[英]how to use tempfile.NamedTemporaryFile() in python
我想使用tempfile.NamedTemporaryFile()
將一些內容寫入其中,然后打開該文件。 我寫了以下代碼:
tf = tempfile.NamedTemporaryFile()
tfName = tf.name
tf.seek(0)
tf.write(contents)
tf.flush()
但我無法打開此文件,並在記事本或類似的應用程序中查看其內容。 有沒有辦法實現這個目標? 為什么我不能這樣做:
os.system('start notepad.exe ' + tfName)
在末尾
您還可以將其與上下文管理器一起使用,以便在文件超出范圍時關閉/刪除該文件。 如果上下文管理器中的代碼引發,它也將被清除。
import tempfile
with tempfile.NamedTemporaryFile() as temp:
temp.write('Some data')
temp.flush()
# do something interesting with temp before it is destroyed
這是一個有用的上下文管理器。 (在我看來,這個功能應該是Python標准庫的一部分。)
# python2 or python3
import contextlib
import os
@contextlib.contextmanager
def temporary_filename(suffix=None):
"""Context that introduces a temporary file.
Creates a temporary file, yields its name, and upon context exit, deletes it.
(In contrast, tempfile.NamedTemporaryFile() provides a 'file' object and
deletes the file as soon as that file object is closed, so the temporary file
cannot be safely re-opened by another library or process.)
Args:
suffix: desired filename extension (e.g. '.mp4').
Yields:
The name of the temporary file.
"""
import tempfile
try:
f = tempfile.NamedTemporaryFile(suffix=suffix, delete=False)
tmp_name = f.name
f.close()
yield tmp_name
finally:
os.unlink(tmp_name)
# Example:
with temporary_filename() as filename:
os.system('echo Hello >' + filename)
assert 6 <= os.path.getsize(filename) <= 8 # depending on text EOL
assert not os.path.exists(filename)
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