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  • Where does the query language sit within the MVC pattern?

    - by weesilmania
    I'd assume that since the query language sits within the controller (typically) that it belongs to that component, but if I play devil's advocate I'd argue that the query language is execute within the domain of the model, and is tightly coupled to that component so it might also be a part of it. Anyone know the answer? Is there a straight answer or is it technology specific?

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  • When designing an event, is it a good idea to prevent listeners from being added twice?

    - by Matt
    I am creating an event-based API where a user can subscribe to an event by adding listener objects (as is common in Java or C#). When the event is raised, all subscribed listeners are invoked with the event information. I initially decided to prevent adding an event listener more than once. If a listener is added that already exists in the listener collection, it is not added again. However, after thinking about it some more, it doesn't seem that most event-based structures actually prevent this. Was my initial instinct wrong? I'm not sure which way to go here. I guess I thought that preventing addition of an existing listener would help to avoid a common programming error. Then again, it could also hide a bug that would lead to code being run multiple times when it shouldn't.

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  • Mocking a namespace in a partial class.

    - by Nix
    I am messing around with Entity Framework 3.5 SP1 and I am trying to find a cleaner way to do the below. Basically I have an EF model and I am adding some Eager Loaded entities and i want to put them in the partial class context Eager namespace. Currently I am using composition but I feel like there is an easier way to do what I want. namespace Entities{ public partial class TestObjectContext { EagerExtensions Eager { get;set;} public TestObjectContext(){ Eager = new EagerExtensions (this); } } public partial class EagerExtensions { TestObjectContext context; public EagerExtensions(TestObjectContext _context){ context = _context; } public IQueryable<TestEntity> TestEntity { get { return context.TestEntity .Include("TestEntityType") .Include("Test.Attached.AttachedType") .AsQueryable(); } } } } public class Tester{ public void ShowHowIWantIt(){ TestObjectContext context= new TestObjectContext(); var query = from a in context.Eager.TestEntity select a; } }

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  • Several C# Language Questions

    - by Water Cooler v2
    1) What is int? Is it any different from the struct System.Int32? I understand that the former is a C# alias (typedef or #define equivalant) for the CLR type System.Int32. Is this understanding correct? 2) When we say: IComparable x = 10; Is that like saying: IComparable x = new System.Int32(); But we can't new a struct, right? or in C like syntax: struct System.In32 *x; x=>someThing = 10; 3) What is String with a capitalized S? I see in Reflector that it is the sealed String class, which, of course, is a reference type, unlike the System.Int32 above, which is a value type. What is string, with an uncapitalized s, though? Is that also the C# alias for this class? Why can I not see the alias definitions in Reflector? 4) Try to follow me down this subtle train of thought, if you please. We know that a storage location of a particular type can only access properties and members on its interface. That means: Person p = new Customer(); p.Name = "Water Cooler v2"; // legal because as Name is defined on Person. but // illegal without an explicit cast even though the backing // store is a Customer, the storage location is of type // Person, which doesn't support the member/method being // accessed/called. p.GetTotalValueOfOrdersMade(); Now, with that inference, consider this scenario: int i = 10; // obvious System.object defines no member to // store an integer value or any other value in. // So, my question really is, when the integer is // boxed, what is the *type* it is actually boxed to. // In other words, what is the type that forms the // backing store on the heap, for this operation? object x = i; Update Thank you for your answers, Eric Gunnerson and Aaronought. I'm afraid I haven't been able to articulate my questions well enough to attract very satisfying answers. The trouble is, I do know the answers to my questions on the surface, and I am, by no means, a newbie programmer. But I have to admit, a deeper understanding to the intricacies of how a language and its underlying platform/runtime handle storage of types has eluded me for as long as I've been a programmer, even though I write correct code.

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  • db optimization - have a total field or query table?

    - by Dorian Fife
    I have an app where users get points for actions they perform - either 1 point for an easy action or 2 for a difficult one. I wish to display to the user the total number of points he got in my app and the points obtained this week (since Monday at midnight). I have a table that records all actions, along with their time and number of points. I have two alternatives and I'm not sure which is better: Every time the user sees the report perform a query and sum the points the user got Add two fields to each user that records the number of points obtained so far (total and weekly). The weekly points value will be set to 0 every Monday at midnight. The first option is easier, but I'm afraid that as I'll get many users and actions queries will take a long time. The second option bares the risk of inconsistency between the table of actions and the summary values. I'm very interested in what you think is the best alternative here. Thanks, Dorian

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  • DDD: Where to create entity objects?

