Add signature to the display of functions in the shell

IPython/core/tests/test_oinspect.py

@@ -1,432 +1,437
 """Tests for the object inspection functionality.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 
 from inspect import Signature, Parameter
 import os
 import re
 import sys
 
 import nose.tools as nt
 
 from .. import oinspect
 from IPython.core.magic import (Magics, magics_class, line_magic,
                                 cell_magic, line_cell_magic,
                                 register_line_magic, register_cell_magic,
                                 register_line_cell_magic)
 from decorator import decorator
 from IPython import get_ipython
 from IPython.testing.tools import AssertPrints, AssertNotPrints
 from IPython.utils.path import compress_user
 
 
 #-----------------------------------------------------------------------------
 # Globals and constants
 #-----------------------------------------------------------------------------
 
 inspector = oinspect.Inspector()
 ip = get_ipython()
 
 #-----------------------------------------------------------------------------
 # Local utilities
 #-----------------------------------------------------------------------------
 
 # WARNING: since this test checks the line number where a function is
 # defined, if any code is inserted above, the following line will need to be
 # updated.  Do NOT insert any whitespace between the next line and the function
 # definition below.
 THIS_LINE_NUMBER = 41  # Put here the actual number of this line
 
 from unittest import TestCase
 
 class Test(TestCase):
 
     def test_find_source_lines(self):
         self.assertEqual(oinspect.find_source_lines(Test.test_find_source_lines),
                     THIS_LINE_NUMBER+6)
 
 
 # A couple of utilities to ensure these tests work the same from a source or a
 # binary install
 def pyfile(fname):
     return os.path.normcase(re.sub('.py[co]$', '.py', fname))
 
 
 def match_pyfiles(f1, f2):
     nt.assert_equal(pyfile(f1), pyfile(f2))
 
 
 def test_find_file():
     match_pyfiles(oinspect.find_file(test_find_file), os.path.abspath(__file__))
 
 
 def test_find_file_decorated1():
 
     @decorator
     def noop1(f):
         def wrapper(*a, **kw):
             return f(*a, **kw)
         return wrapper
 
     @noop1
     def f(x):
         "My docstring"
     
     match_pyfiles(oinspect.find_file(f), os.path.abspath(__file__))
     nt.assert_equal(f.__doc__, "My docstring")
 
 
 def test_find_file_decorated2():
 
     @decorator
     def noop2(f, *a, **kw):
         return f(*a, **kw)
 
     @noop2
     @noop2
     @noop2
     def f(x):
         "My docstring 2"
     
     match_pyfiles(oinspect.find_file(f), os.path.abspath(__file__))
     nt.assert_equal(f.__doc__, "My docstring 2")
     
 
 def test_find_file_magic():
     run = ip.find_line_magic('run')
     nt.assert_not_equal(oinspect.find_file(run), None)
 
 
 # A few generic objects we can then inspect in the tests below
 
 class Call(object):
     """This is the class docstring."""
 
     def __init__(self, x, y=1):
         """This is the constructor docstring."""
 
     def __call__(self, *a, **kw):
         """This is the call docstring."""
 
     def method(self, x, z=2):
         """Some method's docstring"""
 
 class HasSignature(object):
     """This is the class docstring."""
     __signature__ = Signature([Parameter('test', Parameter.POSITIONAL_OR_KEYWORD)])
 
     def __init__(self, *args):
         """This is the init docstring"""
 
 
 class SimpleClass(object):
     def method(self, x, z=2):
         """Some method's docstring"""
 
 
 class OldStyle:
     """An old-style class for testing."""
     pass
 
 
 def f(x, y=2, *a, **kw):
     """A simple function."""
 
 
 def g(y, z=3, *a, **kw):
     pass  # no docstring
 
 
 @register_line_magic
 def lmagic(line):
     "A line magic"
 
 
 @register_cell_magic
 def cmagic(line, cell):
     "A cell magic"
 
 
 @register_line_cell_magic
 def lcmagic(line, cell=None):
     "A line/cell magic"
 
 
 @magics_class
 class SimpleMagics(Magics):
     @line_magic
     def Clmagic(self, cline):
         "A class-based line magic"
         
     @cell_magic
     def Ccmagic(self, cline, ccell):
         "A class-based cell magic"
         
     @line_cell_magic
     def Clcmagic(self, cline, ccell=None):
         "A class-based line/cell magic"
 
 
 class Awkward(object):
     def __getattr__(self, name):
         raise Exception(name)
 
 class NoBoolCall:
     """
     callable with `__bool__` raising should still be inspect-able.
     """
 
     def __call__(self):
         """does nothing"""
         pass
 
     def __bool__(self):
         """just raise NotImplemented"""
         raise NotImplementedError('Must be implemented')
 
 
 class SerialLiar(object):
     """Attribute accesses always get another copy of the same class.
 
     unittest.mock.call does something similar, but it's not ideal for testing
     as the failure mode is to eat all your RAM. This gives up after 10k levels.
     """
     def __init__(self, max_fibbing_twig, lies_told=0):
         if lies_told > 10000:
             raise RuntimeError('Nose too long, honesty is the best policy')
         self.max_fibbing_twig = max_fibbing_twig
         self.lies_told = lies_told
         max_fibbing_twig[0] = max(max_fibbing_twig[0], lies_told)
 
     def __getattr__(self, item):
         return SerialLiar(self.max_fibbing_twig, self.lies_told + 1)
 
 #-----------------------------------------------------------------------------
 # Tests
 #-----------------------------------------------------------------------------
 
 def test_info():
     "Check that Inspector.info fills out various fields as expected."
     i = inspector.info(Call, oname='Call')
     nt.assert_equal(i['type_name'], 'type')
     expted_class = str(type(type))  # <class 'type'> (Python 3) or <type 'type'>
     nt.assert_equal(i['base_class'], expted_class)
     nt.assert_regex(i['string_form'], "<class 'IPython.core.tests.test_oinspect.Call'( at 0x[0-9a-f]{1,9})?>")
     fname = __file__
     if fname.endswith(".pyc"):
         fname = fname[:-1]
     # case-insensitive comparison needed on some filesystems
     # e.g. Windows:
     nt.assert_equal(i['file'].lower(), compress_user(fname).lower())
     nt.assert_equal(i['definition'], None)
     nt.assert_equal(i['docstring'], Call.__doc__)
     nt.assert_equal(i['source'], None)
     nt.assert_true(i['isclass'])
     nt.assert_equal(i['init_definition'], "Call(x, y=1)")
     nt.assert_equal(i['init_docstring'], Call.__init__.__doc__)
 
