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150 lines (123 loc) · 5.42 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.Collections;
using System.Reflection;
using System.Runtime.InteropServices;
namespace Python.Runtime {
//========================================================================
// Implements a Python descriptor type that provides access to CLR fields.
//========================================================================
internal class FieldObject : ExtensionType {
FieldInfo info;
public FieldObject(FieldInfo info) : base() {
this.info = info;
}
//====================================================================
// Descriptor __get__ implementation. This method returns the
// value of the field on the given object. The returned value
// is converted to an appropriately typed Python object.
//====================================================================
public static IntPtr tp_descr_get(IntPtr ds, IntPtr ob, IntPtr tp) {
FieldObject self = (FieldObject)GetManagedObject(ds);
Object result;
if (self == null) {
return IntPtr.Zero;
}
FieldInfo info = self.info;
if ((ob == IntPtr.Zero) || (ob == Runtime.PyNone)) {
if (!info.IsStatic) {
Exceptions.SetError(Exceptions.TypeError,
"instance attribute must be accessed " +
"through a class instance"
);
return IntPtr.Zero;
}
try {
result = info.GetValue(null);
return Converter.ToPython(result, info.FieldType);
}
catch(Exception e) {
Exceptions.SetError(Exceptions.TypeError, e.Message);
return IntPtr.Zero;
}
}
try {
CLRObject co = (CLRObject)GetManagedObject(ob);
result = info.GetValue(co.inst);
return Converter.ToPython(result, info.FieldType);
}
catch(Exception e) {
Exceptions.SetError(Exceptions.TypeError, e.Message);
return IntPtr.Zero;
}
}
//====================================================================
// Descriptor __set__ implementation. This method sets the value of
// a field based on the given Python value. The Python value must be
// convertible to the type of the field.
//====================================================================
public static new int tp_descr_set(IntPtr ds, IntPtr ob, IntPtr val) {
FieldObject self = (FieldObject)GetManagedObject(ds);
Object newval;
if (self == null) {
return -1;
}
if (val == IntPtr.Zero) {
Exceptions.SetError(Exceptions.TypeError,
"cannot delete field"
);
return -1;
}
FieldInfo info = self.info;
if (info.IsLiteral || info.IsInitOnly) {
Exceptions.SetError(Exceptions.TypeError,
"field is read-only"
);
return -1;
}
bool is_static = info.IsStatic;
if ((ob == IntPtr.Zero) || (ob == Runtime.PyNone)) {
if (!is_static) {
Exceptions.SetError(Exceptions.TypeError,
"instance attribute must be set " +
"through a class instance"
);
return -1;
}
}
if (!Converter.ToManaged(val, info.FieldType, out newval,
true)) {
return -1;
}
try {
if (!is_static) {
CLRObject co = (CLRObject)GetManagedObject(ob);
info.SetValue(co.inst, newval);
}
else {
info.SetValue(null, newval);
}
return 0;
}
catch(Exception e) {
Exceptions.SetError(Exceptions.TypeError, e.Message);
return -1;
}
}
//====================================================================
// Descriptor __repr__ implementation.
//====================================================================
public static IntPtr tp_repr(IntPtr ob) {
FieldObject self = (FieldObject)GetManagedObject(ob);
string s = String.Format("<field '{0}'>", self.info.Name);
return Runtime.PyString_FromStringAndSize(s, s.Length);
}
}
}