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  • how to minimize application downtime when updating database and application ORM

    - by yamspog
    We currently run an ecommerce solution for a leisure and travel company. Everytime we have a release, we must bring the ecommerce site down as we update database schema and the data access code. We are using a custom built ORM where each data entity is responsible for their own CRUD operations. This is accomplished by dynamically generating the SQL based on attributes in the data entity. For example, the data entity for an address would be... [tableName="address"] public class address : dataEntity { [column="address1"] public string address1; [column="city"] public string city; } So, if we add a new column to the database, we must update the schema of the database and also update the data entity. As you can expect, the business people are not too happy about this outage as it puts a crimp in their cash-flow. The operations people are not happy as they have to deal with a high-pressure time when database and applications are upgraded. The programmers are upset as they are constantly getting in trouble for the legacy system that they inherited. Do any of you smart people out there have some suggestions?

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  • Exploring the Factory Design Pattern

    - by asksuperuser
    There was an article here: http://msdn.microsoft.com/en-us/library/Ee817667%28pandp.10%29.aspx The first part of tut implemented this pattern with abstract classes. The second part shows an example with Interface class. But nothing in this article discusses why this pattern would rather use abstract or interface. So what explanation (advantages of one over the other) would you give ? Not in general but for this precise pattern.

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  • Improving MVP in Scala

    - by Alexey Romanov
    The classical strongly typed MVP pattern looks like this in Scala: trait IView { } trait Presenter[View <: IView] { // or have it as an abstract type member val view : View } case class View1(...) extends IView { ... } case object Presenter1 extends Presenter[View1] { val view = View1(...) } Now, I wonder if there is any nice way to improve on it which I am missing...

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  • What are some good usability guidelines an average developer should follow?

    - by Allain Lalonde
    I'm not a usability specialist, and I really don't care to be one. I just want a small set of rules of thumb that I can follow while coding my User Interfaces so that my product has decent usability. At first I thought that this question would be easy to answer "Use your common sense", but if it's so common among us developers we wouldn't, as a group, have a reputation for our horrible interfaces. Any Suggestions?

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  • Javascript clarity of purpose

    - by JesDaw
    Javascript usage has gotten remarkably more sophisticated and powerful in the past five years. One aspect of this sort of functional programming I struggle with, esp with Javascript’s peculiarities, is how to make clear either through comments or code just what is happening. Often this sort of code takes a while to decipher, even if you understand the prototypal, first-class functional Javascript way. Any thoughts or techniques for making perfectly clear what your code does and how in Javascript? I've asked this question elsewhere, but haven't gotten much response.

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  • Is it Bad Practice to use C++ only for the STL containers?

    - by gmatt
    First a little background ... In what follows, I use C,C++ and Java for coding (general) algorithms, not gui's and fancy program's with interfaces, but simple command line algorithms and libraries. I started out learning about programming in Java. I got pretty good with Java and I learned to use the Java containers a lot as they tend to reduce complexity of book keeping while guaranteeing great performance. I intermittently used C++, but I was definitely not as good with it as with Java and it felt cumbersome. I did not know C++ enough to work in it without having to look up every single function and so I quickly reverted back to sticking to Java as much as possible. I then made a sudden transition into cracking and hacking in assembly language, because I felt I was concentrated too much attention on a much too high level language and I needed more experience with how a CPU interacts with memory and whats really going on with the 1's and 0's. I have to admit this was one of the most educational and fun experiences I've had with computers to date. For obviously reasons, I could not use assembly language to code on a daily basis, it was mostly reserved for fun diversions. After learning more about the computer through this experience I then realized that C++ is so much closer to the "level of 1's and 0's" than Java was, but I still felt it to be incredibly obtuse, like a swiss army knife with far too many gizmos to do any one task with elegance. I decided to give plain vanilla C a try, and I quickly fell in love. It was a happy medium between simplicity and enough "micromanagent" to not abstract what is really going on. However, I did miss one thing about Java: the containers. In particular, a simple container (like the stl vector) that expands dynamically in size is incredibly useful, but quite a pain to have to implement in C every time. Hence my code currently looks like almost entirely C with containers from C++ thrown in, the only feature I use from C++. I'd like to know if its consider okay in practice to use just one feature of C++, and ignore the rest in favor of C type code?

