[V3 Downloader] Allow for requiring minimum python version (#1455)

redbot/cogs/downloader/downloader.py

@@ -5,6 +5,8 @@ from sys import path as syspath
 from typing import Tuple, Union
 
 import discord
+import sys
+
 from redbot.core import Config
 from redbot.core import checks
 from redbot.core.data_manager import cog_data_path
@@ -275,6 +277,13 @@ class Downloader:
             await ctx.send(_("Error, there is no cog by the name of"
                            " `{}` in the `{}` repo.").format(cog_name, repo_name.name))
             return
+        elif cog.min_python_version > sys.version_info:
+            await ctx.send(_(
+                "This cog requires at least python version {}, aborting install.".format(
+                    '.'.join([str(n) for n in cog.min_python_version])
+                )
+            ))
+            return
 
         if not await repo_name.install_requirements(cog, self.LIB_PATH):
             await ctx.send(_("Failed to install the required libraries for"

redbot/cogs/downloader/installable.py

@@ -38,6 +38,9 @@ class Installable(RepoJSONMixin):
     bot_version : `tuple` of `int`
         The minimum bot version required for this installation. Right now
         this is always :code:`3.0.0`.
+    min_python_version : `tuple` of `int`
+        The minimum python version required for this cog. This field will not
+        apply to repo info.json's.
     hidden : `bool`
         Whether or not this cog will be hidden from the user when they use
         `Downloader`'s commands.
@@ -70,6 +73,7 @@ class Installable(RepoJSONMixin):
 
         self.author = ()
         self.bot_version = (3, 0, 0)
+        self.min_python_version = (3, 5, 1)
         self.hidden = False
         self.required_cogs = {}  # Cog name -> repo URL
         self.requirements = ()
@@ -159,9 +163,15 @@ class Installable(RepoJSONMixin):
         try:
             bot_version = tuple(info.get("bot_version", [3, 0, 0]))
         except ValueError:
-            bot_version = 2
+            bot_version = self.bot_version
         self.bot_version = bot_version
 
+        try:
+            min_python_version = tuple(info.get('min_python_version', [3, 5, 1]))
+        except ValueError:
+            min_python_version = self.min_python_version
+        self.min_python_version = min_python_version
+
         try:
             hidden = bool(info.get("hidden", False))
         except ValueError: