New to OOP

dean_e_boy · 11 Jul 2012 at 12:22

Hi everyone,

I am starting to learn OOP, I am a C programmer by day, and wanted to start to learn about OOP.

One question I do have, is can an object be created dynamically, by this i mean, if I am reading in data from a database and for each unique reference number i want to create a new class with this reference number as the object name?

Is this possible? If I have not worded correctly or need more information, please ask.

Many Thanks for any help with this.

Dean

dazzerd · 11 Jul 2012 at 12:37

Probably a play in words but you only have one class but can have multiple objects.

You initialize the class when you import the data which creates an object, each new object can be unique (say defined/referenced by a name property) and be persistent but you only have one class.

Think of a class as a mold and an object the item what comes from the mold, you only have one mold but can create multiple castings from it.

Always the way I understood it anyway!

Dj_Jestar · 11 Jul 2012 at 12:40

C# example:

Code:

public class SomeClass
{
  public string Name { get; set; }
}

var a = new SomeClass { Name = "Foo" };
var b = new SomeClass { Name = "Bar" };

Console.Out.WriteLine(a.Name);
Console.Out.WriteLine(b.Name);

Resulting output is:

Code:

Foo
Bar

Haircut · 11 Jul 2012 at 12:40

I'm not quite sure what you mean by this.

An object is an instance of a class, so if you have a class that has members that correspond to what you want to retrieve from the database then you can create multiple instances each with their own unique values (e.g. the reference number)

Each of these instances is completely separate and the values in each one can be modified independently of the other instances.
Essentially the class is a template that is populated with different things for each object that is created.

(Note, static members complicate things a little, but as a beginner don't worry about that right now)

dean_e_boy · 11 Jul 2012 at 13:45

Cheers everyone for the info. I will have a read and a play

Many Thanks

djkav · 11 Jul 2012 at 16:04

In c# you can do this thru "system.reflection", altho not efficient.

Maybe you could look at Generics in c# 2.

Dj_Jestar · 11 Jul 2012 at 16:25

What does any of this have to do with reflection or generics?

GravyMonster · 11 Jul 2012 at 16:26

^ S'wat I'm thinking.

djkav · 11 Jul 2012 at 17:07

Dj_Jestar said:
What does any of this have to do with reflection or generics?

Dynamically creating an object/class kind of gives it a point of reference.

is can an object be created dynamically, by this i mean, if I am reading in data from a database and for each unique reference number i want to create a new class with this reference number as the object name?

Means to me, I want to dynamically create an object during runtime with this unique reference number as its name.

Haircut · 11 Jul 2012 at 17:18

djkav said:
Means to me, I want to dynamically create an object during runtime with this unique reference number as its name.

Dj_Jestar already posted a very simple example of how to do this in C# though.
I think you're needlessly over complicating things when all the OP seems to be asking is about constructing objects.

djkav · 11 Jul 2012 at 17:26

Haircut said:
Dj_Jestar already posted a very simple example of how to do this in C# though.
I think you're needlessly over complicating things when all the OP seems to be asking is about constructing objects.

Oh, he doesn't really want to dynamically create objects on the fly. He just wants to do a simple class instantiation. I understand it now, thx.

UncleRuckus · 11 Jul 2012 at 19:48

http://en.wikipedia.org/wiki/Factory_method_pattern