JezK
Edit File: dep_util.py
"""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__ = "$Id$" import os from stat import ST_MTIME from distutils.errors import DistutilsFileError def newer(source, target): """Tells if the target is newer than the source. 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. Note that this test is not very accurate: files created in the same second will have the same "age". """ if not os.path.exists(source): raise DistutilsFileError("file '%s' does not exist" % os.path.abspath(source)) if not os.path.exists(target): return True return os.stat(source)[ST_MTIME] > os.stat(target)[ST_MTIME] 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 source, target in zip(sources, targets): if newer(source, target): n_sources.append(source) n_targets.append(target) return n_sources, n_targets def newer_group(sources, target, missing='error'): """Return true if 'target' is out-of-date with respect to any file listed in 'sources'.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we silently drop any missing source files; if it is "newer", any missing source files make us assume that 'target' is out-of-date (this is handy in "dry-run" mode: it'll make you pretend to carry out commands that wouldn't work because inputs are missing, but that doesn't matter because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 """ # If the target doesn't even exist, then it's definitely out-of-date.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 True # 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. 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 True # out-of-date if os.stat(source)[ST_MTIME] > target_mtime: return True return False