effectivepython/example_code/item_14.py at master · AISTLAB/effectivepython · GitHub

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#!/usr/bin/env python3

# 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)

# Example 3

x, y = 0, 5

result = divide(x, y)

if not result:

print('Invalid inputs') # This is wrong!

else:

assert False

# Example 4

def divide(a, b):

try:

return True, a / b

except ZeroDivisionError:

return False, None

# Example 5

x, y = 5, 0

success, result = divide(x, y)

if not success:

print('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

# 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)

effectivepython/example_code/item_14.py at master · AISTLAB/effectivepython · GitHub

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