implemented __delitem__ for IDictionary<K,V> and IList<T>

fixed crash for all other types (now properly throws TypeError)

fixes pythonnet#2530

Author: lostmsu

CHANGELOG.md

@@ -8,9 +8,14 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 ## Unreleased
 
 ### Added
+
+-  Support `del obj[...]` for types derived from `IList<T>` and `IDictionary<K, V>`
+
 ### Changed
 ### Fixed
 
+-  Fixed crash when trying to `del clrObj[...]` for non-arrays
+
 ## [3.0.5](https://github.com/pythonnet/pythonnet/releases/tag/v3.0.5) - 2024-12-13
 
 ### Added

src/runtime/ClassManager.cs

@@ -213,6 +213,7 @@ internal static void InitClassBase(Type type, ClassBase impl, ReflectedClrType p
             ClassInfo info = GetClassInfo(type, impl);
 
             impl.indexer = info.indexer;
+            impl.del = info.del;
             impl.richcompare.Clear();
 
 
@@ -538,6 +539,21 @@ private static ClassInfo GetClassInfo(Type type, ClassBase impl)
 
                 ob = new MethodObject(type, name, mlist);
                 ci.members[name] = ob.AllocObject();
+                if (name == nameof(IDictionary<int, int>.Remove)
+                    && mlist.Any(m => m.DeclaringType?.GetInterfaces()
+                        .Any(i => i.TryGetGenericDefinition() == typeof(IDictionary<,>)) is true))
+                {
+                    ci.del = new();
+                    ci.del.AddRange(mlist.Where(m => !m.IsStatic));
+                }
+                else if (name == nameof(IList<int>.RemoveAt)
+                         && mlist.Any(m => m.DeclaringType?.GetInterfaces()
+                             .Any(i => i.TryGetGenericDefinition() == typeof(IList<>)) is true))
+                {
+                    ci.del = new();
+                    ci.del.AddRange(mlist.Where(m => !m.IsStatic));
+                }
+
                 if (mlist.Any(OperatorMethod.IsOperatorMethod))
                 {
                     string pyName = OperatorMethod.GetPyMethodName(name);
@@ -581,6 +597,7 @@ private static ClassInfo GetClassInfo(Type type, ClassBase impl)
         private class ClassInfo
         {
             public Indexer? indexer;
+            public MethodBinder? del;
             public readonly Dictionary<string, PyObject> members = new();
 
             internal ClassInfo()

src/runtime/MethodBinder.cs

@@ -54,6 +54,11 @@ internal void AddMethod(MethodBase m)
             list.Add(m);
         }
 
+        internal void AddRange(IEnumerable<MethodBase> methods)
+        {
+            list.AddRange(methods.Select(m => new MaybeMethodBase(m)));
+        }
+
         /// <summary>
         /// Given a sequence of MethodInfo and a sequence of types, return the
         /// MethodInfo that matches the signature represented by those types.

src/runtime/Types/ArrayObject.cs

@@ -247,6 +247,12 @@ public static NewReference mp_subscript(BorrowedReference ob, BorrowedReference
         /// </summary>
         public static int mp_ass_subscript(BorrowedReference ob, BorrowedReference idx, BorrowedReference v)
         {
+            if (v.IsNull)
+            {
+                Exceptions.RaiseTypeError("'System.Array' object does not support item deletion");
+                return -1;
+            }
+
             var obj = (CLRObject)GetManagedObject(ob)!;
             var items = (Array)obj.inst;
             Type itemType = obj.inst.GetType().GetElementType();

src/runtime/Types/ClassBase.cs

@@ -25,6 +25,7 @@ internal class ClassBase : ManagedType, IDeserializationCallback
         [NonSerialized]
         internal List<string> dotNetMembers = new();
         internal Indexer? indexer;
+        internal MethodBinder? del;
         internal readonly Dictionary<int, MethodObject> richcompare = new();
         internal MaybeType type;
 
