Sorry, you need to specify the type when importing a Func<>, you can't leave
it blank as I did in my example code (serves me right for not trying it
before posting)
On Sat, Sep 10, 2011 at 8:31 PM, Michael Minutillo <
michael.minuti...@gmail.com> wrote:
> You can export a Func<> and then call it. Like this:
>
> class BarFactory
> {
> [Import]
> IBlah blah;
>
> [Export(typeof(Func<IBar>))]
>
> IBar CreateBar()
> {
> return new Bar(blah);
> }
> }
>
> class BarProvider
> {
> [Import]
> private Func<IBar> _factory;
>
> [Export]
> public IBar Bar { get { return _factory.Invoke(); } }
> }
>
> Michael M. Minutillo
> Indiscriminate Information Sponge
> http://codermike.com
>
>
> On Sat, Sep 10, 2011 at 7:38 PM, Matt Siebert <mlsieb...@gmail.com> wrote:
>
>> I kind of like this approach, but does MEF allow an Export on a method? If
>> so then I suppose I could do something like:
>>
>> class BarFactory
>> {
>> [Import]
>> IBlah blah;
>>
>> [Export]
>> IBar CreateBar()
>> {
>> return new Bar(blah);
>> }
>> }
>>
>> I can see how imports could be handled with David's approach though.
>>
>> Thanks.
>>
>>
>> On Saturday, September 10, 2011, Michael Minutillo <
>> michael.minuti...@gmail.com> wrote:
>> > One solution would be to add the following class to Foo.dll but it means
>> you're controlling the creation of Bar instead of getting MEF to do it for
>> you
>> > class BarProvider
>> > {
>> > [Export(typeof(IBar))]
>> > IBar ExportedBar = new Bar();
>> > }
>> >
>> >
>> > Michael M. Minutillo
>> > Indiscriminate Information Sponge
>> > http://codermike.com
>> >
>> >
>> > On Fri, Sep 9, 2011 at 2:33 PM, Matt Siebert <mlsieb...@gmail.com>
>> wrote:
>> >>
>> >> Hey folks,
>> >> I'm beginning to use MEF in a solution that involves a mix of .NET 3.5
>> and 4.0 projects. I'm using MEF in the 4.0 projects and I need to register
>> some exports that live in the 3.5 projects. The problem is I need to do
>> this from one of the plugin projects.
>> >> To illustrate this, imagine a console application such as...
>> >>
>> >> class Program
>> >> {
>> >> static void Main(string[] args)
>> >> {
>> >> var program = new Program();
>> >>
>> >> var catalog = new DirectoryCatalog(".");
>> >> using (var container = new CompositionContainer(catalog))
>> >> {
>> >> var batch = new CompositionBatch();
>> >> batch.AddPart(program);
>> >> container.Compose(batch);
>> >>
>> >> program.Test();
>> >> }
>> >> }
>> >>
>> >> [Import]
>> >> private IFoo foo = null;
>> >>
>> >> public void Test()
>> >> {
>> >> Console.WriteLine(foo.Bar);
>> >> }
>> >> }
>> >>
>> >> IFoo is in another DLL with a concrete implementation...
>> >>
>> >> public interface IFoo
>> >> {
>> >> string Bar { get; }
>> >> }
>> >>
>> >> [Export(typeof(IFoo))]
>> >> public class Foo : IFoo
>> >> {
>> >> [Import]
>> >> private IBar bar;
>> >>
>> >> public string Bar
>> >> {
>> >> get { return "Beer " + bar.Foo; }
>> >> }
>> >> }
>> >>
>> >> and finally, IBar is in a .NET 3.5 DLL that isn't using MEF...
>> >>
>> >> public interface IBar
>> >> {
>> >> string Foo { get; }
>> >> }
>> >>
>> >> public class Bar : IBar
>> >> {
>> >> public string Foo
>> >> {
>> >> get { return "me"; }
>> >> }
>> >> }
>> >>
>> >> Is there a way to register an IBar export without the console
>> application referencing Bar.dll?
>> >> Foo.dll has a reference to Bar.dll and could register the export, but
>> in order to do this composition must occur first (so that the app can
>> discover Foo.dll) and that will fail since Foo's IBar import can't be
>> satisfied.
>> >> Cheers.
>> >
>>
>
>
