Using update_wrapper() copies or adds attributes from the original function to the partial object

functools__update_wrapper.py

import functools

def foo(a, b=2):
    """Docstring for foo()."""
    print "called foo with:", (a, b)

def show_details(name, f):
    print "%s:" % name
    print "object:", f
    print "__name__:",
    try:
        print f.__name__
    except AttributeError:
        print "(no __name__)"
    print "__doc__:", repr(f.__doc__)
    print

show_details('foo', foo)

p1 = functools.partial(foo, b=4)
show_details('raw wrapper', p1)

print "Updating wrapper:"
print "assign:", functools.WRAPPER_ASSIGNMENTS
print "update:", functools.WRAPPER_UPDATES
print

functools.update_wrapper(p1, foo)
show_details('updated wrapper', p1)

out.txt

foo:
object: <function foo at 0x7f985e88f7d0>
__name__: foo
__doc__: 'Docstring for foo().'

raw wrapper:
object: <functools.partial object at 0x7f985e8e1fc8>
__name__: (no __name__)
__doc__: 'partial(func, *args, **keywords) - new function with partial application\n    of the given arguments and keywords.\n'

Updating wrapper:
assign: ('__module__', '__name__', '__doc__')
update: ('__dict__',)

updated wrapper:
object: <functools.partial object at 0x7f985e8e1fc8>
__name__: foo
__doc__: 'Docstring for foo().'