    - by ciscoheat
    I have three entities that must interact: User, SupportTicketand PhoneConversation. When someone calls in requesting help, the User should have a SupportTicket assigned to him, with a PhoneConversation assigned to the Ticked describing the call. My question is: In what entity should I put the method CreatePhoneSupportTicket() that creates a new SupportTicket and a PhoneConversation, relates them to each other and finally relates the SupportTicket to the User? I'm guessing it can't be on the user because that would violate the SRP (the user does a few more things). But the method itself does more than one thing, it should create both a SupportTicket and a PhoneConversation. Is this a situation when a Service is a better solution then putting methods on entities? Thanks for your help!

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  • Applet networking patterns

    - by Kristoffersen
    Hi SO. I have an applet that connects to a server, it receives some commands and based on that it haves to draw (or move) different things. Which patterns should I use? I assume that the network connection and applet should run in two different threads? Thanks, Kristoffer

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  • The best way to structure this database?

    - by James P
    At the moment I'm doing this: gems(id, name, colour, level, effects, source) id is the primary key and is not auto-increment. A typical row of data would look like this: id => 40153 name => Veiled Ametrine colour => Orange level => 80 effects => +12 sp, +10 hit source => Ametrine (Some of you gamers might see what I'm doing here :) ) But I realise this could be sorted a lot better. I have studied database relationships and secondary keys in my A-Level computing class but never got as far as to set one up properly. I just need help with how this database should be organised, like what tables should have what data with what secondary and foreign keys? I was thinking maybe 3 tables: gem, effects, source. Which then have relationships to each other? Can anyone shed some light on this? Is a complex way like I'm proposing really the way to go or should I just carry on with what I'm doing? Cheers.

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  • How to handle product ratings in a database

    - by Mel
    Hello, I would like to know what is the best approach to storing product ratings in a database. I have in mind the following two (simplified, and assuming a MySQL db) scenarios: Scenario 1: Create two columns in the product table to store number of votes and the sum of all votes. Use columns to get an average on the product display page: products(productedID, productName, voteCount, voteSum) Pros: I will only need to access one table, and thus execute one query to display product data and ratings. Cons: Write operations will be executed in a table whose original purpose is only to furnish product data. Scenario 2: Create an additional table to store ratings. products(productID, productName) ratings(productID, voteCount, voteSum) Pros: Isolate ratings into a separate table, leaving the products table to furnish data on available products. Cons: I will have to execute two separate queries on product page requests (one for data and another for ratings). In terms of performance, which of the following two approaches is best: Allow users to execute an occasional write query to a table that will handle hundreds of read requests? Execute two queries at every product page, but isolate the write query into a separate table. I'm a novice to database development, and often find myself struggling with simple questions such as these. Many thanks,

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  • Writing my own implementation of stl-like Iterator in C++.

    - by Negai
    Good evening everybody, I'm currently trying to understand the intrinsics of iterators in various languages i.e. the way they are implemented. For example, there is the following class exposing the list interface. template<class T> class List { public: virtual void Insert( int beforeIndex, const T item ) throw( ListException ) =0 ; virtual void Append( const T item ) =0; virtual T Get( int position ) const throw( ListException ) =0; virtual int GetLength() const =0; virtual void Remove( int position ) throw( ListException ) =0; virtual ~List() =0 {}; }; According to GoF, the best way to implement an iterator that can support different kinds of traversal is to create the base Iterator class (friend of List) with protected methods that can access List's members. The concrete implementations of Iterator will handle the job in different ways and access List's private and protected data through the base interface. From here forth things are getting confusing. Say, I have class LinkedList and ArrayList, both derived from List, and there are also corresponding iterators, each of the classes returns. How can I implement LinkedListIterator? I'm absolutely out of ideas. And what kind of data can the base iterator class retrieve from the List (which is a mere interface, while the implementations of all the derived classes differ significantly) ? Sorry for so much clutter. Thanks.

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  • Why is there "data" and "newtype" in Haskell?

