I know what Singleton Pattern means and Abstract class means.What I wanted to know was how would this apply to real world.Could anyone give me any good example or simple explanation.Say I have a simple website, why would I use any of the above if any.Why would it simplify my architechture.
View 3 RepliesI am working on singleton desing patterns and want some real world example of design patterns.Can you please give me an example how you have used singleton pattern in you project. I would appreciate if you can provide code.
View 3 Replieswhat is the function of abstract class, why design pattern need to build BLL and DAL
anyone give an example for my reference as I am getting strat to build my web-based project
See in below I have writtine a
1. Singleton class Emp1 with Display Method and
2. Static Class with Static Method Display.
What is the advantage of singleton class over Static Class with Static members?
[Code]....
Just wanted to know if a singleton class could be inherited and derived.
View 2 RepliesWhat is the use of abstract class design in real time projects
and how to use abstract clases and interfaces
and inheritense concepts
like big shoping portals or content managment,blogs etc
I have a class which fetches the data from the database. Say First name, Last name , Telephone number etc and display it in my .aspx page. This data is common to all the users. So i would like to use Singleton pattern so that the object is not created again ,just use the created object for all the users. Can any one help me with the simple code snippet example.
View 3 RepliesI have a web application where I would like to pull user settings from a database and store them for Global access. Would it make more sense to store the data in a Singleton, or a Session object? What's the difference between the two?Is it better to store the data as an object reference or break it up into value type objects (ints and strings)?
View 3 Repliesi'm building a web application with asp.net c# and i have a class that i want to use in multiple pages witouth instantiate it every time. I need to load the data in it and never lose them during the user session time. I thought about the singleton-pattern but it shared the instance of the class beetween browsers.
View 4 RepliesI'm developing a blog application shared by non-profit organizations. I want each organization to be able to change their own blog settings. I have taken a singleton pattern (from BlogEngine.net) and modified it. (I understand that it is no longer a singleton pattern.) I have tested this approach and it seems to work fine in a development environment. Is this pattern a good practice? Are there issues, which may arise when this is placed in a production environment?
public class UserBlogSettings
{
private UserBlogSettings()
{
Load();
}
public static UserBlogSettings Instance
{
get
{
string cacheKey = "UserBlogSettings-" + HttpContext.Current.Session["userOrgName"].ToString();
object cacheItem = HttpRuntime.Cache[cacheKey] as UserBlogSettings;
if (cacheItem == null)
{
cacheItem = new UserBlogSettings();
HttpRuntime.Cache.Insert(cacheKey, cacheItem, null, DateTime.Now.AddMinutes(1),
Cache.NoSlidingExpiration);
}
return (UserBlogSettings) cacheItem;
}
}
}
(Portions of code were omitted for brevity.)
I have a whole bunch of data access methods where in each one I am doing this
[Code]....
and them moving on with my SqlCommand and SqlDataReader and so on.Is this creating to many instances of an SQLConnection?I was thinking doing this instead. Creating a SqlConnection Manager which would look like this
[Code]....
and then in my database access methods
[Code]....
Is this a good or bad idea and why?Also would this even be neccesary?
If I were to use singleton pattern for menu, would that cause that menu to be created once for application session or once for each user session. Obviously, I want something that will create menu items once per application session.
View 2 Replieswant to make sure I am not assuming something foolish here, when implementing the singleton pattern in an ASP .Net web application the static variable scope is only for the current user session, right? If a second user is accessing the site it is a different memory scope...?
View 4 RepliesIn one of the interview, I was asked why should we have to go for Single Design pattern, instead of just creating static methods. Because creating static methods also serve the same purpose, i.;e avoiding flooding of objects.
View 1 RepliesI have a table which houses two entities. StaticProgram and DynamicProgram. There is one column in that table called ProgramType which determines if a program is of Type static or Dynamic. Though these two entities are stored in one table (I am guessing because the primitive fields for Static and Dynamic programs are exactly the same) but from a business point of view these are two VERY different entities.
So, I created two Classes StaticProgram and DynamicProgram. However, I donot want to create two seperate Data Access Classes because it is going to be the exact same code replicated twice. I tried creating a "Program" class as base class and inherited StaticProgram and DynamicProgram classes but down casting is not supported so I can't return a "Program" object from the data access class and cast it to "StaticProgram" class.So, what are my options? Can I create an IProgram interface and have StaticProgram and DynamicProgram implement that interface and have my Data Access class return IProgram?
