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item_016.py
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#!/usr/bin/env PYTHONHASHSEED=1234 python3
# Copyright 2014-2024 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.
### 책 예제에 맞는 환경 설정을 시작함
import random
random.seed(1234)
import logging
from pprint import pprint
from sys import stdout as STDOUT
# 모든 출력을 임시 디렉터리로 보냄
import atexit
import gc
import io
import os
import tempfile
TEST_DIR = tempfile.TemporaryDirectory()
atexit.register(TEST_DIR.cleanup)
# 윈도우에서 프로세스가 제대로 종료되도록 함
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)
### 책 예제에 맞는 환경설정 끝
print("아이템 16")
print("Example 1")
try:
car_ages = [0, 9, 4, 8, 7, 20, 19, 1, 6, 15]
car_ages_descending = sorted(car_ages, reverse=True)
oldest, second_oldest = car_ages_descending
except:
logging.exception('이 예외가 발생해야 함')
else:
assert False
print("Example 2")
oldest = car_ages_descending[0]
second_oldest = car_ages_descending[1]
others = car_ages_descending[2:]
print(oldest, second_oldest, others)
print("Example 3")
oldest, second_oldest, *others = car_ages_descending
print(oldest, second_oldest, others)
print("Example 4")
oldest, *others, youngest = car_ages_descending
print(oldest, youngest, others)
*others, second_youngest, youngest = car_ages_descending
print(youngest, second_youngest, others)
print("Example 5")
try:
# 컴파일되지 않음
source = """*others = car_ages_descending"""
eval(source)
except:
logging.exception('이 예외가 발생해야 함')
else:
assert False
print("Example 6")
try:
# 컴파일되지 않음
source = """first, *middle, *second_middle, last = [1, 2, 3, 4]"""
eval(source)
except:
logging.exception('이 예외가 발생해야 함')
else:
assert False
print("Example 7")
car_inventory = {
"Downtown": ("Silver Shadow", "Pinto", "DMC"),
"Airport": ("Skyline", "Viper", "Gremlin", "Nova"),
}
((loc1, (best1, *rest1)),
(loc2, (best2, *rest2))) = car_inventory.items()
print(f"Best at {loc1} is {best1}, {len(rest1)} others")
print(f"Best at {loc2} is {best2}, {len(rest2)} others")
print("Example 8")
short_list = [1, 2]
first, second, *rest = short_list
print(first, second, rest)
print("Example 9")
it = iter(range(1, 3))
first, second = it
print(f"{first} and {second}")
print("Example 10")
def generate_csv():
yield ("날짜", "제조사", "모델", "연식", "가격")
for i in range(100):
yield ("2019-03-25", "Hyundai", "Santa Fe", "2010", "$3400")
yield ("2019-03-26", "Kia", "K5", "2008", "$2400")
print("Example 11")
all_csv_rows = list(generate_csv())
header = all_csv_rows[0]
rows = all_csv_rows[1:]
print("CSV 헤더:", header)
print("줄 수: ", len(rows))
print("Example 12")
it = generate_csv()
header, *rows = it
print("CSV 헤더:", header)
print("줄수: ", len(rows))