Where does LINQ fit?

So after having watched a few of Scott Stanfield's LINQ videos, I'm excited to get my hands dirty with some LINQ.

I want to understand best practices about how LINQ would be used in a complex application.  In some of the videos, Scott shows how you can hook into the OR-generated classes for tasks such as data validation by creating a partial class and implementing a partial method.

What are the general guidelines for adding business logic?  Is it a bad idea to just extend the generated classes and add biz logic?

Or should you create separate modules as a separate layer to encapsulate the logic?

I suspect the answer is "it depends" but I'd love to hear a discussion of what y'all have learned from implementing LINQ so far.

(update: LINQPad is awesome.)

Larsenal wrote:

So after having watched a few of Scott Stanfield's LINQ videos, I'm excited to get my hands dirty with some LINQ.

I want to understand best practices about how LINQ would be used in a complex application.  In some of the videos, Scott shows how you can hook into the OR-generated classes for tasks such as data validation by creating a partial class and implementing a partial method.

What are the general guidelines for adding business logic?  Is it a bad idea to just extend the generated classes and add biz logic?

Or should you create separate modules as a separate layer to encapsulate the logic?

I suspect the answer is "it depends" but I'd love to hear a discussion of what y'all have learned from implementing LINQ so far.

(update: LINQPad is awesome.)

Yes LINQ rocks!

I am sure it will be mis-used by some folks and that will have some folks say it's bad/ wrong/ evil/ etc....

one example of using linq:

I have an app I recently finished V1 of for a win CE device, LINQ allows me to not have to use a sql database on that app.
I have a binary serializer we got from a vendor so I can store data
then I use Generics to have typed collections
and LINQ to search / query / iterate over the lists.
just a great fit and done so that 90% of the app does not know the data is just collections and serialized.

I am also using it in places where in the past I would have done the old SQL Connection / Command / Datareader / send to xxxx target with a collection / list / array/

while this is not a paragon of design I do find that it saves me a bunch of code and time and gets what amounts to the same results.

also BTW:

if you do a using (db ) {   db.table.insertonsubmit(foo)   db.submitchanges()   }

type of block that submit will make a sql trasnaction of the updates and inserts for you so if it throws an ex you do not have a mess.
atleast with MS SQL this is true, not tested with others.

Key to adding business logic is realizing the power of partial classes and partial methods (lightweight events).

So in a nutshell you want to add custom code to a new source file that was not originially generated by your OR product. Also realize what hooks exist out of the box with partial methods.