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  • How to determine which inheriting class is using an abstract class' methods.

    - by Kin
    In my console application have an abstract Factory class "Listener" which contains code for listening and accepting connections, and spawning client classes. This class is inherited by two more classes (WorldListener, and MasterListener) that contain more protocol specific overrides and functions. I also have a helper class (ConsoleWrapper) which encapsulates and extends System.Console, containing methods for writing to console info on what is happening to instances of the WorldListener and MasterListener. I need a way to determine in the abstract ListenerClass which Inheriting class is calling its methods. Any help with this problem would be greatly appreciated! I am stumped :X Simplified example of what I am trying to do. abstract class Listener { public void DoSomething() { if(inheriting class == WorldListener) ConsoleWrapper.WorldWrite("Did something!"); if(inheriting class == MasterListener) ConsoleWrapper.MasterWrite("Did something!"); } } public static ConsoleWrapper { public void WorldWrite(string input) { System.Console.WriteLine("[World] {0}", input); } } public class WorldListener : Listener { public void DoSomethingSpecific() { ConsoleWrapper.WorldWrite("I did something specific!"); } } public void Main() { new WorldListener(); new MasterListener(); } Expected output [World] Did something! [World] I did something specific! [Master] Did something! [World] I did something specific!

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  • Finite State Machine : Bad design?

    - by f4
    Are Finite State Machines generally considered as bad design in OOP ? I hear that a lot. And, after I had to work on a really old, undocumented piece of C++ making use of it, I tend to agree. It was a pain to debug. what about readability/maintainability concerns?

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  • Is this a situation where Qt Model/View architecture is not useful?

    - by csmithmaui
    Hi, I am writing a GUI based application where I read a string of values from serial port every few seconds and I need to display most of the values in some type graphical indicator(I was thinking of QprogressBar maybe) that displays the range and the value. Some of the other data that I am parsing from the string are the date and fault codes. Also, the data is hierarchical. I wanted to use the model/view architecture of Qt because I have been interested in MVC stuff for a while but have never quite wrapped my brain around how to implement it very well. As of now, I have subclassed QAbstractItemModel and in the model I read the serial port and wrap the items parsed from the string in a Tree data structure. I can view all of the data in a QtreeView with no issues. I have also began to subclass QAbstractItemView to build my custom view with all of the Graphical Indicators and such. This is where I am getting stuck. It seems to me that in order for me to design a view that knows how to display my custom model the view needs to know exactly how all of the data in the model is organized. Doesn't that defeat the purpose of Model/View? The QTreeView I tested the model with is basically just displaying the model as it is setup in the Tree structure but I don't want to do that because the data is not all of the same type. Is the type of data or the way you would like to present it to the user a determining factor in whether or not you should use this architecture? I always assumed it was just always better to design in an MVC style. It seems to me like it might have been better to just subclass QWidget and then read in from the serial port and update all of subwidgets(graphical indicators, labels, etc...) from the subclass. Essentially, do everything in one class. Does anybody understand this issue that can explain to me either what I am missing or why I shouldn't be doing it this way. As of now I am a little confused. Thanks so much for any help!

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  • How should Application.Run() be called for the main presenter of a MVP WinForms app?

    - by Mr Roys
    I'm learning to apply MVP to a simple WinForms app (only one form) in C# and encountered an issue while creating the main presenter in static void Main(). Is it a good idea to expose a View from the Presenter in order to supply it as a parameter to Application.Run()? Currently, I've implemented an approach which allows me to not expose the View as a property of Presenter: static void Main() { IView view = new View(); Model model = new Model(); Presenter presenter = new Presenter(view, model); presenter.Start(); Application.Run(); } The Start and Stop methods in Presenter: public void Start() { view.Start(); } public void Stop() { view.Stop(); } The Start and Stop methods in View (a Windows Form): public void Start() { this.Show(); } public void Stop() { // only way to close a message loop called // via Application.Run(); without a Form parameter Application.Exit(); } The Application.Exit() call seems like an inelegant way to close the Form (and the application). The other alternative would be to expose the View as a public property of the Presenter in order to call Application.Run() with a Form parameter. static void Main() { IView view = new View(); Model model = new Model(); Presenter presenter = new Presenter(view, model); Application.Run(presenter.View); } The Start and Stop methods in Presenter remain the same. An additional property is added to return the View as a Form: public void Start() { view.Start(); } public void Stop() { view.Stop(); } // New property to return view as a Form for Application.Run(Form form); public System.Windows.Form View { get { return view as Form(); } } The Start and Stop methods in View (a Windows Form) would then be written as below: public void Start() { this.Show(); } public void Stop() { this.Close(); } Could anyone suggest which is the better approach and why? Or there even better ways to resolve this issue?