@@ -465,6 +466,11 @@ static int mp_ass_subscript_impl(BorrowedReference ob, BorrowedReference idx, Bo
             // with the index arg (method binders expect arg tuples).
             NewReference argsTuple = default;
 
+            if (v.IsNull)
+            {
+                return DelImpl(ob, idx, cls);
+            }
+
             if (!Runtime.PyTuple_Check(idx))
             {
                 argsTuple = Runtime.PyTuple_New(1);
@@ -501,6 +507,44 @@ static int mp_ass_subscript_impl(BorrowedReference ob, BorrowedReference idx, Bo
             return result.IsNull() ? -1 : 0;
         }
 
+        /// Implements __delitem__ (del x[...]) for IList&lt;T&gt; and IDictionary&lt;TKey, TValue&gt;.
+        private static int DelImpl(BorrowedReference ob, BorrowedReference idx, ClassBase cls)
+        {
+            if (cls.del is null)
+            {
+                Exceptions.SetError(Exceptions.TypeError, "object does not support item deletion");
+                return -1;
+            }
+
+            if (Runtime.PyTuple_Check(idx))
+            {
+                Exceptions.SetError(Exceptions.TypeError, "multi-index deletion not supported");
+                return -1;
+            }
+
+            using var argsTuple = Runtime.PyTuple_New(1);
+            Runtime.PyTuple_SetItem(argsTuple.Borrow(), 0, idx);
+            using var result = cls.del.Invoke(ob, argsTuple.Borrow(), kw: null);
+            if (result.IsNull())
+                return -1;
+
+            if (Runtime.PyBool_CheckExact(result.Borrow()))
+            {
+                if (Runtime.PyObject_IsTrue(result.Borrow()) != 0)
+                    return 0;
+
+                Exceptions.SetError(Exceptions.KeyError, "key not found");
+                return -1;
+            }
+
+            if (!result.IsNone())
+            {
+                Exceptions.warn("unsupported return type for __delitem__", Exceptions.TypeError);
+            }
+
+            return 0;
+        }
+
         static NewReference tp_call_impl(BorrowedReference ob, BorrowedReference args, BorrowedReference kw)
         {
             BorrowedReference tp = Runtime.PyObject_TYPE(ob);

src/runtime/Util/ReflectionUtil.cs

@@ -53,4 +53,11 @@ public static BindingFlags GetBindingFlags(this PropertyInfo property)
         flags |= accessor.IsPublic ? BindingFlags.Public : BindingFlags.NonPublic;
         return flags;
     }
+
+    public static Type? TryGetGenericDefinition(this Type type)
+    {
+        if (type is null) throw new ArgumentNullException(nameof(type));
+
+        return type.IsConstructedGenericType ? type.GetGenericTypeDefinition() : null;
+    }
 }

tests/test_indexer.py

@@ -668,3 +668,39 @@ def test_public_inherited_overloaded_indexer():
 
     with pytest.raises(TypeError):
         ob[[]]
+
+def test_del_indexer_dict():
+    """Test deleting indexers (__delitem__)."""
+    from System.Collections.Generic import Dictionary, KeyNotFoundException
+    d = Dictionary[str, str]()
+    d["delme"] = "1"
+    with pytest.raises(KeyError):
+        del d["nonexistent"]
+    del d["delme"]
+    with pytest.raises(KeyError):
+        del d["delme"]
+
+def test_del_indexer_list():
+    """Test deleting indexers (__delitem__)."""
+    from System import ArgumentOutOfRangeException
+    from System.Collections.Generic import List
+    l = List[str]()
+    l.Add("1")
+    with pytest.raises(ArgumentOutOfRangeException):
+        del l[3]
+    del l[0]
+    assert len(l) == 0
+
+def test_del_indexer_array():
+    """Test deleting indexers (__delitem__)."""
+    from System import Array
+    l = Array[str](0)
+    with pytest.raises(TypeError):
+        del l[0]
+
+def test_del_indexer_absent():
+    """Test deleting indexers (__delitem__)."""
+    from System import Uri
+    l = Uri("http://www.example.com")
+    with pytest.raises(TypeError):
+        del l[0]