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  • How to implement Administrator rights in Java Application?

    - by Yatendra Goel
    I am developing a Data Modeling Software that is implemented in Java. This application converts the textual data (stored in a database) to graphical form so that users can interpret the data in a more efficient form. Now, this application will be accessed by 3 kinds of persons: 1. Managers (who can fill the database with data and they can also view the visual form of the data after entering the data into the database) 2. Viewers (who can only view the visual form of data that has been filled by managers) 3. Administrators (who can create and manage other administrators, managers and viewers) Now, how to implement 3 diff. views of the same application. Note: Managers, Viewers and Administrators can be located in any part of the world and should access the application through internet. One idea that came in my mind is as follows: Step1: Code all the business logic in EJBs so that it can be used in distributed environment (means which can be accessed by several users through internet) Step2: Code 3 Swing GUI Clients: One for administrators, one for managers and one for viewers. These 3 GUI clients can access business logic written in EJBs. Step3: Distribute the clients corresponding to their users. For instance, manager client to managers. =================================QUESTIONS======================================= Q1. Is the above approach is correct? Q2. This is very common functionality that various softwares have. So, Do they implement this kind of functionality through this way or any other way? Q3. If any other approach would be more better, then what is that approach?

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  • Opinions regarding C++ programming practice

    - by Sagar
    I have a program that I am writing, not too big. Apart from the main function, it has about 15 other functions that called for various tasks at various times. The code works just fine all in one file, and as it is right now. However, I was wondering if anyone had any advice on whether it is smarter/more efficient/better programming to put those functions in a separate file different from where main is, or whether it even matters at all. If yes, why? If no, why not? I am not new at C++, but definitely not an expert either, so if you think this question is stupid, feel free to tell me so. Thanks for your time!

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  • Is the a pattern for iterating over lists held by a class (dynamicly typed OO languages)

    - by Roman A. Taycher
    If I have a class that holds one or several lists is it better to allow other classes to fetch those lists(with a getter) or to implement a doXList/eachXList type method for that list that take a function and call that function on each element of the list contained by that object. I wrote a program that did a ton of this and I hated passing around all these lists sometimes with method in class a calling method in class B to return lists contained in class C, B contains a C or multiple C's (note question is about dynamically typed OO languages languages like ruby or smalltalk) ex. (that came up in my program) on a Person class containing scheduling preferences and a scheduler class needing to access them.

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  • Design pattern to integrate Rails with a Comet server

    - by empire29
    I have a Ruby on Rails (2.3.5) application and an APE (Ajax Push Engine) server. When records are created within the Rails application, i need to push the new record out on applicable channels to the APE server. Records can be created in the rails app by the traditional path through the controller's create action, or it can be created by several event machines that are constantly monitoring various inputstream and creating records when they see data that meets a certain criteria. It seems to me that the best/right place to put the code that pushes the data out to the APE server (which in turn pushes it out to the clients) is in the Model's after_create hook (since not all record creations will flow through the controller's create action). The final caveat is I want to push a piece of formatted HTML out to the APE server (rather than a JSON representation of the data). The reason I want to do this is 1) I already have logic to produce the desired layout in existing partials 2) I don't want to create a javascript implementation of the partials (javascript that takes a JSON object and creates all the HTML around it for presentation). This would quickly become a maintenance nightmare. The problem with this is it would require "rendering" partials from within the Model (which im having trouble doing anyhow because they don't seem to have access to Helpers when they're rendered in this manner). Anyhow - Just wondering what the right way to go about organizing all of this is. Thanks

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  • Is there a more correct type for passing in the file path and file name to a method

    - by Rihan Meij
    Hi What I mean by this question is, when you need to store or pass a URL around, using a string is probably a bad practice, and a better approach would be to use a URI type. However it is so easy to make complex things more complex and bloated. So if I am going to be writing to a file on disk, do I pass it a string, as the file name and file path, or is there a better type that will be better suited to the requirement? This code seems to be clunky, and error prone? I would also need to do a whole bit of checking if it is a valid file name, if the string contains data and the list goes on. private void SaveFile(string fileNameAndPath) { //The normal stuff to save the file }

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  • Why are there magic attributes exposed in the Servlet spec?

