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  • doubleton pattern in C++

    - by benjamin button
    I am aware of the singleton pattern in C++. but what is the logic to get two instances of the object? is there any such pattern where we could easily get 2 pattern. for the logic i could think of is that i can change the singleton pattern itself to have two objects created inside the class.this works. but if the requirement grows like if i need only 3 or only 4 what is the deswign pattern that i could think of to qualify such requirement?

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  • Meaning of Primary Key to Microsoft SQL Server 2008

    - by usr
    What meaning does the concept of a primary key have to the database engine of SQL Server? I don't mean the clustered/nonclustered index created on the "ID" column, i mean the constraint object "primary key". Does it matter if it exists or not? Alternatives: alter table add primary key clustered alter table create clustered index Does it make a difference?

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  • What is the basic pattern for using (N)Hibernate?

    - by Vilx-
    I'm creating a simple Windows Forms application with NHibernate and I'm a bit confused about how I'm supposed to use it. To quote the manual: ISession (NHibernate.ISession) A single-threaded, short-lived object representing a conversation between the application and the persistent store. Wraps an ADO.NET connection. Factory for ITransaction. Holds a mandatory (first-level) cache of persistent objects, used when navigating the object graph or looking up objects by identifier. Now, suppose I have the following scenario: I have a simple classifier which is a MSSQL table with two columns - ID (auto_increment) and Name (nvarchar). To edit this classifier I create a form which contains a single gridview and two buttons - OK and Cancel. The user can nearly directly edit the table in the gridview, and when he hits OK the changes he made are persisted to the DB (or if he hits cancel, nothing happens). Now, I have several questions about how to organize this: What should the lifetime of my ISession be? Should I create a single ISession for my whole application; an ISession for each of my forms (the application is single-threaded MDI); or an ISession for every DB operation/transaction? Does NHibernate offer some kind of built-in dirty tracking or must I do this myself? The manual mentions something like it here and there but does not go into details. How is this done? Is there not a huge overhead? Is it somehow tied with the cache(s) that NHibernate has? What are these caches for? Are they not specific to a single ISession? That is, if I use a seperate ISession for every transaction, won't it break the dirty tracking? How does the built-in dirty tracking detect deleted objects?

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  • How to easily substitute a Base class

    - by JTom
    Hi, I have the following hierarchy of classes class classOne { virtual void abstractMethod() = 0; }; class classTwo : public classOne { }; class classThree : public classTwo { }; All classOne, classTwo and classThree are abstract classes, and I have another class that is defining the pure virtual methods class classNonAbstract : public classThree { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; And right now I need it differently...I need it like class classNonAbstractOne : public classOne { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; class classNonAbstractTwo : public classTwo { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; and class classNonAbstractThree : public classThree { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; But all the nonAbstract classes have the same new methods, with the same code...and I would like to avoid copying all the methods and it's code to every nonAbstract class. How could I accomplish that? Hopefully it's understandable...

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  • css sprite button is jumping around

    - by Richard
    Hello everyone, Does anyone know what is causing the sprite rollover to jump around It is I think more likely a photoshop question, but I am not completely sure. I hope to get an answer here anyway, since I think most webdesigners/programmers problably worked with photoshop also. This is what I want the rollover to do example 1 and this is my testpage (see the play button) I made the sprite with spriteme.com thanks, Richard

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  • If you are forced to use an Anemic domain model, where do you put your business logic and calculated

    - by Jess
    Our current O/RM tool does not really allow for rich domain models, so we are forced to utilize anemic (DTO) entities everywhere. This has worked fine, but I continue to struggle with where to put basic object-based business logic and calculated fields. Current layers: Presentation Service Repository Data/Entity Our repository layer has most of the basic fetch/validate/save logic, although the service layer does a lot of the more complex validation & saving (since save operations also do logging, checking of permissions, etc). The problem is where to put code like this: Decimal CalculateTotal(LineItemEntity li) { return li.Quantity * li.Price; } or Decimal CalculateOrderTotal(OrderEntity order) { Decimal orderTotal = 0; foreach (LineItemEntity li in order.LineItems) { orderTotal += CalculateTotal(li); } return orderTotal; } Any thoughts?

