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• Revisions: algorithm and data structure

  - by SODA

  Hi, I need ideas for structuring and processing data with revisions. For example, I have a database of objects (e.g. cars). Each object has a number of properties, which can be arbitrary, so there's no a set schema to describe these objects. These objects are probably saved as key-value pairs. Now I need to change property of an object. I don't want to completely rewrite it - I want to be able to go back and see history of changes to these properties, that's why I want to add new property and keep the old one (so I guess a timestamp would do the job of telling which property is the latest). At the same time I want to be able to get info about any object in a snap, with only latest versions of each of the properties. Any ideas what would be the best approach? At least please point me in the right direction. Thanks!

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• How to implement Auto_Increment per User, on the same table?

  - by Jonas

  I would like to have multiple users that share the same tables in the database, but have one auto_increment value per user. I will use an embedded database, JavaDB and as what I know it doesn't support this functionality. How can I implement it? Should I implement a trigger on inserts that lookup the users last inserted row, and then add one, or are there any better alternative? Or is it better to implement this in the application code? Or is this just a bad idea? I think this is easier to maintain than creating new tables for every user. Example: table +----+-------------+---------+------+ | ID | ID_PER_USER | USER_ID | DATA | +----+-------------+---------+------+ | 1 | 1 | 2 | 3454 | | 2 | 2 | 2 | 6567 | | 3 | 1 | 3 | 6788 | | 4 | 3 | 2 | 1133 | | 5 | 4 | 2 | 4534 | | 6 | 2 | 3 | 4366 | | 7 | 3 | 3 | 7887 | +----+-------------+---------+------+ SELECT * FROM table WHERE USER_ID = 3 +----+-------------+---------+------+ | ID | ID_PER_USER | USER_ID | DATA | +----+-------------+---------+------+ | 3 | 1 | 3 | 6788 | | 6 | 2 | 3 | 4366 | | 7 | 3 | 3 | 7887 | +----+-------------+---------+------+ SELECT * FROM table WHERE USER_ID = 2 +----+-------------+---------+------+ | ID | ID_PER_USER | USER_ID | DATA | +----+-------------+---------+------+ | 1 | 1 | 2 | 3454 | | 2 | 2 | 2 | 6567 | | 4 | 3 | 2 | 1133 | | 5 | 4 | 2 | 4534 | +----+-------------+---------+------+

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• Why state cannot be part of Presenter in MVP?

  - by rFactor

  I read http://www.codeproject.com/KB/architecture/MVC_MVP_MVVM_design.aspx and it said: As powerful as they are, both MVC and MVP have their problems. One of them is persistence of the View’s state. For instance, if the Model, being a domain object, does not know anything about the UI, and the View does not implement any business logic, then where would we store the state of the View’s elements such as selected items? Fowler comes up with a solution in the form of a Presentation Model pattern. I wonder why Presenter can't hold View state? It already holds all View logic. As far as I understand, in MVC and MVP the state is kept in View. In PM and MVVM the state is kept in the Presentation Model. Why can't Presenter follow PM in this particular case and contain the state of the view? Here is another article which says Presenter does not hold View state, instead the view does: http://www.codeproject.com/KB/aspnet/ArchitectureComparison.aspx

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• Sorting data by relevance, from multiple tables

  - by Oden

  Hey, How is it possible to sort data from multiple tables by relevance? My table structure is following: I have 3 tables in my database, one table contains the name of solar systems, the second for e.g. of planets. There is one more table, witch is a connection between solar systems and planets. If I want to get data of a planet, witch is in the Milky Way, i post this data to the server, and it gives me a multi-dimensional array witch contains: The Milky Way, with every planet in it Every planet, witch name contains the string Milky Way (maybe thats a bat example because i don't think that theres but one planet with this name, but the main concept is on file) But, i want to set the most relevant restaurants to the top of the array. (for the relevance i would check the description of the restaurants or something like that) So, how would you do that kind of data sorting?

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• I want define tables from a part of my ER Diagram.

