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item_42.py
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item_42.py
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#!/usr/bin/env python3
# Copyright 2014 Brett Slatkin, Pearson Education Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Preamble to mimick book environment
import logging
from pprint import pprint
from sys import stdout as STDOUT
# Example 1
def trace(func):
def wrapper(*args, **kwargs):
result = func(*args, **kwargs)
print('%s(%r, %r) -> %r' %
(func.__name__, args, kwargs, result))
return result
return wrapper
# Example 2
@trace
def fibonacci(n):
"""Return the n-th Fibonacci number"""
if n in (0, 1):
return n
return (fibonacci(n - 2) + fibonacci(n - 1))
# Example 3
def fibonacci(n):
"""Return the n-th Fibonacci number"""
if n in (0, 1):
return n
return (fibonacci(n - 2) + fibonacci(n - 1))
fibonacci = trace(fibonacci)
# Example 4
fibonacci(3)
# Example 5
print(fibonacci)
# Example 6
try:
# Example of how pickle breaks
import pickle
def my_func():
return 1
# This will be okay
print(pickle.dumps(my_func))
@trace
def my_func2():
return 2
# This will explode
print(pickle.dumps(my_func2))
except:
logging.exception('Expected')
else:
assert False
# Example 7
help(fibonacci)
# Example 8
from functools import wraps
def trace(func):
@wraps(func)
def wrapper(*args, **kwargs):
result = func(*args, **kwargs)
print('%s(%r, %r) -> %r' %
(func.__name__, args, kwargs, result))
return result
return wrapper
@trace
def fibonacci(n):
"""Return the n-th Fibonacci number"""
if n in (0, 1):
return n
return (fibonacci(n - 2) +
fibonacci(n - 1))
# Example 9
help(fibonacci)