add py.builtin.callable

--HG--
branch : trunk

py/__init__.py

@@ -151,6 +151,7 @@ initpkg(__name__,
     'builtin._totext'        : ('./builtin/builtin31.py', '_totext'),
     'builtin.builtins'       : ('./builtin/builtin31.py', 'builtins'),
     'builtin.execfile'       : ('./builtin/builtin31.py', 'execfile'),
+    'builtin.callable'       : ('./builtin/builtin31.py', 'callable'),
 
     # gateways into remote contexts
     'execnet.__doc__'        : ('./execnet/__init__.py', '__doc__'),

py/builtin/builtin31.py

@@ -26,10 +26,14 @@ if sys.version_info >= (3, 0):
             fp.close()
         exec_(source, globs, locs)
 
+    def callable(obj):
+        return hasattr(obj, "__call__")
+
 else:
     _totext = unicode 
     _basestring = basestring
     execfile = execfile
+    callable = callable
 
     import __builtin__ as builtins
     def print_(*args, **kwargs):

py/builtin/testing/test_builtin.py

@@ -96,6 +96,15 @@ def test_execfile(tmpdir):
         py.builtin.execfile(str(test_file))
     assert A.x == 3
 
+def test_callable():
+    class A: pass
+    assert py.builtin.callable(test_callable)
+    assert py.builtin.callable(A)
+    assert py.builtin.callable(list)
+    assert py.builtin.callable(id)
+    assert not py.builtin.callable(4)
+    assert not py.builtin.callable("hi")
+
 def test_totext():
     py.builtin._totext("hello", "UTF-8")