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  • Double reversals on technology decisions

    - by Kev
    Have you ever gone through a painful switch from one technology to another, only to switch back later in a project's lifetime? Was it because the technologies evolved differently than you expected, or because of something you didn't understand about them in the first place, or because they didn't fly when it came to beta testing or production? Did you regret the switch back too?

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  • Many tables for many users?

    - by Seagull
    I am new to web programming, so excuse the ignorance... ;-) I have a web application that in many ways can be considered to be a multi-tenant environment. By this I mean that each user of the application gets their own 'custom' environment, with absolutely no interaction between those users. So far I have built the web application as a 'single user' environment. In other words, I haven't actually done anything to support multi-users, but only worked on the functionality I want from the app. Here is my problem... What's the best way to build a multi-user environment: All users point to the same 'core' backend. In other words, I build the logic to separate users via appropriate SQL queries (eg. select * from table where user='123' and attribute='456'). Each user points to a unique tablespace, which is built separately as they join the system. In this case I would simply generate ALL the relevant SQL tables per user, with some sort of suffix for the user. (eg. now a query would look like 'select * from table_ where attribute ='456'). In short, it's a difference between "select * from table where USER=" and "select * from table_USER".

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  • Why doesn't Java warn about a == "something"?

    - by Marius
    This might sound stupid, but why doesn't the Java compiler warn about the expression in the following if statement: String a = "something"; if(a == "something"){ System.out.println("a is equal to something"); }else{ System.out.println("a is not equal to something"); } I realize why the expression is untrue, but AFAIK, a can never be equal to the String literal "something". The compiler should realize this and at least warn me that I'm an idiot who is coding way to late at night.

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  • CRUD operations; do you notify whether the insert,update etc. went well ?

    - by danielovich
    Hi guys. I have a simple question for you (i hope) :) I have pretty much always used void as a "return" type when doing CRUD operations on data. Eg. Consider this code: public void Insert(IAuctionItem item) { if (item == null) { AuctionLogger.LogException(new ArgumentNullException("item is null")); } _dataStore.DataContext.AuctionItems.InsertOnSubmit((AuctionItem)item); _dataStore.DataContext.SubmitChanges(); } and then considen this code: public bool Insert(IAuctionItem item) { if (item == null) { AuctionLogger.LogException(new ArgumentNullException("item is null")); } _dataStore.DataContext.AuctionItems.InsertOnSubmit((AuctionItem)item); _dataStore.DataContext.SubmitChanges(); return true; } It actually just comes down to whether you should notify that something was inserted (and went well) or not ?

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  • Storing information for drop-down menus

    - by Mark
    Suppose you're building an HTML form and you want to have 2 or more drop-down menus, where after picking an option from the first, the 2nd menu is populated, and so forth. For example, choosing a country would bring up a list of provinces for that country, which would in turn list the cities. How would you store that sort of information in a database? Would you have a table Countries(id, name), Provinces(id, country_id, name), Cities(id, province_id, name) or would you have just one big denormalized table Entries(country, province, city)? (Why?)

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  • Is there anything wrong with having a few private methods exposing IQueryable<T> and all public meth