I am a newbie to asp.net and work in a firm where the projects are quite small.
I was told by my manager that in a few weeks or so we would be getting a bigger project and I need to be well versed with Design Patterns and N tier arcihtecture.
I would really appreciate if someone could provide me some links and also drop me a few sentences on how this things are useful?
I have searched deference between Static and Singleton Patten on google but did not get it clearly.
View 12 RepliesWhen to use Abstract class and when to use Interface class.
View 10 RepliesFrom the following URL i got some doubts about the Recommendations for using Abstract class vs interfaces
[URL]
1. If you anticipate creating multiple versions of your component, create an abstract class. Abstract classes provide a simple and easy way to version your components. By updating the base class, all inheriting classes are automatically updated with the change. Interfaces, on the other hand, cannot be changed once created. If a new version of an interface is required, you must create a whole new interface. { Is there any example for this t ounderstand throughly ?} If you are designing small, concise bits of functionality, use interfaces. If you are designing large functional units, use an abstract class. If you want to provide common, implemented functionality among all implementations of your component, use an abstract class. Abstract classes allow you to partially implement your class, whereas interfaces contain no implementation for any members. { Is there any example for this t ounderstand throughly?
I am trying to compile the following code and i am getting the error:
Cannot create instance of abstract class .
m_objExcel = new Excel.Application();
m_objBooks = (Excel.Workbooks)m_objExcel.Workbooks;
m_objBook = (Excel._Workbook)(m_objBooks.Add(m_objOpt));
m_objSheets = (Excel.Sheets)m_objBook.Worksheets;
m_objSheet = (Excel._Worksheet)(m_objSheets.get_Item(1));
// Create an array for the headers and add it to cells A1:C1.
object[] objHeaders = {"Order ID", "Amount", "Tax"};
m_objRange = m_objSheet.get_Range("A1", "C1");
m_objRange.Value = objHeaders;
m_objFont = m_objRange.Font;
m_objFont.Bold=true;
// Create an array with 3 columns and 100 rows and add it to
// the worksheet starting at cell A2.
object[,] objData = new Object[100,3];
Random rdm = new Random((int)DateTime.Now.Ticks);
double nOrderAmt, nTax;
for(int r=0;r<100;r++)
{
objData[r,0] = "ORD" + r.ToString("0000");
nOrderAmt = rdm.Next(1000);
objData[r,1] = nOrderAmt.ToString("c");
nTax = nOrderAmt*0.07;
objData[r,2] = nTax.ToString("c");
}
m_objRange = m_objSheet.get_Range("A2", m_objOpt);
m_objRange = m_objRange.get_Resize(100,3);
m_objRange.Value = objData;
// Save the Workbook and quit Excel.
m_objBook.SaveAs(m_strSampleFolder + "Book2.xls", m_objOpt, m_objOpt,
m_objOpt, m_objOpt, m_objOpt, Excel.XlSaveAsAccessMode.xlNoChange,
m_objOpt, m_objOpt, m_objOpt, m_objOpt);
m_objBook.Close(false, m_objOpt, m_objOpt);
m_objExcel.Quit();
I just want to know that how can I utilize the concept of Abstract class, virtual class etc. in my shopping cart website. I have read the tutorial out there on internet and I saw some examples too, but those examples are so general that they dosen't fit into real world scenerio like I am searching for a shopping website. Same questions again and again comes to my mind that why to made a class only to give the declaration of methods and property.
View 4 RepliesWe all know that, we cannot create the object of Abstract class.
But why it is so?
I mean, can anyone explain it with real time example?
Why do we use the reference of abstract class (or base class) to create object of it's sub-class. eg: TextWriter is the abstract class for StreamWriter & StreamWriter.
TextWriter writer = new StreamWriter();
why can't we simply use :
StreamWriter writer = new StreamWriter();
Error 1279 Cannot create an instance of the abstract class or interface 'System.Web.Mvc.FileResult'
[Code]....
I am using MVC 2. The same code works in my onather application. I have no idea about this error.
guide in typical 4 layered architecture (having User Interface, Custom Types, Business Logic, Data Access Layer) do we follow some design pattern ? I am not clear what pattern it is or what pattern it should be called.
View 3 Replies