  - by M R Jafari

  I have a ER-Diagram (Show in http://www.4freeimagehost.com/show.php?i=f82997ca4d5d.png). In the diagram you see 2 entities and a 1:N relataion together. Project has 2 columns as ProjectID, ProjectName. Employee has 3 colums as EmployeeID, EmployeeName and ProjectID. A project has ONLY 1 project-manager and project-manager is a employee. What columns add them?

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• Perls Of Wisdom For a .Net Programmer [closed]

  - by DeanMc

  Hi Guys, I like to think that recently I have moved from complete beginner to beginner. It has been a hard road and one on which I took many wrong turns. Very rarely in any profession is there a place where so many rock stars gather, this is something I would like to take advantage of. What I would like to ask is what are your perls of wisdom for a .net programmer. They can be anything you feel of value, a concept, a book, a process that should be followed, anything of that nature, it doesn't have to be .net specific just contextual. Thanks for taking the time to read this and respond.

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• How do you create your own drag-n-drop GUI designer ?

  - by panzerschreck

  Hello I was looking at creating a UI for developing web forms, similar to the Netbeans Visual JSF form designer.It will be targeted to use GWT/GXT components.I am looking at a look very similar to VS/Netbeans. Any thoughts on where/how to start ? Initially, I would prefer to have it as a standalone application, later develop it as eclipse plugin. I have already evaluated the extjs designer and the eclipse plugin from instantiations, but i would prefer to have it developed on my own, as it looks challenging, Also, I have few custom components that have been developed. Thanks

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• "FirstName" and "LastName" store in database USER or USER_PROFILE table?

  - by Khou

  Currently I store the user's "FirstName" and "LastName" in the USER table, but i also have a USER PROFILE table (which provides additional information about the user) and it would makes sense to have the user's "FirstName" and "LastName" in the USER PROFILE table aswell. So what do i do? make two copies of "FirstName" and "LastName"?

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• C++: calling non-member functions with the same syntax of member ones

  - by peoro

  One thing I'd like to do in C++ is to call non-member functions with the same syntax you call member functions: class A { }; void f( A & this ) { /* ... */ } // ... A a; a.f(); // this is the same as f(a); Of course this could only work as long as f is not virtual (since it cannot appear in A's virtual table. f doesn't need to access A's non-public members. f doesn't conflict with a function declared in A (A::f). I'd like such a syntax because in my opinion it would be quite comfortable and would push good habits: calling str.strip() on a std::string (where strip is a function defined by the user) would sound a lot better than calling strip( str );. most of the times (always?) classes provide some member functions which don't require to be member (ie: are not virtual and don't use non-public members). This breaks encapsulation, but is the most practical thing to do (due to point 1). My question here is: what do you think of such feature? Do you think it would be something nice, or something that would introduce more issues than the ones it aims to solve? Could it make sense to propose such a feature to the next standard (the one after C++0x)? Of course this is just a brief description of this idea; it is not complete; we'd probably need to explicitly mark a function with a special keyword to let it work like this and many other stuff.

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• multiple classes with same methods - best pattern

  - by Tony

  I have a few classes in my current project where validation of Email/Website addresses is necessary. The methods to do that are all the same. I wondered what's the best way to implement this, so I don't need to have these methods copy pasted everywhere? The classes themselves are not necessarily related, they only have those validation methods in common.

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• Building a professional company website

  - by Sphynx

  Hi fellows, I want to create a professional website for my company. I'm not a designer. I know some html/css, but I don't have much experience making up advanced pages and layouts. I'd expect public area, with various articles, and a "customer zone", accessible via username and password, where clients will be able to track their orders and download files. It needs to look very modern. I don't want to use website templates, because they're too simple. I know some Wordpress, but that's mostly for blogs, and anyways you need to find a right theme besides the CMS itself... Is there any alternative solution, some kind of framework for building such portals? Preferably a system that doesn't require designer skills. Thanks!