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  • Rank Source Control Optionsl-VSS vs CVS vs none vs your own hell

    - by Roman A. Taycher
    It seems like a lit of people here and on many programmer wikis/blogs/ect. elsewhere really dislike VSS. A lot of people also have a serious dislike for cvs. In many places I have heard a lot of differing opinions on whether or not using vss or cvs is better or worse then using no source control, please rate the worst and explain why!!!!! you rated them this way. Feel free to throw in your own horrible system in the rankings. If you feel it depends on the circumstances try to explain the some of the different scenarios which lead to different rankings. (note:I see a lot of discussion of what is better but little of what is worse.) second note: while both answers are nice I'm looking less for good replacements and more for a comparison of which is worse and more importantly why!!!!!

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  • What Date Format Should I Send When Using Oracle.DataAcess.

    - by discwiz
    Converting from usind Micorsofts Syste.Data.OracleClient to what I believe is called Oracles ODT (Oracle.DataAccess 10.2.0.100). When I try and send a date I get this error "ORA-1858: a non-numeric character was found where a numeric was expected". This code worked great using System.Data.OracleClient. cmd.Parameters.Add(New OracleParameter("I_FIRST_LOSS_EVENT_DATE", OracleDbType.Date)).Value = .LossEventsMessages(0).LossEventTime Thanks, Dave

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  • Which layer should create DataContext?

    - by Kevin
    I have a problem to decide which layer in my system should create DataContext. I have read a book, saying that if do not pass the same DataContext object for all the database updates, it will sometimes get an exception thrown from the DataContext. That's why i initially create new instance of DataContext in business layer, and pass it into data access layer. So that the same datacontext is used for all the updates. But this lead to one design problem, if i wanna change my DAL to Non-LinqToSQL in future, i need to re-write the code in business layer as well. Please give me some advice on this. Thanks. Example code 'Business Layer Public Sub SaveData(name As String) Using ts AS New TransactionScope() Using db As New MyDataContext() DAL.Insert(db,name) DAL.Insert(db,name) End Using ts.Complete() End Using End Sub 'Data Access Layer Public Sub Insert(db as MyDataContext,name As string) db.TableAInsert(name) End Sub

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  • Is it good or bad practice to use var everywhere? [closed]

    - by Earlz
    Possible Duplicate: Use of var keyword in C# Hello, I've recently been discovering the awesomeness that is the var keyword in C#. Well, I didn't think about it before but I just wrote lines of code that are along the lines of var con=CreateNewConnection(); Where this would usually be IdbConnection con=CreateNewConnection(); Is this a good use of var? Is it possible to use var too often? Are there any downsides to using it? Also, one more point of consideration: We are not worried about backwards compatability. We just care that it runs on .NET 3.5

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  • Does overloading Grails static 'mapping' property to bolt on database objects violate DRY?

    - by mikesalera
    Does Grails static 'mapping' property in Domain classes violate DRY? Let's take a look at the canonical domain class: class Book {      Long id      String title      String isbn      Date published      Author author      static mapping = {             id generator:'hilo', params:[table:'hi_value',column:'next_value',max_lo:100]      } } or: class Book { ...         static mapping = {             id( generator:'sequence', params:[sequence_name: "book_seq"] )     } } And let us say, continuing this thought, that I have my Grails application working with HSQLDB or MySQL, but the IT department says I must use a commercial software package (written by a large corp in Redwood Shores, Calif.). Does this change make my web application nobbled in development and test environments? MySQL supports autoincrement on a primary key column but does support sequence objects, for example. Is there a cleaner way to implement this sort of 'only when in production mode' without loading up the domain class?

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  • New design patterns/design strategies

    - by steven
    I've studied and implemented design patterns for a few years now, and I'm wondering. What are some of the newer design patterns (since the GOF)? Also, what should one, similar to myself, study [in the way of software design] next? Note: I've been using TDD, and UML for some time now. I'm curious about the newer paradigm shifts, and or newer design patterns.

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  • Explaining the need to avoid horizontal scroll

    - by Bradley Herman
    I need help explaining to my boss why her design is poor on a client's website. She has no knowledge of the web, and it can be difficult as a web developer working with a woman who is a graphic designer (not even a web designer really). On a current site she has designed, an image bar "needs" to be ~1200px according to her, though it isn't necessary with the content. A quick sketch to illustrate what's going on: As you see, the banner spills out past the 960px of the content and as wide as 1200px. This creates a horizontal scroll when all the content is viewable within the 960px wide viewport. I need to make this an <img and not a CSS background because it's a jQuery slideshow that fades from image to image. I think this is a big problem because a lot of people are going to get a horizontal scroll bar imposed in their browser when they're still able to see all the relevant content. She thinks no one will notice and it'll be fine; I think it's very bad practice and confusing to the end user. How do I explain the problem to her?