     i = inspector.info(Call, detail_level=1)
     nt.assert_not_equal(i['source'], None)
     nt.assert_equal(i['docstring'], None)
 
     c = Call(1)
     c.__doc__ = "Modified instance docstring"
     i = inspector.info(c)
     nt.assert_equal(i['type_name'], 'Call')
     nt.assert_equal(i['docstring'], "Modified instance docstring")
     nt.assert_equal(i['class_docstring'], Call.__doc__)
     nt.assert_equal(i['init_docstring'], Call.__init__.__doc__)
     nt.assert_equal(i['call_docstring'], Call.__call__.__doc__)
 
 def test_class_signature():
     info = inspector.info(HasSignature, 'HasSignature')
     nt.assert_equal(info['init_definition'], "HasSignature(test)")
     nt.assert_equal(info['init_docstring'], HasSignature.__init__.__doc__)
 
 def test_info_awkward():
     # Just test that this doesn't throw an error.
     inspector.info(Awkward())
 
 def test_bool_raise():
     inspector.info(NoBoolCall())
 
 def test_info_serialliar():
     fib_tracker = [0]
     inspector.info(SerialLiar(fib_tracker))
 
     # Nested attribute access should be cut off at 100 levels deep to avoid
     # infinite loops: https://github.com/ipython/ipython/issues/9122
     nt.assert_less(fib_tracker[0], 9000)
 
 def test_calldef_none():
     # We should ignore __call__ for all of these.
     for obj in [f, SimpleClass().method, any, str.upper]:
         print(obj)
         i = inspector.info(obj)
         nt.assert_is(i['call_def'], None)
 
 def f_kwarg(pos, *, kwonly):
     pass
 
 def test_definition_kwonlyargs():
     i = inspector.info(f_kwarg, oname='f_kwarg')  # analysis:ignore
     nt.assert_equal(i['definition'], "f_kwarg(pos, *, kwonly)")
 
 def test_getdoc():
     class A(object):
         """standard docstring"""
         pass
 
     class B(object):
         """standard docstring"""
         def getdoc(self):
             return "custom docstring"
     
     class C(object):
         """standard docstring"""
         def getdoc(self):
             return None
     
     a = A()
     b = B()
     c = C()
     
     nt.assert_equal(oinspect.getdoc(a), "standard docstring")
     nt.assert_equal(oinspect.getdoc(b), "custom docstring")
     nt.assert_equal(oinspect.getdoc(c), "standard docstring")
 
 
 def test_empty_property_has_no_source():
     i = inspector.info(property(), detail_level=1)
     nt.assert_is(i['source'], None)
 
 
 def test_property_sources():
-    import zlib
+    import posixpath 
+    # A simple adder whose source and signature stays
+    # the same across Python distributions
+    def simple_add(a, b):
+        "Adds two numbers"
+        return a + b
 
     class A(object):
         @property
         def foo(self):
             return 'bar'
 
         foo = foo.setter(lambda self, v: setattr(self, 'bar', v))
 
-        id = property(id)
-        compress = property(zlib.compress)
+        dname = property(posixpath.dirname)
+        adder = property(simple_add) 
 
     i = inspector.info(A.foo, detail_level=1)
     nt.assert_in('def foo(self):', i['source'])
     nt.assert_in('lambda self, v:', i['source'])
 
-    i = inspector.info(A.id, detail_level=1)
-    nt.assert_in('fget = <function id>', i['source'])
+    i = inspector.info(A.dname, detail_level=1)
+    nt.assert_in('def dirname(p)', i['source'])
 
-    i = inspector.info(A.compress, detail_level=1)
-    nt.assert_in('fget = <function zlib.compress>', i['source'])
+    i = inspector.info(A.adder, detail_level=1)
+    nt.assert_in('def simple_add(a, b)', i['source'])
 
 
 def test_property_docstring_is_in_info_for_detail_level_0():
     class A(object):
         @property
         def foobar(self):
             """This is `foobar` property."""
             pass
 
     ip.user_ns['a_obj'] = A()
     nt.assert_equal(
         'This is `foobar` property.',
         ip.object_inspect('a_obj.foobar', detail_level=0)['docstring'])
 
     ip.user_ns['a_cls'] = A
     nt.assert_equal(
         'This is `foobar` property.',
         ip.object_inspect('a_cls.foobar', detail_level=0)['docstring'])
 
 
 def test_pdef():
     # See gh-1914
     def foo(): pass
     inspector.pdef(foo, 'foo')
 
 
 def test_pinfo_nonascii():
     # See gh-1177
     from . import nonascii2
     ip.user_ns['nonascii2'] = nonascii2
     ip._inspect('pinfo', 'nonascii2', detail_level=1)
 
 
 def test_pinfo_docstring_no_source():
     """Docstring should be included with detail_level=1 if there is no source"""
     with AssertPrints('Docstring:'):
         ip._inspect('pinfo', 'str.format', detail_level=0)
     with AssertPrints('Docstring:'):
         ip._inspect('pinfo', 'str.format', detail_level=1)
 
 
 def test_pinfo_no_docstring_if_source():
     """Docstring should not be included with detail_level=1 if source is found"""
     def foo():
         """foo has a docstring"""
 
     ip.user_ns['foo'] = foo
 
     with AssertPrints('Docstring:'):
         ip._inspect('pinfo', 'foo', detail_level=0)
     with AssertPrints('Source:'):
         ip._inspect('pinfo', 'foo', detail_level=1)
     with AssertNotPrints('Docstring:'):
         ip._inspect('pinfo', 'foo', detail_level=1)
 
 
 def test_pinfo_docstring_if_detail_and_no_source():
     """ Docstring should be displayed if source info not available """
     obj_def = '''class Foo(object):
                   """ This is a docstring for Foo """
                   def bar(self):
                       """ This is a docstring for Foo.bar """
                       pass
               ''' 
     
     ip.run_cell(obj_def)
     ip.run_cell('foo = Foo()')
     
     with AssertNotPrints("Source:"):
         with AssertPrints('Docstring:'):
             ip._inspect('pinfo', 'foo', detail_level=0)
         with AssertPrints('Docstring:'):
             ip._inspect('pinfo', 'foo', detail_level=1)
         with AssertPrints('Docstring:'):
             ip._inspect('pinfo', 'foo.bar', detail_level=0)
 
     with AssertNotPrints('Docstring:'):
         with AssertPrints('Source:'):
             ip._inspect('pinfo', 'foo.bar', detail_level=1)
 
 
 def test_pinfo_magic():
     with AssertPrints('Docstring:'):
         ip._inspect('pinfo', 'lsmagic', detail_level=0)
 
     with AssertPrints('Source:'):
         ip._inspect('pinfo', 'lsmagic', detail_level=1)
 
 
 def test_init_colors():
     # ensure colors are not present in signature info
     info = inspector.info(HasSignature)
     init_def = info['init_definition']
     nt.assert_not_in('[0m', init_def)
 
 
 def test_builtin_init():
     info = inspector.info(list)
     init_def = info['init_definition']
     # Python < 3.4 can't get init definition from builtins,
     # but still exercise the inspection in case of error-raising bugs.
     if sys.version_info >= (3,4):
         nt.assert_is_not_none(init_def)
 

IPython/lib/pretty.py

@@ -1,867 +1,871
 # -*- coding: utf-8 -*-
 """
 Python advanced pretty printer.  This pretty printer is intended to
 replace the old `pprint` python module which does not allow developers
 to provide their own pretty print callbacks.
 