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• Immutable classes in C++

  - by ereOn

  Hi, In one of my projects, I have some classes that represent entities that cannot change once created, aka. immutable classes. Example : A class RSAKey that represent a RSA key which only has const methods. There is no point changing the existing instance: if you need another one, you just create one. My objects sometimes are heavy and I enforced the use of smart pointers to avoid copy. So far, I have the following pattern for my classes: class RSAKey : public boost::noncopyable, public boost::enable_shared_from_this<RSAKey> { public: /** * \brief Some factory. * \param member A member value. * \return An instance. */ static boost::shared_ptr<const RSAKey> createFromMember(int member); /** * \brief Get a member. * \return The member. */ int getMember() const; private: /** * \brief Constructor. * \param member A member. */ RSAKey(int member); /** * \brief Member. */ const int m_member; }; So you can only get a pointer (well, a smart pointer) to a const RSAKey. To me, it makes sense, because having a non-const reference to the instance is useless (it only has const methods). Do you guys see any issue regarding this pattern ? Are immutable classes something common in C++ or did I just created a monster ? Thank you for your advices !

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• Adobe File Type Icons (.png)

  - by kilrizzy

  Does anybody know where i can find a list of Adobe icons? Not for the programs themselves but the recognized file types. ie: http://blogs.adobe.com/typblography/cs5icons/CS5_file_swf.png Or does anyone know where the .ico might be stored on a windows 7 machine?

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• In a star schema, are foreign key constraints between facts and dimensions neccessary?

  - by Garett

  I'm getting my first exposure to data warehousing, and I’m wondering is it necessary to have foreign key constraints between facts and dimensions. Are there any major downsides for not having them? I’m currently working with a relational star schema. In traditional applications I’m used to having them, but I started to wonder if they were needed in this case. I’m currently working in a SQL Server 2005 environment.

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• Java compilers or JVM languages that support goto?

  - by unknown

  Is there a java compiler flag that allows me to use goto as a valid construct? If not, are there any third-party java compilers that supports goto? If not, are there any other languages that support goto while at the same time can easily call methods written in Java? The reason is I'm making a language that is implemented in Java. Gotos are an important part of my language; I want to be able to compile it to native or JVM bytecode, although it has to be able to easily use Java libraries (ie. C supports goto, but to use it I'd have to rewrite the libraries in C). I want to generate C or Java, etc source files, and not bytecode or machine code. I'm using a third-party compiler to do that.

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• MyController class must produce class according to the enum type.

  - by programmerist

  GenoTipController must produce class according to the enum type. i have 3 class: _Company,_Muayene,_Radyoloji. Also i have CompanyView Class GetPersonel method. if you look GenoTipController my codes need refactoring. Can you understand me? i need a class according to ewnum type must me produce class. For example; case DataModelType.Radyoloji it must return radyoloji= new Radyoloji . Everything must be one switch case? public class GenoTipController { public _Company GenerateCompany(DataModelType modeltype) { _Company company = null; switch (modeltype) { case DataModelType.Radyoloji: break; case DataModelType.Satis: break; case DataModelType.Muayene: break; case DataModelType.Company: company = new Company(); break; default: break; } return company; } public _Muayene GenerateMuayene(DataModelType modeltype) { _Muayene muayene = null; switch (modeltype) { case DataModelType.Radyoloji: break; case DataModelType.Satis: break; case DataModelType.Muayene: muayene = new Muayene(); break; case DataModelType.Company: break; default: break; } return muayene; } public _Radyoloji GenerateRadyoloji(DataModelType modeltype) { _Radyoloji radyoloji = null; switch (modeltype) { case DataModelType.Radyoloji: radyoloji = new Radyoloji(); break; case DataModelType.Satis: break; case DataModelType.Muayene: break; case DataModelType.Company: break; default: break; } return radyoloji; } } public class CompanyView { public static List GetPersonel() { GenoTipController controller = new GenoTipController(); _Company company = controller.GenerateCompany(DataModelType.Company); return company.GetPersonel(); } } public enum DataModelType { Radyoloji, Satis, Muayene, Company } }

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• WPF buttons same/recommended width

  - by rwallace

  Suppose you have a window with multiple buttons such as Ok/Cancel or Yes/No/Cancel. All the buttons need to be the same width. Obviously this could be done by just guessing a number and hardwiring all of them to that number. Is there a better way to do it, one that would take into account preferred/recommended sizes (just how wide should an Ok button be anyway? This is not a rhetorical question, I actually don't know the answer!), what's needed by the text of the longest caption, what happens if the font size is increased etc?

