// This is the ONLY method which is not executed under the ImportEngine composition lock.
// We need to protect all state that is accesses
public override object GetExportedValue(ExportDefinition definition)
{
this.RequiresRunning();
// given the implementation of the ImportEngine, this iwll be called under a lock if the part is still being composed
// This is only called outside of the lock when the part is fully composed
// based on that we only protect:
// _exportsCache - and thus all calls to GetExportingMemberFromDefinition
// access to _importValues
// access to _initialCompositionComplete
// access to _instance
Requires.NotNull(definition, "definition");
ExportingMember member = null;
lock (this._lock)
{
member = GetExportingMemberFromDefinition(definition);
if (member == null)
{
throw ExceptionBuilder.CreateExportDefinitionNotOnThisComposablePart("definition");
}
this.EnsureGettable();
}
return(this.GetExportedValue(member));
}
private object GetExportedValue(ExportingMember member)
{
object instance = null;
if (member.RequiresInstance)
{ // Only activate the instance if we actually need to
instance = this.GetInstanceActivatingIfNeeded();
}
return(member.GetExportedValue(instance, this._lock));
}
public override object GetExportedValue(ExportDefinition definition)
{
this.EnsureRunning();
Requires.NotNull(definition, "definition");
ExportingMember member = GetExportingMemberFromDefinition(definition);
if (member == null)
{
throw ExceptionBuilder.CreateExportDefinitionNotOnThisComposablePart("definition");
}
this.EnsureGettable();
return(this.GetExportedValue(member));
}
// alwayc called under a lock
private bool RequiresActivation()
{
// If we have any imports then we need activation
// (static imports are not supported)
if (this.ImportDefinitions.Any())
{
return(true);
}
// If we have any instance exports, then we also
// need activation.
return(this.ExportDefinitions.Any(definition =>
{
ExportingMember member = GetExportingMemberFromDefinition(definition);
return member.RequiresInstance;
}));
}