Add signature to the display of functions in the shell

IPython/core/tests/test_oinspect.py

@@ -305,7 +305,12 b' def test_empty_property_has_no_source():'
 
 
 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
@@ -314,18 +319,18 b' def test_property_sources():'
 
         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():

IPython/lib/pretty.py

@@ -88,7 +88,7 b' 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']
@@ -711,7 +711,11 b' def _function_pprint(obj, p, cycle):'
     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):

IPython/lib/tests/test_pretty.py

@@ -405,3 +405,19 b' def test_mappingproxy():'
     ]
     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))
+