fix: refactor InstallHandler slightly, for easier customization

src/wuttjamaican/install.py

@@ -161,6 +161,17 @@ class InstallHandler(GenericHandler):
         any problem is found the installer should exit with code 2.
 
         This is normally called by :meth:`run()`.
+
+        The default logic here just calls :meth:`check_appdir()`.
+        """
+        self.check_appdir()
+
+    def check_appdir(self):
+        """
+        Check if the :term:`app dir` already exists; exit with code 2
+        if so.
+
+        This is normally called from :meth:`sanity_check()`.
         """
         # appdir must not yet exist
         appdir = os.path.join(sys.prefix, "app")
@@ -340,19 +351,48 @@ class InstallHandler(GenericHandler):
 
         File templates for this come from
         ``wuttjamaican:templates/install`` by default.
+
+        This method calls
+        :meth:`~wuttjamaican.app.AppHandler.make_appdir()` for the
+        basic structure and then :meth:`write_all_config_files()` for
+        the gory details.
         """
         # app handler makes appdir proper
         appdir = appdir or self.app.get_appdir()
         self.app.make_appdir(appdir)
 
         # but then we also generate some files...
+        self.write_all_config_files(appdir, context)
 
-        # wutta.conf
+        self.rprint(f"\n\tappdir created at:  [bold green]{appdir}[/bold green]")
+
+    def write_all_config_files(self, appdir, context):
+        """
+        This method should write all config files within the app dir.
+        It's called from :meth:`make_appdir()`.
+
+        Subclass can override this for specialized installers.
+
+        Note that the app dir may or may not be newly-created, when
+        this method is called.  Some installers may support a
+        "refresh" of the existing app dir.
+
+        Default logic (over)writes 3 files:
+
+        * ``wutta.conf``
+        * ``web.cof``
+        * ``upgrade.sh``
+        """
+        self.write_wutta_conf(appdir, context)
+        self.write_web_conf(appdir, context)
+        self.write_upgrade_sh(appdir, context)
+
+    def write_wutta_conf(self, appdir, context):
         self.make_config_file(
             "wutta.conf.mako", os.path.join(appdir, "wutta.conf"), **context
         )
 
-        # web.conf
+    def write_web_conf(self, appdir, context):
         web_context = dict(context)
         web_context.setdefault("beaker_key", context.get("pkg_name", "poser"))
         web_context.setdefault("beaker_secret", "TODO_YOU_SHOULD_CHANGE_THIS")
@@ -362,7 +402,7 @@ class InstallHandler(GenericHandler):
             "web.conf.mako", os.path.join(appdir, "web.conf"), **web_context
         )
 
-        # upgrade.sh
+    def write_upgrade_sh(self, appdir, context):
         template = self.templates.get_template("upgrade.sh.mako")
         output_path = os.path.join(appdir, "upgrade.sh")
         self.render_mako_template(template, context, output_path=output_path)
@@ -371,8 +411,6 @@ class InstallHandler(GenericHandler):
             stat.S_IRWXU | stat.S_IRGRP | stat.S_IXGRP | stat.S_IROTH | stat.S_IXOTH,
         )
 
-        self.rprint(f"\n\tappdir created at:  [bold green]{appdir}[/bold green]")
-
     def render_mako_template(
         self,
         template,