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  • .net Value Class sorting with IComparable

    - by greggorob64
    I'm running into an issue using a DataGridView bound to a iBindingListView implementation (third party dll) attached to a large collection. There's a certain property in my collection type, named MyDateTime, which is a value class similar to DateTime, but also with some legacy code. This VALUE CLASS implements iComparable, iComparable<T>, and iEquatable<T>. The issue I'm having is this: When I apply a sort to the iBindingListView, or the Automatic Sorting provided by the DGV on the MyDateTimeColumn, it ALWAYS uses the non-generic iComparer, causing hundreds of thousands of unnecessary boxing and unboxing. When I remove the non-generic iComparer, the generic one is still not used, it just does a string compare on the .ToString(). Am I missing something? Why is my generic comparer not bieng called on a sort?

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  • android activity class does not exists?

    - by user975234
    I have been developing a project in eclipse for an android app. An error which i frequently get is that of- activity class does not exist. But when i just save the manifest file once again the error vanishes and the program runs correctly. Why then do i get the same error again and again. ? Console error: [2011-11-18 15:08:38 - link] Starting activity acb.abc.LinkActivity on device emulator-5554 [2011-11-18 15:08:40 - link] ActivityManager: Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=acb.abc/.LinkActivity } [2011-11-18 15:08:40 - link] New package not yet registered with the system. Waiting 3 seconds before next attempt. [2011-11-18 15:08:40 - link] ActivityManager: Error: Activity class {acb.abc/acb.abc.LinkActivity} does not exist.

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  • Issue with class template partial specialization

    - by DeadMG
    I've been trying to implement a function that needs partial template specializations and fallen back to the static struct technique, and I'm having a number of problems. template<typename T> struct PushImpl<const T&> { typedef T* result_type; typedef const T& argument_type; template<int StackSize> static result_type Push(IStack<StackSize>* sptr, argument_type ref) { // Code if the template is T& } }; template<typename T> struct PushImpl<const T*> { typedef T* result_type; typedef const T* argument_type; template<int StackSize> static result_type Push(IStack<StackSize>* sptr, argument_type ptr) { return PushImpl<const T&>::Push(sptr, *ptr); } }; template<typename T> struct PushImpl { typedef T* result_type; typedef const T& argument_type; template<int StackSize> static result_type Push(IStack<StackSize>* sptr, argument_type ref) { // Code if the template is neither T* nor T& } }; template<typename T> typename PushImpl<T>::result_type Push(typename PushImpl<T>::argument_type ref) { return PushImpl<T>::Push(this, ref); } First: The struct is nested inside another class (the one that offers Push as a member func), but it can't access the template parameter (StackSize), even though my other nested classes all could. I've worked around it, but it would be cleaner if they could just access StackSize like a normal class. Second: The compiler complains that it doesn't use or can't deduce T. Really? Thirdly: The compiler complains that it can't specialize a template in the current scope (class scope). I can't see what the problem is. Have I accidentally invoked some bad syntax?

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  • database design question

    - by Leonardo
    Hi all, I am building a database as a simple exercise, it could be hosted on any database server, so I am trying to keep things as much standard as possible. Basically what I would like to do is a 'code' table that get referenced by other entities. I explain: xcode id code r role p property code r admin r staff p title .... then I would like to have some view like: role (select * from code where xcode='r') r admin r staff property (select * from code where xcode='p') p title then, suppose we have an entity myentity id - 1 role - admin (foreign key to role) title - title (foreign key to property) Obviously I cannot create foreign key to a view, but this is to tell the idea I have in mind. How can I reflect such behaviour using whenever possible, standard sql syntax, then as a second option, database additional features like trigger ecc... ? Because if I tell that role and title in myentity are foreign key to 'code', instead of the views, nothing would stop me to insert a role in title field. thanks Leonardo

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  • What's the difference between the 'DES' class and The 'DESCryptoServiceProvider' class?

    - by IbrarMumtaz
    All I can make out is that one of them is the BC for all 'DES' algorithms to be derived from and the later is a wrapper for the Cryptographic service provider implementation of the DES algorithm. The reason why I ask is that I am going over .Net Security and the MS official training book simply refers to the DES class but the another official MS book refers to the DESCrypto' class. What's the difference between these two? When would you use either of them? What do I need to know as far as the 70-536 exam is concerned. I am asking my question from an educational P.O.V as far as the 70-536 exam is concerned. Thanks In Advance. Ibrar

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  • Custom array class with assotiated objects

    - by FancyDancy
    I have a simple structure, it's just an array of model's objects. For example, it's a users with books. @books = Book.find(:all, :include = :users) I need to check, does user have a book? I have written a helper method: def has_book?(user_id) @books.select{|b| b.user_id == user_id}.any? end Then, i need to get only books from selected library def in_library(n) @books.select{|b| b.library == n} end I have tried to make custom Array class: class BooksList < Array def initialize(books) self << books end # its my custom methods def has_book?(user_id) self.select{|b| b.user_id == user_id}.any? end def in_library(n) self.select{|b| b.library == n} end end It works, but i have only one problem. I can't access Book's assotiated object (user). So i can't write: @books = BookList.new(Book.find(:all, :include => :users)) @books.first.user.id # it says undefined method `user' for #<Array:0x104b43e08>

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  • Practical differences between classes and structs in .net (not conceptual)?