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  • Database solutions for storing/searching EXIF data

    - by webdestroya
    I have thousands of photos on my site (each with a numeric PhotoID) and I have EXIF data (photos can have different EXIF tags as well). I want to be able to store the data effectively and search it. Some photos have more EXIF data than others, some have the same, so on.. Basically, I want to be able to query say 'Select all photos that have a GPS location' or 'All photos with a specific camera' I can't use MySQL (tried it, it doesn't work). I thought about Cassandra, but I don't think it lets me query on fields. I looked at SimpleDB, but I would rather: not pay for the system, and I want to be able to run more advanced queries on the data. Also, I use PHP and Linux, so it would be awesome if it could interface nicely to PHP. Any ideas?

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  • Time/resource allocation on a Stylish vs. Functional user interface

    - by jasonk
    When developing applications how much focus/time do you place on an application’s style vs. functionality. Battleship gray apps drive me insane. On the other hand maximizing a business application’s "style" can tax time and financial resources. Applications need to be appealing to resell or meet basic customer expectations, but defining a healthy medium can be difficult. What would you say are reasonable "standards" for allocating develop time/resources should be dedicated to stylizing a business application?

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  • Optional Member Objects

    - by David Relihan
    Okay, so you have a load of methods sprinkled around your systems main class. So you do the right thing and refactor by creating a new class and perform move method(s) into a new class. The new class has a single responsibility and all is right with the world again: class Feature { public: Feature(){}; void doSomething(); void doSomething1(); void doSomething2(); }; So now your original class has a member variable of type object: Feature _feature; Which you will call in the main class. Now if you do this many times, you will have many member-objects in your main class. Now these features may or not be required based on configuration so in a way it's costly having all these objects that may or not be needed. Can anyone suggest a way of improving this? At the moment I plan to test in the newly created class if the feature is enabled - so the when a call is made to method I will return if it is not enabled. I could have a pointer to the object and then only call new if feature is enabled - but this means I will have to test before I call a method on it which would be potentially dangerous and not very readable. Would having an auto_ptr to the object improve things: auto_ptr<Feature> feature; Or am I still paying the cost of object invokation even though the object may\or may not be required. BTW - I don't think this is premeature optimisation - I just want to consider the possibilites.

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  • Updating multiple tables with LinqToSql in one unit of work

    - by zsharp
    Table 1: int ID-a(pk) Table 2: int ID-a(pk), int ID-b(pk) Table 3: int ID-b(pk), string C I have the data to insert into Table 1. But I do not have the ID-a, which is autogenerated. I have many string C to insert in Table 3. I am trying to insert row into Table 1, get the ID-a to insert in Table 2 along with the ID-b that is auto-Generated in Table 3 when I submit each string C, all in one submission to db. Right now I am calling dc.SubmitChanges twice in same call. Is it efficient to have to submit changes twice on same DataContext or can this be combined further?

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  • IE8 displays white page when adding Javascript

    - by Chris
    I recently created a website and added some jQuery into it. However doing this makes IE8 display a white page. Whenever I remove the Javascript IE8 renders the site fine. I have tested locally as well as on the internet, the problem still persists. This is my code to include my .js files: <script type="text/javascript" src="jQuery/jQuery.js" /> <script type="text/javascript" src="jQuery/effects.js" />

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  • Best way to plan a task ?

    - by Indigo Praveen
    Hi All, As I am very new to programming, I am very curious about learning the best ways/practices of programming. Whenever I want to write any program , I strat directly with coding while some guys say that you should plan your program first before starting the code. But I don't understand the real value of creating the class diagrams and all that kind of stuff coz I think that ultimately I have to write the code. Can you guys please share your experiences about how you are doing your programming means what is your first step when you start an application.

