using System;
using System.Collections;
using System.Diagnostics;
using System.Reflection;
namespace Python.Runtime
{
///
/// Implements a Python descriptor type that provides access to CLR events.
///
[Serializable]
internal class EventObject : ExtensionType
{
internal readonly string name;
internal readonly EventHandlerCollection reg;
public EventObject(EventInfo info)
{
Debug.Assert(!info.AddMethod.IsStatic);
this.name = info.Name;
this.reg = new EventHandlerCollection(info);
}
///
/// Descriptor __get__ implementation. A getattr on an event returns
/// a "bound" event that keeps a reference to the object instance.
///
public static NewReference tp_descr_get(BorrowedReference ds, BorrowedReference ob, BorrowedReference tp)
{
var self = GetManagedObject(ds) as EventObject;
if (self == null)
{
return Exceptions.RaiseTypeError("invalid argument");
}
if (ob == null)
{
return new NewReference(ds);
}
if (Runtime.PyObject_IsInstance(ob, tp) < 1)
{
return Exceptions.RaiseTypeError("invalid argument");
}
return new EventBinding(self.name, self.reg, new PyObject(ob)).Alloc();
}
///
/// Descriptor __set__ implementation. This actually never allows you
/// to set anything; it exists solely to support the '+=' spelling of
/// event handler registration. The reason is that given code like:
/// 'ob.SomeEvent += method', Python will attempt to set the attribute
/// SomeEvent on ob to the result of the '+=' operation.
///
public static int tp_descr_set(BorrowedReference ds, BorrowedReference ob, BorrowedReference val)
{
if (GetManagedObject(val) is EventBinding _)
{
return 0;
}
Exceptions.RaiseTypeError("cannot set event attributes");
return -1;
}
///
/// Descriptor __repr__ implementation.
///
public static NewReference tp_repr(BorrowedReference ob)
{
var self = (EventObject)GetManagedObject(ob)!;
return Runtime.PyString_FromString($"");
}
}
internal class Handler
{
public readonly nint hash;
public readonly Delegate del;
public Handler(nint hash, Delegate d)
{
this.hash = hash;
this.del = d;
}
}
}