    - by Gulshan
    Whenever I tried to search about differences between classes and structs in C# or .net, I ended up with the conceptual overview of the two things like value type or the reference type, where the variables are allocated etc. But I need some practical differences. I have found some like different behavior of assignment operator, having constructors etc. Can anybody provide some more practical differences which will be directly useful while coding? Like the things works with one but not with other or same operation showing different behavior. And some common mistakes regarding these two. Also please suggest where to consider using a struct instead of a class. And where the structs should not be used.

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  • how design architecture of .NET CF WinForm?

    - by MicTech
    I'm starting with .NET CF WinForm application and I have some experience with .NET WinForm. What is better for UI, form for each dialog or one form and changing user controls on that form? I'm asking for that, because screen on mobile devices are very small and I designed more then ten different screens for my application.

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  • c# binarysearch a list<T> by a member of T

    - by Pygmy
    I have a baseclass Event with a DateTime member TimeStamp. Lots of other event-classes will derive from this. I want to be able to search a list of events (that can contain events with duplicate timestamps) fast, so I'd like to use a binary search. So I started out writing something like this : public class EventList<T> : List<T> where T : Event { private IComparer<T> comparer = (x, y) => Comparer<DateTime>.Default.Compare(x.TimeStamp, y.TimeStamp); public IEnumerable<T> EventsBetween(DateTime inFromTime, DateTime inToTime) { // Find the index for the beginning. int index = this.BinarySearch(inFromTime, comparer); // BLAH REST OF IMPLEMENTATION } } The problem is that the BinarySearch only accepts T (so - an Event type) as parameter, while I want to search based on a member of T - the TimeStamp. What would be a good way to approach this ?

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  • What to name this class?

    - by orlandu63
    (This is not an interface: I simply omitted the method bodies) class _ { protected $_data = array(); function __construct($data); function set($name, $value); function get($name); function __set($name, $value); function __get($name); //aliases for their respective non-magic methods. # and some other generic methods } Essentially it's a class that provides a magical object-oriented reusable access layer to some data. I've considered DataLayer, DataObject and some others; I'd like to hear some suggestions from someone who's more terminologically savvy.

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  • Custom iterator for a class based on two sets

    - by Dan Hook
    I have a class that contains two sets. They both contain the same key type but have different compare operations. I would like to provide an iterator for the class that iterates through the elements of both sets. I want to start with one set, then when I increment an iterator pointing to the last element of the first set, I want to go to the first element of the second set. How do I do this? I would like to preserve the bidirectional iterator semantics of std::set, but if it turns out that implementing a forward iterator is much easier, so be it. I'm willing to use the Boost Iterator library if that would help.

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  • How does this ruby custom accessor work

    - by ennuikiller
    So the method below in class_eval dynamically creates accessors for attributes defined at runtime. It can be used, for example, to create configuration objects with attributes read from a config file (and unknown until runtime). I understanding all of it except for the else branch. If I am correct the else branch returns the attribute value (val[0]) if there is one value passed in *val. However the way its written I would expect it to return an array (val) if there is more then one value passed in *var. In particular, if I have something like the following: value = 5 then from reading the code I would expect "#{@value}" to be [=,5]. However "#{@value}" returns 5 and not the array [=,5]. How is this possible? class Module def dsl_accessor(*symbols) symbols.each do |sym| class_eval %{ def #{sym}(*val) if val.empty? @#{sym} else @#{sym} = val.size == 1 ? val[0] : val end end } end end end

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  • Problem in Report Design Layout

    - by Prasanna
    Hi, I have a jasper report with 4 subreports in the detail band of the master report. If data is available for first subreport, it starts displaying from page 1 with the header of the subreport. When second subreport starts printing data, it prints only header in page 1 and the page breaks and in the page 2, it prints header again n data for that. I dont want the header of the second subreport to be printed in page1. It should start print in the page 2. How to solve this..? How could i page break...? its urgent.Please help. Thanks in advance, Prasanna

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  • Connection string in app.config in a class library

