public override IEnumerable<ExportDescriptorPromise> GetExportDescriptors(CompositionContract contract, DependencyAccessor descriptorAccessor)
{
// Avoid trying to create defaults-of-defaults-of...
if (contract.ContractName != null && contract.ContractName.StartsWith(Constants.DefaultContractNamePrefix))
return NoExportDescriptors;
var implementations = descriptorAccessor.ResolveDependencies("test for default", contract, false);
if (implementations.Any())
return NoExportDescriptors;
var defaultImplementationDiscriminator = Constants.DefaultContractNamePrefix + (contract.ContractName ?? "");
IDictionary<string, object> copiedConstraints = null;
if (contract.MetadataConstraints != null)
copiedConstraints = contract.MetadataConstraints.ToDictionary(k => k.Key, k => k.Value);
var defaultImplementationContract = new CompositionContract(contract.ContractType, defaultImplementationDiscriminator, copiedConstraints);
CompositionDependency defaultImplementation;
if (!descriptorAccessor.TryResolveOptionalDependency("default", defaultImplementationContract, true, out defaultImplementation))
return NoExportDescriptors;
return new[]
{
new ExportDescriptorPromise(
contract,
"Default Implementation",
false,
() => new[] {defaultImplementation},
_ =>
{
var defaultDescriptor = defaultImplementation.Target.GetDescriptor();
return ExportDescriptor.Create((c, o) => defaultDescriptor.Activator(c, o), defaultDescriptor.Metadata);
})
};
}
public override IEnumerable<ExportDescriptorPromise> GetExportDescriptors(CompositionContract contract, DependencyAccessor descriptorAccessor)
{
if (!contract.Equals(_supportedContract))
return NoExportDescriptors;
var implementations = descriptorAccessor.ResolveDependencies("test for existing", contract, false);
if (implementations.Any())
return NoExportDescriptors;
return new[] { new ExportDescriptorPromise(contract, "test metadataProvider", false, NoDependencies, _ => ExportDescriptor.Create((c, o) => DefaultObject, NoMetadata)) };
}
