Added unfix(), corrected fix()

[moe.git] / t / moe / config.py

diff --git a/t/moe/config.py b/t/moe/config.py
index dacaf42a7a1450e45fa505c266cb7fecc1b01e1d..e6ce045913797a4ff411ee84357fe543f1ab9a1d 100644 (file)
--- a/t/moe/config.py
+++ b/t/moe/config.py
@@ -55,6 +55,17 @@ class VariableFixedError(ConfigError):
 class CyclicConfigError(ConfigError):
   pass
 
+class ParseProxy(list):
+  """Proxy helper class around values returned by `parse` and `parse_file`, 
+  useful in "with" constructs."""
+  def __init__(self, config, parsed_ops):
+    super(ParseProxy, self).__init__(parsed_ops)  
+    self.config = config
+  def __enter__(self):
+    pass
+  def __exit__(self, etype, value, traceback):
+    self.config.remove(list(self))
+
 
 class ConfigTree(object):
   """
@@ -99,21 +110,47 @@ class ConfigTree(object):
     if isinstance(keys, types.StringTypes):
       keys = [keys]
     for key in keys:
-      self.lookup(key, create=True).fix()
+      self.lookup(key, create=False).fix()
+  
+  def unfix(self, keys):
+    "Unfix value of variable or list of variables. Unfixing undefined variable raises `UndefinedError`."
+    if isinstance(keys, types.StringTypes):
+      keys = [keys]
+    for key in keys:
+      self.lookup(key, create=False).unfix()
 
-  def parse(self, s, source=None, level=0):
-    """Parse `s` (stream/string) into the tree, see `moe.confparser.ConfigParser` for details."""
+  def remove(self, parsed):
+    """Given a list [(varname, `Operation`)] as returned by `parse` or `parse_file`, 
+    removes the operations from the respective variables config tree.
+    Variables/operations not present int the tree raise ValueError.
+    """
+    for vname, o in parsed:
+      v = self.lookup(vname, create = True)
+      v.remove_operation(o)
+
+  def parse(self, s, source=None, level=0, proxy=True):
+    """Parse `s` (stream/string) into the tree, see `moe.config_parser.ConfigParser` for details.
+    Returns list of parset operations: [(varname, `Operation`)].
+    By default returns a proxy list-like object that can be used in "with" constructs:
+      
+      with config.parse("TEST='1'"):
+       print config['TEST']
+       raise StupidError
+    """
     import moe.config_parser
     p = moe.config_parser.ConfigParser(s, self, source=source, level=level)
-    p.parse()
+    l = p.parse()
+    if not proxy:
+      return l
+    return ParseProxy(self, l)
 
-  def parse_file(self, filename, desc=None, level=0):
-    """Parse an utf-8 file into the tree, see `moe.confparser.ConfigParser` for details. 
+  def parse_file(self, filename, desc=None, level=0, proxy=True):
+    """Parse an utf-8 file into the tree using func:`parse`. 
     Names the source "`filename` <`desc`>". """
     with open(filename, 'rt') as f:
       if desc: 
        filename += " <" + desc + ">" 
-      self.parse(f, source=filename, level=level)
+      return self.parse(f, source=filename, level=level, proxy=proxy)
 
 
 class ConfigElem(object):
@@ -268,7 +305,9 @@ class ConfigVar(ConfigElem):
 
   def variables(self):
     "Return a set of variables used in the expressions"
-    return set(sum([ list(op.expression.variables()) for op in self.operations ], []))
+    if not self.operations:
+      return set([])
+    return set.union(*[ op.expression.variables() for op in self.operations ])
 
   def fix(self):
     """
@@ -318,7 +357,7 @@ class ConfigVar(ConfigElem):
     self.invalidate()
     # Remove the operation 
     self.operations.remove(operation)
-    # Remove dependencies on variables unused in other operations
+    # Remove dependencies on variables unused in other defining operations
     vs = self.variables()
     for v in operation.expression.variables():
       if v not in vs:
@@ -383,8 +422,8 @@ class ConfigExpression(object):
          self.exprlist[i] = unicode(e, 'ascii')
 
   def variables(self):
-    "Return an iterator of variables user in the expression"
-    return itertools.ifilter(lambda e: isinstance(e, ConfigVar), self.exprlist)
+    "Return a set of variables used in the expression"
+    return set([e for e in self.exprlist if isinstance(e, ConfigVar)])
 
   def __str__(self):
     return self.original