import functools
def myfunc(a, b=2):
 "Docstring for myfunc()."
 print(' called myfunc with:', (a, b))
def show_details(name, f, is_partial=False):
 "Show details of a callable object."
 print('{}:'.format(name))
 print(' object:', f)
 if not is_partial:
  print(' __name__:', f.__name__)
 if is_partial:
  print(' func:', f.func)
  print(' args:', f.args)
  print(' keywords:', f.keywords)
 return
show_details('myfunc', myfunc)
myfunc('a', 3)
print()
# Set a different default value for 'b', but require
# the caller to provide 'a'.
p1 = functools.partial(myfunc, b=4)
show_details('partial with named default', p1, True)
p1('passing a')
p1('override b', b=5)
print()
# Set default values for both 'a' and 'b'.
p2 = functools.partial(myfunc, 'default a', b=99)
show_details('partial with defaults', p2, True)
p2()
p2(b='override b')
print()
print('Insufficient arguments:')
p1()

import functools
def myfunc(a, b=2):
 "Docstring for myfunc()."
 print(' called myfunc with:', (a, b))
def show_details(name, f):
 "Show details of a callable object."
 print('{}:'.format(name))
 print(' object:', f)
 print(' __name__:', end=' ')
 try:
  print(f.__name__)
 except AttributeError:
  print('(no __name__)')
 print(' __doc__', repr(f.__doc__))
 print()
show_details('myfunc', myfunc)
p1 = functools.partial(myfunc, 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, myfunc)
show_details('updated wrapper', p1)

import functools
class MyClass:
 "Demonstration class for functools"
 
 def __call__(self, e, f=6):
  "Docstring for MyClass.__call__"
  print(' called object with:', (self, e, f))
def show_details(name, f):
 "Show details of a callable object."
 print('{}:'.format(name))
 print(' object:', f)
 print(' __name__:', end=' ')
 try:
  print(f.__name__)
 except AttributeError:
  print('(no __name__)')
 print(' __doc__', repr(f.__doc__))
 return
o = MyClass()
show_details('instance', o)
o('e goes here')
print()
p = functools.partial(o, e='default for e', f=8)
functools.update_wrapper(p, o)
show_details('instance wrapper', p)
p()

import functools
def standalone(self, a=1, b=2):
 "Standalone function"
 print(' called standalone with:', (self, a, b))
 if self is not None:
  print(' self.attr =', self.attr)
class MyClass:
 "Demonstration class for functools"
 
 def __init__(self):
  self.attr = 'instance attribute'
 method1 = functools.partialmethod(standalone)
 method2 = functools.partial(standalone)
o = MyClass()
print('standalone')
standalone(None)
print()
print('method1 as partialmethod')
o.method1()
print()
print('method2 as partial')
try:
 o.method2()
except TypeError as err:
 print('ERROR: {}'.format(err))

import functools
def show_details(name, f):
 "Show details of a callable object."
 print('{}:'.format(name))
 print(' object:', f)
 print(' __name__:', end=' ')
 try:
  print(f.__name__)
 except AttributeError:
  print('(no __name__)')
 print(' __doc__', repr(f.__doc__))
 print()
def simple_decorator(f):
 @functools.wraps(f)
 def decorated(a='decorated defaults', b=1):
  print(' decorated:', (a, b))
  print(' ', end=' ')
  return f(a, b=b)
 return decorated
def myfunc(a, b=2):
 "myfunc() is not complicated"
 print(' myfunc:', (a, b))
 return
 
# The raw function
show_details('myfunc', myfunc)
myfunc('unwrapped, default b')
myfunc('unwrapped, passing b', 3)
print()
# Wrap explicitly
wrapped_myfunc = simple_decorator(myfunc)
show_details('wrapped_myfunc', wrapped_myfunc)
wrapped_myfunc()
wrapped_myfunc('args to wrapped', 4)
print()
# Wrap with decorator syntax
@simple_decorator
def decorated_myfunc(a, b):
 myfunc(a, b)
 return
show_details('decorated_myfunc', decorated_myfunc)
decorated_myfunc()
decorated_myfunc('args to decorated', 4)

import functools
import inspect
from pprint import pprint
@functools.total_ordering
class MyObject:
 def __init__(self, val):
  self.val = val
 def __eq__(self, other):
  print(' testing __eq__({}, {})'.format(
   self.val, other.val))
  return self.val == other.val
 def __gt__(self, other):
  print(' testing __gt__({}, {})'.format(
   self.val, other.val))
  return self.val > other.val
print('Methods:\n')
pprint(inspect.getmembers(MyObject, inspect.isfunction))
a = MyObject(1)
b = MyObject(2)
print('\nComparisons:')
for expr in ['a < b', 'a <= b', 'a == b', 'a >= b', 'a > b']:
 print('\n{:<6}:'.format(expr))
 result = eval(expr)
 print(' result of {}: {}'.format(expr, result))

