Are templates usefull?

[luke]

Are they?
I mean, you could always downcast them for particular use, but then the
system would be well designed with intefaces instead of generics, and for
other uses I don't see any sense (collections excluded). Why do I need to
hold something of type 'object'? For what concrete usage? I am confused with
interfaces and generics... Please someone explain to me.

[Nicholas Paldino [.NET/C# MVP]]

luke,

Generics are a great way to get general functionality while exposing
specific types.

You have already mentioned the example of collections, for example.

With interfaces and generics, they are a way of specifying the specific
type to use for the contract that makes up the interface.

For example, you know that the IEnumerator interface is going to iterate
through a list/collection/whatever. In order to support all types, it just
returns an object, which you then have to cast. This isn't type safe, and
an erroneous cast will be caught at run-time, not compile time.

With IEnumerator<T>, you don't have to cast, because the Current
property returns T. If you try to misassign this to another variable, you
catch it at compile time.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"luke" <lu**@hotmail.com> wrote in message
news:dr**********@sunce.iskon.hr...

Are they?
I mean, you could always downcast them for particular use, but then the
system would be well designed with intefaces instead of generics, and for
other uses I don't see any sense (collections excluded). Why do I need to
hold something of type 'object'? For what concrete usage? I am confused
with interfaces and generics... Please someone explain to me.

[luke]

> With IEnumerator<T>, you don't have to cast, because the Current

property returns T. If you try to misassign this to another variable, you
catch it at compile time.

Hope this helps.

Yes it does, thanks.

[Nick Hounsome]

"luke" <lu**@hotmail.com> wrote in message
news:dr**********@sunce.iskon.hr...

With IEnumerator<T>, you don't have to cast, because the Current
property returns T. If you try to misassign this to another variable,
you catch it at compile time.

Hope this helps.

Yes it does, thanks.

But be aware that you can't just update all your old code because of at
least 1 big gotcha [it got me :-(] IList<T> does NOT derive from IList (and
there IS a good(ish) reason for this)

This causes a problem where a method must continues to take IList and you
are now trying to pass IList<T>