    - by Copeleto
    I am creating solution and inside I have three projects: A WCF Service Library Project A DataAccess Project (Class Library) A Web site for hosting WCF service The implementation of the service is on the project # 1, but in order to access the DataBase I use a second project that implements the data access using a class library project. That problem is in order to get data access I need to configure a connection string, but that connection string must be configurable in a production environment, I meant in production I am going to deploy the site, which is a very simple project that contains only a reference WCF Service Library Project then a guy from database department will configure the connection string. In development I have an app.config on the data access project but when I do the release that app.config is embedded on the dll. Any ideas how can we achieve our purpose

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  • C# ArrayList calling on a constructor class

    - by EvanRyan
    I'm aware that an ArrayList is probably not the way to go with this particular situation, but humor me and help me lose this headache. I have a constructor class like follows: class Peoples { public string LastName; public string FirstName; public Peoples(string lastName, string firstName) { LastName = lastName; FirstName = firstName; } } And I'm trying to build an ArrayList to build a collection by calling on this constructor. However, I can't seem to find a way to build the ArrayList properly when I use this constructor. I have figured it out with an Array, but not an ArrayList. I have been messing with this to try to build my ArrayList: ArrayList people = new ArrayList(); people[0] = new Peoples("Bar", "Foo"); people[1] = new Peoples("Quirk", "Baz"); people[2] = new Peopls("Get", "Gad"); My indexing is apparently out of range according to the exception I get.

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  • expected class,delegate,enum,interface or struct

    - by Luke
    Hello, I am writing a class. I have encountered the problem in the title. Here is the code: class delivery { private string strDeliveryName; private string strDeliveryAddress; private string strDeliveryDay; private string strDeliveryTime; private string strDeliveryMeal; private string strDeliveryInstructions; private string strDeliveryStatus; } public delivery(string deliveryName, string deliveryAddress, string deliveryDay, string deliveryTime, string deliveryMeal, string deliveryInstructions, string deliveryStatus) { strDeliveryName = deliveryName; strDeliveryAddress = deliveryAddress; strDeliveryDay = deliveryDay; strDeliveryTime = deliveryTime; strDeliveryMeal = deliveryMeal; strDeliveryInstructions = deliveryInstructions; strDeliveryStatus = deliveryStatus; } I get the error on the public delivery, any idea why?

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  • Calling different layers from the same class

    - by khalid
    Hi, I am here to seek some help with my code which i am facing a dead end road with. I'm trying to pass values from screen1.java using Intent to screen2.java. Passing the values is fine and I managed to get through it; however, when I check using if statement the program crash down. Here are my files, plzzzzzzzzzzz help screen1.java package test.android; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; public class screen1 extends Activity { static String strKey = "Hello"; static final String strValue = "Hello"; public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.screen1); //** button A Button A = (Button) findViewById(R.id.btnClickA); A.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { Intent i = new Intent(screen1.this, screen2.class); strKey = "NAME"; i.setClassName("packageName", "packageName.IntentClass"); String term = "Hello"; i.putExtra("packageName.term", term); //i.putExtra(strKey, strValue); startActivity(i); } }); //** //** button B Button B = (Button) findViewById(R.id.btnClickB); B.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { Intent i = new Intent(screen1.this, screen3.class); startActivity(i); } }); //** } } screen2.java package test.android; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.Button; public class screen2 extends Activity { public void onCreate(Bundle icicle) { Bundle extras = getIntent().getExtras(); String term = extras.getString("packageName.term"); System.out.println("--- Name is -->"+ term); if(term.equalsIgnoreCase("Hello") || term.equalsIgnoreCase("Name")){ super.onCreate(icicle); setContentView(R.layout.screen3); Button b = (Button) findViewById(R.id.btnClick3); b.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { setResult(RESULT_OK); finish(); } }); } else { super.onCreate(icicle); setContentView(R.layout.screen2); Button b = (Button) findViewById(R.id.btnClick2); b.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { setResult(RESULT_OK); finish(); } }); } // DOES NOT WORK !!!!!!!!! System.out.println("--- Name is --"+ term); } } Layouts: screen1.xml screen2.xml screen3.xml AndroidManifest.xml <activity android:name="screen1" android:label="SCREEN 1"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name="screen2" android:label="SCREEN 2"> </activity> <activity android:name="screen3" android:label="SCREEN 3"> </activity> ===== The error is caused by these lines of code in screen2.java: if(term.equalsIgnoreCase("Hello") || term.equalsIgnoreCase("Name")){ super.onCreate(icicle); setContentView(R.layout.screen3); Button b = (Button) findViewById(R.id.btnClick3); b.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { setResult(RESULT_OK); finish(); } }); } else { super.onCreate(icicle); setContentView(R.layout.screen2); Button b = (Button) findViewById(R.id.btnClick2); b.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { setResult(RESULT_OK); finish(); } }); } **notice if I get rid of the entire IF statement and go with only the ELSE the program works fine.