    - by martingw
    To me it seems that a newtype definition is just a data definition that obeys some restrictions (only one constructor and such), and that due to these restrictions the runtime system can handle newtypes more efficiently. Ok, and the handling of pattern matching for undefined values is slightly different. But suppose Haskell would only knew data definitions, no newtypes: Couldn't the compiler find out for himself whether a given data definition obeys these restrictions, and automatically treat it more efficiently? I'm sure I'm missing out on something, these Haskell designers are so clever, there must be some deeper reason for this...

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  • C++0x implementation guesstimates?

    - by dsimcha
    The C++0x standard is on its way to being complete. Until now, I've dabbled in C++, but avoided learning it thoroughly because it seems like it's missing a lot of modern features that I've been spoiled by in other languages. However, I'd be very interested in C++0x, which addresses a lot of my complaints. Any guesstimates, after the standard is ratified, as to how long it will take for major compiler vendors to provide reasonably complete, production-quality implementations? Will it happen soon enough to reverse the decline in C++'s popularity, or is it too little, too late? Do you believe that C++0x will become "the C++" within a few years, or do you believe that most people will stick to the earlier standard in practice and C++0x will be somewhat of a bastard stepchild, kind of like C99?

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  • 4GB limitation on these embedded/express DBs good enough? what's next if limitation is reached?

    - by edwin.nathaniel
    I'm wondering how long a (theoretically) desktop-app can consume the full 4GB limitation of these express/embedded database products (SQL-Server Express, Oracle Express, SQLite3, etc) provided that big blobs will be stored in filesystem. Also what would be your strategy when it hits the 4GB? Archive the old DB Copy 1-3 months of data to the new DB (consider this as cache strategy?) Start using the new DB from this point onward (How do you access the old data?) I understand that the answer might varies depending on how much data you stored in the table/column. But please describe based on your experience (what kind of desktop-app, write/read heavy, how long will it reach according to your guess).

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  • When to use basic types (Integer, String), and when to write a new class?

    - by belgarat
    Stackoverflow users: A lot of things can be represented in programs by using the basic types, or we can create a new class for it. Example: A social security number can be a number, string or its own object. (Other common examples: Phone numbers, names, zip codes, user id, order id and other id's.) My question is: When should the basic types be used, and when should we write ourselves a new class? I see that when you need to add behavior, you'll want to create a class (example, social security number parsing, validation, formatting, etc). But is this the only criteria? I have come across cases where many of these things are represented as java Integers and/or Strings. We loose the benefit of type-checking, and I have often seen bugs caused by parameters being mixed in calls to function(Intever, Integer, Integer, Integer). On the other hand, some programmers are opposed to over-designing by creating classes for "eveything". Obviously, the answer is "it depends". But, what do you think, and what do you normally do?

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  • does anyone see any issues with this thread pattern?

    - by prmatta
    Here is a simple thread pattern that I use when writing a class that needs just one thread, and needs to a specific task. The usual requirements for such a class are that it should be startable, stopable and restartable. Does anyone see any issues with this pattern that I use? public class MyThread implements Runnable { private boolean _exit = false; private Thread _thread = null; public void start () { if (_thread == null) { _thread = new Thread(this, "MyThread"); _thread.start(); } } public void run () { while (_exit) { //do something } } public void stop () { _exit = true; if (_thread != null) { _thread.interrupt(); _thread = null; } } } I am looking for comments around if I am missing something, or if there is a better way to write this.

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  • How to simplify the code?

    - by Tattat
    I have objectA, and objectB.... also I have objectAs, and objectBs. the objectA is only have the init method, and ObjectAs have somethings like this: #import "ObjectAs.h" @implementation ObjectAs @synthesize objectAs; -(id) init{ if( (self=[super init])) { self.objectAs = [[NSMutableArray alloc] init]; } return self; } -(int)getObjectAsNumber{ return [self.objectAs count]; } -(void)addObjectA:(ObjectA *)newObjectA{ [self.objectAs addObject:newObjectA]; } -(id)getObjectAByIdx:(int)objectAIdx{ return [self.objectAs objectAtIndex:objectAIdx]; } -(void)dealloc{ [super dealloc]; [objectAs release]; } @end The objectBs have similar have, I know that I can copy and paste, and replace it. Is there any way to simplify the objectBs, and objectAs? thz a lot.

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  • what is main focus for a developer when coding?