    - by Brabster
    It's always seemed a little at odds with the principles of Java that the Java Servlet Spec (2.5 version here) includes a set of magic attributes containing info about included resources, namely: javax.servlet.include.request_uri javax.servlet.include.context_path javax.servlet.include.servlet_path javax.servlet.include.path_info javax.servlet.include.query_string It's not even specifically pointed out in the API documentation, only in the spec where it is a must for correct implementation. This approach feels very wrong, an exposed implementation detail that clients will use and depend on. Why is this information exposed in this way?

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  • Lazy loading? Better avoiding it?

    - by Charlie Pigarelli
    I just read about this design pattern: Lazy Load. And, since in the application i'm working on i have all the classes in one folder, i was wondering if this pattern could just make me avoiding the include() function for every class. I mean: It's nice to know that if i forgot to include a class, PHP, before falling into an error, trough an __autoload() function try to get it. But is it fine enough to just don't care about including classes and let PHP do it by your own every time? Or we should write __autoload() just in case it is needed?

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  • Multiple asserts in single test?

    - by Gern Blandston
    Let's say I want to write a function that validates an email address with a regex. I write a little test to check my function and write the actual function. Make it pass. However, I can come up with a bunch of different ways to test the same function ([email protected]; [email protected]; test.test.com, etc). Do I put all the incantations that I need to check in the same, single test with several ASSERTS or do I write a new test for every single thing I can think of? Thanks!

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  • Arranging VS2008 generated LinqToSql/EntityFramework data models/contexts in assemblies.

    - by JMSA
    What pattern should I use for data-access in case of VS2008 generated L2s or EF DataModels? Repository-pattern or what? As we know VS2008 generates Data-Models and DataContexts/ObjectContexts in the same file, then, how should I arrange my VS2008 assemblies in my VS2008 solution to achieve a layered design? If I use repository pattern, how should I arrange my assemblies in the VS2008 solution (as Data-Models and Data/Object-Contexts are stored in the same file...)? Any web/example link would be appreciated.

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  • Connecting data to a GUI - OOP

    - by tau
    I have an application with several graphs and tables on it. I worked fast and just made classes like Graph and Table that each contained a request object (pseudo-code): class Graph { private request; public function setDateRange(dateRange) { request.setDateRange(dateRange); } public function refresh() { request.getData(function() { //refresh the display }); } } Upon a GUI event (say, someone changes the date range dropdown), I'd just call the setters on the Graph instance and then refresh it. Well, when I added other GUI elements like tables and whatnot, they all basically had similar methods (setDateRange and other things common to the request). What are some more elegant OOP ways of doing this? The application is very simple and I don't want to over-architect it, but I also don't want to have a bunch of classes with basically the same methods that are just routing to a request object. I also don't want to set up each GUI class as inheriting from the request class, but I'm open to any ideas really.

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  • Representing xml through a single class

    - by Charles
    I am trying to abstract away the difficulties of configuring an application that we use. This application takes a xml configuration file and it can be a bit bothersome to manually edit this file, especially when we are trying to setup some automatic testing scenarios. I am finding that reading xml is nice, pretty easy, you get a network of element nodes that you can just go through and build your structures quite nicely. However I am slowly finding that the reverse is not quite so nice. I want to be able to build a xml configuration file through a single easy to use interface and because xml is composed of a system of nodes I am having a lot of struggle trying to maintain the 'easy' part. Does anyone know of any examples or samples that easily and intuitively build xml files without declaring a bunch of element type classes and expect the user to build the network themselves? For example if my desired xml output is like so <cook version="1.1"> <recipe name="chocolate chip cookie"> <ingredients> <ingredient name="flour" amount="2" units="cups"/> <ingredient name="eggs" amount="2" units="" /> <ingredient name="cooking chocolate" amount="5" units="cups" /> </ingredients> <directions> <direction name="step 1">Preheat oven</direction> <direction name="step 2">Mix flour, egg, and chocolate</direction> <direction name="step 2">bake</direction> </directions> </recipe> <recipe name="hot dog"> ... How would I go about designing a class to build that network of elements and make one easy to use interface for creating recipes? Right now I have a recipe object, an ingredient object, and a direction object. The user must make each one, set the attributes in the class and attach them to the root object which assembles the xml elements and outputs the formatted xml. Its not very pretty and I just know there has to be a better way. I am using python so bonus points for pythonic solutions