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  • Fixed footer with 960.gs

    - by Oguz
    I want to create fixed footer but , is it possible with 960 gs , because I am having trouble with height of container div . I can no set it to %100. <div class="container_12" > <div class="grid_3" id="side-space"></div> <div class="grid_6"> <div id="content-box"></div> </div> <div class="grid_3" id="side-space"></div> </div>

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  • SEO with image link alt text vs standard text-based link

    - by Infiniti Fizz
    Hi, I'm currently developing a website and the main navigation is made up of image links because the font used for them isn't standard. My client's only worry is will this mess up search engine optimization? Can I just add alt text to the images like "link 1" or use the name attribute of the anchor tag? Or would it be better to just have the navigation as anchor tags with the names of the links in them like: <a href="...">link 1</a>? I'm new to SEO so really don't know which to suggest to him, Thanks for your time, InfinitiFizz

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  • Any tips of how to handle hierarchical trees in relational model?

    - by George
    Hello all. I have a tree structure that can be n-levels deep, without restriction. That means that each node can have another n nodes. What is the best way to retrieve a tree like that without issuing thousands of queries to the database? I looked at a few other models, like flat table model, Preorder Tree Traversal Algorithm, and so. Do you guys have any tips or suggestions of how to implement a efficient tree model? My objective in the real end is to have one or two queries that would spit the whole tree for me. With enough processing i can display the tree in dot net, but that would be in client machine, so, not much of a big deal. Thanks for the attention

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  • Inheritance: when implementing an interface which define a base class property why cant the class im

    - by Deepak
    Lets create some interfaces public interface ITimeEventHandler { string Open(); } public interface IJobTimeEventHandler: ITimeEventHandler { string DeleteJob(); } public interface IActivityTimeEventHandler: ITimeEventHandler { string DeleteActivity(); } public interface ITimeEvent { ITimeEventHandler Handler; } Another Interface public interface IJobTimeEvent :ITimeEvent { int JobID; } Create a class public class JobTimeEvent : IJobTimeEvent { public int JobID = 0; public IJobTimeEventHandler Handler = null; } My question is .. when implementing an interface which define a base class property why cant the class implementing interface return a derived class type object ?? For ex in class JobTimeEvent, IJobtimeEvent needs a property of type ITimeEventHandler but why IJobTimeEventHandler type is not allowed which derived from ITimeEventHandler

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  • Looking for Suggestion on Multi-Consumer Service Development

    - by DaveDev
    How would I model a system that needs to be able to provide content in a format that would be consumable by iphone, Android or web browser (or whatever). All a new consumer would have to do is build a UI with rules on how to handle the data. I'm thinking something RESTful returning JSON or something. I'm really looking for suggestions on the kinds of things I'd need to learn in order to be able to implement a system on this scale. As an ASP.NET MVC developer, would that be the best framework/archetectrue to go with? Thanks

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  • How to secure authorization of methods

    - by Kurresmack
    I am building a web site in C# using MVC.Net How can I secure that no unauthorized persons can access my methods? What I mean is that I want to make sure that only admins can create articles on my page. If I put this logic in the method actually adding this to the database, wouldn't I have business logic in my data layer? Is it a good practise to have a seperate security layer that is always in between of the data layer and the business layer to make? The problem is that if I protect at a higher level I will have to have checks on many places and it is more likely that I miss one place and users can bypass security. Thanks!