    - by Nate Bross
    I'm wondering if there is a better way to approach this problem. The objective is to reuse code. Let’s say that I have a Linq-To-SQL datacontext and I've written a "repository style" class that wraps up a lot of the methods I need and exposes IQueryables. (so far, no problem). Now, I'm building a service layer to sit on top of this repository, many of the service methods will be 1<-1 with repository methods, but some will not. I think a code sample will illustrate this better than words. public class ServiceLayer { MyClassDataContext context; IMyRepository rpo; public ServiceLayer(MyClassDataContext ctx) { context = ctx; rpo = new MyRepository(context); } private IQueryable<MyClass> ReadAllMyClass() { // pretend there is some complex business logic here // and maybe some filtering of the current users access to "all" // that I don't want to repeat in all of the public methods that access // MyClass objects. return rpo.ReadAllMyClass(); } public IEnumerable<MyClass> GetAllMyClass() { // call private IQueryable so we can do attional "in-database" processing return this.ReadAllMyClass(); } public IEnumerable<MyClass> GetActiveMyClass() { // call private IQueryable so we can do attional "in-database" processing // in this case a .Where() clause return this.ReadAllMyClass().Where(mc => mc.IsActive.Equals(true)); } #region "Something my class MAY need to do in the future" private IQueryable<MyOtherTable> ReadAllMyOtherTable() { // there could be additional constrains which define // "all" for the current user return context.MyOtherTable; } public IEnumerable<MyOtherTable> GetAllMyOtherTable() { return this.ReadAllMyOtherTable(); } public IEnumerable<MyOtherTable> GetInactiveOtherTable() { return this.ReadAllMyOtherTable.Where(ot => ot.IsActive.Equals(false)); } #endregion } This particular case is not the best illustration, since I could just call the repository directly in the GetActiveMyClass method, but let’s presume that my private IQueryable does some extra processing and business logic that I don't want to replicate in both of my public methods. Is that a bad way to attack an issue like this? I don't see it being so complex that it really warrants building a third class to sit between the repository and the service class, but I'd like to get your thoughts. For the sake of argument, lets presume two additional things. This service is going to be exposed through WCF and that each of these public IEnumerable methods will be calling a .Select(m => m.ToViewModel()) on each returned collection which will convert it to a POCO for serialization. The service will eventually need to expose some context.SomeOtherTable which wont be wrapped into the repository.

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  • What is the best way to expose a callback API - C++

    - by rursw1
    Hi, I have a C++ library that should expose some system\ resource calls as callbacks from the linked application. For example: the interfacing application (which uses this library) can send socket management callback functions - send, receive, open, close etc., and the library will use this implementation in stead of the library's implementation. (This way enables the application to manage the sockets by itself, can be useful). This library has to expose also more callbacks, like, for example, a password validation, so I wonder if there is a preferred method to expose the callback sending option in one API. Something like: int AddCallbackFunc (int functionCallbackType, <generic function prototype>, <generic way to pass some additional arguments>) Then within my library I will assign the callback to the appropriate function pointer according to the functionCallbackType parameter. Is there any way to implement it in a generic way which will fit ANY function prototype and ANY additional arguments? Your help will be more than appreciated... Thanks!

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  • Adding behaviour to a set of classes

    - by devoured elysium
    I have defined an Event class: Event and all the following classes inherit from Event: SportEventType1 SportEventType2 SportEventType3 SportEventType4 Right now I will only have SportEvents but I don't know if in the future I'll want some other kind of events that doesn't even have anything to do with Sports. Later, I will want to draw some graphics with info taken from Events, and the drawing logic can be a bit complex. But, for the moment, I think I shouldn't think of how the drawing will be done and I believe that maybe it'd be better if that drawing part was not put as an integral part of the Event/SportEventX class chain. I am looking for solutions for this problem. I know I could just make Event have an instance variable(attribute, for the java crowds) pointing to something as an IDrawInterface, but that would make the Event class "assume" it will be later used for drawing. I would like to make the Event class oblivious to this if possible. Thanks!

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  • Foreign keys and NULL in mySQL

    - by Industrial
    Hi everyone, Can I have a column in my values table (value) referenced as a foreign key to knownValues table, and let it be NULL whenever needed, like in the example: Table: values product type value freevalue 0 1 NULL 100 1 2 NULL 25 3 3 1 NULL Table: types id name prefix 0 length cm 1 weight kg 2 fruit NULL Table: knownValues id Type name 0 2 banana Note: The types in the table values & knownValues are of course referenced into the types table. Thanks!

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  • Simple OOP-related question.

    - by M4design
    This question came to my mind quite a few times. Let my explain my question through an example. Say I've got two classes: 1- Grid. 2- Cell. Now the location of the cell 'should' be stored in the grid class, not in the cell class itself. Say that the cell wanted to get its location through a method in the grid. How can it do that? Keep in mind that the cell was created/initialised by the Grid class. What good OO approach to solve this problem? Thank you

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  • Ensuring uniqueness on a varchar greater than 255 in MYSQL/InnoDB

    - by Vijay Boyapati
    I have a table which contains HTML entries for news pages. When I initially designed it I used URL as the primary key. I've learned the error of my ways because left-joining is super slow. So I want to redesign the table with an integer (id) primary key, but still keep the rows unique based on the URL. The problem is that I've found URLs longer than 255 characters, and MySQL isn't letting my create a key on the URL. I'm using an InnoDB/UTF8 table. From what I understand it's using multiple bytes per character with a limit of 766 bytes for the key (in InnoDB). I would really love suggestions on an elegant way of keeping the rows unique based on URL, while using an integer primary key. Thanks!