 This module is based on ruby's `prettyprint.rb` library by `Tanaka Akira`.
 
 
 Example Usage
 -------------
 
 To directly print the representation of an object use `pprint`::
 
     from pretty import pprint
     pprint(complex_object)
 
 To get a string of the output use `pretty`::
 
     from pretty import pretty
     string = pretty(complex_object)
 
 
 Extending
 ---------
 
 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 `_repr_pretty_` method to your object and call the methods on the
 pretty printer passed::
 
     class MyObject(object):
 
         def _repr_pretty_(self, p, cycle):
             ...
 
 Here is an example implementation of a `_repr_pretty_` method for a list
 subclass::
 
     class MyList(list):
 
         def _repr_pretty_(self, p, cycle):
             if cycle:
                 p.text('MyList(...)')
             else:
                 with p.group(8, 'MyList([', '])'):
                     for idx, item in enumerate(self):
                         if idx:
                             p.text(',')
                             p.breakable()
                         p.pretty(item)
 
 The `cycle` parameter is `True` if pretty detected a cycle.  You *have* to
 react to that or the result is an infinite loop.  `p.text()` just adds
 non breaking text to the output, `p.breakable()` either adds a whitespace
 or breaks here.  If you pass it an argument it's used instead of the
 default space.  `p.pretty` prettyprints another object using the pretty print
 method.
 
 The first parameter to the `group` function specifies the extra indentation
 of the next line.  In this example the next item will either be on the same
 line (if the items are short enough) or aligned with the right edge of the
 opening bracket of `MyList`.
 
 If you just want to indent something you can use the group function
 without open / close parameters.  You can also use this code::
 
     with p.indent(2):
         ...
 
 Inheritance diagram:
 
 .. inheritance-diagram:: IPython.lib.pretty
    :parts: 3
 
 :copyright: 2007 by Armin Ronacher.
             Portions (c) 2009 by Robert Kern.
 :license: BSD License.
 """
 from contextlib import contextmanager
 import sys
 import types
 import re
 import datetime
 from collections import deque
 from io import StringIO
 from warnings import warn
 
 from IPython.utils.decorators import undoc
 from IPython.utils.py3compat import PYPY
-
+from IPython.utils.signatures import signature
 
 __all__ = ['pretty', 'pprint', 'PrettyPrinter', 'RepresentationPrinter',
     'for_type', 'for_type_by_name']
 
 
 MAX_SEQ_LENGTH = 1000
 _re_pattern_type = type(re.compile(''))
 
 def _safe_getattr(obj, attr, default=None):
     """Safe version of getattr.
     
     Same as getattr, but will return ``default`` on any Exception,
     rather than raising.
     """
     try:
         return getattr(obj, attr, default)
     except Exception:
         return default
 
 @undoc
 class CUnicodeIO(StringIO):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         warn(("CUnicodeIO is deprecated since IPython 6.0. "
               "Please use io.StringIO instead."),
              DeprecationWarning, stacklevel=2)
 
 def _sorted_for_pprint(items):
     """
     Sort the given items for pretty printing. Since some predictable
     sorting is better than no sorting at all, we sort on the string
     representation if normal sorting fails.
     """
     items = list(items)
     try:
         return sorted(items)
     except Exception:
         try:
             return sorted(items, key=str)
         except Exception:
             return items
 
 def pretty(obj, verbose=False, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH):
     """
     Pretty print the object's representation.
     """
     stream = StringIO()
     printer = RepresentationPrinter(stream, verbose, max_width, newline, max_seq_length=max_seq_length)
     printer.pretty(obj)
     printer.flush()
     return stream.getvalue()
 
 
 def pprint(obj, verbose=False, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH):
     """
     Like `pretty` but print to stdout.
     """
     printer = RepresentationPrinter(sys.stdout, verbose, max_width, newline, max_seq_length=max_seq_length)
     printer.pretty(obj)
     printer.flush()
     sys.stdout.write(newline)
     sys.stdout.flush()
 
 class _PrettyPrinterBase(object):
 
     @contextmanager
     def indent(self, indent):
         """with statement support for indenting/dedenting."""
         self.indentation += indent
         try:
             yield
         finally:
             self.indentation -= indent
 
     @contextmanager
     def group(self, indent=0, open='', close=''):
         """like begin_group / end_group but for the with statement."""
         self.begin_group(indent, open)
         try:
             yield
         finally:
             self.end_group(indent, close)
 
 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 `_repr_pretty_`
     callback method.
     """
 
     def __init__(self, output, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH):
         self.output = output
         self.max_width = max_width
         self.newline = newline
         self.max_seq_length = max_seq_length
         self.output_width = 0
         self.buffer_width = 0
         self.buffer = deque()
 
         root_group = Group(0)
         self.group_stack = [root_group]
         self.group_queue = GroupQueue(root_group)
         self.indentation = 0
 
     def _break_outer_groups(self):
         while self.max_width < self.output_width + self.buffer_width:
             group = self.group_queue.deq()
             if not group:
                 return
             while group.breakables:
                 x = self.buffer.popleft()
                 self.output_width = x.output(self.output, self.output_width)
                 self.buffer_width -= x.width
             while self.buffer and isinstance(self.buffer[0], Text):
                 x = self.buffer.popleft()
                 self.output_width = x.output(self.output, self.output_width)
                 self.buffer_width -= x.width
 
     def text(self, obj):
         """Add literal text to the output."""
         width = len(obj)
         if self.buffer:
             text = self.buffer[-1]
             if not isinstance(text, Text):
                 text = Text()
                 self.buffer.append(text)
             text.add(obj, width)
             self.buffer_width += width
             self._break_outer_groups()
         else:
             self.output.write(obj)
             self.output_width += width
 
