--- a/licenser/licenses.py	Mon May 10 09:18:26 2010 -0700
+++ b/licenser/licenses.py	Mon May 10 11:24:02 2010 -0700
@@ -1,6 +1,56 @@
+import os
+
 from datetime import datetime
 
-class MPL(object):
+class License(object):
+  """Abstract base class for a license"""
+
+  variables = [] # required variables
+
+  def __init__(self):
+    if not os.path.isabs(self.template):
+      self.template = os.path.join(os.path.dirname(__file__),
+                                   'licenses',
+                                   self.template)
+    assert os.path.exists(self.template)
+
+  def __call__(self, directory, **kw):
+    for var in self.variables:
+      if var not in kw:
+        print 'Enter %s: ' % var,
+        kw[var] = raw_input()
+    self.pre(kw)
+    self.interpolate(directory, kw)
+
+  def pre(self, variables):
+    """do anything that needs to be done before interpolation"""
+
+  def interpolate(self, directory, variables):
+    for file in self.files(directory):
+      pass
+
+  def isempty(self, path):
+    """
+    determines if a python file is empty;  that is, contains only comments
+    """
+    for line in file(path, 'r').readlines():
+        line = line.strip()
+        if line and line[0] != '#':
+            return False
+    return True
+
+  def files(self, directory):
+    files = set()
+    for dirpath, _, filenames in os.walk(directory):
+        for f in filenames:
+            if f.endswith('.py'): # could use os.path.splitext()
+                path = os.path.join(dirpath, f)
+                if not self.isempty(path):
+                    files.add(path)
+    return files
+
+
+class MPL(License):
   """Mozilla Public License"""
   template = 'MPL' # could be implicit here
   variables = [ 'author' ]