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  • Why can't I create an abstract constructor on an abstract C# class?

    - by Anthony D
    I am creating an abstract class. I want each of my derived classes to be forced to implement a specific signature of constructor. As such, I did what I would have done has I wanted to force them to implement a method, I made an abstract one. public abstract class A { abstract A(int a, int b); } However I get a message saying the abstract modifier is invalid on this item. My goal was to force some code like this. public class B : A { public B(int a, int b) : base(a, b) { //Some other awesome code. } } This is all C# .NET code. Can anyone help me out? Update 1 I wanted to add some things. What I ended up with was this. private A() { } protected A(int a, int b) { //Code } That does what some folks are saying, default is private, and the class needs to implement a constructor. However that doesn't FORCE a constructor with the signature A(int a, int b). public abstract class A { protected abstract A(int a, int b) { } } Update 2 I should be clear, to work around this I made my default constructor private, and my other constructor protected. I am not really looking for a way to make my code work. I took care of that. I am looking to understand why C# does not let you do this.

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  • Which of these methods provides for the fastest page loading?

    - by chromedude
    I am building a database in MySQL that will be accessed by PHP scripts. I have a table that is the activity stream. This includes everything that goes on on the website (following of many different things, liking, upvoting etc.). From this activity stream I am going to run an algorithm for each user depending on their activity and display relevant activity. Should I create another table that stores the activity for each user once the algorithm has been run on the activity or should I run the algorithm on the activity table every time the user accesses the site? UPDATE:(this is what is above except rephrased hopefully in an easier to understand way) I have a database table called activity. This table creates a new row every time an action is performed by a user on the website. Every time a user logs in I am going to run an algorithm on the new rows (since the users last login) in the table (activity) that apply to them. For example if the user is following a user who upvoted a post in the activity stream that post will be displayed when the user logs in. I want the ability for the user to be able to access previous content applying to them. Would it be easiest to create another table that saved the rows that have already been run over with the algorithm except attached to individual users names? (a row can apply to multiple different users)

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  • Can I set ignore_dup_key on for a primary key?

    - by Mr. Flibble
    I have a two-column primary key on a table. I have attempted to alter it to set the ignore_dup_key to on with this command: ALTER INDEX PK_mypk on MyTable SET (IGNORE_DUP_KEY = ON); But I get this error: Cannot use index option ignore_dup_key to alter index 'PK_mypk' as it enforces a primary or unique constraint. How else should I set IGNORE_DUP_KEY to on?

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  • Detect session hang and kill it

    - by Jack Juiceson
    Hi all, I have an asp.net page that runs certain algorithm and returns it's output. I was wondering what will happen and how to handle a case where the algorithm due to a bug goes into infinite loop. It will hog the cpu and other sessions will be served very slowly. I would love to have a way to tell IIS, if processing Algo.aspx takes more than 5 seconds, kill it or something like that. Thanks in advance

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  • Is there anything wrong with a class with all static methods?

    - by MatthewMartin
    I'm doing code review and came across a class that uses all static methods. The entrance method takes several arguments and then starts calling the other static methods passing along all or some of the arguments the entrance method received. It isn't like a Math class with largely unrelated utility functions. In my own normal programming, I rarely write methods where Resharper pops and says "this could be a static method", when I do, they tend to be mindless utility methods. Is there anything wrong with this pattern? Is this just a matter of personal choice if the state of a class is held in fields and properties or passed around amongst static methods using arguments?

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  • Ignoring (serious) errors to keep the program alive?

    - by SQuirreL bites
    One of the main things I wanted to achieve in my experimental programming language was: When errors occur (Syntax, Name, Type, etc.) keep the program running, no matter how serious or devastating it is. I know that this is probably very bad, but I just wanted something that doesn't kill itself on every error - I find it interesting what happens when a serious error occurs but the program continues. Does this "paradigm" have a name? I mean expect for How bad is it to do the above? Are there programs in use out there that just follow: "Hey, this is a fatal, unexpected error - but you know what? I don't care!"?

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