Provide get_python_exe for old versions of FreeCAD

Author: chennes

addonmanager_freecad_interface.py

@@ -32,13 +32,46 @@
 import json
 import logging
 import os
+import platform
+import shutil
 import tempfile
 
 # pylint: disable=too-few-public-methods
 
 try:
     import FreeCAD
-    from freecad.utils import get_python_exe
+
+    try:
+        from freecad.utils import get_python_exe
+    except ImportError:
+        # This was only added in FreeCAD 1.0 -- to support FreeCAD 0.21 a backup strategy must be
+        # used. This code is borrowed from FreeCAD 1.1dev.
+        def get_python_exe():
+            prefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/PythonConsole")
+            python_exe = prefs.GetString("ExternalPythonExecutable", "Not set")
+            fc_dir = FreeCAD.getHomePath()
+            if not python_exe or python_exe == "Not set" or not os.path.exists(python_exe):
+                python_exe = os.path.join(fc_dir, "bin", "python3")
+                if "Windows" in platform.system():
+                    python_exe += ".exe"
+
+            if not python_exe or not os.path.exists(python_exe):
+                python_exe = os.path.join(fc_dir, "bin", "python")
+                if "Windows" in platform.system():
+                    python_exe += ".exe"
+
+            if not python_exe or not os.path.exists(python_exe):
+                python_exe = shutil.which("python3")
+
+            if not python_exe or not os.path.exists(python_exe):
+                python_exe = shutil.which("python")
+
+            if not python_exe or not os.path.exists(python_exe):
+                return ""
+
+            python_exe = python_exe.replace("/", os.path.sep)
+            prefs.SetString("ExternalPythonExecutable", python_exe)
+            return python_exe
 
     if not hasattr(FreeCAD, "Console"):
         raise ImportError("Unrecognized FreeCAD version")
@@ -105,6 +138,9 @@ def translate(context: str, sourceText: str, disambiguation: str = "", n: int =
     def Version():
         return 1, 1, 0, "dev"
 
+    def get_python_exe():
+        return shutil.which("python3")
+
     class ConsoleReplacement:
         """If FreeCAD's Console is not available, create a replacement by redirecting FreeCAD
         log calls to Python's built-in logging facility."""

addonmanager_utilities.py

@@ -49,14 +49,6 @@
 
 import addonmanager_freecad_interface as fci
 
-try:
-    from freecad.utils import get_python_exe
-except ImportError:
-
-    def get_python_exe():
-        """Use shutil.which to find python executable"""
-        return shutil.which("python")
-
 
 if fci.FreeCADGui:
 
@@ -597,7 +589,7 @@ def create_pip_call(args: List[str]) -> List[str]:
         call_args = [python_exe, "-m", "pip", "--disable-pip-version-check"]
         call_args.extend(args)
     else:
-        python_exe = get_python_exe()
+        python_exe = fci.get_python_exe()
         if not python_exe:
             raise RuntimeError("Could not locate Python executable on this system")
         call_args = [python_exe, "-m", "pip", "--disable-pip-version-check"]