Advice method can accept various arguments that represent information about target and triggers and can be used in complex scenarios.
Name argument carries a name of a target. If the target is a method, then the name will be the name of the method. If injection is applied to a whole property or an event then the name will be the name of the property or the event.
class LogAspect {
[Advice(Kind.Before, Targets = Target.Method)]
public void LogEnter([Argument(Source.Name)] string name)
{
Console.WriteLine($"Entering method '{name}'.");
}
}
Type argument carries a type that contains the target method.
class CountCreationAspect {
private int _count = 0;
[Advice(Kind.Before, Targets = Target.Constructor)]
public void LogEnter([Argument(Source.Type)] Type type)
{
Console.WriteLine($"Instance of type {type.Name} created {++_count} times.");
}
}
Type argument has a reference to the instance that owns target method. Note that the reference can be null when the target method is static.
class FreezableAspect {
[Advice(Kind.Before, Targets = Target.Public | Target.Setter)]
public void CheckIfFrozen([Argument(Source.Instance)] object instance)
{
if (instance is IFreezable freezable && freezable.IsFrozen)
throw new InvalidOperationException("Attempt to modify frozen object.");
}
}
Metadata argument refers to reflection metadata of a target method.