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  • Scripting Languages vs. Compiled Languages for web development

    - by Austin Hyde
    Though I come from a purely PHP background on the web development side of programming, I have also spent much time with C# and C++ on the desktop. I don't really want to spark any flame wars, but: When should you use scripting languages over compiled languages for website development? (and vice versa) Just to clarify, for the sake of this question, I define a "scripting language" to mean an interpreted language like PHP, Python, or Ruby, and a "compiled language" to mean a strongly typed, compiled language like C#, C++, Java, or VB.

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  • More pythonic way to iterate

    - by fmark
    I am using a module that is part of a commercial software API. The good news is there is a python module - the bad news is that its pretty unpythonic. To iterate over rows, the follwoing syntax is used: cursor = gp.getcursor(table) row = cursor.Next() while row: #do something with row row = cursor.next() What is the most pythonic way to deal with this situation? I have considered creating a first class function/generator and wrapping calls to a for loop in it: def cursor_iterator(cursor): row = cursor.Next() while row: yield row row = cursor.next() [...] cursor = gp.getcursor(table) for row in cursor_iterator(cursor): # do something with row This is an improvement, but feels a little clumsy. Is there a more pythonic approach? Should I create a wrapper class around the table type?

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  • comparator with null values.

    - by pvgoddijn
    Hi, We have some code wich sorts a list of addresses based on the distance between their coordinates. this is done through collections.sort with a custom comparator. However from time to time an adress without coordinates is in the list causing a NullPointerException. My initial idea to fix this was to have the comparator return 0 as dististance for addresses where at least one of the coordinates is null. I fear this might lead to corruption of the order the 'valid' elements in the list. so is returning a '0' values for null data in a comparator ok, or is there a cleaner way to resolve this.

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  • Multi-tenant Access Control: Repository or Service layer?

    - by FreshCode
    In a multi-tenant ASP.NET MVC application based on Rob Conery's MVC Storefront, should I be filtering the tenant's data in the repository or the service layer? 1. Filter tenant's data in the repository: public interface IJobRepository { IQueryable<Job> GetJobs(short tenantId); } 2. Let the service filter the repository data by tenant: public interface IJobService { IList<Job> GetJobs(short tenantId); } My gut-feeling says to do it in the service layer (option 2), but it could be argued that each tenant should in essence have their own "virtual repository," (option 1) where this responsibility lies with the repository. Which is the most elegant approach: option 1, option 2 or is there a better way? Update: I tried the proposed idea of filtering at the repository, but the problem is that my application provides the tenant context (via sub-domain) and only interacts with the service layer. Passing the context all the way to the repository layer is a mission. So instead I have opted to filter my data at the service layer. I feel that the repository should represent all data physically available in the repository with appropriate filters for retrieving tenant-specific data, to be used by the service layer. Final Update: I ended up abandoning this approach due to the unnecessary complexities. See my answer below.

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  • effective retrieve for a voting system in PHP

    - by Adnan
    Hello, I have a system where registered users can vote up/vote down comment for a picture. Something very similar to SO's voting system. I store the votes in a table with values as such; vote_id | vote_comment_id | vote_user_id | vote_date Now I have few a question concerned the speed and efficiency for the following; PROB: Once a user opens the picture page with comments I need, if that user has already voted UP/DOWN a comment to show it like; "you voted up" or "you voted down" next to the comment (in SO it the vote image is highlighted) MY POSSIBLE SOL: Right now when I open a picture page for each comment I loop thru, I loop thru my table of votes as well and check if a user has voted and show the status (I compare the vote_user_id with the user's session). How efficient is this? Anyone have a better approach to tackle this kind of problem?

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  • How to identify unique user?

    - by smotchkkiss
    How can you determine if a user is unique or not? I understand there are many ways to do this using cookies, but what about methods that don't use cookies? For example, go to Urban Dictionary and click one of the up/down vote buttons. Even if you delete your cookies and come back to the page, you will not be allowed to cast a vote on the same definition. How do they do this?

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  • How to control respond_to based on variable in Rails controller?