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  • DDD: Enum like entities

    - by Chris
    Hi all, I have the following DB model: **Person table** ID | Name | StateId ------------------------------ 1 Joe 1 2 Peter 1 3 John 2 **State table** ID | Desc ------------------------------ 1 Working 2 Vacation and domain model would be (simplified): public class Person { public int Id { get; } public string Name { get; set; } public State State { get; set; } } public class State { private int id; public string Name { get; set; } } The state might be used in the domain logic e.g.: if(person.State == State.Working) // some logic So from my understanding, the State acts like a value object which is used for domain logic checks. But it also needs to be present in the DB model to represent a clean ERM. So state might be extended to: public class State { private int id; public string Name { get; set; } public static State New {get {return new State([hardCodedIdHere?], [hardCodeNameHere?]);}} } But using this approach the name of the state would be hardcoded into the domain. Do you know what I mean? Is there a standard approach for such a thing? From my point of view what I am trying to do is using an object (which is persisted from the ERM design perspective) as a sort of value object within my domain. What do you think? Question update: Probably my question wasn't clear enough. What I need to know is, how I would use an entity (like the State example) that is stored in a database within my domain logic. To avoid things like: if(person.State.Id == State.Working.Id) // some logic or if(person.State.Id == WORKING_ID) // some logic

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  • How should my team decide between 3-tier and 2-tier architectures?

    - by j0rd4n
    My team is discussing the future direction we take our projects. Half the team believes in a pure 3-tier architecture while the other half favors a 2-tier architecture. Project Assumptions: Enterprise business applications Business logic needed between user and database Data validation necessary Service-oriented (prefer RESTful services) Multi-year maintenance plan Support hundreds of users 3-tier Team Favors: Persistant layer <== Domain layer <== UI layer Service boundary between at least persistant layer and domain layer. Domain layer might have service boundary between it. Translations between each layer (clean DTO separation) Hand roll persistance unless we can find creative yet elegant automation 2-tier Team Favors: Entity Framework + WCF Data Service layer <== UI layer Business logic kept in WCF Data Service interceptors Minimal translation between layers - favor faster coding So that's the high-level argument. What considerations should we take into account? What experiences have you had with either approach?

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  • How to expose a constructor variable(sic!) as read-only?

    - by Malax
    Hi StackOverflow! I have this rather simple question about Scala. Given that i have to following class definition: class Foo(var bar: Int) The code which is able to construct an instance of Foo must be able to pass the initial value for bar. But if I define bar as var the User is also able to change its value at runtime which is not what I want. The User should only be able to read bar. bar itself is modified internally so a val is not an option. I think I might be getting an answer very soon as this question is so simple. :-) Cheers, Malax

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  • What design pattern to use for one big method calling many private methods

    - by Jeune
    I have a class that has a big method that calls on a lot of private methods. I think I want to extract those private methods into their own classes for one because they contain business logic and I think they should be public so they can be unit tested. Here's a sample of the code: public void handleRow(Object arg0) { if (continueRunning){ hashData=(HashMap<String, Object>)arg0; Long stdReportId = null; Date effDate=null; if (stdReportIds!=null){ stdReportId = stdReportIds[index]; } if (effDates!=null){ effDate = effDates[index]; } initAndPutPriceBrackets(hashData, stdReportId, effDate); putBrand(hashData,stdReportId,formHandlerFor==0?true:useLiveForFirst); putMultiLangDescriptions(hashData,stdReportId); index++; if (stdReportIds!=null && stdReportIds[0].equals(stdReportIds[1])){ continueRunning=false; } if (formHandlerFor==REPORTS){ putBeginDate(hashData,effDate,custId); } //handle logic that is related to pricemaps. lstOfData.add(hashData); } } What design pattern should I apply to this problem?

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