     def breakable(self, sep=' '):
         """
         Add a breakable separator to the output.  This does not mean that it
         will automatically break here.  If no breaking on this position takes
         place the `sep` is inserted which default to one space.
         """
         width = len(sep)
         group = self.group_stack[-1]
         if group.want_break:
             self.flush()
             self.output.write(self.newline)
             self.output.write(' ' * self.indentation)
             self.output_width = self.indentation
             self.buffer_width = 0
         else:
             self.buffer.append(Breakable(sep, width, self))
             self.buffer_width += width
             self._break_outer_groups()
             
     def break_(self):
         """
         Explicitly insert a newline into the output, maintaining correct indentation.
         """
         self.flush()
         self.output.write(self.newline)
         self.output.write(' ' * self.indentation)
         self.output_width = self.indentation
         self.buffer_width = 0
         
 
     def begin_group(self, indent=0, open=''):
         """
         Begin a group.  If you want support for python < 2.5 which doesn't has
         the with statement this is the preferred way:
 
             p.begin_group(1, '{')
             ...
             p.end_group(1, '}')
 
         The python 2.5 expression would be this:
 
             with p.group(1, '{', '}'):
                 ...
 
         The first parameter specifies the indentation for the next line (usually
         the width of the opening text), the second the opening text.  All
         parameters are optional.
         """
         if open:
             self.text(open)
         group = Group(self.group_stack[-1].depth + 1)
         self.group_stack.append(group)
         self.group_queue.enq(group)
         self.indentation += indent
     
     def _enumerate(self, seq):
         """like enumerate, but with an upper limit on the number of items"""
         for idx, x in enumerate(seq):
             if self.max_seq_length and idx >= self.max_seq_length:
                 self.text(',')
                 self.breakable()
                 self.text('...')
                 return
             yield idx, x
     
     def end_group(self, dedent=0, close=''):
         """End a group. See `begin_group` for more details."""
         self.indentation -= dedent
         group = self.group_stack.pop()
         if not group.breakables:
             self.group_queue.remove(group)
         if close:
             self.text(close)
 
     def flush(self):
         """Flush data that is left in the buffer."""
         for data in self.buffer:
             self.output_width += data.output(self.output, self.output_width)
         self.buffer.clear()
         self.buffer_width = 0
 
 
 def _get_mro(obj_class):
     """ Get a reasonable method resolution order of a class and its superclasses
     for both old-style and new-style classes.
     """
     if not hasattr(obj_class, '__mro__'):
         # Old-style class. Mix in object to make a fake new-style class.
         try:
             obj_class = type(obj_class.__name__, (obj_class, object), {})
         except TypeError:
             # Old-style extension type that does not descend from object.
             # FIXME: try to construct a more thorough MRO.
             mro = [obj_class]
         else:
             mro = obj_class.__mro__[1:-1]
     else:
         mro = obj_class.__mro__
     return mro
 
 
 class RepresentationPrinter(PrettyPrinter):
     """
     Special pretty printer that has a `pretty` method that calls the pretty
     printer for a python object.
 
     This class stores processing data on `self` so you must *never* use
     this class in a threaded environment.  Always lock it or reinstanciate
     it.
 
     Instances also have a verbose flag callbacks can access to control their
     output.  For example the default instance repr prints all attributes and
     methods that are not prefixed by an underscore if the printer is in
     verbose mode.
     """
 
     def __init__(self, output, verbose=False, max_width=79, newline='\n',
         singleton_pprinters=None, type_pprinters=None, deferred_pprinters=None,
         max_seq_length=MAX_SEQ_LENGTH):
 
         PrettyPrinter.__init__(self, output, max_width, newline, max_seq_length=max_seq_length)
         self.verbose = verbose
         self.stack = []
         if singleton_pprinters is None:
             singleton_pprinters = _singleton_pprinters.copy()
         self.singleton_pprinters = singleton_pprinters
         if type_pprinters is None:
             type_pprinters = _type_pprinters.copy()
         self.type_pprinters = type_pprinters
         if deferred_pprinters is None:
             deferred_pprinters = _deferred_type_pprinters.copy()
         self.deferred_pprinters = deferred_pprinters
 
     def pretty(self, obj):
         """Pretty print the given object."""
         obj_id = id(obj)
         cycle = obj_id in self.stack
         self.stack.append(obj_id)
         self.begin_group()
         try:
             obj_class = _safe_getattr(obj, '__class__', None) or type(obj)
             # 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 walk the mro and check for either:
             #   1) a registered printer
             #   2) a _repr_pretty_ method
             for cls in _get_mro(obj_class):
                 if cls in self.type_pprinters:
                     # printer registered in self.type_pprinters
                     return self.type_pprinters[cls](obj, self, cycle)
                 else:
                     # deferred printer
                     printer = self._in_deferred_types(cls)
                     if printer is not None:
                         return printer(obj, self, cycle)
                     else:
                         # Finally look for special method names.
                         # Some objects automatically create any requested
                         # attribute. Try to ignore most of them by checking for
                         # callability.
                         if '_repr_pretty_' in cls.__dict__:
                             meth = cls._repr_pretty_
                             if callable(meth):
                                 return meth(obj, self, cycle)
             return _default_pprint(obj, self, cycle)
         finally:
             self.end_group()
             self.stack.pop()
 
     def _in_deferred_types(self, cls):
         """
         Check if the given class is specified in the deferred type registry.
 
         Returns the printer from the registry if it exists, and None if the
         class is not in the registry. Successful matches will be moved to the
         regular type registry for future use.
         """
         mod = _safe_getattr(cls, '__module__', None)
         name = _safe_getattr(cls, '__name__', None)
         key = (mod, name)
         printer = None
         if key in self.deferred_pprinters:
             # Move the printer over to the regular registry.
             printer = self.deferred_pprinters.pop(key)
             self.type_pprinters[cls] = printer
         return printer
 
 
 class Printable(object):
 
     def output(self, stream, output_width):
         return output_width
 
 
 class Text(Printable):
 
     def __init__(self):
         self.objs = []
         self.width = 0
 
     def output(self, stream, output_width):
         for obj in self.objs:
             stream.write(obj)
         return output_width + self.width
 
     def add(self, obj, width):
         self.objs.append(obj)
         self.width += width
 
 
 class Breakable(Printable):
 
     def __init__(self, seq, width, pretty):
         self.obj = seq
         self.width = width
         self.pretty = pretty
         self.indentation = pretty.indentation
         self.group = pretty.group_stack[-1]
         self.group.breakables.append(self)
 
