all Python 3deprecated in 3.14argparseterm

argparse.FileType

argument types

Deprecated since 3.14: a type factory that turned an argument into an already opened file. Accept a path instead and open the file after parsing.

Syntax

parser.add_argument('out', type=argparse.FileType('w', encoding='utf-8'))

The file is opened during parsing: if a later argument turns out to be invalid, parse_args() exits and the open file is never closed, and mode 'w' has already truncated it. Use type=pathlib.Path instead and open the file in a with block after parsing. In 3.14 creating a FileType emits PendingDeprecationWarning; no removal version has been set yet.

Examples

import argparse
import pathlib
parser = argparse.ArgumentParser(prog='app')
parser.add_argument('out', type=pathlib.Path)  # вместо FileType
args = parser.parse_args(['out.txt'])
with args.out.open('w', encoding='utf-8') as f:
    f.write('ok')
print(args.out.read_text(encoding='utf-8'))  # → ok

See also

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