NewReference type and an example usage

lostmsu · lostmsu · commit 4a84a1e35f07 · 2020-02-13T14:42:46.000-08:00
diff --git a/src/runtime/NewReference.cs b/src/runtime/NewReference.cs
@@ -0,0 +1,26 @@
+namespace Python.Runtime
+{
+    using System;
+    [NonCopyable]
+    ref struct NewReference
+    {
+        public IntPtr Pointer { get; set; }
+        public bool IsNull => this.Pointer == IntPtr.Zero;
+
+        public PyObject ToPyObject()
+        {
+            if (this.IsNull) throw new NullReferenceException();
+
+            var result = new PyObject(this.Pointer);
+            this.Pointer = IntPtr.Zero;
+            return result;
+        }
+
+        public void Dispose()
+        {
+            if (!this.IsNull)
+                Runtime.XDecref(this.Pointer);
+            this.Pointer = IntPtr.Zero;
+        }
+    }
+}
diff --git a/src/runtime/NonCopyableAttribute.cs b/src/runtime/NonCopyableAttribute.cs
@@ -0,0 +1,6 @@
+namespace Python.Runtime
+{
+    using  System;
+    [AttributeUsage(AttributeTargets.Struct)]
+    class NonCopyableAttribute : Attribute { }
+}
diff --git a/src/runtime/Python.Runtime.15.csproj b/src/runtime/Python.Runtime.15.csproj
@@ -30,7 +30,7 @@
     <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
     <PythonBuildDir Condition="'$(PythonBuildDir)' == ''">$(SolutionDir)\bin\</PythonBuildDir>
     <PublishDir Condition="'$(TargetFramework)'!='net40'">$(PythonBuildDir)\$(TargetFramework)\</PublishDir>
-    <LangVersion>7.3</LangVersion>
+    <LangVersion>8.0</LangVersion>
     <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
     <AssemblyOriginatorKeyFile>..\pythonnet.snk</AssemblyOriginatorKeyFile>
     <CustomDefineConstants Condition="'$(CustomDefineConstants)' == ''">$(PYTHONNET_DEFINE_CONSTANTS)</CustomDefineConstants>
@@ -129,6 +129,13 @@
     <PackageReference Include="Microsoft.TargetingPack.NETFramework.v4.5" Version="1.0.1" ExcludeAssets="All" PrivateAssets="All" />
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Include="NonCopyableAnalyzer" Version="0.5.1">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
   <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />
 
   <PropertyGroup>
diff --git a/src/runtime/pydict.cs b/src/runtime/pydict.cs
@@ -139,12 +139,13 @@ public PyObject Values()
         /// </remarks>
         public PyObject Items()
         {
-            IntPtr items = Runtime.PyDict_Items(obj);
-            if (items == IntPtr.Zero)
+            using var items = Runtime.PyDict_Items(this.obj);
+            if (items.IsNull)
             {
                 throw new PythonException();
             }
-            return new PyObject(items);
+
+            return items.ToPyObject();
         }
 
 
diff --git a/src/runtime/runtime.cs b/src/runtime/runtime.cs
@@ -1591,7 +1591,7 @@ internal static bool PyDict_Check(IntPtr ob)
         internal static extern IntPtr PyDict_Values(IntPtr pointer);
 
         [DllImport(_PythonDll, CallingConvention = CallingConvention.Cdecl)]
-        internal static extern IntPtr PyDict_Items(IntPtr pointer);
+        internal static extern NewReference PyDict_Items(IntPtr pointer);
 
         [DllImport(_PythonDll, CallingConvention = CallingConvention.Cdecl)]
         internal static extern IntPtr PyDict_Copy(IntPtr pointer);

Original file line number	Diff line number	Diff line change
`@@ -139,12 +139,13 @@ public PyObject Values()`
`139`	`139`	`/// </remarks>`
`140`	`140`	`public PyObject Items()`
`141`	`141`	`{`
`142`		`- IntPtr items = Runtime.PyDict_Items(obj);`
`143`		`- if (items == IntPtr.Zero)`
	`142`	`+ using var items = Runtime.PyDict_Items(this.obj);`
	`143`	`+ if (items.IsNull)`
`144`	`144`	`{`
`145`	`145`	`throw new PythonException();`
`146`	`146`	`}`
`147`		`- return new PyObject(items);`
	`147`	`+`
	`148`	`+ return items.ToPyObject();`
`148`	`149`	`}`
`149`	`150`
`150`	`151`