using System;
using System.Reflection;
namespace Python.Runtime
{
///
/// Implements a Python descriptor type that provides access to CLR fields.
///
[Serializable]
internal class FieldObject : ExtensionType
{
private FieldInfo info;
public FieldObject(FieldInfo info)
{
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)
{
var 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
{
var co = (CLRObject)GetManagedObject(ob);
if (co == null)
{
Exceptions.SetError(Exceptions.TypeError, "instance is not a clr object");
return IntPtr.Zero;
}
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 new static int tp_descr_set(IntPtr ds, IntPtr ob, IntPtr val)
{
var 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)
{
var co = (CLRObject)GetManagedObject(ob);
if (co == null)
{
Exceptions.SetError(Exceptions.TypeError, "instance is not a clr object");
return -1;
}
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)
{
var self = (FieldObject)GetManagedObject(ob);
return Runtime.PyString_FromString($"");
}
}
}