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  • Declaring data types in SQLite

    - by dan04
    I'm familiar with how type affinity works in SQLite: You can declare column types as anything you want, and all that matters is whether the type name contains "INT", "CHAR", "FLOA", etc. But is there a commonly-used convention on what type names to use? For example, if you have an integer column, is it better to distinguish between TINYINT, SMALLINT, MEDIUMINT, and BIGINT, or just declare everything as INTEGER? So far, I've been using the following: INTEGER REAL CHAR(n) -- for strings with a known fixed with VARCHAR(n) -- for strings with a known maximum width TEXT -- for all other strings BLOB BOOLEAN DATE -- string in "YYYY-MM-DD" format TIME -- string in "HH:MM:SS" format TIMESTAMP -- string in "YYYY-MM-DD HH:MM:SS" format (Note that the last three are contrary to the type affinity.)

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  • GOTO still considered harmful?

    - by Kyle Cronin
    Everyone is aware of Dijkstra's Letters to the editor: go to statement considered harmful (also here .html transcript and here .pdf) and there has been a formidable push since that time to eschew the goto statement whenever possible. While it's possible to use goto to produce unmaintainable, sprawling code, it nevertheless remains in modern programming languages. Even the advanced continuation control structure in Scheme can be described as a sophisticated goto. What circumstances warrant the use of goto? When is it best to avoid? As a followup question: C provides a pair of functions, setjmp and longjmp, that provide the ability to goto not just within the current stack frame but within any of the calling frames. Should these be considered as dangerous as goto? More dangerous? Dijkstra himself regretted that title, of which he was not responsible for. At the end of EWD1308 (also here .pdf) he wrote: Finally a short story for the record. In 1968, the Communications of the ACM published a text of mine under the title "The goto statement considered harmful", which in later years would be most frequently referenced, regrettably, however, often by authors who had seen no more of it than its title, which became a cornerstone of my fame by becoming a template: we would see all sorts of articles under the title "X considered harmful" for almost any X, including one titled "Dijkstra considered harmful". But what had happened? I had submitted a paper under the title "A case against the goto statement", which, in order to speed up its publication, the editor had changed into a "letter to the Editor", and in the process he had given it a new title of his own invention! The editor was Niklaus Wirth. A well thought out classic paper about this topic, to be matched to that of Dijkstra, is Structured Programming with go to Statements (also here .pdf), by Donald E. Knuth. Reading both helps to reestablish context and a non-dogmatic understanding of the subject. In this paper, Dijkstra's opinion on this case is reported and is even more strong: Donald E. Knuth: I believe that by presenting such a view I am not in fact disagreeing sharply with Dijkstra's ideas, since he recently wrote the following: "Please don't fall into the trap of believing that I am terribly dogmatical about [the go to statement]. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a single trick, by a simple form of coding discipline!"

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  • Validation without ServiceLocator

    - by Dmitriy Nagirnyak
    Hi, I am getting back again and again to it thinking about the best way to perform validation on POCO objects that need access to some context (ISession in NH, IRepository for example). The only option I still can see is to use S*ervice Locator*, so my validation would look like: public User : ICanValidate { public User() {} // We need this constructor (so no context known) public virtual string Username { get; set; } public IEnumerable<ValidationError> Validate() { if (ServiceLocator.GetService<IUserRepository>().FindUserByUsername(Username) != null) yield return new ValidationError("Username", "User already exists.") } } I already use Inversion Of control and Dependency Injection and really don't like the ServiceLocator due to number of facts: Harder to maintain implicit dependencies. Harder to test the code. Potential threading issues. Explicit dependency only on the ServiceLocator. The code becomes harder to understand. Need to register the ServiceLocator interfaces during the testing. But on the other side, with plain POCO objects, I do not see any other way of performing the validation like above without ServiceLocator and only using IoC/DI. So the question would be: is there any way to use DI/IoC for the situation described above? Thanks, Dmitriy.

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  • ORM market analysis

    - by bonefisher
    I would like to see your experience with popular ORM tools outhere, like NHibernate, LLBLGen, EF, S2Q, Genom-e, LightSpeed, DataObjects.NET, OpenAccess, ... From my exp: - Genom-e is quiet capable of Linq & performance, dev support - EF lacks on some key features like lazy loading, Poco support, pers.ignorance... but in 4.o it may have overcome .. - DataObjects.Net so far good, althrough I found some bugs - NHibernate steep learning curve, no 100% Linq support (like in Genom-e and DataObjects.Net), but very supportive, extensible and mature

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  • Confused about this factory, as it doesn't look like an Abstract Factory nor Factory Method

    - by Pin
    I'm looking into Guice and I've been reading its documentation recently. Reading the motivation section I don't understand the factories part, why they name it that way. To me that factory is just a wrapper for the implementing class they want it to return after calling getInstance(). public class CreditCardProcessorFactory { private static CreditCardProcessor instance; public static void setInstance(CreditCardProcessor creditCardProcessor) { instance = creditCardProcessor; } public static CreditCardProcessor getInstance() { if (instance == null) { throw new IllegalStateException("CreditCardProcessorFactory not initialized. " + "Did you forget to call CreditCardProcessor.setInstance() ?"); } return instance; } } Why do they call it factory as well if it is neither an abstract factory nor a factory method? Or am I missing something? Thanks.

