Not completely with this.
This bit.....
foreach(IList list in containingLists)
{
// yadda yadda
}
What sort of things are you doing in the "yadda yadda" bit.....
If you don't know the type of the elements of list you can't access them.
If you do know the type of the elements then, the type is known.
P.S.
I tend to do this with most techniques that are new to me, I abuse them to
the point where they become impractical.....and then I know their
limits....I'm just taking generics to an extreme in order to get a feel for
their practical limits/application.
-----Original Message-----
From: Discussion of advanced .NET topics.
[mailto:[EMAIL PROTECTED] On Behalf Of Frans Bouma
Sent: 18 October 2006 10:30
To: ADVANCED-DOTNET@DISCUSS.DEVELOP.COM
Subject: Re: [ADVANCED-DOTNET] Type declarations in ide....
> You'll have to explain with an example.....it's early in the
> morning and my brain isn't up to it.
public class Foo : ISomething
{
private List<Bar> _bars;
//... ctor, creation etc.
List<Object> ISomething.GetContainingLists()
{
List<Object> toReturn = new List<Object>();
toReturn.Add(_bars);
return toReturn;
}
}
Now, in some other code, an ISomething instance is passed in. This can be a
Foo instance, but it can also be a FooToo instance:
public class FooToo : ISomething
{
private List<BarToo> _bars;
//... ctor, creation etc.
List<Object> ISomething.GetContainingLists()
{
List<Object> toReturn = new List<Object>();
toReturn.Add(_bars);
return toReturn;
}
}
So, consuming code, which consumes ISomething looks like:
private void ProcessISomething(ISomething toProcess)
{
List<Object> containingLists = toProcess.GetContainingLists();
// and now what... how to access the lists inside containingLists ?
// that's right, via a non-generic interface. because any generic
interface
// would require _at compile time_ the generic type. Which is
UNKNOWN.
foreach(IList list in containingLists)
{
// yadda yadda
}
}
You might think: I can solve this with a helper method:
private void DoProcessing<T>(List<T> toProcess)
{
// yadday yadda
}
and write ProcessISomething as:
However, how would you use T in this method? You've to specify a
where clause, and ProcessISomething, how would you write
that?
See, with generic interfaces, you don't solve this, as you then
still need a generic type parameter to specify _at compile
time_ . With NON generic interfaces you solve this. That's why non-generic
interfaces should be used to consume generic code in
routines which don't know the type of the generic parameter.
Using interfaces is also a way to do generic programming, i.e. write
a program that can work with multiple types. Mixing
interfaces and generics, makes things only more complicated instead of more
usable and readable.
Frans
>
> -----Original Message-----
> From: Discussion of advanced .NET topics.
> [mailto:[EMAIL PROTECTED] On Behalf Of Frans Bouma
> Sent: 17 October 2006 16:39
> To: ADVANCED-DOTNET@DISCUSS.DEVELOP.COM
> Subject: Re: [ADVANCED-DOTNET] Type declarations in ide....
>
> > I agree....its more of an experiment at the moment.....and they are
> > interfaces....just parametised ones.
>
> Generic interfaces? Isn't that mitigating the aspect
> of interfaces?
> I mean: if you have an instance of Class<T>, and pass that to
> some code and inside that code you don't know the type of T
> (this can happen), you can refer to the instance of Class<T>
> with the interface, so your code will become very simple. If
> you have generic interfaces as well, the problem remains and
> you have to at some point need to know the type of T to get
> things compiled.
>
> This especially creates problems when T has to be of
> some type, so where clauses have to be added to the method.
> With an interface you can solve this problem. so I always use
> the rule of thumb: use interfaces to use generic classes in
> code where you don't know the generic parameter type, and
> thus keep your interfaces non-generic just for this purpose.
>
> FB
>
> >
> > -----Original Message-----
> > From: Discussion of advanced .NET topics.
> > [mailto:[EMAIL PROTECTED] On Behalf Of
> Frans Bouma
> > Sent: 17 October 2006 13:17
> > To: ADVANCED-DOTNET@DISCUSS.DEVELOP.COM
> > Subject: Re: [ADVANCED-DOTNET] Type declarations in ide....
> >
> > > A slightly bizarre question....
> > >
> > > I've got some generic methods that return generic types,
> > the problem
> > > is that sometimes the types get very large...e.h.
> > >
> > >
> > > Foo<Foo<Bar<Foo<Bar>,Foo<Foo>>>> x =
> > > a.GetFoo<Foo<Bar<Foo<Bar>,Foo<Foo>>>>
> > > (b);
> > >
> > > is there a way of getting the IDE to auto generate the type
> > > declaration, so I don't spend hours foo'ing and bar'ing.
> >
> > I'm not sure if you should continue with this. It
> makes code
> > VERY unreadable. Too much of a good is still 'too much' ;)
> >
> > You might want to use an interface here and there.
> >
> > Frans
> >
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