     def output(self, stream, output_width):
         self.group.breakables.popleft()
         if self.group.want_break:
             stream.write(self.pretty.newline)
             stream.write(' ' * self.indentation)
             return self.indentation
         if not self.group.breakables:
             self.pretty.group_queue.remove(self.group)
         stream.write(self.obj)
         return output_width + self.width
 
 
 class Group(Printable):
 
     def __init__(self, depth):
         self.depth = depth
         self.breakables = deque()
         self.want_break = False
 
 
 class GroupQueue(object):
 
     def __init__(self, *groups):
         self.queue = []
         for group in groups:
             self.enq(group)
 
     def enq(self, group):
         depth = group.depth
         while depth > len(self.queue) - 1:
             self.queue.append([])
         self.queue[depth].append(group)
 
     def deq(self):
         for stack in self.queue:
             for idx, group in enumerate(reversed(stack)):
                 if group.breakables:
                     del stack[idx]
                     group.want_break = True
                     return group
             for group in stack:
                 group.want_break = True
             del stack[:]
 
     def remove(self, group):
         try:
             self.queue[group.depth].remove(group)
         except ValueError:
             pass
 
 
 def _default_pprint(obj, p, cycle):
     """
     The default print function.  Used if an object does not provide one and
     it's none of the builtin objects.
     """
     klass = _safe_getattr(obj, '__class__', None) or type(obj)
     if _safe_getattr(klass, '__repr__', None) is not object.__repr__:
         # A user-provided repr. Find newlines and replace them with p.break_()
         _repr_pprint(obj, p, cycle)
         return
     p.begin_group(1, '<')
     p.pretty(klass)
     p.text(' at 0x%x' % id(obj))
     if cycle:
         p.text(' ...')
     elif p.verbose:
         first = True
         for key in dir(obj):
             if not key.startswith('_'):
                 try:
                     value = getattr(obj, key)
                 except AttributeError:
                     continue
                 if isinstance(value, types.MethodType):
                     continue
                 if not first:
                     p.text(',')
                 p.breakable()
                 p.text(key)
                 p.text('=')
                 step = len(key) + 1
                 p.indentation += step
                 p.pretty(value)
                 p.indentation -= step
                 first = False
     p.end_group(1, '>')
 
 
 def _seq_pprinter_factory(start, end, basetype):
     """
     Factory that returns a pprint function useful for sequences.  Used by
     the default pprint for tuples, dicts, and lists.
     """
     def inner(obj, p, cycle):
         typ = type(obj)
         if basetype is not None and typ is not basetype and typ.__repr__ != basetype.__repr__:
             # If the subclass provides its own repr, use it instead.
             return p.text(typ.__repr__(obj))
 
         if cycle:
             return p.text(start + '...' + end)
         step = len(start)
         p.begin_group(step, start)
         for idx, x in p._enumerate(obj):
             if idx:
                 p.text(',')
                 p.breakable()
             p.pretty(x)
         if len(obj) == 1 and type(obj) is tuple:
             # Special case for 1-item tuples.
             p.text(',')
         p.end_group(step, end)
     return inner
 
 
 def _set_pprinter_factory(start, end, basetype):
     """
     Factory that returns a pprint function useful for sets and frozensets.
     """
     def inner(obj, p, cycle):
         typ = type(obj)
         if basetype is not None and typ is not basetype and typ.__repr__ != basetype.__repr__:
             # If the subclass provides its own repr, use it instead.
             return p.text(typ.__repr__(obj))
 
         if cycle:
             return p.text(start + '...' + end)
         if len(obj) == 0:
             # Special case.
             p.text(basetype.__name__ + '()')
         else:
             step = len(start)
             p.begin_group(step, start)
             # Like dictionary keys, we will try to sort the items if there aren't too many
             if not (p.max_seq_length and len(obj) >= p.max_seq_length):
                 items = _sorted_for_pprint(obj)
             else:
                 items = obj
             for idx, x in p._enumerate(items):
                 if idx:
                     p.text(',')
                     p.breakable()
                 p.pretty(x)
             p.end_group(step, end)
     return inner
 
 
 def _dict_pprinter_factory(start, end, basetype=None):
     """
     Factory that returns a pprint function used by the default pprint of
     dicts and dict proxies.
     """
     def inner(obj, p, cycle):
         typ = type(obj)
         if basetype is not None and typ is not basetype and typ.__repr__ != basetype.__repr__:
             # If the subclass provides its own repr, use it instead.
             return p.text(typ.__repr__(obj))
 
         if cycle:
             return p.text('{...}')
         step = len(start)
         p.begin_group(step, start)
         keys = obj.keys()
         # if dict isn't large enough to be truncated, sort keys before displaying
         if not (p.max_seq_length and len(obj) >= p.max_seq_length):
             keys = _sorted_for_pprint(keys)
         for idx, key in p._enumerate(keys):
             if idx:
                 p.text(',')
                 p.breakable()
             p.pretty(key)
             p.text(': ')
             p.pretty(obj[key])
         p.end_group(step, end)
     return inner
 
 
 def _super_pprint(obj, p, cycle):
     """The pprint for the super type."""
     p.begin_group(8, '<super: ')
     p.pretty(obj.__thisclass__)
     p.text(',')
     p.breakable()
     if PYPY: # In PyPy, super() objects don't have __self__ attributes
         dself = obj.__repr__.__self__
         p.pretty(None if dself is obj else dself)
     else:
         p.pretty(obj.__self__)
     p.end_group(8, '>')
 
 
 def _re_pattern_pprint(obj, p, cycle):
     """The pprint function for regular expression patterns."""
     p.text('re.compile(')
     pattern = repr(obj.pattern)
     if pattern[:1] in 'uU':
         pattern = pattern[1:]
         prefix = 'ur'
     else:
         prefix = 'r'
     pattern = prefix + pattern.replace('\\\\', '\\')
     p.text(pattern)
     if obj.flags:
         p.text(',')
         p.breakable()
         done_one = False
         for flag in ('TEMPLATE', 'IGNORECASE', 'LOCALE', 'MULTILINE', 'DOTALL',
             'UNICODE', 'VERBOSE', 'DEBUG'):
             if obj.flags & getattr(re, flag):
                 if done_one:
                     p.text('|')
                 p.text('re.' + flag)
                 done_one = True
     p.text(')')
 
 
 def _type_pprint(obj, p, cycle):
     """The pprint for classes and types."""
     # Heap allocated types might not have the module attribute,
     # and others may set it to None.
 
