Add IsNone() and Runtime.None (pythonnet#1137)

henon · web-flow · commit 960286d51bf9 · 2020-05-11T07:39:25.000+02:00
* Add `PyObject.IsNone()`
* Add `Runtime.None` which returns a reference to `None` as a `PyObject` to be able to pass it into Python from .NET
diff --git a/AUTHORS.md b/AUTHORS.md
@@ -45,6 +45,7 @@
 -   Luke Stratman ([@lstratman](https://github.com/lstratman))
 -   Konstantin Posudevskiy ([@konstantin-posudevskiy](https://github.com/konstantin-posudevskiy))
 -   Matthias Dittrich ([@matthid](https://github.com/matthid))
+-   Meinrad Recheis ([@henon](https://github.com/henon))
 -   Mohamed Koubaa ([@koubaa](https://github.com/koubaa))
 -   Patrick Stewart ([@patstew](https://github.com/patstew))
 -   Raphael Nestler ([@rnestler](https://github.com/rnestler))
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -14,6 +14,8 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 -   Added support for Jetson Nano.
 -   Added support for __len__ for .NET classes that implement ICollection
 -   Added PythonException.Format method to format exceptions the same as traceback.format_exception
+-   Added Runtime.None to be able to pass None as parameter into Python from .NET
+-   Added PyObject.IsNone() to check if a Python object is None in .NET.
 
 ### Changed
 
diff --git a/src/runtime/pyobject.cs b/src/runtime/pyobject.cs
@@ -979,6 +979,10 @@ public bool IsTrue()
             return Runtime.PyObject_IsTrue(obj) != 0;
         }
 
+        /// <summary>
+        /// Return true if the object is None
+        /// </summary>
+        public bool IsNone() => CheckNone(this) == null;
 
         /// <summary>
         /// Dir Method
diff --git a/src/runtime/runtime.cs b/src/runtime/runtime.cs
@@ -473,6 +473,16 @@ private static void ResetPyMembers()
         internal static IntPtr PyNone;
         internal static IntPtr Error;
 
+        public static PyObject None
+        {
+            get
+            {
+                var none = Runtime.PyNone;
+                Runtime.XIncref(none);
+                return new PyObject(none);
+            }
+        }
+
         /// <summary>
         /// Check if any Python Exceptions occurred.
         /// If any exist throw new PythonException.

Original file line number	Diff line number	Diff line change
`@@ -979,6 +979,10 @@ public bool IsTrue()`
`979`	`979`	`return Runtime.PyObject_IsTrue(obj) != 0;`
`980`	`980`	`}`
`981`	`981`
	`982`	`+ /// <summary>`
	`983`	`+ /// Return true if the object is None`
	`984`	`+ /// </summary>`
	`985`	`+ public bool IsNone() => CheckNone(this) == null;`
`982`	`986`
`983`	`987`	`/// <summary>`
`984`	`988`	`/// Dir Method`