Update repr() and str() of some common objects.issue236

Only InterfaceClass got a str, so it now has a distinction. Other objects only got updated reprs.

Note: This may potentially break some doctests.

In many cases, the ``repr()`` is now something that can be evaluated
to produce an equal object. For example, what was previously printed
as ``<implementedBy builtins.list>`` is now shown as
``classImplements(list, IMutableSequence, IIterable)``.

Fixes #236

Here's a before with ZOPE_INTERFACE_LOG_CHANGED_IRO=1 in BTrees:
```
Object <implementedBy builtins.list> has different legacy and C3 MROs:
  Legacy RO (len=11)                                                        C3 RO (len=11; inconsistent=no)
  ==================================================================================================================================================
    <implementedBy builtins.list>                                             <implementedBy builtins.list>
    <ABCInterfaceClass zope.interface.common.collections.IMutableSequence>    <ABCInterfaceClass zope.interface.common.collections.IMutableSequence>
    <ABCInterfaceClass zope.interface.common.collections.ISequence>           <ABCInterfaceClass zope.interface.common.collections.ISequence>
    <ABCInterfaceClass zope.interface.common.collections.IReversible>         <ABCInterfaceClass zope.interface.common.collections.IReversible>
    <ABCInterfaceClass zope.interface.common.collections.ICollection>         <ABCInterfaceClass zope.interface.common.collections.ICollection>
    <ABCInterfaceClass zope.interface.common.collections.ISized>              <ABCInterfaceClass zope.interface.common.collections.ISized>
                                                                            + <ABCInterfaceClass zope.interface.common.collections.IIterable>
    <ABCInterfaceClass zope.interface.common.collections.IContainer>          <ABCInterfaceClass zope.interface.common.collections.IContainer>
  - <ABCInterfaceClass zope.interface.common.collections.IIterable>
    <ABCInterfaceClass zope.interface.common.ABCInterface>                    <ABCInterfaceClass zope.interface.common.ABCInterface>
                                                                            + <implementedBy builtins.object>
    <InterfaceClass zope.interface.Interface>                                 <InterfaceClass zope.interface.Interface>
  - <implementedBy builtins.object>
Object <ABCInterfaceClass zope.interface.common.mapping.IFullMapping> has different legacy and C3 MROs:
  Legacy RO (len=18)                                                       C3 RO (len=18; inconsistent=no)
  ================================================================================================================================================
    <ABCInterfaceClass zope.interface.common.mapping.IFullMapping>           <ABCInterfaceClass zope.interface.common.mapping.IFullMapping>
    <ABCInterfaceClass zope.interface.common.collections.IMutableMapping>    <ABCInterfaceClass zope.interface.common.collections.IMutableMapping>
    <ABCInterfaceClass zope.interface.common.collections.IMapping>           <ABCInterfaceClass zope.interface.common.collections.IMapping>
    <ABCInterfaceClass zope.interface.common.collections.ICollection>        <ABCInterfaceClass zope.interface.common.collections.ICollection>
  - <ABCInterfaceClass zope.interface.common.collections.IIterable>
    <InterfaceClass zope.interface.common.mapping.IExtendedReadMapping>      <InterfaceClass zope.interface.common.mapping.IExtendedReadMapping>
    <InterfaceClass zope.interface.common.mapping.IIterableMapping>          <InterfaceClass zope.interface.common.mapping.IIterableMapping>
    <InterfaceClass zope.interface.common.mapping.IExtendedWriteMapping>     <InterfaceClass zope.interface.common.mapping.IExtendedWriteMapping>
    <InterfaceClass zope.interface.common.mapping.IClonableMapping>          <InterfaceClass zope.interface.common.mapping.IClonableMapping>
    <InterfaceClass zope.interface.common.mapping.IMapping>                  <InterfaceClass zope.interface.common.mapping.IMapping>
    <InterfaceClass zope.interface.common.mapping.IWriteMapping>             <InterfaceClass zope.interface.common.mapping.IWriteMapping>
    <InterfaceClass zope.interface.common.mapping.IEnumerableMapping>        <InterfaceClass zope.interface.common.mapping.IEnumerableMapping>
    <ABCInterfaceClass zope.interface.common.collections.ISized>             <ABCInterfaceClass zope.interface.common.collections.ISized>
                                                                           + <ABCInterfaceClass zope.interface.common.collections.IIterable>
    <InterfaceClass zope.interface.common.mapping.IReadMapping>              <InterfaceClass zope.interface.common.mapping.IReadMapping>
    <ABCInterfaceClass zope.interface.common.collections.IContainer>         <ABCInterfaceClass zope.interface.common.collections.IContainer>
    <ABCInterfaceClass zope.interface.common.ABCInterface>                   <ABCInterfaceClass zope.interface.common.ABCInterface>
    <InterfaceClass zope.interface.common.mapping.IItemMapping>              <InterfaceClass zope.interface.common.mapping.IItemMapping>
    <InterfaceClass zope.interface.Interface>                                <InterfaceClass zope.interface.Interface>
Object <InterfaceClass BTrees.Interfaces.ISet> has different legacy and C3 MROs:
  Legacy RO (len=7)                                  C3 RO (len=7; inconsistent=no)
  ====================================================================================================
    <InterfaceClass BTrees.Interfaces.ISet>            <InterfaceClass BTrees.Interfaces.ISet>
    <InterfaceClass BTrees.Interfaces.IKeySequence>    <InterfaceClass BTrees.Interfaces.IKeySequence>
  - <InterfaceClass BTrees.Interfaces.ISized>
    <InterfaceClass BTrees.Interfaces.ISetMutable>     <InterfaceClass BTrees.Interfaces.ISetMutable>
    <InterfaceClass BTrees.Interfaces.IKeyed>          <InterfaceClass BTrees.Interfaces.IKeyed>
    <InterfaceClass BTrees.Interfaces.ICollection>     <InterfaceClass BTrees.Interfaces.ICollection>
                                                     + <InterfaceClass BTrees.Interfaces.ISized>
    <InterfaceClass zope.interface.Interface>          <InterfaceClass zope.interface.Interface>
```