    - by ajsie
    i read a lot of books about how to code right and usually the are talking about all these techniques from a point of view i can't understand. eg. lets consider the singleton pattern. i'm restricting so the class can only be instantiated once. but since it's only me creating the application, if i know that the class only should be instantiated once, then why would i create it a second time? i feel like missing the big picture. what is my main goal when coding an application? how should i think? thanks

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  • Do null SQLite Data fields take up extra memory?

    - by CSharperWithJava
    I'm using the built in sqlite library on the Android platform. I'm considering adding several general purpose fields that users will be able to use for their own custom applications, but these fields will be blank most of the time. My question is, how much overhead will these blank fields add to my database? Do null fields even take up per record memory in sqlite? If so, how much? I don't quite understand the inner workings of a sqlite database.

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  • Changes to data inside class not being shown when accessed from outside class.

    - by Hypatia
    I have two classes, Car and Person. Car has as one of its members an instance of Person, driver. I want to move a car, while keeping track of its location, and also move the driver inside the car and get its location. However, while this works from inside the class (I have printed out the values as they are calculated), when I try to access the data from main, there's nothing there. I.e. the array position[] ends up empty. I am wondering if there is something wrong with the way I have set up the classes -- could it be a problem of the scope of the object? I have tried simplifying the code so that I only give what is necessary. Hopefully that covers everything that you would need to see. The constructer Car() fills the offset array of driver with nonzero values. class Car{ public: Container(float=0,float=0,float=0); ~Container(); void move(float); void getPosition(float[]); void getDriverPosition(float[]); private: float position[3]; Person driver; float heading; float velocity; }; class Person{ public: Person(float=0,float=0,float=0); ~Person(); void setOffset(float=0,float=0,float=0); void setPosition(float=0,float=0,float=0); void getOffset(float[]); void getPosition(float[]); private: float position[3]; float offset[3]; }; Some of the functions: void Car::move(float time){ float distance = velocity*time; location[0] += distance*cos(PI/2 - heading); location[1] += distance*sin(PI/2 - heading); float driverLocation [3]; float offset[3]; driver->getOffset(offset); for (int i = 0; i < 3; i++){ driverLocation[i] = offset[i] + location[i]; } } void Car::getDriverPosition(float p[]){ driver.getPosition(p); } void Person::getPosition(float p[]){ for (int i = 0; i < 3; i++){ p[i] = position[i]; } } void Person::getOffset(float o[]){ for (int i = 0; i < 3; i++){ o[i] = offset[i]; } } In Main: Car * car = new Car(); car->move(); float p[3]; car->getDriverPosition(p); When I print driverLocation[] inside the move() function, I have actual nonzero values. When I print p[] inside main, all I get are zeros.

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  • What considerations should be made when creating a reporting framework for a business?

    - by Andrew Dunaway
    It's a pretty classic problem. The company I work for has numerous business reports that are used to track sales, data feeds, and various other metrics. Of course this also means that there is a conglomerate of disparate frameworks, ASP.net pages, and areas where these reports can be found. There have been some attempts at consolidating these into a single entity, but nothing has stuck yet. Since this is a common problem, and I am sure solved innumerable times, I wanted to see what others have done. For the most part these can be boiled down to the following pieces: A SQL query against our database to gather data A presentation of data, generally in a data grid Filtering that can vary based on data types and the business needs Some way to organize the reports, a single drop down gets long and unmanageable quickly A method to download data to alter further, perhaps a csv file My first thought was to create a framework in Silverlight with Linq to Sql. Mainly just because I like it and want to play with it which probably is not the best reason. I also thought the controls grant a lot of functionality like sorting, dragging columns, etc. I was also curious about the printing in Silverlight 4. Which brings me around to my original question, what is the best way to do this? Is there a package out there I can just buy that will do it for me? The Silverlight approach seems pretty easy, after it's setup and templated, but maybe it's a bad idea and I can learn from someone else?

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  • Table in DB for generating primary keys?

    - by Sapphire
    Do you ever use a separate table for "generating" artificial primary keys for DB (and why)? What I mean is to have a table with two columns, table name and current ID - with which you could get new "ID" for some table by simply locking the row with that table name, getting the current value of the key, increment it by one, and unlock the row. Why would you prefer this over standard integer identity column? P.S. The "idea" is from Fowlers Patterns of Enterprise Application Architecture, btw...

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