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• Using NULLs in matchup table

  - by TomWilsonFL

  I am working on the accounting portion of a reservation system (think limo company). In the system there are multiple objects that can either be paid or submit a payment. I am tracking all of these "transactions" in three tables called: tx, tx_cc, and tx_ch. tx generates a new tx_id (for transaction ID) and keeps the information about amount, validity, etc. Tx_cc and tx_ch keep the information about the credit card or check used, respectively, which link to other tables (credit_card and bank_account among others). This seems fairly normalized to me, no? Now here is my problem: The payment transaction can take place for a myriad of reasons. Either a reservation is being paid for, a travel agent that booked a reservation is being paid, a driver is being paid, etc. This results in multiple tables, one for each of the entities: agent_tx, driver_tx, reservation_tx, etc. They look like this: CREATE TABLE IF NOT EXISTS `driver_tx` ( `tx_id` int(10) unsigned zerofill NOT NULL, `driver_id` int(11) NOT NULL, `reservation_id` int(11) default NULL, `reservation_item_id` int(11) default NULL, PRIMARY KEY (`tx_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; Now this transaction is for a driver, but could be applied to an individual item on the reservation or the entire reservation overall. Therefore I demand either reservation_id OR reservation_item_id to be null. In the future there may be other things which a driver is paid for, which I would also add to this table, defaulting to null. What is the rule on this? Opinion? Obviously I could break this out into MANY three column tables, but the amount of OUTER JOINing needed seems outrageous. Your input is appreciated. Peace, Tom

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• Domain Model and Contracts

  - by devoured elysium

  I am modelling a DVD Rental Store: A Client gives its clientNumber to the System. The System checks whenever the given clientNumber is valid. The Client gives the name of the DVD he wants to rent. ... n. ...I will later have to form an association between a new instance of "RentDVD" class concept to the current Client c. My Domain Model is something like: I've made the Contract for the first and second operations as: Preconditions: none Postconditions: there exists a Client c such that c.clientNumber = clientNumber. Now, I don't know if I should form an association between this Client c and the DVDStore(that I intend to use as front-end). If I don't make the association, how will I later be able to "reference" this same Client? Should I be making an association between Client and a different concept? Thanks

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• What is the simplest, but solid, interface from WinForms to a SQL Server database?

  - by Greg

  Hi, If I wanted to have my data in SQL Server, but wanted to use a thick client WinForms application for users, what would be the best practice way to have calls occurring from WinForms to database? And how simple is this? I guess I'm trying to gauge to what extent there are issues with this approach and one needs to go for some (a) middle tier with web services, or (b) have to go asp.net or something. I really just have a simple app that needs a database and I'll only have a 10 - 30 clients on a LAN/WAN network that would be connecting in.

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• How big is too big (for NTFS)

  - by BCS

  I have a program and as it's done now, it has a data directory with something like 10-30K files in it and it's starting to cause problems. Should I expect that to cause problems and my only solution to tweak my file structure or does that indicate other problems?

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• help Implementing Object Oriented ansi-C approach??