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  • [NEWVERSION]algorithm || method to write prog[UNSOLVED] [closed]

    - by fatai
    I am one of the computer science student. Everyone solve problem with a different or same method, ( but actually I dont know whether they use method or I dont know whether there are such common method to approach problem.) if there are common method, What is it ? If there are different method, which method are you using ? All teacher give us problem which in simple form sometimes, but they donot introduce any approach or method(s) so that we cannot make a decision to choose the method then apply that one to problem , afterward find solution then write code.No help from teacher , push us to find method to solve homework. Ex: my friend is using no method , he says "I start to construct algorithm while I try to write prog." I have found one method when I failed the course, More accurately, my method: When I counter problem in language , I will get more paper and then ; first, input/ output step ; my prog will take this / these there argument(s) and return namely X , ex : in c, input length is not known and at same type , so I must use pointer desired output is in form of package , so use structure second, execution part ; in that step , I am writing all step which are goes to final output ex : in python ; 1.) [ + , [- , 4 , [ * , 1 , 2 ]], 5] 2.) [ + , [- , 4 , 2 ],5 ] 3.) [ + , 2 , 5] 4.) 7 ==> return 7 third, I will write test code ex : in c++ input : append 3 4 5 6 vector_x remove 0 1 desired output vector_x holds : 5 6 now, my other question is ; What is/are other method(s) which have/has been; used to construct class :::: for c++ , python, java used to communicate classes / computers used for solving embedded system problem ::::: for c by other user? Some programmer uses generalized method without considering prog-language(java , perl .. ), what is this method ? Why I wonder , because I learn if you dont costruct algorithm on paper, you may achieve your goal. Like no money no lunch , I can say no algorithm no prog therefore , feel free when you write your own method , a way which is introduced by someone else but you are using and you find it is so efficient

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  • Patterns to implement this grammar into C# code

    - by MexicanHacker
    Hey guys, I'm creating this little BNF grammar and I wanted to <template>::= <types><editors> <types>::= <type>+ <type>::= <property>+ <property>::= <name><type> <editors>::= <editor>+ <editor>::= <name><type>(<textfield>|<form>|<list>|<pulldown>)+ <textfield>::= <label><property>[<editable>] <form>::= <label><property><editor> <list>::= <label><property><item-editor> <pulldown>::= <label><property><option>+ <option>::= <value> One possible solution we have in mind is to create POCO's that have annotations of the XMLSerialization namespace, like this, for example: [XMLRoot("template")] public class Template{ [XMLElement("types")] public Types types{ } } However I want to explore more solutions, what do you guys think?

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  • How to pass data to another droid device when the other device isn't expecting it

    - by James Black
    I am working on an application and one feature that would make it really useful is the ability to share some information, but the other device may not be expecting the data to be sent. For example, if I am reading a really good book, and I realize that a friend may like it, I could use an application to send the data to him, so he could order the book from Amazon. But, since he isn't expecting the data, I would hate for the application to be polling a server every so often, as that will be needlessly draining the battery. Ideally it would be great if there was a way to make a phone call to the target device, send a data packet and end the call. If it could be done and prevent the phone from ringing, then it would be very useful to me. I am curious if there is some way to send data between devices without polling.

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  • Cpp some basic problems

    - by DevAno1
    Hello. My task was as follows : Create class Person with char*name and int age. Implement contructor using dynamic allocation of memory for variables, destructor, function init and friend function show. Then transform this class to header and cpp file and implement in other program. Ok so I've almost finished my Person class, but I get error after destructor. First question is how to write this properly ? #include <iostream> using namespace std; class Person { char* name; int age; public: int * take_age(); Person(){ int size=0; cout << "Give length of char*" << endl; cin >> size; name = new char[size]; age = 0; } ~Person(){ cout << "Destroying resources" << endl; delete *[] name; delete * take_age(); } friend void(Person &p); int * Person::take_age(){ return age; } void init(char* n, int a) { name = n; age = a; } void show(Person &p){ cout << "Name: " << p.name << "," << "age: " << p.age << endl; } }; int main(void) { Person *p = new Person; p->init("Mary", 25); p.show(); system("PAUSE"); return 0; } And now with header/implementation part : - do I need to introduce constructor in header/implementation files ? If yes - how? - my show() function is a friendly function. Should I take it into account somehow ? I already failed to return this task on my exam, but still I'd like to know how to implement it.

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