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  • Calling a method with an instance of derived class of derived generic type

    - by madsbirk
    Okay, so I have classes class B<T> : A<T> class L : K and a method void Method(A<K> a) {...} What I would like to do is this b = new B<L>(); Method(b); //error But it is not possible to b to the correct type. Indeed it is not possible to make this cast A<K> t = new A<L>(); //error I would really like to not have to change the internals of Method. I have no problems making changes to B and/or L. Do I have any options for making some sort of workaround? I guess it should be possible for Method to execute all of its method calls etc. on b, since B derives from A and L derives from K?

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  • Spring Design By Contract: where to start?

    - by Build Monkey
    I am trying to put a "Contract" on a method call. My web application is in Spring 3. Is writing customs Annotations the right way to go. If so, any pointers( I didn't find anything in spring reference docs). Should I use tools like "Modern Jass", JML ...? Again any pointers will be useful. Thanks

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  • Book Recommendation for OO design and TDD

    - by whatispunk
    I know there are a ton of books available on the subject but I want one that is recent and describes OOD in terms of TDD, dependency injection, IoC containers, and mocking frameworks. I realize this question is subjective, but I trust in the opinions of SO-ers and am having difficult using Google to provide any real results. Thanks.

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  • JPA optimistic lock - setting @Version to entity class cause query to include VERSION as column

    - by masato-san
    I'm using JPA Toplink Essential, Netbean6.8, GlassFish v3 In my Entity class I added @Version annotation to enable optimistic locking at transaction commit however after I added the annotation, my query started including VERSION as column thus throwing SQL exception. None of this is mentioned in any tutorial I've seen so far. What could be wrong? Snippet public class MasatosanTest2 implements Serializable { private static final long serialVersionUID = 1L; @Id @Basic(optional = false) @Column(name = "id") private Integer id; @Column(name = "username") private String username; @Column(name = "note") private String note; //here adding Version @Version int version; query used: SELECT m FROM MasatosanTest2 m Internal Exception: com.microsoft.sqlserver.jdbc.SQLServerException Call: SELECT id, username, note, VERSION FROM MasatosanTest2

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  • How to save big "database-like" class in python

    - by Rafal
    Hi there, I'm doing a project with reasonalby big DataBase. It's not a probper DB file, but a class with format as follows: DataBase.Nodes.Data=[[] for i in range(1,1000)] f.e. this DataBase is all together something like few thousands rows. Fisrt question - is the way I'm doing efficient, or is it better to use SQL, or any other "proper" DB, which I've never used actually. And the main question - I'd like to save my DataBase class with all record, and then re-open it with Python in another session. Is that possible, what tool should I use? cPickle - it seems to be only for strings, any other? In matlab there's very useful functionality named save workspace - it saves all Your variables to a file that You can open at another session - this would be vary useful in python!

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  • Advice on software / database design to avoid using cursors when updating database

    - by Remnant
    I have a database that logs when an employee has attended a course and when they are next due to attend the course (courses tend to be annual). As an example, the following employee attended course '1' on 1st Jan 2010 and, as the course is annual, is due to attend next on the 1st Jan 2011. As today is 20th May 2010 the course status reads as 'Complete' i.e. they have done the course and do not need to do it again until next year: EmployeeID CourseID AttendanceDate DueDate Status 123456 1 01/01/2010 01/01/2011 Complete In terms of the DueDate I calculate this in SQL when I update the employee's record e.g. DueDate = AttendanceDate + CourseFrequency (I pull course frequency this from a separate table). In my web based app (asp.net mvc) I pull back this data for all employees and display it in a grid like format for HR managers to review. This allows HR to work out who needs to go on courses. The issue I have is as follows. Taking the example above, suppose today is 2nd Jan 2011. In this case, employee 123456 is now overdue for the course and I would like to set the Status to Incomplete so that the HR manager can see that they need to action this i.e. get employee on the course. I could build a trigger in the database to run overnight to update the Status field for all employees based on the current date. From what I have read I would need to use cursors to loop over each row to amend the status and this is considered bad practice / inefficient or at least something to avoid if you can??? Alternatively, I could compute the Status in my C# code after I have pulled back the data from the database and before I display it on screen. The issue with this is that the Status in the database would not necessarily match what is shown on screen which just feels plain wrong to me. Does anybody have any advice on the best practice approach to such an issue? It helps, if I did use a cursor I doubt I would be looping over more than 1000 records at any given time. Maybe this is such small volume that using cursors is okay?

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