     # Checks for a __repr__ override in the metaclass. Can't compare the
     # type(obj).__repr__ directly because in PyPy the representation function
     # inherited from type isn't the same type.__repr__
     if [m for m in _get_mro(type(obj)) if "__repr__" in vars(m)][:1] != [type]:
         _repr_pprint(obj, p, cycle)
         return
 
     mod = _safe_getattr(obj, '__module__', None)
     try:
         name = obj.__qualname__
         if not isinstance(name, str):
             # This can happen if the type implements __qualname__ as a property
             # or other descriptor in Python 2.
             raise Exception("Try __name__")
     except Exception:
         name = obj.__name__
         if not isinstance(name, str):
             name = '<unknown type>'
 
     if mod in (None, '__builtin__', 'builtins', 'exceptions'):
         p.text(name)
     else:
         p.text(mod + '.' + name)
 
 
 def _repr_pprint(obj, p, cycle):
     """A pprint that just redirects to the normal repr function."""
     # Find newlines and replace them with p.break_()
     output = repr(obj)
     for idx,output_line in enumerate(output.splitlines()):
         if idx:
             p.break_()
         p.text(output_line)
 
 
 def _function_pprint(obj, p, cycle):
     """Base pprint for all functions and builtin functions."""
     name = _safe_getattr(obj, '__qualname__', obj.__name__)
     mod = obj.__module__
     if mod and mod not in ('__builtin__', 'builtins', 'exceptions'):
         name = mod + '.' + name
-    p.text('<function %s>' % name)
+    try:
+       func_def = name + str(signature(obj))
+    except ValueError:
+       func_def = name
+    p.text('<function %s>' % func_def)
 
 
 def _exception_pprint(obj, p, cycle):
     """Base pprint for all exceptions."""
     name = getattr(obj.__class__, '__qualname__', obj.__class__.__name__)
     if obj.__class__.__module__ not in ('exceptions', 'builtins'):
         name = '%s.%s' % (obj.__class__.__module__, name)
     step = len(name) + 1
     p.begin_group(step, name + '(')
     for idx, arg in enumerate(getattr(obj, 'args', ())):
         if idx:
             p.text(',')
             p.breakable()
         p.pretty(arg)
     p.end_group(step, ')')
 
 
 #: the exception base
 try:
     _exception_base = BaseException
 except NameError:
     _exception_base = Exception
 
 
 #: printers for builtin types
 _type_pprinters = {
     int:                        _repr_pprint,
     float:                      _repr_pprint,
     str:                        _repr_pprint,
     tuple:                      _seq_pprinter_factory('(', ')', tuple),
     list:                       _seq_pprinter_factory('[', ']', list),
     dict:                       _dict_pprinter_factory('{', '}', dict),
     
     set:                        _set_pprinter_factory('{', '}', set),
     frozenset:                  _set_pprinter_factory('frozenset({', '})', frozenset),
     super:                      _super_pprint,
     _re_pattern_type:           _re_pattern_pprint,
     type:                       _type_pprint,
     types.FunctionType:         _function_pprint,
     types.BuiltinFunctionType:  _function_pprint,
     types.MethodType:           _repr_pprint,
     
     datetime.datetime:          _repr_pprint,
     datetime.timedelta:         _repr_pprint,
     _exception_base:            _exception_pprint
 }
 
 try:
     # In PyPy, types.DictProxyType is dict, setting the dictproxy printer
     # using dict.setdefault avoids overwritting the dict printer
     _type_pprinters.setdefault(types.DictProxyType,
                                _dict_pprinter_factory('dict_proxy({', '})'))
     _type_pprinters[types.ClassType] = _type_pprint
     _type_pprinters[types.SliceType] = _repr_pprint
 except AttributeError: # Python 3
     _type_pprinters[types.MappingProxyType] = \
         _dict_pprinter_factory('mappingproxy({', '})')
     _type_pprinters[slice] = _repr_pprint
     
 try:
     _type_pprinters[long] = _repr_pprint
     _type_pprinters[unicode] = _repr_pprint
 except NameError:
     _type_pprinters[range] = _repr_pprint
     _type_pprinters[bytes] = _repr_pprint
 
 #: printers for types specified by name
 _deferred_type_pprinters = {
 }
 
 def for_type(typ, func):
     """
     Add a pretty printer for a given type.
     """
     oldfunc = _type_pprinters.get(typ, None)
     if func is not None:
         # To support easy restoration of old pprinters, we need to ignore Nones.
         _type_pprinters[typ] = func
     return oldfunc
 
 def for_type_by_name(type_module, type_name, func):
     """
     Add a pretty printer for a type specified by the module and name of a type
     rather than the type object itself.
     """
     key = (type_module, type_name)
     oldfunc = _deferred_type_pprinters.get(key, None)
     if func is not None:
         # To support easy restoration of old pprinters, we need to ignore Nones.
         _deferred_type_pprinters[key] = func
     return oldfunc
 
 
 #: printers for the default singletons
 _singleton_pprinters = dict.fromkeys(map(id, [None, True, False, Ellipsis,
                                       NotImplemented]), _repr_pprint)
 
 
 def _defaultdict_pprint(obj, p, cycle):
     name = obj.__class__.__name__
     with p.group(len(name) + 1, name + '(', ')'):
         if cycle:
             p.text('...')
         else:
             p.pretty(obj.default_factory)
             p.text(',')
             p.breakable()
             p.pretty(dict(obj))
 
 def _ordereddict_pprint(obj, p, cycle):
     name = obj.__class__.__name__
     with p.group(len(name) + 1, name + '(', ')'):
         if cycle:
             p.text('...')
         elif len(obj):
             p.pretty(list(obj.items()))
 
 def _deque_pprint(obj, p, cycle):
     name = obj.__class__.__name__
     with p.group(len(name) + 1, name + '(', ')'):
         if cycle:
             p.text('...')
         else:
             p.pretty(list(obj))
 
 
 def _counter_pprint(obj, p, cycle):
     name = obj.__class__.__name__
     with p.group(len(name) + 1, name + '(', ')'):
         if cycle:
             p.text('...')
         elif len(obj):
             p.pretty(dict(obj))
 
 for_type_by_name('collections', 'defaultdict', _defaultdict_pprint)
 for_type_by_name('collections', 'OrderedDict', _ordereddict_pprint)
 for_type_by_name('collections', 'deque', _deque_pprint)
 for_type_by_name('collections', 'Counter', _counter_pprint)
 
 if __name__ == '__main__':
     from random import randrange
     class Foo(object):
         def __init__(self):
             self.foo = 1
             self.bar = re.compile(r'\s+')
             self.blub = dict.fromkeys(range(30), randrange(1, 40))
             self.hehe = 23424.234234
             self.list = ["blub", "blah", self]
 
         def get_foo(self):
             print("foo")
 
     pprint(Foo(), verbose=True)

