Renamed __pretty__ to _repr_pretty_ and changed updated pretty.py

* Throughout the codebase, __pretty__ has been changed to
  _repr_pretty_ to match general convention for special method
  names.
* The logic in pretty.py now matches that in formatters.py in that
  formatters that are callables are tried first and then special
  methods are used.

IPython/core/formatters.py

@@ -343,8 +343,8 b' class PlainTextFormatter(BaseFormatter):'
     # something.
     enabled = Bool(True, config=False)
 
-    # Look for a __pretty__ methods to use for pretty printing.
-    print_method = Str('__pretty__')
+    # Look for a _repr_pretty_ methods to use for pretty printing.
+    print_method = Str('_repr_pretty_')
 
     # Whether to pretty-print or not.
     pprint = Bool(True, config=True)

IPython/lib/pretty.py

@@ -29,12 +29,12 b''
 
     The pretty library allows developers to add pretty printing rules for their
     own objects.  This process is straightforward.  All you have to do is to
-    add a `__pretty__` method to your object and call the methods on the
+    add a `_repr_pretty_` method to your object and call the methods on the
     pretty printer passed::
 
         class MyObject(object):
 
-            def __pretty__(self, p, cycle):
+            def _repr_pretty_(self, p, cycle):
                 ...
 
     Depending on the python version you want to support you have two
@@ -42,13 +42,13 b''
     compatibility one.
 
 
-    Here the example implementation of a `__pretty__` method for a list
+    Here the example implementation of a `_repr_pretty_` method for a list
     subclass for python 2.5 and higher (python 2.5 requires the with statement
     __future__ import)::
 
         class MyList(list):
 
-            def __pretty__(self, p, cycle):
+            def _repr_pretty_(self, p, cycle):
                 if cycle:
                     p.text('MyList(...)')
                 else:
@@ -75,7 +75,7 b''
 
         class MyList(list):
 
-            def __pretty__(self, p, cycle):
+            def _repr_pretty_(self, p, cycle):
                 if cycle:
                     p.text('MyList(...)')
                 else:
@@ -164,7 +164,7 b' class PrettyPrinter(_PrettyPrinterBase):'
     """
     Baseclass for the `RepresentationPrinter` prettyprinter that is used to
     generate pretty reprs of objects.  Contrary to the `RepresentationPrinter`
-    this printer knows nothing about the default pprinters or the `__pretty__`
+    this printer knows nothing about the default pprinters or the `_repr_pretty_`
     callback method.
     """
 
@@ -330,14 +330,14 b' class RepresentationPrinter(PrettyPrinter):'
         self.begin_group()
         try:
             obj_class = getattr(obj, '__class__', None) or type(obj)
-            if hasattr(obj_class, '__pretty__'):
-                return obj_class.__pretty__(obj, self, cycle)
+            # First try to find registered singleton printers for the type.
             try:
                 printer = self.singleton_pprinters[obj_id]
             except (TypeError, KeyError):
                 pass
             else:
                 return printer(obj, self, cycle)
+            # Next look for type_printers.
             for cls in _get_mro(obj_class):
                 if cls in self.type_pprinters:
                     return self.type_pprinters[cls](obj, self, cycle)
@@ -345,6 +345,9 b' class RepresentationPrinter(PrettyPrinter):'
                     printer = self._in_deferred_types(cls)
                     if printer is not None:
                         return printer(obj, self, cycle)
+            # Finally look for special method names.
+            if hasattr(obj_class, '_repr_pretty_'):
+                return obj_class._repr_pretty_(obj, self, cycle)
             return _default_pprint(obj, self, cycle)
         finally:
             self.end_group()

docs/examples/core/display.py

@@ -14,8 +14,6 b' class Circle(object):'
     def _repr_pretty_(self, p, cycle):
         p.text(u"\u25CB")
 
-    __pretty__ = _repr_pretty_
-
     def _repr_html_(self):
         return "<h1>Cirle: radius=%s</h1>" % self.radius