Reuse PyEnumerable, removing need for PyKeyValuePairEnumerable

src/CSnakes.Runtime/Python/PyDictionary.cs

@@ -84,7 +84,7 @@ public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
         using (GIL.Acquire())
         {
             using var items = PyObject.Create(CPythonAPI.PyMapping_Items(_dictionaryObject));
-            return new PyKeyValuePairEnumerable<TKey, TValue>(items).GetEnumerator();
+            return new PyEnumerable<KeyValuePair<TKey, TValue>, PyObjectImporter<TKey, TValue>>(items).GetEnumerator();
         }
     }
 

src/CSnakes.Runtime/Python/PyEnumerable.cs

@@ -3,7 +3,8 @@
 
 namespace CSnakes.Runtime.Python;
 
-internal class PyEnumerable<TValue> : IEnumerable<TValue>, IEnumerator<TValue>, IDisposable
+internal class PyEnumerable<TValue, TImporter> : IEnumerable<TValue>, IEnumerator<TValue>, IDisposable
+    where TImporter : IPyObjectImporter<TValue>
 {
     private readonly PyObject _pyIterator;
     private TValue current = default!;
@@ -40,7 +41,7 @@ public bool MoveNext()
             }
 
             using PyObject pyObject = PyObject.Create(result);
-            current = pyObject.As<TValue>();
+            current = TImporter.Import(pyObject);
             return true;
         }
     }
@@ -49,3 +50,8 @@ public bool MoveNext()
 
     IEnumerator IEnumerable.GetEnumerator() => this;
 }
+
+internal class PyEnumerable<TValue> : PyEnumerable<TValue, PyObjectImporter<TValue>>
+{
+    internal PyEnumerable(PyObject pyObject) : base(pyObject) { }
+}

src/CSnakes.Runtime/Python/PyObjectImporter.cs

@@ -0,0 +1,22 @@
+using CSnakes.Runtime.Python;
+
+internal interface IPyObjectImporter<out T>
+{
+    static abstract T Import(PyObject pyObj);
+}
+
+internal sealed class PyObjectImporter<T> :
+    IPyObjectImporter<T>
+{
+    private PyObjectImporter() { }
+
+    public static T Import(PyObject pyObj) => pyObj.As<T>();
+}
+
+internal sealed class PyObjectImporter<TKey, TValue> :
+    IPyObjectImporter<KeyValuePair<TKey, TValue>>
+{
+    private PyObjectImporter() { }
+
+    public static KeyValuePair<TKey, TValue> Import(PyObject pyObj) => pyObj.As<TKey, TValue>();
+}