    - by smotchkkiss
    The dilemma I'm using a before_filter in my controller that restricts access to admins. However, I want to allow access public access to some methods based on request format. See the index method to understand what I'm talking about. items_controller.rb class ItemsController < ApplicationController before_filter :superuser_required layout 'superuser' def index @items = Item.all respond_to do |format| format.html format.js # I want public to have access to this end end def show @item = Item.find(params[:id]) respond_to do |format| format.html end end def new @item = Item.new respond_to do |format| format.html end end # remaining controller methods # ... def superuser_required redirect_to login_path unless current_user.superuser? end end

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  • To HTML 5 or not to HTML 5 ?

    - by ZX12R
    I am a designer whose main marketing strategy is multi browser compatibility. I assure my clients that the site will work even in IE6 (!). Of late i have been pondering over the question of moving to HTML 5. The reason behind my apprehension is that IE6 is still a major player in terms of market share and i don't want to lose it. Is there any way of moving to HTML 5 and still promise multi browser compatibility? Thank you.

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  • How to restrict access to a class's data based on state?

    - by Marcus Swope
    In an ETL application I am working on, we have three basic processes: Validate and parse an XML file of customer information from a third party Match values received in the file to values in our system Load customer data in our system The issue here is that we may need to display the customer information from any or all of the above states to an internal user and there is data in our customer class that will never be populated before the values have been matched in our system (step 2). For this reason, I would like to have the values not even be available to be accessed when the customer is in this state, and I would like to have to avoid some repeated logic everywhere like: if (customer.IsMatched) DisplayTextOnWeb(customer.SomeMatchedValue); My first thought for this was to add a couple interfaces on top of Customer that would only expose the properties and behaviors of the current state, and then only deal with those interfaces. The problem with this approach is that there seems to be no good way to move from an ICustomerWithNoMatchedValues to an ICustomerWithMatchedValues without doing direct casts, etc... (or at least I can't find one). I can't be the first to have come across this, how do you normally approach this? As a last caveat, I would like for this solution to play nice with FluentNHibernate :) Thanks in advance...

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  • ActionScript 3.0: placing code on stage/MC timelines a la AS2 instead of in classes

    - by BoltClock
    I'm aware that ActionScript 3.0 is designed from the ground up to be a largely object-oriented language and using it means less or even no timeline code in Flash documents. I'm quite experienced with OOP and am comfortable writing classes. However, since I mostly use Flash for animations, I hardly ever need to write ActionScript code other than for preloaders, subtitles, quality controls, website links and so on. In fact, I still set my Flash movies to use AS2 to this day because I'm used to gotoAndPlay()/gotoAndStop(), AS2 preloaders, subtitles, quality controls and even getURL(). Of course, I really want to move on now that practically everyone's on Flash Player 9 or 10 and now that I've dabbled with other OO languages like Java, C# and Objective-C too. I'm a complete newcomer to AS3 and am not very learned with AS2 either. Considering my current use of ActionScript, are there any cases where it's still OK to use very simple AS3 code in the timeline instead of moving code to a class, especially since moving to a class might mean unnecessarily increasing the number of LOC from 4 to 40? (Heck, is the latter case ('instead of ...') even a valid concern at all?)

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  • How to connect remote EJB module from application client

    - by Zeck
    Hi guys, I have a EJB module in remote Glassfish server and application client in my computer. I want to connect from the application client to the remote EJB. Here is the my EJB interface: @Remote public interface BookEJBRemote { public String getTitle(); } Here is the my ejb: @Stateless public class BookEJB implements BookEJBRemote { @Override public String getTitle() { return "Twenty Thousand Leagues Under the Sea"; } } I have several questions : Can I use Dependency Injection in the remote application client to connect to the ejb? If so what can i do to achieve this. Do i need to configure in the sun-ejb-jar.xml and sun-application-client.xml? In other words, if i use DI like @EJB MyEJBRemote ejb; How application client container know what ejb to be injected? Where should i specify the information? How can i run the application client? I tried to run package-appclient in the glassfish server to get appclient.jar and copy it to my computer. Then i type appclient.jar -client myAppClient.jar . It didn't work. How do i point the target server? if i cannot use DI in the client then i guess i have to use JNDI lookup. Do i need to configure jndi name in sun-ejb-jar.xml or in the sun-application-client.xml? No matter how i try i never manage to run application client ? Can you guys put some working example? And thank you for every advises and examples?

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  • How to handle input and parameter validation between layers?

    - by developr
    If I have a 3 layer web forms application that takes user input, I know I can validate that input using validation controls in the presentation layer. Should I also validate in the business and data layers as well to protect against SQL injection and also issues? What validations should go in each layer? Another example would be passing a ID to return a record. Should the data layer ensure that the id is valid or should that happen in BLL / UI?

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