bpo-40884: Added defaults parameter for logging.Formatter (GH-20668)
Docs and tests are underway.
Automerge-Triggered-By: @vsajip
diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
index 1c446fd..94361ca 100644
--- a/Lib/logging/__init__.py
+++ b/Lib/logging/__init__.py
@@ -411,8 +411,9 @@
asctime_search = '%(asctime)'
validation_pattern = re.compile(r'%\(\w+\)[#0+ -]*(\*|\d+)?(\.(\*|\d+))?[diouxefgcrsa%]', re.I)
- def __init__(self, fmt):
+ def __init__(self, fmt, *, defaults=None):
self._fmt = fmt or self.default_format
+ self._defaults = defaults
def usesTime(self):
return self._fmt.find(self.asctime_search) >= 0
@@ -423,7 +424,11 @@
raise ValueError("Invalid format '%s' for '%s' style" % (self._fmt, self.default_format[0]))
def _format(self, record):
- return self._fmt % record.__dict__
+ if defaults := self._defaults:
+ values = defaults | record.__dict__
+ else:
+ values = record.__dict__
+ return self._fmt % values
def format(self, record):
try:
@@ -441,7 +446,11 @@
field_spec = re.compile(r'^(\d+|\w+)(\.\w+|\[[^]]+\])*$')
def _format(self, record):
- return self._fmt.format(**record.__dict__)
+ if defaults := self._defaults:
+ values = defaults | record.__dict__
+ else:
+ values = record.__dict__
+ return self._fmt.format(**values)
def validate(self):
"""Validate the input format, ensure it is the correct string formatting style"""
@@ -467,8 +476,8 @@
asctime_format = '${asctime}'
asctime_search = '${asctime}'
- def __init__(self, fmt):
- self._fmt = fmt or self.default_format
+ def __init__(self, *args, **kwargs):
+ super().__init__(*args, **kwargs)
self._tpl = Template(self._fmt)
def usesTime(self):
@@ -490,7 +499,11 @@
raise ValueError('invalid format: no fields')
def _format(self, record):
- return self._tpl.substitute(**record.__dict__)
+ if defaults := self._defaults:
+ values = defaults | record.__dict__
+ else:
+ values = record.__dict__
+ return self._tpl.substitute(**values)
BASIC_FORMAT = "%(levelname)s:%(name)s:%(message)s"
@@ -546,7 +559,8 @@
converter = time.localtime
- def __init__(self, fmt=None, datefmt=None, style='%', validate=True):
+ def __init__(self, fmt=None, datefmt=None, style='%', validate=True, *,
+ defaults=None):
"""
Initialize the formatter with specified format strings.
@@ -565,7 +579,7 @@
if style not in _STYLES:
raise ValueError('Style must be one of: %s' % ','.join(
_STYLES.keys()))
- self._style = _STYLES[style][0](fmt)
+ self._style = _STYLES[style][0](fmt, defaults=defaults)
if validate:
self._style.validate()
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index e719d26..2ae00b6 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -3710,6 +3710,9 @@
'args': (2, 'placeholders'),
}
self.variants = {
+ 'custom': {
+ 'custom': 1234
+ }
}
def get_record(self, name=None):
@@ -3926,6 +3929,26 @@
)
self.assertRaises(ValueError, logging.Formatter, '${asctime', style='$')
+ def test_defaults_parameter(self):
+ fmts = ['%(custom)s %(message)s', '{custom} {message}', '$custom $message']
+ styles = ['%', '{', '$']
+ for fmt, style in zip(fmts, styles):
+ f = logging.Formatter(fmt, style=style, defaults={'custom': 'Default'})
+ r = self.get_record()
+ self.assertEqual(f.format(r), 'Default Message with 2 placeholders')
+ r = self.get_record("custom")
+ self.assertEqual(f.format(r), '1234 Message with 2 placeholders')
+
+ # Without default
+ f = logging.Formatter(fmt, style=style)
+ r = self.get_record()
+ self.assertRaises(ValueError, f.format, r)
+
+ # Non-existing default is ignored
+ f = logging.Formatter(fmt, style=style, defaults={'Non-existing': 'Default'})
+ r = self.get_record("custom")
+ self.assertEqual(f.format(r), '1234 Message with 2 placeholders')
+
def test_invalid_style(self):
self.assertRaises(ValueError, logging.Formatter, None, None, 'x')