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  • Fluent API Style Usage

    - by Chris Dwyer
    When programming against a fluent API, I've seen the style mostly like this: var obj = objectFactory.CreateObject() .SetObjectParameter(paramName, value) .SetObjectParameter(paramName, value) .DoSomeTransformation(); What is the reasoning behind putting the dot at the beginning of the line instead of the end of the line like this: var obj = objectFactory.CreateObject(). SetObjectParameter(paramName, value). SetObjectParameter(paramName, value). DoSomeTransformation(); Or, is it merely a style thing that a team makes a consensus on?

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  • Whats the point of STL?

    - by Jonathan D
    I've been programming c++ for about a year now and when i'm looking about i see lots of references to STL. Can some one please tell me what it does? and the advantages and disadvantageous of it? thanks

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  • How to avoid using this in a contructor

    - by Paralife
    I have this situation: interface MessageListener { void onMessageReceipt(Message message); } class MessageReceiver { MessageListener listener; public MessageReceiver(MessageListener listener, other arguments...) { this.listener = listener; } loop() { Message message = nextMessage(); listener.onMessageReceipt(message); } } and I want to avoid the following pattern: (Using the this in the Client constructor) class Client implements MessageListener { MessageReceiver receiver; MessageSender sender; public Client(...) { receiver = new MessageReceiver(this, other arguments...); sender = new Sender(...); } . . . @Override public void onMessageReceipt(Message message) { if(Message.isGood()) sender.send("Congrtulations"); else sender.send("Boooooooo"); } } The reason why i need the above functionality is because i want to call the sender inside the onMessageReceipt() function, for example to send a reply. But I dont want to pass the sender into a listener, so the only way I can think of is containing the sender in a class that implements the listener, hence the above resulting Client implementation. Is there a way to achive this without the use of 'this' in the constructor? It feels bizare and i dont like it, since i am passing myself to an object(MessageReceiver) before I am fully constructed. On the other hand, the MessageReceiver is not passed from outside, it is constructed inside, but does this 'purifies' the bizarre pattern? I am seeking for an alternative or an assurance of some kind that this is safe, or situations on which it might backfire on me.

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  • Casting functions -- Is it a code smell?

    - by Earlz
    I recently began to start using functions to make casting easier on my fingers for one instance I had something like this ((Dictionary<string,string>)value).Add(foo); and converted it to a tiny little helper function so I can do this ToDictionary(value).Add(foo); Is this a code smell? (also I've marked this language agnostic even though my example is C#)

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  • C# integer primary key generation using Entity Framework with local database file (Sdf)

    - by Ronny
    Hello, I'm writing a standalone application and I thought using Entity Framework to store my data. At the moment the application is small so I can use a local database file to get started. The thing is that the local database file doesn't have the ability to auto generate integer primary keys as SQL Server does. Any suggestions how to manage primary keys for entities in a local database file that will be compatible with SQL Server in the future? Thanks, Ronny

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  • Removing duplicates without overriding hash method

    - by Javi
    Hello, I have a List which contains a list of objects and I want to remove from this list all the elements which have the same values in two of their attributes. I had though about doing something like this: List<Class1> myList; .... Set<Class1> mySet = new HashSet<Class1>(); mySet.addAll(myList); and overriding hash method in Class1 so it returns a number which depends only in the attributes I want to consider. The problem is that I need to do a different filtering in another part of the application so I can't override hash method in this way (I would need two different hash methods). What's the most efficient way of doing this filtering without overriding hash method? Thanks

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  • Can a script called by XHR reference $_COOKIE?

    - by Christian Mann
    Quick yes/no - I'm building an AJAX application and some scripts require authentication. Can I read $_COOKIE['username'] and $_COOKIE['password'] on the server if the PHP script was called via XHR, whether that be $.get() or $.post()? Side question: Can it also set cookies? Is that considered "good practice"?

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  • What version numbering scheme to use?

    - by deamon
    I'm looking for a version numbering scheme that expresses the extent of change, especially compatiblity. Apache APR, for example, use the well known version numbering scheme <major>.<minor>.<patch> example: 4.5.11 Maven suggests a similar but more detailed schema: <major>.<minor>.<patch>-<qualifier>-<build number> example: 4.5.11-RC1-3732 Where is the Maven versioning scheme defined? Are there conventions for qualifier and build number? Probably it is a bad idea to use maven but not to follow the Maven version scheme ... What other version numbering schemes do you know? What scheme would you prefer and why?

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  • Advantages of a build server?

    - by CraigS
    I am attempting to convince my colleagues to start using a build server and automated building for our Silverlight application. I have justified it on the grounds that we will catch integration errors more quickly, and will also always have a working dev copy of the system with the latest changes. But some still don't get it. What are the most significant advantages of using a Build Server for your project?

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  • How to handle BL cache for multiple web applications?

