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#!/usr/bin/env PYTHONHASHSEED=1234 python3

# Copyright 2014-2019 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.

# Reproduce book environment

import random

random.seed(1234)

import logging

from pprint import pprint

from sys import stdout as STDOUT

# Write all output to a temporary directory

import atexit

import gc

import io

import os

import tempfile

TEST_DIR = tempfile.TemporaryDirectory()

atexit.register(TEST_DIR.cleanup)

# Make sure Windows processes exit cleanly

OLD_CWD = os.getcwd()

atexit.register(lambda: os.chdir(OLD_CWD))

os.chdir(TEST_DIR.name)

def close_open_files():

everything = gc.get_objects()

for obj in everything:

if isinstance(obj, io.IOBase):

obj.close()

atexit.register(close_open_files)

# Example 1

counters = {

'pumpernickel': 2,

'sourdough': 1,

}

# Example 2

key = 'wheat'

if key in counters:

count = counters[key]

else:

count = 0

counters[key] = count + 1

print(counters)

# Example 3

key = 'brioche'

try:

count = counters[key]

except KeyError:

count = 0

counters[key] = count + 1

print(counters)

# Example 4

key = 'multigrain'

count = counters.get(key, 0)

counters[key] = count + 1

print(counters)

# Example 5

key = 'baguette'

if key not in counters:

counters[key] = 0

counters[key] += 1

key = 'ciabatta'

if key in counters:

counters[key] += 1

else:

counters[key] = 1

key = 'ciabatta'

try:

counters[key] += 1

except KeyError:

counters[key] = 1

print(counters)

# Example 6

votes = {

'baguette': ['Bob', 'Alice'],

'ciabatta': ['Coco', 'Deb'],

}

key = 'brioche'

who = 'Elmer'

if key in votes:

names = votes[key]

else:

votes[key] = names = []

names.append(who)

print(votes)

# Example 7

key = 'rye'

who = 'Felix'

try:

names = votes[key]

except KeyError:

votes[key] = names = []

names.append(who)

print(votes)

# Example 8

key = 'wheat'

who = 'Gertrude'

names = votes.get(key)

if names is None:

votes[key] = names = []

names.append(who)

print(votes)

# Example 9

key = 'brioche'

who = 'Hugh'

if (names := votes.get(key)) is None:

votes[key] = names = []

names.append(who)

print(votes)

# Example 10

key = 'cornbread'

who = 'Kirk'

names = votes.setdefault(key, [])

names.append(who)

print(votes)

# Example 11

data = {}

key = 'foo'

value = []

data.setdefault(key, value)

print('Before:', data)

value.append('hello')

print('After: ', data)

# Example 12

key = 'dutch crunch'

count = counters.setdefault(key, 0)

counters[key] = count + 1

print(counters)