expr: Improve documentation.

diff --git a/bulletml/expr.py b/bulletml/expr.py
index a00c99eefa4c27f1b9f14d9751d5784f491e5135..385b31b5ab1d8fc1122d1f903f076a938876ba69 100644 (file)
--- a/bulletml/expr.py
+++ b/bulletml/expr.py
@@ -11,6 +11,8 @@ import re
 
 from bulletml.errors import Error
 
+__all__ = ["ExprError", "NumberDef", "INumberDef"]
+
 class ExprError(Error):
     """Raised when an invalid expression is evaluated/compiled."""
     pass
@@ -19,7 +21,6 @@ class NumberDef(object):
     """BulletML numeric expression.
 
     This translates BulletML numeric expressions into Python expressions.
-    The 
 
     Examples:
     35
@@ -75,6 +76,7 @@ class INumberDef(NumberDef):
             self._value = int(round(self._value))
 
     def __call__(self, params, rank):
+        # Avoid int(round(__call__())) overhead for constants.
         if self._value is not None:
             return self._value
         return int(round(super(INumberDef, self).__call__(params, rank)))