IPython/lib/tests/test_pretty.py

@@ -1,407 +1,423
 # coding: utf-8
 """Tests for IPython.lib.pretty."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 
 from collections import Counter, defaultdict, deque, OrderedDict
 import types
 import string
 import unittest
 
 import nose.tools as nt
 
 from IPython.lib import pretty
 from IPython.testing.decorators import skip_without
 
 from io import StringIO
 
 
 class MyList(object):
     def __init__(self, content):
         self.content = content
     def _repr_pretty_(self, p, cycle):
         if cycle:
             p.text("MyList(...)")
         else:
             with p.group(3, "MyList(", ")"):
                 for (i, child) in enumerate(self.content):
                     if i:
                         p.text(",")
                         p.breakable()
                     else:
                         p.breakable("")
                     p.pretty(child)
 
 
 class MyDict(dict):
     def _repr_pretty_(self, p, cycle):
         p.text("MyDict(...)")
 
 class MyObj(object):
     def somemethod(self):
         pass
 
 
 class Dummy1(object):
     def _repr_pretty_(self, p, cycle):
         p.text("Dummy1(...)")
 
 class Dummy2(Dummy1):
     _repr_pretty_ = None
 
 class NoModule(object):
     pass
 
 NoModule.__module__ = None
 
 class Breaking(object):
     def _repr_pretty_(self, p, cycle):
         with p.group(4,"TG: ",":"):
             p.text("Breaking(")
             p.break_()
             p.text(")")
 
 class BreakingRepr(object):
     def __repr__(self):
         return "Breaking(\n)"
 
 class BreakingReprParent(object):
     def _repr_pretty_(self, p, cycle):
         with p.group(4,"TG: ",":"):
             p.pretty(BreakingRepr())
 
 class BadRepr(object):
     
     def __repr__(self):
         return 1/0
 
 
 def test_indentation():
     """Test correct indentation in groups"""
     count = 40
     gotoutput = pretty.pretty(MyList(range(count)))
     expectedoutput = "MyList(\n" + ",\n".join("   %d" % i for i in range(count)) + ")"
 
     nt.assert_equal(gotoutput, expectedoutput)
 
 
 def test_dispatch():
     """
     Test correct dispatching: The _repr_pretty_ method for MyDict
     must be found before the registered printer for dict.
     """
     gotoutput = pretty.pretty(MyDict())
     expectedoutput = "MyDict(...)"
 
     nt.assert_equal(gotoutput, expectedoutput)
 
 
 def test_callability_checking():
     """
     Test that the _repr_pretty_ method is tested for callability and skipped if
     not.
     """
     gotoutput = pretty.pretty(Dummy2())
     expectedoutput = "Dummy1(...)"
 
     nt.assert_equal(gotoutput, expectedoutput)
 
 
 def test_sets():
     """
     Test that set and frozenset use Python 3 formatting.
     """
     objects = [set(), frozenset(), set([1]), frozenset([1]), set([1, 2]),
         frozenset([1, 2]), set([-1, -2, -3])]
     expected = ['set()', 'frozenset()', '{1}', 'frozenset({1})', '{1, 2}',
         'frozenset({1, 2})', '{-3, -2, -1}']
     for obj, expected_output in zip(objects, expected):
         got_output = pretty.pretty(obj)
         yield nt.assert_equal, got_output, expected_output
 
 
 @skip_without('xxlimited')
 def test_pprint_heap_allocated_type():
     """
     Test that pprint works for heap allocated types.
     """
     import xxlimited
     output = pretty.pretty(xxlimited.Null)
     nt.assert_equal(output, 'xxlimited.Null')
 
 def test_pprint_nomod():
     """
     Test that pprint works for classes with no __module__.
     """
     output = pretty.pretty(NoModule)
     nt.assert_equal(output, 'NoModule')
     
 def test_pprint_break():
     """
     Test that p.break_ produces expected output
     """
     output = pretty.pretty(Breaking())
     expected = "TG: Breaking(\n    ):"
     nt.assert_equal(output, expected)
 
 def test_pprint_break_repr():
     """
     Test that p.break_ is used in repr
     """
     output = pretty.pretty(BreakingReprParent())
     expected = "TG: Breaking(\n    ):"
     nt.assert_equal(output, expected)
 
 def test_bad_repr():
     """Don't catch bad repr errors"""
     with nt.assert_raises(ZeroDivisionError):
         pretty.pretty(BadRepr())
 
 class BadException(Exception):
     def __str__(self):
         return -1
 
 class ReallyBadRepr(object):
     __module__ = 1
     @property
     def __class__(self):
         raise ValueError("I am horrible")
     
     def __repr__(self):
         raise BadException()
 
 def test_really_bad_repr():
     with nt.assert_raises(BadException):
         pretty.pretty(ReallyBadRepr())
 
 
 class SA(object):
     pass
 
 class SB(SA):
     pass
 
 class TestsPretty(unittest.TestCase):
 
     def test_super_repr(self):
         # "<super: module_name.SA, None>"
         output = pretty.pretty(super(SA))
         self.assertRegex(output, r"<super: \S+.SA, None>")
 
         # "<super: module_name.SA, <module_name.SB at 0x...>>"
         sb = SB()
         output = pretty.pretty(super(SA, sb))
         self.assertRegex(output, r"<super: \S+.SA,\s+<\S+.SB at 0x\S+>>")
 
 
     def test_long_list(self):
         lis = list(range(10000))
         p = pretty.pretty(lis)
         last2 = p.rsplit('\n', 2)[-2:]
         self.assertEqual(last2, [' 999,', ' ...]'])
 
     def test_long_set(self):
         s = set(range(10000))
         p = pretty.pretty(s)
         last2 = p.rsplit('\n', 2)[-2:]
         self.assertEqual(last2, [' 999,', ' ...}'])
 
     def test_long_tuple(self):
         tup = tuple(range(10000))
         p = pretty.pretty(tup)
         last2 = p.rsplit('\n', 2)[-2:]
         self.assertEqual(last2, [' 999,', ' ...)'])
 
