"""distutils.dep_util
Utility functions for simple, timestamp-based dependency of files
and groups of files; also, function based entirely on such
timestamp dependency analysis."""
__revision__ = "$Id: dep_util.py 58054 2007-09-08 17:39:28Z thomas.wouters $"
import os
from distutils.errors import DistutilsFileError
def newer (source, target):
"""Return true if 'source' exists and is more recently modified than
'target', or if 'source' exists and 'target' doesn't. Return false if
both exist and 'target' is the same age or younger than 'source'.
Raise DistutilsFileError if 'source' does not exist.
"""
if not os.path.exists(source):
raise DistutilsFileError("file '%s' does not exist" %
os.path.abspath(source))
if not os.path.exists(target):
return 1
from stat import ST_MTIME
mtime1 = os.stat(source)[ST_MTIME]
mtime2 = os.stat(target)[ST_MTIME]
return mtime1 > mtime2
# newer ()
def newer_pairwise (sources, targets):
"""Walk two filename lists in parallel, testing if each source is newer
than its corresponding target. Return a pair of lists (sources,
targets) where source is newer than target, according to the semantics
of 'newer()'.
"""
if len(sources) != len(targets):
raise ValueError("'sources' and 'targets' must be same length")
# build a pair of lists (sources, targets) where source is newer
n_sources = []
n_targets = []
for i in range(len(sources)):
if newer(sources[i], targets[i]):
n_sources.append(sources[i])
n_targets.append(targets[i])
return (n_sources, n_targets)
# newer_pairwise ()
def newer_group (sources, target, missing='error'):
"""Return true if 'target' is out-of-date with respect to any file
listed in 'sources'. In other words, if 'target' exists and is newer
than every file in 'sources', return false; otherwise return true.
'missing' controls what we do when a source file is missing; the
default ("error") is to blow up with an OSError from inside 'stat()';
if it is "ignore", we silently drop any missing source files; if it is
"newer", any missing source files make us assume that 'target' is
out-of-date (this is handy in "dry-run" mode: it'll make you pretend to
carry out commands that wouldn't work because inputs are missing, but
that doesn't matter because you're not actually going to run the
commands).
"""
# If the target doesn't even exist, then it's definitely out-of-date.
if not os.path.exists(target):
return 1
# Otherwise we have to find out the hard way: if *any* source file
# is more recent than 'target', then 'target' is out-of-date and
# we can immediately return true. If we fall through to the end
# of the loop, then 'target' is up-to-date and we return false.
from stat import ST_MTIME
target_mtime = os.stat(target)[ST_MTIME]
for source in sources:
if not os.path.exists(source):
if missing == 'error': # blow up when we stat() the file
pass
elif missing == 'ignore': # missing source dropped from
continue # target's dependency list
elif missing == 'newer': # missing source means target is
return 1 # out-of-date
source_mtime = os.stat(source)[ST_MTIME]
if source_mtime > target_mtime:
return 1
else:
return 0
# newer_group ()
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