result = array_map("unserialize", array_unique(array_map("serialize", $array))); foreach ($result as $key => $value) { if ( is_array($value) ) { $result[$key] = super_unique($value); } } return $result; } if (!empty($_POST['query'])) { $query = trim($_POST['query']); $count = 0; $people = array(); $link = mysql_connect('localhost', 'mysqluser', 'yea right!'); if (!$link) { die('Could not connect: ' . mysql_error()); } mysql_select_db("1up"); $sql = "SELECT id, name, INET_NTOA(ip) AS ip, guid, INET_NTOA(server) AS server, date FROM 1up_people WHERE (name LIKE \"%$query%\" OR INET_NTOA(ip) LIKE \"%$query%\" OR guid LIKE \"%$query%\")"; $result = mysql_query($sql, $link); if (!$result) { die(mysql_error()); } // Now take the initial results and parse each column into its own array while ($row = mysql_fetch_array($result, MYSQL_NUM)) { $name = htmlspecialchars($row[1]); $people[] = array( 'id' => $row[0], 'name' => $name, 'ip' => $row[2], 'guid' => $row[3], 'server' => $row[4], 'date' => $row[5] ); } // now for each name, ip, guid in results, find additonal records $people2 = array(); foreach ($people AS $person) { $ip = $person['ip']; $sql = "SELECT id, name, INET_NTOA(ip) AS ip, guid, INET_NTOA(server) AS server, date FROM 1up_people WHERE (ip = \"$ip\")"; $result = mysql_query($sql, $link); while ($row = mysql_fetch_array($result, MYSQL_NUM)) { $name = htmlspecialchars($row[1]); $people2[] = array( 'id' => $row[0], 'name' => $name, 'ip' => $row[2], 'guid' => $row[3], 'server' => $row[4], 'date' => $row[5] ); } } $people3 = array(); foreach ($people AS $person) { $guid = $person['guid']; $sql = "SELECT id, name, INET_NTOA(ip) AS ip, guid, INET_NTOA(server) AS server, date FROM 1up_people WHERE (guid = \"$guid\")"; $result = mysql_query($sql, $link); while ($row = mysql_fetch_array($result, MYSQL_NUM)) { $name = htmlspecialchars($row[1]); $people3[] = array( 'id' => $row[0], 'name' => $name, 'ip' => $row[2], 'guid' => $row[3], 'server' => $row[4], 'date' => $row[5] ); } } $people4 = array(); foreach ($people AS $person) { $name = $person['name']; $sql = "SELECT id, name, INET_NTOA(ip) AS ip, guid, INET_NTOA(server) AS server, date FROM 1up_people WHERE (name = \"$name\")"; $result = mysql_query($sql, $link); while ($row = mysql_fetch_array($result, MYSQL_NUM)) { $name = htmlspecialchars($row[1]); $people4[] = array( 'id' => $row[0], 'name' => $name, 'ip' => $row[2], 'guid' => $row[3], 'server' => $row[4], 'date' => $row[5] ); } } // Combine people and people2 into just people $people = array_merge($people, $people2); $people = array_merge($people, $people3); $people = array_merge($people, $people4); $people = super_unique($people); foreach ($people AS $person) { $date = ($person['date']) ? date("M d, Y", $person['date']) : 'Before 8/1/10'; echo "<tr>\n"; echo "<td>".$person['id']."</td>"; echo "<td>".$person['name']."</td>"; echo "<td>".$person['ip']."</td>"; echo "<td>".$person['guid']."</td>"; echo "<td>".$person['server']."</td>"; echo "<td>".$date."</td>"; echo "</tr>\n"; $count++; } // Find Total Records //$result = mysql_query("SELECT id FROM 1up_people", $link); //$total = mysql_num_rows($result); mysql_close($link); } ?> </tbody> </table> <p> <?php echo $count." Records Found for \"".$_POST['query']."\" out of $total"; ?> </p> <?php } $time_stop = microtime(true); print("Done (ran for ".round($time_stop-$time_start)." seconds)."); ?> Any help at all is appreciated! Thank you.

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  • c# reflection: How can I invoke a method with an out parameter ?

    - by ldp615
    I want expose WebClient.DownloadDataInternal method like below: [ComVisible(true)] public class MyWebClient : WebClient { private MethodInfo _DownloadDataInternal; public MyWebClient() { _DownloadDataInternal = typeof(WebClient).GetMethod("DownloadDataInternal", BindingFlags.NonPublic | BindingFlags.Instance); } public byte[] DownloadDataInternal(Uri address, out WebRequest request) { _DownloadDataInternal.Invoke(this, new object[] { address, out request }); } } WebClient.DownloadDataInternal has a out parameter, I don't know how to invoke it. Help!

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  • Sending data back to Controller Spring-MVC

    - by Umesh Awasthi
    I am not sure if this is a complex problem but as a starting person this seems a bit complex to me. I have an object based on which i need to show some values on the UI and let user select some of them, i need to send data back to another controller when user click on the submit button.Here is the structure of my data object public class PrsData{ private Map<String, List<PrsCDData>> prsCDData; } public class PrsCDData{ private Map<String, Collection<ConfiguredDesignData>> configuredDesignData; } public ConfiguredDesignData{ // simple fields } I have set the object in model before showing the view like model.addAttribute("prsData", productData.getPrData()); In the form i have following settings <form:form method="post" commandName="prsData" action="${addProductToCartAction}" > <form:hidden path="prsCDData['${prsCDDataMap.key}'] [${status.index}].configuredDesignData['${configuredDesignDataMap.key}'] [${configuredDesignDataStatus.index}].code"/> <form:hidden path="prsCDData['${prsCDDataMap.key}'] [${status.index}].configuredDesignData['${configuredDesignDataMap.key}'] [${configuredDesignDataStatus.index}].description"/> </form:form> This is what i have at AddProductToCartController public String addToCart(@RequestParam("productCodePost") final String code, @ModelAttribute("prsData") final PrsData prsData, final Model model, @RequestParam(value = "qty", required = false, defaultValue = "1") final long qty) On submitting the form i am getting following exception org.springframework.beans.NullValueInNestedPathException: Invalid property 'prsCDData[Forced][0]' of bean class [com.product.data.PrsData]: Cannot access indexed value of property referenced in indexed property path 'prsCDData[Forced][0]': returned null It seems like its trying to access the values on this controller while i am trying to send value to that controller and trying to create same object with selected values Can any one tell me where i am doing wrong and what i need to take care of

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  • problem in extending a class

    - by Vineeth
    there are two classes public class Account { public Acconut() { //constructor } } public class SavingsAccount extends Account { } while doing the inheritance i have got an error message "cannont find symbol Symbol: constructor Account()" what might be the error in my code...??

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  • .NET immutable object usage best practices? Should I be using them as much as possible?

    - by Daniel
    Say I have a simple object such as class Something { public int SomeInt { get; set; } } I have read that using immutable objects are faster and a better means of using business objects? If this is so, should i strive to make all my objects as such: class ImmutableSomething { public int SomeInt { get { return m_someInt; } } private int m_someInt = 0; public void ChangeSomeInt(int newValue) { m_someInt = newvalue; } } What do you reckon?

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