Add namespace selection for rlcompleter. Closes SF patch 490026.

Lib/rlcompleter.py

 """Word completion for GNU readline 2.0.
 
-This requires the latest extension to the readline module (the
-completes keywords, built-ins and globals in __main__; when completing
-NAME.NAME..., it evaluates (!) the expression up to the last dot and
-completes its attributes.
+This requires the latest extension to the readline module. The completer
+completes keywords, built-ins and globals in a selectable namespace (which
+defaults to __main__); when completing NAME.NAME..., it evaluates (!) the
+expression up to the last dot and completes its attributes.
 
 It's very cool to do "import string" type "string.", hit the
 completion key (twice), and see the list of names defined by the
@@ -46,6 +46,32 @@ import __main__
 __all__ = ["Completer"]
 
 class Completer:
+    def __init__(self, namespace = None):
+        """Create a new completer for the command line.
+
+        Completer([namespace]) -> completer instance.
+
+        If unspecified, the default namespace where completions are performed
+        is __main__ (technically, __main__.__dict__). Namespaces should be
+        given as dictionaries.
+
+        Completer instances should be used as the completion mechanism of
+        readline via the set_completer() call:
+
+        readline.set_completer(Completer(my_namespace).complete)
+        """
+        
+        if namespace and not isinstance(namespace, dict):
+            raise TypeError,'namespace must be a dictionary'
+
+        # Don't bind to namespace quite yet, but flag whether the user wants a
+        # specific namespace or to use __main__.__dict__. This will allow us
+        # to bind to __main__.__dict__ at completion time, not now.
+        if namespace is None:
+            self.use_main_ns = 1
+        else:
+            self.use_main_ns = 0
+            self.namespace = namespace
 
     def complete(self, text, state):
         """Return the next possible completion for 'text'.
@@ -54,6 +80,9 @@ class Completer:
         returns None.  The completion should begin with 'text'.
 
         """
+        if self.use_main_ns:
+            self.namespace = __main__.__dict__
+            
         if state == 0:
             if "." in text:
                 self.matches = self.attr_matches(text)
@@ -67,8 +96,8 @@ class Completer:
     def global_matches(self, text):
         """Compute matches when text is a simple name.
 
-        Return a list of all keywords, built-in functions and names
-        currently defines in __main__ that match.
+        Return a list of all keywords, built-in functions and names currently
+        defined in self.namespace that match.
 
         """
         import keyword
@@ -76,7 +105,7 @@ class Completer:
         n = len(text)
         for list in [keyword.kwlist,
                      __builtin__.__dict__.keys(),
-                     __main__.__dict__.keys()]:
+                     self.namespace.keys()]:
             for word in list:
                 if word[:n] == text and word != "__builtins__":
                     matches.append(word)
@@ -86,10 +115,9 @@ class Completer:
         """Compute matches when text contains a dot.
 
         Assuming the text is of the form NAME.NAME....[NAME], and is
-        evaluatable in the globals of __main__, it will be evaluated
-        and its attributes (as revealed by dir()) are used as possible
-        completions.  (For class instances, class members are are also
-        considered.)
+        evaluatable in self.namespace, it will be evaluated and its attributes
+        (as revealed by dir()) are used as possible completions.  (For class
+        instances, class members are are also considered.)
 
         WARNING: this can still invoke arbitrary C code, if an object
         with a __getattr__ hook is evaluated.
@@ -100,7 +128,7 @@ class Completer:
         if not m:
             return
         expr, attr = m.group(1, 3)
-        object = eval(expr, __main__.__dict__)
+        object = eval(expr, self.namespace)
         words = dir(object)
         if hasattr(object,'__class__'):
             words.append('__class__')