Turn some of this into an object so it can be extended (slightly).

It may be reasonable to change this more, but the benefits aren't clear.
(These changes will be used from the new-install-branch.)

src/ZEO/mkzeoinst.py

@@ -113,6 +113,12 @@ exec %(zdctl)s -C "$INSTANCE/etc/%(package)sctl.conf" ${1+"$@"}
 """
 
 def main():
+    ZEOInstanceBuilder().run()
+    print "All done."
+
+
+class ZEOInstanceBuilder:
+    def run(self):
         try:
             opts, args = getopt.getopt(sys.argv[1:], "h", ["help"])
         except getopt.error, msg:
@@ -135,7 +141,11 @@ def main():
         else:
             port = 9999
         checkport(port)
-    params = {
+        params = self.get_params(home, port)
+        self.create(home, params)
+
+    def get_params(self, home, port):
+        return {
             "package": "zeo",
             "PACKAGE": "ZEO",
             "home": home,
@@ -145,6 +155,8 @@ def main():
             "zdrun": which("zdrun.py"),
             "zdctl": which("zdctl.py"),
             }
+
+    def create(self, home, params):
         makedir(home)
         makedir(home, "etc")
         makedir(home, "var")
@@ -153,7 +165,7 @@ def main():
         makefile(zeo_conf_template, home, "etc", "zeo.conf", **params)
         makefile(runner_conf_template, home, "etc", "zeoctl.conf", **params)
         makexfile(zdctl_template, home, "bin", "zeoctl", **params)
-    print "All done."
+
 
 def checkport(port):
     import socket