Migrating from Net Framework 4.x to Net Core

Migrating from Net Framework 4.x to Net Core

PythonNet3 is available from Revit 2025 as a package (called PythonNet3 Engine) and therefore runs under .NET 8+ (Core) instead of .NET Framework 4.x. This change has significant implications for interoperability and certain APIs.

Here are some common examples:

Access to the Global Assembly Cache (GAC)

It is now impossible to directly use the “assemblies” present in the Windows GAC (like Excel Interop or Word Interop).

Solution: Consider migrating to native Python solutions like openpyxl or the OpenXML SDK. If using Excel Interop is absolutely necessary, you must create an instance and use .NET Reflection to interact with it.

Example of using Reflection for Excel Interop (Excerpt):

import clr
import sys
import System
from System import Array
from System.Collections.Generic import List, Dictionary, IDictionary

clr.AddReference("System.Reflection")
from System.Reflection import BindingFlags

from System.Runtime.InteropServices import Marshal

clr.AddReference("System.Core")
clr.ImportExtensions(System.Linq)

xls_filePath = IN[0]
xls_SheetName = IN[1]
dict_values = {}

systemType = System.Type.GetTypeFromProgID("Excel.Application", True)
try:
    ex = System.Activator.CreateInstance(systemType)
except:
    methodCreate = next((m for m in clr.GetClrType(System.Activator)\
            .GetMethods() if "CreateInstance(System.Type)" in m.ToString()), None)
    ex = methodCreate.Invoke(None, (systemType, ))

ex.Visible = False
workbooks = ex.GetType().InvokeMember("Workbooks", BindingFlags.GetProperty ,None, ex, None)
workbook = workbooks.GetType().InvokeMember("Open", BindingFlags.InvokeMethod , None, workbooks, (xls_filePath, )) 
worksheets = workbook.GetType().InvokeMember("Worksheets", BindingFlags.GetProperty ,None, workbook, None)

ws = worksheets.GetType().InvokeMember("Item", BindingFlags.GetProperty ,None, worksheets, (xls_SheetName,))

Changing Methods and Namespaces

Some Windows-specific or obsolete technologies have been removed or replaced by new implementations with new namespaces.

Accessing COM objects

The method Marshal.GetActiveObject() to get the running COM instance of a specified object is no longer available.

Solutions:

1. Use BindToMoniker if you know the path of the file in use.

2. Code a library in C# using the class structure Marshal.GetActiveObject() Example of using BindToMoniker:

import clr
import os
import time
import System

clr.AddReference("System.Reflection")
from System.Reflection import BindingFlags

clr.AddReference("AcMgd")
clr.AddReference("AcCoreMgd")
clr.AddReference("Autodesk.AutoCAD.Interop")

from System import *

from Autodesk.AutoCAD.Runtime import *
from Autodesk.AutoCAD.ApplicationServices import *
from Autodesk.AutoCAD.Interop import *
from Autodesk.AutoCAD.ApplicationServices import Application as acapp

changeViewCommand = "_VIEW "

adoc = Application.DocumentManager.MdiActiveDocument
currentFileName = adoc.Name
print(currentFileName)
com_doc = System.Runtime.InteropServices.Marshal.BindToMoniker(currentFileName)
args = System.Array[System.Object]([changeViewCommand])
com_doc.GetType().InvokeMember("SendCommand", BindingFlags.InvokeMethod, None, com_doc, args)

OUT = True