import functools
class MyObject:
 def __init__(self, val):
  self.val = val
 def __str__(self):
  return 'MyObject({})'.format(self.val)
def compare_obj(a, b):
 """Old-style comparison function.
 """
 print('comparing {} and {}'.format(a, b))
 if a.val < b.val:
  return -1
 elif a.val > b.val:
  return 1
 return 0
# Make a key function using cmp_to_key()
get_key = functools.cmp_to_key(compare_obj)
def get_key_wrapper(o):
 "Wrapper function for get_key to allow for print statements."
 new_key = get_key(o)
 print('key_wrapper({}) -> {!r}'.format(o, new_key))
 return new_key
objs = [MyObject(x) for x in range(5, 0, -1)]
for o in sorted(objs, key=get_key_wrapper):
 print(o)

import functools
@functools.lru_cache()
def expensive(a, b):
 print('expensive({}, {})'.format(a, b))
 return a * b
MAX = 2
 
print('First set of calls:')
for i in range(MAX):
 for j in range(MAX):
  expensive(i, j)
print(expensive.cache_info())
print('\nSecond set of calls:')
for i in range(MAX + 1):
 for j in range(MAX + 1):
  expensive(i, j)
print(expensive.cache_info())
print('\nClearing cache:')
expensive.cache_clear()
print(expensive.cache_info())
print('\nThird set of calls:')
for i in range(MAX):
 for j in range(MAX):
  expensive(i, j)
print(expensive.cache_info())

import functools
@functools.lru_cache(maxsize=2)
def expensive(a, b):
 print('called expensive({}, {})'.format(a, b))
 return a * b
def make_call(a, b):
 print('({}, {})'.format(a, b), end=' ')
 pre_hits = expensive.cache_info().hits
 expensive(a, b)
 post_hits = expensive.cache_info().hits
 if post_hits > pre_hits:
  print('cache hit')
print('Establish the cache')
make_call(1, 2)
make_call(2, 3)
print('\nUse cached items')
make_call(1, 2)
make_call(2, 3)
print('\nCompute a new value, triggering cache expiration')
make_call(3, 4)
print('\nCache still contains one old item')
make_call(2, 3)
print('\nOldest item needs to be recomputed')
make_call(1, 2)

import functools
@functools.lru_cache(maxsize=2)
def expensive(a, b):
 print('called expensive({}, {})'.format(a, b))
 return a * b
def make_call(a, b):
 print('({}, {})'.format(a, b), end=' ')
 pre_hits = expensive.cache_info().hits
 expensive(a, b)
 post_hits = expensive.cache_info().hits
 if post_hits > pre_hits:
  print('cache hit')
make_call(1, 2)
try:
 make_call([1], 2)
except TypeError as err:
 print('ERROR: {}'.format(err))
try:
 make_call(1, {'2': 'two'})
except TypeError as err:
 print('ERROR: {}'.format(err))

import functools
def do_reduce(a, b):
 print('do_reduce({}, {})'.format(a, b))
 return a + b
data = range(1, 5)
print(data)
result = functools.reduce(do_reduce, data)
print('result: {}'.format(result))

import functools
def do_reduce(a, b):
 print('do_reduce({}, {})'.format(a, b))
 return a + b
data = range(1, 5)
print(data)
result = functools.reduce(do_reduce, data, 99)
print('result: {}'.format(result))

import functools
def do_reduce(a, b):
 print('do_reduce({}, {})'.format(a, b))
 return a + b
print('Single item in sequence:',
  functools.reduce(do_reduce, [1]))
print('Single item in sequence with initializer:',
  functools.reduce(do_reduce, [1], 99))
print('Empty sequence with initializer:',
  functools.reduce(do_reduce, [], 99))
try:
 print('Empty sequence:', functools.reduce(do_reduce, []))
except TypeError as err:
 print('ERROR: {}'.format(err))

import functools
@functools.singledispatch
def myfunc(arg):
 print('default myfunc({!r})'.format(arg))
@myfunc.register(int)
def myfunc_int(arg):
 print('myfunc_int({})'.format(arg))
@myfunc.register(list)
def myfunc_list(arg):
 print('myfunc_list()')
 for item in arg:
  print(' {}'.format(item))
myfunc('string argument')
myfunc(1)
myfunc(2.3)
myfunc(['a', 'b', 'c'])

import functools
class A:
 pass
class B(A):
 pass
class C(A):
 pass
class D(B):
 pass
class E(C, D):
 pass
@functools.singledispatch
def myfunc(arg):
 print('default myfunc({})'.format(arg.__class__.__name__))
@myfunc.register(A)
def myfunc_A(arg):
 print('myfunc_A({})'.format(arg.__class__.__name__))
@myfunc.register(B)
def myfunc_B(arg):
 print('myfunc_B({})'.format(arg.__class__.__name__))
@myfunc.register(C)
def myfunc_C(arg):
 print('myfunc_C({})'.format(arg.__class__.__name__))
myfunc(A())
myfunc(B())
myfunc(C())
myfunc(D())
myfunc(E())