Warn if running too-new, untested Python version. Break out version reqs into separate file for more visibility.

evennia/VERSION_REQS.txt

@@ -0,0 +1,10 @@
+# These are read by the evennia/server/evennia_launcher.py to give more explicit
+# errors/warnings when trying to run Evennia with wrong/unexpected versions (this happens
+# when people upgrade outside regular channels). This file only supports lines of
+# `value = number` and only specific names supported by the handler.
+
+PYTHON_MIN = 3.9
+PYTHON_MAX_TESTED = 3.11
+TWISTED_MIN = 20.3.0
+DJANGO_MIN = 4.0.2
+DJANGO_LT = 4.1

evennia/server/evennia_launcher.py

@@ -90,11 +90,28 @@ SSHUTD = chr(17)  # server-only shutdown
 PSTATUS = chr(18)  # ping server or portal status
 SRESET = chr(19)  # shutdown server in reset mode
 
-# requirements
+# live version requirement checks (from VERSION_REQS.txt file)
-PYTHON_MIN = "3.9"
+PYTHON_MIN = None
-TWISTED_MIN = "20.3.0"
+PYTHON_MAX_TESTED = None
-DJANGO_MIN = "4.0.2"
+TWISTED_MIN = None
-DJANGO_LT = "4.1"
+DJANGO_MIN = None
+DJANGO_LT = None
+
+with open(os.path.join(EVENNIA_LIB, "VERSION_REQS.txt")) as fil:
+    for line in fil.readlines():
+        if line.startswith("#") or not "=" in line:
+            continue
+        match tuple(part.strip() for part in line.split("=", 1)):
+            case ("PYTHON_MIN", *value):
+                PYTHON_MIN = value[0] if value else "0"
+            case ("PYTHON_MAX_TESTED", *value):
+                PYTHON_MAX_TESTED = value[0] if value else "100"
+            case ("TWISTED_MIN", *value):
+                TWISTED_MIN = value[0] if value else "0"
+            case ("DJANGO_MIN", *value):
+                DJANGO_MIN = value[0] if value else "0"
+            case ("DJANGO_LT", *value):
+                DJANGO_LT = value[0] if value else "100"
 
 try:
     sys.path[1] = EVENNIA_ROOT
@@ -364,6 +381,12 @@ ERROR_PYTHON_VERSION = """
     {python_min} or higher.
     """
 
+WARNING_PYTHON_MAX_TESTED_VERSION = """
+    WARNING: Python {pversion} used. Evennia is only tested with Python
+    versions {python_min} to {python_max_tested}. If you see unexpected errors, try
+    reinstalling with a tested Python version instead.
+    """
+
 ERROR_TWISTED_VERSION = """
     ERROR: Twisted {tversion} found. Evennia requires
     version {twisted_min} or higher.
@@ -1262,6 +1285,13 @@ def check_main_evennia_dependencies():
     if LooseVersion(pversion) < LooseVersion(PYTHON_MIN):
         print(ERROR_PYTHON_VERSION.format(pversion=pversion, python_min=PYTHON_MIN))
         error = True
+    if LooseVersion(pversion) > LooseVersion(PYTHON_MAX_TESTED):
+        print(
+            WARNING_PYTHON_MAX_TESTED_VERSION.format(
+                pversion=pversion, python_min=PYTHON_MIN, python_max_tested=PYTHON_MAX_TESTED
+            )
+        )
+
     # Twisted
     try:
         import twisted