forked from enshahar/effectivepython_3rd_kor
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathitem_028.py
More file actions
executable file
·192 lines (151 loc) · 4.09 KB
/
item_028.py
File metadata and controls
executable file
·192 lines (151 loc) · 4.09 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
#!/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 28")
print("Example 1")
pictures = {}
path = "profile_1234.png"
with open(path, "wb") as f:
f.write(b"image data here 1234")
if (handle := pictures.get(path)) is None:
try:
handle = open(path, "a+b")
except OSError:
print(f"파일을 열 수 없음: {path}")
raise
else:
pictures[path] = handle
handle.seek(0)
image_data = handle.read()
print(pictures)
print(image_data)
print("Example 2")
# Examples using in and KeyError
pictures = {}
path = "profile_9991.png"
with open(path, "wb") as f:
f.write(b"image data here 9991")
if path in pictures:
handle = pictures[path]
else:
try:
handle = open(path, "a+b")
except OSError:
print(f"파일을 열 수 없음: {path}")
raise
else:
pictures[path] = handle
handle.seek(0)
image_data = handle.read()
print(pictures)
print(image_data)
pictures = {}
path = "profile_9922.png"
with open(path, "wb") as f:
f.write(b"image data here 9991")
try:
handle = pictures[path]
except KeyError:
try:
handle = open(path, "a+b")
except OSError:
print(f"파일을 열 수 없음: {path}")
raise
else:
pictures[path] = handle
handle.seek(0)
image_data = handle.read()
print(pictures)
print(image_data)
print("Example 3")
pictures = {}
path = "profile_9239.png"
with open(path, "wb") as f:
f.write(b"image data here 9239")
try:
handle = pictures.setdefault(path, open(path, "a+b"))
except OSError:
print(f"파일을 열 수 없음: {path}")
raise
else:
handle.seek(0)
image_data = handle.read()
print(pictures)
print(image_data)
print("Example 4")
try:
path = "profile_4555.csv"
with open(path, "wb") as f:
f.write(b"image data here 9239")
from collections import defaultdict
def open_picture(profile_path):
try:
return open(profile_path, "a+b")
except OSError:
print(f"파일을 열 수 없음: {profile_path}")
raise
pictures = defaultdict(open_picture)
handle = pictures[path]
handle.seek(0)
image_data = handle.read()
except:
logging.exception('이 예외가 발생해야 함')
else:
assert False
print("Example 5")
path = "account_9090.csv"
with open(path, "wb") as f:
f.write(b"image data here 9090")
def open_picture(profile_path):
try:
return open(profile_path, "a+b")
except OSError:
print(f"파일을 열 수 없음: {profile_path}")
raise
class Pictures(dict):
def __missing__(self, key):
value = open_picture(key)
self[key] = value
return value
pictures = Pictures()
handle = pictures[path]
handle.seek(0)
image_data = handle.read()
print(pictures)
print(image_data)