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"""
A module that implements tooling to enable easy warnings about deprecations.
"""
import logging
import warnings
from typing import Any, Optional, TextIO, Type, Union
from pip._vendor.packaging.version import parse
from pip import __version__ as current_version # NOTE: tests patch this name.
DEPRECATION_MSG_PREFIX = "DEPRECATION: "
class PipDeprecationWarning(Warning):
pass
_original_showwarning: Any = None
# Warnings <-> Logging Integration
def _showwarning(
message: Union[Warning, str],
category: Type[Warning],
filename: str,
lineno: int,
file: Optional[TextIO] = None,
line: Optional[str] = None,
) -> None:
if file is not None:
if _original_showwarning is not None:
_original_showwarning(message, category, filename, lineno, file, line)
elif issubclass(category, PipDeprecationWarning):
# We use a specially named logger which will handle all of the
# deprecation messages for pip.
logger = logging.getLogger("pip._internal.deprecations")
logger.warning(message)
else:
_original_showwarning(message, category, filename, lineno, file, line)
def install_warning_logger() -> None:
# Enable our Deprecation Warnings
warnings.simplefilter("default", PipDeprecationWarning, append=True)
global _original_showwarning
if _original_showwarning is None:
_original_showwarning = warnings.showwarning
warnings.showwarning = _showwarning
def deprecated(
*,
reason: str,
replacement: Optional[str],
gone_in: Optional[str],
feature_flag: Optional[str] = None,
issue: Optional[int] = None,
) -> None:
"""Helper to deprecate existing functionality.
reason:
Textual reason shown to the user about why this functionality has
been deprecated. Should be a complete sentence.
replacement:
Textual suggestion shown to the user about what alternative
functionality they can use.
gone_in:
The version of pip does this functionality should get removed in.
Raises an error if pip's current version is greater than or equal to
this.
feature_flag:
Command-line flag of the form --use-feature={feature_flag} for testing
upcoming functionality.
issue:
Issue number on the tracker that would serve as a useful place for
users to find related discussion and provide feedback.
"""
# Determine whether or not the feature is already gone in this version.
is_gone = gone_in is not None and parse(current_version) >= parse(gone_in)
message_parts = [
(reason, f"{DEPRECATION_MSG_PREFIX}{{}}"),
(
gone_in,
(
"pip {} will enforce this behaviour change."
if not is_gone
else "Since pip {}, this is no longer supported."
),
),
(
replacement,
"A possible replacement is {}.",
),
(
feature_flag,
(
"You can use the flag --use-feature={} to test the upcoming behaviour."
if not is_gone
else None
),
),
(
issue,
"Discussion can be found at https://github.com/pypa/pip/issues/{}",
),
]
message = " ".join(
format_str.format(value)
for value, format_str in message_parts
if format_str is not None and value is not None
)
# Raise as an error if this behaviour is deprecated.
if is_gone:
raise PipDeprecationWarning(message)
warnings.warn(message, category=PipDeprecationWarning, stacklevel=2)
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