Support the same files with new param in shutil.copyfile

[milanbalazs]

BPO	43165
Nosy	@serhiy-storchaka, @milanbalazs
PRs	bpo-43165 - Support the same files with new param in shutil.copyfile #24482

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-02-08.17:32:01.861>
labels = ['type-feature', 'library', '3.10']
title = 'Support the same files with new param in shutil.copyfile'
updated_at = <Date 2021-03-18.08:31:52.431>
user = 'https://github.com/milanbalazs'

bugs.python.org fields:

activity = <Date 2021-03-18.08:31:52.431>
actor = 'milanbalazs'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-02-08.17:32:01.861>
creator = 'milanbalazs'
dependencies = []
files = []
hgrepos = []
issue_num = 43165
keywords = ['patch']
message_count = 4.0
messages = ['386634', '386639', '386641', '388998']
nosy_count = 2.0
nosy_names = ['serhiy.storchaka', 'milanbalazs']
pr_nums = ['24482']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue43165'
versions = ['Python 3.10']

[milanbalazs]

The "shutil.copyfile" raises a "SameFileError" exception if the src and dts files are the same.

There is no option to allow the same files(like in case of shutil.copytree(dirs_exist_ok=False)).

For example:

import shutil

shutil.copyfile("test.txt", "test.txt")

Output:

>>> python3 test.py 
Traceback (most recent call last):
  File "test.py", line 3, in <module>
    shutil.copyfile("test.txt", "test.txt")
  File "/usr/lib/python3.6/shutil.py", line 104, in copyfile
    raise SameFileError("{!r} and {!r} are the same file".format(src, dst))
shutil.SameFileError: 'test.txt' and 'test.txt' are the same file

[serhiy-storchaka]

You can use try/except.

try:
shutil.copyfile("test.txt", "test.txt")
except SameFileError:
pass

[milanbalazs]

Sure, you can use try/except but it would be nice if the "shutil.copyfile" function supports the same files.

If I have many files (more thousand), I don't want to check them with a try/except.

Furthermore if I want to cover the unexpected exceptions as well I need to use nested try/except (I guess it's not the most elegant way).

Eg.:

try:
shutil.copyfile("test.txt", "test.txt")
except SameFileError:
pass
except Exception as unexpected_exception:
raise unexpected_exception

[milanbalazs]

Could you somebody review the PR for this ticket, please?