And here's after:

```
Object classImplements(list, IMutableSequence, IIterable) has different legacy and C3 MROs:
  Legacy RO (len=11)                                    C3 RO (len=11; inconsistent=no)
  ==========================================================================================================
    classImplements(list, IMutableSequence, IIterable)    classImplements(list, IMutableSequence, IIterable)
    zope.interface.common.collections.IMutableSequence    zope.interface.common.collections.IMutableSequence
    zope.interface.common.collections.ISequence           zope.interface.common.collections.ISequence
    zope.interface.common.collections.IReversible         zope.interface.common.collections.IReversible
    zope.interface.common.collections.ICollection         zope.interface.common.collections.ICollection
    zope.interface.common.collections.ISized              zope.interface.common.collections.ISized
                                                        + zope.interface.common.collections.IIterable
    zope.interface.common.collections.IContainer          zope.interface.common.collections.IContainer
  - zope.interface.common.collections.IIterable
    zope.interface.common.ABCInterface                    zope.interface.common.ABCInterface
                                                        + classImplements(object)
    zope.interface.Interface                              zope.interface.Interface
  - classImplements(object)
Object <ABCInterfaceClass zope.interface.common.mapping.IFullMapping> has different legacy and C3 MROs:
  Legacy RO (len=18)                                     C3 RO (len=18; inconsistent=no)
  ============================================================================================================
    zope.interface.common.mapping.IFullMapping             zope.interface.common.mapping.IFullMapping
    zope.interface.common.collections.IMutableMapping      zope.interface.common.collections.IMutableMapping
    zope.interface.common.collections.IMapping             zope.interface.common.collections.IMapping
    zope.interface.common.collections.ICollection          zope.interface.common.collections.ICollection
  - zope.interface.common.collections.IIterable
    zope.interface.common.mapping.IExtendedReadMapping     zope.interface.common.mapping.IExtendedReadMapping
    zope.interface.common.mapping.IIterableMapping         zope.interface.common.mapping.IIterableMapping
    zope.interface.common.mapping.IExtendedWriteMapping    zope.interface.common.mapping.IExtendedWriteMapping
    zope.interface.common.mapping.IClonableMapping         zope.interface.common.mapping.IClonableMapping
    zope.interface.common.mapping.IMapping                 zope.interface.common.mapping.IMapping
    zope.interface.common.mapping.IWriteMapping            zope.interface.common.mapping.IWriteMapping
    zope.interface.common.mapping.IEnumerableMapping       zope.interface.common.mapping.IEnumerableMapping
    zope.interface.common.collections.ISized               zope.interface.common.collections.ISized
                                                         + zope.interface.common.collections.IIterable
    zope.interface.common.mapping.IReadMapping             zope.interface.common.mapping.IReadMapping
    zope.interface.common.collections.IContainer           zope.interface.common.collections.IContainer
    zope.interface.common.ABCInterface                     zope.interface.common.ABCInterface
    zope.interface.common.mapping.IItemMapping             zope.interface.common.mapping.IItemMapping
    zope.interface.Interface                               zope.interface.Interface
Object <InterfaceClass BTrees.Interfaces.ISet> has different legacy and C3 MROs:
  Legacy RO (len=7)                 C3 RO (len=7; inconsistent=no)
  ==================================================================
    BTrees.Interfaces.ISet            BTrees.Interfaces.ISet
    BTrees.Interfaces.IKeySequence    BTrees.Interfaces.IKeySequence
  - BTrees.Interfaces.ISized
    BTrees.Interfaces.ISetMutable     BTrees.Interfaces.ISetMutable
    BTrees.Interfaces.IKeyed          BTrees.Interfaces.IKeyed
    BTrees.Interfaces.ICollection     BTrees.Interfaces.ICollection
                                    + BTrees.Interfaces.ISized
    zope.interface.Interface          zope.interface.Interface
```

1 files changed, 13 insertions, 9 deletions

diff --git a/src/zope/interface/interface.py b/src/zope/interface/interface.py
index 53049e2..7447641 100644
--- a/src/zope/interface/interface.py
+++ b/src/zope/interface/interface.py
@@ -890,10 +890,10 @@ class InterfaceClass(_InterfaceClassBase):
                 try:
                     invariant(obj)
                 except Invalid as error:
-                     if errors is not None:
-                         errors.append(error)
-                     else:
-                         raise
+                    if errors is not None:
+                        errors.append(error)
+                    else:
+                        raise
 
         if errors:
             raise Invalid(errors)
@@ -925,18 +925,22 @@ class InterfaceClass(_InterfaceClassBase):
             keys.update(base.getDirectTaggedValueTags())
         return keys
 
-    def __repr__(self):  # pragma: no cover
+    def __repr__(self):
         try:
             return self._v_repr
         except AttributeError:
-            name = self.__name__
-            m = self.__ibmodule__
-            if m:
-                name = '%s.%s' % (m, name)
+            name = str(self)
             r = "<%s %s>" % (self.__class__.__name__, name)
             self._v_repr = r # pylint:disable=attribute-defined-outside-init
             return r
 
+    def __str__(self):
+        name = self.__name__
+        m = self.__ibmodule__
+        if m:
+            name = '%s.%s' % (m, name)
+        return name
+
     def _call_conform(self, conform):
         try:
             return conform(self)