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extensiontype.cs
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129 lines (93 loc) · 4.68 KB
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// ==========================================================================
// This software is subject to the provisions of the Zope Public License,
// Version 2.0 (ZPL). A copy of the ZPL should accompany this distribution.
// THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
// WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
// FOR A PARTICULAR PURPOSE.
// ==========================================================================
using System;
using System.Runtime.InteropServices;
using System.Collections;
using System.Reflection;
namespace Python.Runtime {
/// <summary>
/// Base class for extensions whose instances *share* a single Python
/// type object, such as the types that represent CLR methods, fields,
/// etc. Instances implemented by this class do not support subtyping.
/// </summary>
internal abstract class ExtensionType : ManagedType {
public ExtensionType() : base() {
// Create a new PyObject whose type is a generated type that is
// implemented by the particuar concrete ExtensionType subclass.
// The Python instance object is related to an instance of a
// particular concrete subclass with a hidden CLR gchandle.
IntPtr tp = TypeManager.GetTypeHandle(this.GetType());
// int rc = (int)Marshal.ReadIntPtr(tp, TypeOffset.ob_refcnt);
// if (rc > 1050) {
// DebugUtil.Print("tp is: ", tp);
// DebugUtil.DumpType(tp);
// }
IntPtr py = Runtime.PyType_GenericAlloc(tp, 0);
GCHandle gc = GCHandle.Alloc(this);
Marshal.WriteIntPtr(py, ObjectOffset.magic(), (IntPtr)gc);
// We have to support gc because the type machinery makes it very
// hard not to - but we really don't have a need for it in most
// concrete extension types, so untrack the object to save calls
// from Python into the managed runtime that are pure overhead.
Runtime.PyObject_GC_UnTrack(py);
this.tpHandle = tp;
this.pyHandle = py;
this.gcHandle = gc;
}
//====================================================================
// Common finalization code to support custom tp_deallocs.
//====================================================================
public static void FinalizeObject(ManagedType self) {
Runtime.PyObject_GC_Del(self.pyHandle);
Runtime.Decref(self.tpHandle);
self.gcHandle.Free();
}
//====================================================================
// Type __setattr__ implementation.
//====================================================================
public static int tp_setattro(IntPtr ob, IntPtr key, IntPtr val) {
string message = "type does not support setting attributes";
if (val == IntPtr.Zero) {
message = "readonly attribute";
}
Exceptions.SetError(Exceptions.TypeError, message);
return -1;
}
//====================================================================
// Default __set__ implementation - this prevents descriptor instances
// being silently replaced in a type __dict__ by default __setattr__.
//====================================================================
public static int tp_descr_set(IntPtr ds, IntPtr ob, IntPtr val) {
string message = "attribute is read-only";
Exceptions.SetError(Exceptions.AttributeError, message);
return -1;
}
//====================================================================
// Required Python GC support.
//====================================================================
public static int tp_traverse(IntPtr ob, IntPtr func, IntPtr args) {
return 0;
}
public static int tp_clear(IntPtr ob) {
return 0;
}
public static int tp_is_gc(IntPtr type) {
return 1;
}
//====================================================================
// Default dealloc implementation.
//====================================================================
public static void tp_dealloc(IntPtr ob) {
// Clean up a Python instance of this extension type. This
// frees the allocated Python object and decrefs the type.
ManagedType self = GetManagedObject(ob);
FinalizeObject(self);
}
}
}