    - by Eran Betzalel
    I recently received a project that contains multiple web applications with no MVC structure. For starters I've created a library (DLL) that will contain the main Business Logic. The problem is with Caching - If I use the current web context cache object than I might end up with duplicate caching (as the web context will be different for every application). I'm currently thinking about implementing a simple caching mechanism with a singleton pattern that will allow the different web sites (aka different application domains) to share their "caching wisdom". I'd like to know what is the best way to solve this problem.

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  • automated email downloading and treading similar messages

    - by Michael
    Okay here it is : I have built an c# console app that downloads email, save attachments , and stores the subject, from, to, body to a MS SQL Database. I use aspNetPOP3 Component to do this. I have build a front end ASP.NET application to search and view the messages. Works great. Next Steps (this is where I need help ): Now I want my users (of the asp.net app) to reply to this message send the email to the originator, and tread any additional replies back and forth on from that original message(like basecamp). This would allow my end user not to have to log-in to a system, they just continue using email (our users can as well). The question is what should I use to determine if messages are related? Subject line I think is a bad approach. I believe the best method i've seen so far is way basecamp does it, but I'm not sure how that is done, here is a real example of the reply to address from a basecamp email (I've changed the host name): [email protected] Basecamp obviously are prefixing the pre-pending a tracking id to the email address, however , when I try this with my mail service, it's rejected. Is this the best approach, is there a way I can accomplish this, is there a better approach, or even a better email component tool? Thanks, Mike

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  • Business Layer Pattern on Rails? MVCL

    - by Fabiano PS
    That is a broad question, and I appreciate no short/dumb asnwers like: "Oh that is the model job, this quest is retarded (period)" PROBLEM Where I work at people created a system over 2 years for managing the manufacture process over demand in the most simplified still broad as possible, involving selling, buying, assemble, The system is coded over Ruby On Rails. The result has been changed lots of times and the result is a mess on callbacks (some are called several times), 200+ models, and fat controllers: Total bad. The QUESTION is, if there is a gem, or pattern designed to handle Rails large app logic? The logic whould be able to fully talk to models (whose only concern would be data format handling and validation) What I EXPECT is to reduce complexity from various controllers, and hard to track callbacks into files with the responsibility to handle a business operation logic. In some cases there is the need to wait for a response, in others, only validation of the input is enough and a bg process would take place. ie: -- Sell some products (need to wait the operation to finish) 1. Set a View able to get the products input 2. Controller gets the product list inputed by employee and call the logic Logic::ExecuteWithResponse('sell', 'products', :prods => @product_list_with_qtt, :when => @date, :employee => current_user() ) This Logic would handle buying order, assemble order, machine schedule, warehouse reservation, and others

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  • Objective C -std=c99 usage

    - by Andy White
    Is there any reason why you shouldn't use the "-std=c99" flag for compiling Objective-C programs on Mac? The one feature in C99 that I really like is the ability to declare variables anywhere in code, rather than just at the top of methods, but does this flag causes any problems or create incompatibilities for iPhone or Cocoa apps?

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  • How to: mirror a staging server from a production server

    - by Zombies
    We want to mirror our current production app server (Oracle Application Server) onto our staging server. As it stands right now, various things are out of sync, and what may work in testing/QA can easily fail in production because of settings/patch/etc inconsistencies. I was thinking what would be best is to clone the entire disk daily and push it onto the staging server... Would this be the best method...?

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  • jQuery global variable best practice & options?

    - by Kris Krause
    Currently I am working on a legacy web page that uses a ton of javascript, jquery, microsoft client javascript, and other libraries. The bottom line - I cannot rewrite the entire page from scratch as the business cannot justify it. So... it is what it is. Anyway, I need to pollute (I really tried not too) the global namespace with a variable. There are the three options I was thinking - Just store/retrieve it using a normal javascript declaration - var x = 0; Utilize jQuery to store/retrieve the value in a DOM tag - $("body").data("x", 0); Utilize a hidden form field, and set/retrieve the value with jQuery - $("whatever").data("x", 0); What does everyone think? Is there a better way? I looked at the existing pile of code and I do not believe the variable can be scoped in a function.

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  • DRY programming dilemma

    - by fayer
    the situation is like this: im creating a Logger class that can write to a file but the write_to_file() function is in a helper class as a static function. i could call that function but then the Log class would be dependent to the helper class. isn't dependency bad? but if i can let it use a helper function then what is the point of having helper functions? what should one prioritize here: using helper functions and have to include this helper class everywhere (but the other 99 methods wont be useful) or just copy and paste into the Log class (but then if i have done this 100 times and then make a change i have to change in 100 places). share your thoughts and experience!

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  • where should we send notification for updating many views?

    - by Thanh-Cong Vo
    Hi all, I want to ask about software design. I have a task, the view controller handles UI event for calling a model manger to perform that task. After finishing, the model manager will callback to update the view. There have also other views who care about that task, and also want to update its own view when that task is finished. So I register a Notification for that task in each views. The problem is defining where should I send Notification, in Model manager or in the View who handles event and receives the callback from Model manager? What is better design? Shoud the model care about send this "common" task, or shoud the view? Thanks

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