# 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 divide(a, b):
try:
return a / b
except ZeroDivisionError:
return None
assert divide(4, 2) == 2
assert divide(0, 1) == 0
assert divide(3, 6) == 0.5
assert divide(1, 0) == None
# Example 2
x, y = 1, 0
result = divide(x, y)
if result is None:
print('Invalid inputs')
else:
print('Result is %.1f' % result)
Invalid inputs
# Example 3
x, y = 0, 5
result = divide(x, y)
if not result:
print('Invalid inputs') # This is wrong!
else:
assert False
Invalid inputs
# Example 4
def divide(a, b):
try:
return True, a / b
except ZeroDivisionError:
return False, None
print(divide(0, 5))
(True, 0.0)
# Example 5
x, y = 5, 0
success, result = divide(x, y)
if not success:
print('Invalid inputs')
Invalid inputs
# Example 6
x, y = 5, 0
_, result = divide(x, y)
if not result:
print('Invalid inputs') # This is right
x, y = 0, 5
_, result = divide(x, y)
if not result:
print('Invalid inputs') # This is wrong
Invalid inputs Invalid inputs
# Example 7
def divide(a, b):
try:
return a / b
except ZeroDivisionError as e:
raise ValueError('Invalid inputs') from e
# Example 8
x, y = 5, 2
try:
result = divide(x, y)
except ValueError:
print('Invalid inputs')
else:
print('Result is %.1f' % result)
Result is 2.5