1783 Implement Interface And Inherit Class #2028

rmadsen-ks · 2022-11-29T14:11:56Z

Added support for multiple inheritance when inheriting from one base class and/or multiple interfaces.

Added a unit test verifying that it works with a simple class and interface. This unit test would previously have failed since multiple types are in the class super class list.

Close #1783

Checklist

Check all those that are applicable and complete.

Make sure to include one or more tests for your change
If an enhancement PR, please create docs and at best an example
Ensure you have signed the .NET Foundation CLA
Add yourself to AUTHORS
Updated the CHANGELOG

src/runtime/TypeManager.cs

src/runtime/Types/MetaType.cs

lostmsu · 2022-11-29T22:05:31Z

src/runtime/Types/MetaType.cs

+                {
+                    if (cb2.type.Valid && cb2.type.Value.IsInterface)
+                        interfaces.Add(cb2.type.Value);
+                    else baseType.Add(cb2);


IMHO, it is better to enforce the order to be BaseClass, IInterface1, IInterface2, etc.

I believe the current code has a bug down below because it uses base_type which is not the BaseClass if the order is different.

I have only added this functionality for types which goes through TypeManager.CreateSubType, so it should only affect that branch.

for code flows not invoking CreateSubType, the behavior willl be exactly the same as before.

lostmsu

Please, rebase before posting a new iteration.

P.S. sorry for the late response

lostmsu · 2023-02-02T02:59:57Z

src/runtime/Types/MetaType.cs

+                    if (classBaseIt.type.Valid && classBaseIt.type.Value.IsInterface)
+                        interfaces.Add(classBaseIt.type.Value);
+                    else baseTypes.Add(classBaseIt);
+                }


What if it is not a .NET class or interface? You can't simply ignore it.

Added exceptions here in the latest version.

lostmsu · 2023-02-02T03:05:07Z

src/runtime/Types/MetaType.cs


            BorrowedReference slots = Runtime.PyDict_GetItem(dict, PyIdentifier.__slots__);
            if (slots != null)
            {
                return Exceptions.RaiseTypeError("subclasses of managed classes do not support __slots__");
            }

-            // If __assembly__ or __namespace__ are in the class dictionary then create
+            // If the base class has a parameterless constructor, or


If the base class has a parameterless constructor

??? What is this for? If that's right, it seems breaking to me.

I forget, but that does not actually seem to be included with these changes. It is in my fork though.

lostmsu · 2023-02-02T03:06:39Z

src/runtime/Types/MetaType.cs

                }
            }

+            var base_type = Runtime.PyTuple_GetItem(bases, 0);


bases here can be empty since you removed check above.

How can bases be length 0? This should only be called when a C# type is subclassed, right? In this case, it should at least be length 1.

lostmsu · 2023-02-02T03:08:04Z

src/runtime/Types/MetaType.cs

-            // That type must itself have a managed implementation. We check
-            // that by making sure its metatype is the CLR metatype.
+            // Extract interface types and base class types.
+            var interfaces = new List<Type>();


IMHO, repeating the same base interface multiple times should be an error.

And it might be, add a test.

Test added.

lostmsu · 2023-02-02T03:09:05Z

src/runtime/Types/MetaType.cs

+            // Multiple inheritance is not supported, unless the other types are interfaces
+            if (baseTypes.Count > 1)
+            {
+                return Exceptions.RaiseTypeError("cannot use multiple inheritance with managed classes");


Since you collected multiple base types, perhaps it would be useful to list them in the error message in case user did not notice which ones are classes.

Ok, I'll include this.

lostmsu · 2023-02-02T03:17:51Z

src/runtime/Types/MetaType.cs

+
+                if (GetManagedObject(baseTypeIt) is ClassBase classBaseIt)
+                {
+                    if (classBaseIt.type.Valid && classBaseIt.type.Value.IsInterface)


Invalid ClassBase instances should also raise an error regardless of anything else.

got it, adding exceptions.

Added support for multiple inheritance when inheriting from one base class and/or multiple interfaces. Added a unit test verifying that it works with a simple class and interface. This unit test would previously have failed since multiple types are in the class super class list.

- Added exceptions during unintended use of superclasses. - Removed invalid comment. - Improved exceptions from MetaType slightly.

rmadsen-ks · 2023-02-02T21:24:55Z

@lostmsu,

Thanks for doing the review.

I have rebased and fixed things you mentioned.

Will you mark the conversations resolved where appropriate?

lostmsu · 2023-02-03T22:59:52Z

Thank you for the contribution!

* 1783 Implement Interface And Inherit Class Added support for multiple inheritance when inheriting from one base class and/or multiple interfaces. Added a unit test verifying that it works with a simple class and interface. This unit test would previously have failed since multiple types are in the class super class list.

rmadsen-ks mentioned this pull request Nov 29, 2022

Object identity, Interfaces and Attributes #2019

Closed

5 tasks

lostmsu requested changes Nov 29, 2022

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eirannejad mentioned this pull request Dec 19, 2022

Improved Type Interop with CLR #2055

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5 tasks

lostmsu requested changes Feb 2, 2023

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rmadsen-ks added 3 commits February 2, 2023 21:48

Added a few cleanups based on feedback.

f92a26b

1783 Implement Interface And Inherit Class: Cleanup

7acbb22

- Added exceptions during unintended use of superclasses. - Removed invalid comment. - Improved exceptions from MetaType slightly.

rmadsen-ks force-pushed the 1783-ImplementInterfaceAndInheritClass branch from cf4d59a to 7acbb22 Compare February 2, 2023 21:07

lostmsu approved these changes Feb 3, 2023

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lostmsu merged commit a404d6e into pythonnet:master Feb 3, 2023

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1783 Implement Interface And Inherit Class #2028

1783 Implement Interface And Inherit Class #2028

rmadsen-ks commented Nov 29, 2022

lostmsu Nov 29, 2022

rmadsen-ks Nov 30, 2022

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lostmsu commented Feb 3, 2023

1783 Implement Interface And Inherit Class #2028

1783 Implement Interface And Inherit Class #2028

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rmadsen-ks commented Nov 29, 2022

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rmadsen-ks commented Feb 2, 2023

lostmsu commented Feb 3, 2023