Python temporary file
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- Python Programming
Python’s tempfile standard library is pretty neat when we need to create a temporary file and/or directories. Instead of having a much of code like this:
import pathlib
def create_file(filename):
if pathlib.Path(filename).exists():
# handle path removal/rewrite/backup
pass
with open(filename, "w") as f:
# write to file
pass
We can ask Python to take care of handling this type of tasks for us. tempfile
handles most of the OS API, so we can focus on writting the logic instead.
import tempfile
def create_file():
return tempfile.NamedTemporaryFile(mode="w", encoding="utf-8")
# file one
print(create_file())
print(create_file().name)
# file two
print(create_file())
print(create_file().name)
<tempfile._TemporaryFileWrapper object at 0x10d173d30>
/var/folders/gf/7vcrg3d57pn8j_30zvkz94x00000gn/T/tmphxf3mze8
<tempfile._TemporaryFileWrapper object at 0x10d1b1130>
/var/folders/gf/7vcrg3d57pn8j_30zvkz94x00000gn/T/tmpsz20r_u3
NamedTemporaryFile returns a file-like object that can be used as a temporary
storage, however, contrary to TemporaryFile, a file created with
NamedTemporaryFile is guaranteed to have a visible name during its lifetime.
TemporaryFile gets destroyed as soon as the file is closed, NamedTemporaryFile
has support for the delete flags, which defaults to True
You can also change the default filename prefix and suffix.
import tempfile
def create_file(suffix=".json", prefix="tmpfile"):
return tempfile.NamedTemporaryFile(
mode="w",
encoding="utf-8",
suffix=suffix,
prefix=prefix,
)
# file one
print(create_file(suffix=".csv"))
print(create_file(suffix=".csv").name)
print(create_file(suffix=".csv", prefix="hello-world").name)
<tempfile._TemporaryFileWrapper object at 0x10df3d0a0>
/var/folders/gf/7vcrg3d57pn8j_30zvkz94x00000gn/T/tmpfilei92azs5a.csv
/var/folders/gf/7vcrg3d57pn8j_30zvkz94x00000gn/T/hello-worlduk8_07f5.csv
With TemporaryFile it returns a TextIOWrapper:
import tempfile
def create_file(suffix=".json", prefix="tmpfile"):
return tempfile.TemporaryFile(
mode="w",
encoding="utf-8",
suffix=suffix,
prefix=prefix,
)
# file one
print(create_file(suffix=".csv"))
print(create_file(suffix=".csv", prefix="hello-world").name)
<_io.TextIOWrapper name=6 mode='w' encoding='utf-8'>
6