ORM Manager

ORM manager will populate the data stored in the persistent storage like a database in the form of an object graph. ORM manager will use different object mapping strategies like table per hierarchy [TPH], table per type [TPT] or table per concrete class [TPC], etc. in populating the object graph. LINQ to SQL is based on TPH. Hibernate supports TPC, TPH and table per subclass mapping strategy [1]. Following is an example of the TPH.

Table Per Hierarchy ORM implementation

Reference:
1. http://www.hibernate.org/hib_docs/reference/en/html/inheritance.html accessed on 08/21/2008

Meaningful Identifiers

Anthony, _anthony and anthony were good friends. Anthony is a grown up guy,_anthony is a boy and anthony is a dog. One day, Anthony invited _anthony and anthony to his place for the party. _anthony was not feeling well but decided to tag along anthony. _anthony is too young to drive so they decided to walk to the Anthony’s place. Unfortunately, anthony could not walk so they called a cab. _anthony…

Who cannot walk? A dog or a boy…

Let’s re-factor this story a little bit. Let’s rename Anthony to MAnthony, _anthony to BAnthony and anthony to DAnthony. M for men, B for boy and D for dog.

With these new identifiers this story will be much better [to read and understand]. As in any story or a novel, meaningful identifiers are really important. Identifiers in any source code provide a meaningful token for the underlying memory. Identifiers tell a lot about the program. Just looking at the identifiers like account, debit and credit one can figure out that the system is a financial system.

This is a good read for anyone interested in more details on the way we program

VS 2008 Debugger going crazy?

Look at the code below and put the breakpoint on line
if (_s == null)

observe the behavior when we do something like
s2 = Singleton.getSingletonInstance();

using System;

namespace Pattern
{
class Program
{
static void Main(string[] args)
{
Singleton s1, s2;

s1 = Singleton.getSingletonInstance();

s1.instanceCount = 100;

s2 = Singleton.getSingletonInstance();
}
}


sealed class Singleton
{
private static Singleton _s = null;
public int instanceCount;

private Singleton()
{
}

public static Singleton getSingletonInstance()
{
if (_s == null)
{
_s = new Singleton();
}

return _s;
}

}
}

When the breakpoint will hit, try watching the value of _s. The watch window will pop endlessly all over the screen when you click on the following + sign next to the static members icon.
Screenshot:

SoCal Code Camp 2008

I will be presenting at Next Code Camp June 28th and 29th at University California San Diego Extension [www.socalcodecamp.com]

Topic: Using LinqDataSource with ASP.NET data controls

When: 3:00 PM - Sessions Room 110 on 06/29/2008 - driving directions can be found here

Check out LinqDataSource Sample


We will work on this sample in session.

Thanks

LINQ to SQL model

Type of Exceptions

Nullable Object Pattern