Python classes cannot inherit from C# interfaces that themselves inherit from C# interfaces with methods:
namespace A
{
public interface B
{
void C();
}
public interface D : B
{
}
}import clr
clr.AddReference('A')
import A
class E(A.D):
__namespace__ = 'F'
def C(self):
passOutput:
Traceback (most recent call last):
File "<stdin>", line 6, in <module>
TypeError: Failed to create Python type for F.E
Extending from B works. It also works if C is removed from B.
Possibly related to #2511. Reverting to 3.0.3 (before 9ebfbde) provides the moderately-more-useful error TypeError: VTable setup of type F.E failed.
Please do NOT convert this to a discussion. It is a real bug that requires fixing. As noted above, providing a definition for C does not affect whether the bug occurs.
I have tested this with mono 6.8 and 6.12, as well as with MSCV. The latter gives the slightly-different error:
Traceback (most recent call last):
File "<stdin>", line 6, in <module>
class E(A.D):
TypeError: Method 'C' in type 'F.E' from assembly 'Python.Runtime.Dynamic, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' does not have an implementation.
Note that C was defined as above.
As a workaround, the following can be done...
import clr
clr.AddReference('A')
import A
class E(A.B):
__namespace__ = 'F'
class G(E, A.D):
__namespace__ = 'F'
def C(self):
pass
G().C()And for some reason C has to be implemented in G and not E:
System.NotImplementedException: Python object does not have a 'C' method
at Python.Runtime.PythonDerivedType.InvokeMethodVoid (Python.Runtime.IPythonDerivedType obj, System.String methodName, System.String origMethodName, System.Object[] args, System.RuntimeMethodHandle methodHandle, System.RuntimeTypeHandle declaringTypeHandle) [0x00151] in <e8135b23d9064b84a255057569ff100a>:0
at F.E.C () [0x00000] in <d16dd79070534f72b8760f94ab2e0924>:0
at F.G._E__C () [0x00000] in <d16dd79070534f72b8760f94ab2e0924>:0
at (wrapper managed-to-native) System.Reflection.RuntimeMethodInfo.InternalInvoke(System.Reflection.RuntimeMethodInfo,object,object[],System.Exception&)
at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x0007c] in <12b418a7818c4ca0893feeaaf67f1e7f>:0
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "<stdin>", line 14, in <module>
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NotImplementedException: Python object does not have a 'C' method
at Python.Runtime.PythonDerivedType.InvokeMethodVoid (Python.Runtime.IPythonDerivedType obj, System.String methodName, System.String origMethodName, System.Object[] args, System.RuntimeMethodHandle methodHandle, System.RuntimeTypeHandle declaringTypeHandle) [0x00151] in <e8135b23d9064b84a255057569ff100a>:0
at F.E.C () [0x00000] in <d16dd79070534f72b8760f94ab2e0924>:0
at F.G._E__C () [0x00000] in <d16dd79070534f72b8760f94ab2e0924>:0
at (wrapper managed-to-native) System.Reflection.RuntimeMethodInfo.InternalInvoke(System.Reflection.RuntimeMethodInfo,object,object[],System.Exception&)
at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x0007c] in <12b418a7818c4ca0893feeaaf67f1e7f>:0
--- End of inner exception stack trace ---
at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x0009a] in <12b418a7818c4ca0893feeaaf67f1e7f>:0
at System.RuntimeType.InvokeMember (System.String name, System.Reflection.BindingFlags bindingFlags, System.Reflection.Binder binder, System.Object target, System.Object[] providedArgs, System.Reflection.ParameterModifier[] modifiers, System.Globalization.CultureInfo culture, System.String[] namedParams) [0x007b0] in <12b418a7818c4ca0893feeaaf67f1e7f>:0
at System.Type.InvokeMember (System.String name, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object target, System.Object[] args) [0x00000] in <12b418a7818c4ca0893feeaaf67f1e7f>:0
at Python.Runtime.PythonDerivedType.InvokeMethodVoid (Python.Runtime.IPythonDerivedType obj, System.String methodName, System.String origMethodName, System.Object[] args, System.RuntimeMethodHandle methodHandle, System.RuntimeTypeHandle declaringTypeHandle) [0x0015d] in <e8135b23d9064b84a255057569ff100a>:0
at F.G.C () [0x00000] in <d16dd79070534f72b8760f94ab2e0924>:0
at (wrapper managed-to-native) System.Reflection.RuntimeMethodInfo.InternalInvoke(System.Reflection.RuntimeMethodInfo,object,object[],System.Exception&)
at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x0007c] in <12b418a7818c4ca0893feeaaf67f1e7f>:0
Python classes cannot inherit from C# interfaces that themselves inherit from C# interfaces with methods:
Output:
Extending from
Bworks. It also works ifCis removed fromB.Possibly related to #2511. Reverting to 3.0.3 (before 9ebfbde) provides the moderately-more-useful error
TypeError: VTable setup of type F.E failed.Please do NOT convert this to a discussion. It is a real bug that requires fixing. As noted above, providing a definition for
Cdoes not affect whether the bug occurs.I have tested this with mono 6.8 and 6.12, as well as with MSCV. The latter gives the slightly-different error:
Note that
Cwas defined as above.As a workaround, the following can be done...
And for some reason C has to be implemented in G and not E: