--- a/gub/context.py	Wed Jul 11 21:59:59 2007 +0200
+++ b/gub/context.py	Wed Jul 11 22:06:18 2007 +0200
@@ -47,12 +47,21 @@
         self.const = const
     def __call__ (self):
         return self.const
-    
+
+class SetAttrTooLate(Exception):
+    pass
+
 class Context:
     def __init__ (self, parent = None):
         self._substitution_dict = None
         self._parent = parent
 
+    def __setattr__(self, k, v):
+        if k <> '_substitution_dict' and self._substitution_dict:
+            raise SetAttrTooLate((k, self))
+
+        self.__dict__[k] = v
+        
     def get_constant_substitution_dict (self):
         d = {}
         if self._parent:

--- a/gub/installer.py	Wed Jul 11 21:59:59 2007 +0200
+++ b/gub/installer.py	Wed Jul 11 22:06:18 2007 +0200
@@ -21,7 +21,7 @@
         self.no_binary_strip_extensions = ['.la', '.py', '.def', '.scm', '.pyc']
         self.installer_uploads = settings.uploads
         self.checksum = '0000'
-
+        assert settings._substitution_dict == None
     @context.subst_method
     def version (self):
         return self.settings.installer_version
@@ -279,12 +279,12 @@
     def strip_prefixes (self):
         return Installer.strip_prefixes (self)
 
-    def create_tarball (self):
+    def create_tarball (self, bundle_tarball):
         self.system ('tar --owner=0 --group=0 -C %(installer_root)s -jcf %(bundle_tarball)s .', locals ())
 
     def create (self):
         Installer.create (self)
-        self.create_tarball ()
+        self.create_tarball (self.bundle_tarball)
 
 def create_shar (orig_file, hello, head, target_shar):
     length = os.stat (orig_file)[6]
@@ -311,10 +311,8 @@
     def create (self):
         Linux_installer.create (self)
         target_shar = self.expand ('%(installer_uploads)s/%(name)s-%(installer_version)s-%(installer_build)s.%(platform)s.sh')
-
         head = self.expand ('%(sourcefiledir)s/sharhead.sh')
         tarball = self.expand (self.bundle_tarball)
-
         hello = self.expand ("version %(installer_version)s release %(installer_build)s")
         create_shar (tarball, hello, head, target_shar)
         self.write_checksum ()
@@ -342,4 +340,5 @@
 #        'mingw' : MingwRoot,
     }
 
-    return installer_class[settings.platform] (settings)
+    installer = installer_class[settings.platform] (settings)
+    return installer