all Python 3warningsfunction

warnings.showwarning()

displaying warnings

The function the warnings module uses to display each warning that passes the filters; by default it writes to stderr and it can be replaced.

Syntax

warnings.showwarning(message, category, filename, lineno, file=None, line=None)

Replacing warnings.showwarning routes warnings to your own UI or file, but it does not bypass the filters: a silenced warning, or one already shown for that line, never reaches it. Replace it inside catch_warnings(), which restores the original on exit. For logging there is logging.captureWarnings(True), which replaces exactly this function.

Examples

import warnings
def to_stdout(message, category, filename, lineno, file=None, line=None):
    print(f'[{category.__name__}] {message}')
with warnings.catch_warnings():
    warnings.simplefilter('always')
    warnings.showwarning = to_stdout
    warnings.warn('кэш устарел')
    to_stdout('проверка', UserWarning, '', 0)  # → [UserWarning] проверка

See also

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