     def test_long_dict(self):
         d = { n:n for n in range(10000) }
         p = pretty.pretty(d)
         last2 = p.rsplit('\n', 2)[-2:]
         self.assertEqual(last2, [' 999: 999,', ' ...}'])
 
     def test_unbound_method(self):
         output = pretty.pretty(MyObj.somemethod)
         self.assertIn('MyObj.somemethod', output)
 
 
 class MetaClass(type):
     def __new__(cls, name):
         return type.__new__(cls, name, (object,), {'name': name})
 
     def __repr__(self):
         return "[CUSTOM REPR FOR CLASS %s]" % self.name
 
 
 ClassWithMeta = MetaClass('ClassWithMeta')
 
 
 def test_metaclass_repr():
     output = pretty.pretty(ClassWithMeta)
     nt.assert_equal(output, "[CUSTOM REPR FOR CLASS ClassWithMeta]")
 
 
 def test_unicode_repr():
     u = u"üniçodé"
     ustr = u
     
     class C(object):
         def __repr__(self):
             return ustr
     
     c = C()
     p = pretty.pretty(c)
     nt.assert_equal(p, u)
     p = pretty.pretty([c])
     nt.assert_equal(p, u'[%s]' % u)
 
 
 def test_basic_class():
     def type_pprint_wrapper(obj, p, cycle):
         if obj is MyObj:
             type_pprint_wrapper.called = True
         return pretty._type_pprint(obj, p, cycle)
     type_pprint_wrapper.called = False
 
     stream = StringIO()
     printer = pretty.RepresentationPrinter(stream)
     printer.type_pprinters[type] = type_pprint_wrapper
     printer.pretty(MyObj)
     printer.flush()
     output = stream.getvalue()
 
     nt.assert_equal(output, '%s.MyObj' % __name__)
     nt.assert_true(type_pprint_wrapper.called)
 
 
 def test_collections_defaultdict():
     # Create defaultdicts with cycles
     a = defaultdict()
     a.default_factory = a
     b = defaultdict(list)
     b['key'] = b
 
     # Dictionary order cannot be relied on, test against single keys.
     cases = [
         (defaultdict(list), 'defaultdict(list, {})'),
         (defaultdict(list, {'key': '-' * 50}),
          "defaultdict(list,\n"
          "            {'key': '--------------------------------------------------'})"),
         (a, 'defaultdict(defaultdict(...), {})'),
         (b, "defaultdict(list, {'key': defaultdict(...)})"),
     ]
     for obj, expected in cases:
         nt.assert_equal(pretty.pretty(obj), expected)
 
 
 def test_collections_ordereddict():
     # Create OrderedDict with cycle
     a = OrderedDict()
     a['key'] = a
 
     cases = [
         (OrderedDict(), 'OrderedDict()'),
         (OrderedDict((i, i) for i in range(1000, 1010)),
          'OrderedDict([(1000, 1000),\n'
          '             (1001, 1001),\n'
          '             (1002, 1002),\n'
          '             (1003, 1003),\n'
          '             (1004, 1004),\n'
          '             (1005, 1005),\n'
          '             (1006, 1006),\n'
          '             (1007, 1007),\n'
          '             (1008, 1008),\n'
          '             (1009, 1009)])'),
         (a, "OrderedDict([('key', OrderedDict(...))])"),
     ]
     for obj, expected in cases:
         nt.assert_equal(pretty.pretty(obj), expected)
 
 
 def test_collections_deque():
     # Create deque with cycle
     a = deque()
     a.append(a)
 
     cases = [
         (deque(), 'deque([])'),
         (deque(i for i in range(1000, 1020)),
          'deque([1000,\n'
          '       1001,\n'
          '       1002,\n'
          '       1003,\n'
          '       1004,\n'
          '       1005,\n'
          '       1006,\n'
          '       1007,\n'
          '       1008,\n'
          '       1009,\n'
          '       1010,\n'
          '       1011,\n'
          '       1012,\n'
          '       1013,\n'
          '       1014,\n'
          '       1015,\n'
          '       1016,\n'
          '       1017,\n'
          '       1018,\n'
          '       1019])'),
         (a, 'deque([deque(...)])'),
     ]
     for obj, expected in cases:
         nt.assert_equal(pretty.pretty(obj), expected)
 
 def test_collections_counter():
     class MyCounter(Counter):
         pass
     cases = [
         (Counter(), 'Counter()'),
         (Counter(a=1), "Counter({'a': 1})"),
         (MyCounter(a=1), "MyCounter({'a': 1})"),
     ]
     for obj, expected in cases:
         nt.assert_equal(pretty.pretty(obj), expected)
 
 def test_mappingproxy():
     MP = types.MappingProxyType
     underlying_dict = {}
     mp_recursive = MP(underlying_dict)
     underlying_dict[2] = mp_recursive
     underlying_dict[3] = underlying_dict
 
     cases = [
         (MP({}), "mappingproxy({})"),
         (MP({None: MP({})}), "mappingproxy({None: mappingproxy({})})"),
         (MP({k: k.upper() for k in string.ascii_lowercase}),
          "mappingproxy({'a': 'A',\n"
          "              'b': 'B',\n"
          "              'c': 'C',\n"
          "              'd': 'D',\n"
          "              'e': 'E',\n"
          "              'f': 'F',\n"
          "              'g': 'G',\n"
          "              'h': 'H',\n"
          "              'i': 'I',\n"
          "              'j': 'J',\n"
          "              'k': 'K',\n"
          "              'l': 'L',\n"
          "              'm': 'M',\n"
          "              'n': 'N',\n"
          "              'o': 'O',\n"
          "              'p': 'P',\n"
          "              'q': 'Q',\n"
          "              'r': 'R',\n"
          "              's': 'S',\n"
          "              't': 'T',\n"
          "              'u': 'U',\n"
          "              'v': 'V',\n"
          "              'w': 'W',\n"
          "              'x': 'X',\n"
          "              'y': 'Y',\n"
          "              'z': 'Z'})"),
         (mp_recursive, "mappingproxy({2: {...}, 3: {2: {...}, 3: {...}}})"),
         (underlying_dict,
          "{2: mappingproxy({2: {...}, 3: {...}}), 3: {...}}"),
     ]
     for obj, expected in cases:
         nt.assert_equal(pretty.pretty(obj), expected)
+
+def test_function_pretty():
+    "Test pretty print of function"
+    # posixpath is a pure python function, its interface is consistent
+    # across Python distributions
+    import os
+    nt.assert_equal(pretty.pretty(os.path.join), '<function posixpath.join(a, *p)>')
+ 
+    # custom function
+    def meaning_of_life(question=None):
+        if question:
+            return 42
+        return "Don't panic"
+
+    nt.assert_in('meaning_of_life(question=None)', pretty.pretty(meaning_of_life))
+