  - by No Money

  Hey there, I am an Intermediate programmer in Java and know some of the basics in C++. I recently started to scam over "C language" [please note that i emphasized on C language and want to stick with C as i found it to be a perfect tool, so no need for suggestions focusing on why should i move back to C++ or Java]. Moving on, I code an Object Oriented approach in C but kindda scramble with the pointers part. Please understand that I am just a noob trying to extend my knowledge beyond what i learned in High School. Here is my code..... #include <stdio.h> typedef struct per{ int privateint; char *privateString; struct per (*New) (); void (*deleteperOBJ) (struct t_person *); void (*setperNumber) ((struct*) t_person,int); void (*setperString) ((struct*) t_person,char *); void (*dumpperState) ((struct*) t_person); }t_person; void setperNumber(t_person *const per,int num){ if(per==NULL) return; per->privateint=num; } void setperString(t_person *const per,char *string){ if(per==NULL) return; per->privateString=string; } void dumpperState(t_person *const per){ if(per==NULL) return; printf("value of private int==%d\n", per->privateint); printf("value of private string==%s\n", per->privateString); } void deleteperOBJ(struct t_person *const per){ free((void*)t_person->per); t_person ->per = NULL; } main(){ t_person *const per = (struct*) malloc(sizeof(t_person)); per = t_person -> struct per -> New(); per -> setperNumber (t_person *per, 123); per -> setperString(t_person *per, "No money"); dumpperState(t_person *per); deleteperOBJ(t_person *per); } Just to warn you, this program has several errors and since I am a beginner I couldn't help except to post this thread as a question. I am looking forward for assistance. Thanks in advance.

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• Why Does Private Access Remain Non-Private in .NET Within a Class?

  - by AMissico

  While cleaning some code today written by someone else, I changed the access modifier from Public to Private on a class variable/member/field. I expected a long list of compiler errors that I use to "refactor/rework/review" the code that used this variable. Imagine my surprise when I didn't get any errors. After reviewing, it turns out that another instance of the Class can access the private members of another instance declared within the Class. Totally unexcepted. Is this normal? I been coding in .NET since the beginning and never ran into this issue, nor read about it. I may have stumbled onto it before, but only "vaguely noticed" and move on. Can anyone explain this behavoir to me? Am I doing something wrong? I found this behavior in both C# and VB.NET. The code seems to take advantage of the ability to access private variables. Sincerely, Totally Confused Class Foo Private _int As Integer Private _foo As Foo Private _jack As Jack Private _fred As Fred Public Sub SetPrivate() _foo = New Foo _foo._int = 3 'TOTALLY UNEXPECTED _jack = New Jack '_jack._int = 3 'expected compile error because Foo doesn't know Jack _fred = New Fred '_fred._int = 3 'expected compile error because Fred hides from Foo End Sub Private Class Fred Private _int As Integer End Class End Class Class Jack Private _int As Integer End Class

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• Aligning inputs on bootstrap using the Fluid Grid System

  - by sguha

  I am creating a form that requires the user to input their name and email address. The first line of the form has two inputs side by side for each part of the name and the 2nd line has one input for the email address that should be the same width as the first line combined. I'm trying to use the fluid grid system but can't line up the 2nd row with the first. <form action="/subscriptions" method="post"> <fieldset> <div class="control-group"> <label class="control-label" for="name">Name</label> <div class="controls row-fluid"> <input class="span2" id="first_name" name="first_name" placeholder="First" required="required" type="text"> <input class="span2" id="last_name" name="last_name" placeholder="Last" required="required" type="text"> </div> </div> <div class="control-group"> <label class="control-label" for="email">Email</label> <div class="controls row-fluid"> <input class="span4" id="email" name="email" type="email"> </div> </div> </fieldset> </form>? http://jsfiddle.net/sguha095/v4amX/

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• how can i use switch statement on type-safe enum pattern

  - by Fer

  I found a goodlooking example about implementation enums in a different way. That is called type-safe enum pattern i think. I started using it but i realized that i can not use it in a switch statement. My implementation looks like the following: public sealed class MyState { private readonly string m_Name; private readonly int m_Value; public static readonly MyState PASSED= new MyState(1, "OK"); public static readonly MyState FAILED= new MyState(2, "ERROR"); private MyState(int value, string name) { m_Name = name; m_Value = value; } public override string ToString() { return m_Name; } public int GetIntValue() { return m_Value; } } What can i add to my class in order to be able to use this pattern in switch statements in C#? Thanks.

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