Implemented simple variable fixing.

diff --git a/t/moe/conf.py b/t/moe/conf.py
index f561b750773ce752d3d043c570f7411d514dd722..ec657ffc51041db5a5b867899c3eca87eb68ef09 100644 (file)
--- a/t/moe/conf.py
+++ b/t/moe/conf.py
@@ -17,11 +17,10 @@ NOTE: If no 'SET' applies, a variable is still undefined even if some 'APPEND' a
 NOTE: All expanded data should be (or is converted to) unicode 
 
 
-TODO: Fixing value of variables.
 TODO: Cleanup of unused undefined variables.
 TODO: Better variable name checking (no name '.'-structural prefix of another)
 TODO: Implemet "subtree" listing.
-TODO: Test conditions and unicode
+TODO: Test fixing, conditions and unicode
 """
 
 import types, itertools, re, bisect
@@ -55,6 +54,9 @@ class UndefinedError(ConfigError):
 class VariableNameError(ConfigError):
   pass
 
+class VariableFixedError(ConfigError):
+  pass
+
 class CyclicConfigError(ConfigError):
   pass
 
@@ -216,12 +218,29 @@ class ConfigVar(ConfigElem):
     # Ordered list of `Operations` (ascending by `level`)
     self.operations = []
     # Fixed to value (may be None) 
-    # TODO: fixing
     self.fixed = False
     self.fixed_val = None
   def variables(self):
     "Return a set of variables used in the expressions"
     return set(sum([ list(op.expression.variables()) for op in self.operations ], []))
+  def fix(self):
+    """
+    Fixes the value of the variable. Exception is raised should the variable
+    evaluate to a different value while fixed. 
+    """
+    if self.fixed: 
+      return 
+    self.fixed = True
+    self.fixed_val = self.value()
+  def unfix(self):
+    "Set the variable to be modifiable again."
+    self.fixed = False
+  def value(self, depth=0):
+    "Handle the case when fixed, raise exc. on different evaluation"
+    val = super(ConfigVar,self).value(depth)
+    if self.fixed and self.fixed_val != val:
+      raise VariableFixedError("value of var %s was fixed to %r but evaluated to %r", self.name, self.fixed_val, val)
+    return val
   def add_operation(self, operation):
     """
     Inserts an operation. The operations are sorted by `level` (ascending), new operation goes last among