Class syntax with C#

Question

Possible Duplicate:
What does “T” mean in C#?
What does <T> denote in C#

I have searched about the question, but because I do not have any idea about that syntax, I could not search well enough. Well, after the short explanation my question is :

While I was looking to a particle effect library I meet this :

[Serializable]
public class DPSF<Particle, Vertex> : IDPSFParticleSystem
  where Particle : global::DPSF.DPSFParticle, new()
  where Vertex : struct, global::DPSF.IDPSFParticleVertex
{
  // constructors, methods, parameters here ...
}

What does this notation mean in blankets (<...>) and how it is used ?

http://msdn.microsoft.com/en-us/library/ms379564%28VS.80%29.aspx — BlueRaja - Danny Pflughoeft, Apr 20 '12 at 14:24
possible duplicate of [What does "T" mean in C#?](http://stackoverflow.com/questions/400314/what-does-t-mean-in-c) and [What does denote in C#](http://stackoverflow.com/questions/9857180/what-does-t-denote-in-c-sharp) — BlueRaja - Danny Pflughoeft, Apr 20 '12 at 14:25
thanks ! I'm reading the post and i'm curious why there is "where Particle : ... " is it a restriction ? I know what T means, but I have never seen it using with a class ! I know using T at function, but still I want to learn its concept using at classes — icaptan, Apr 20 '12 at 14:26
@icaptan yes, they're formally called constraints. There is a section describing them in the article linked to by BlueRaja — heavyd, Apr 20 '12 at 14:28
[The section](http://msdn.microsoft.com/en-us/library/ms379564%28VS.80%29.aspx#csharp_generics_topic4) mentioned by @heavyd — BlueRaja - Danny Pflughoeft, Apr 20 '12 at 14:29

score 2 · Answer 1 · answered Apr 20 '12 at 14:27

2

They are generic types that you can pass into a class definition:

A simple example:

public class Test<T>
{
   public T yourVariable;  
}

Test<int> intClass = new Test();
Test<string> stringClass = new Test();

intClass.yourVariable // would be of type int
stringClass.yourVariable // would be of type string

Where T is the type you want (i.e. another class, a string, integer, anything generic)

where Particle : global::DPSF.DPSFParticle - means that the Particle object must inherit from DPSF.DPSFParticle

answered Apr 20 '12 at 14:27

Darren

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and what about the where clouse ? is it a restriction ? – icaptan Apr 20 '12 at 14:29
Must inherit from DPSF.DPSFParticle. – Darren Apr 20 '12 at 14:30
Thanks i understood the answer well ! thank you all very much ! – icaptan Apr 20 '12 at 14:31

score 1 · Answer 2 · answered Apr 20 '12 at 14:27

It means that DPSF class is a generic class. Particle and Vertex between <> are type parameters. It means that DPSF gets two types as parameters and serves as a generic class.

Take a look at here: MSDN: Generics

EDIT Where keyword allows you to restrict type parameters. where:class means parameter must be a class in order this generic class to work.

Class syntax with C#

2 Answers2