Mercurial > hg
view tests/test-walkrepo.py @ 14007:d764463b433e
atomictempfile: avoid infinite recursion in __del__().
The problem is that a programmer using atomictempfile directly can
make an innocent everyday mistake -- not enough args to the
constructor -- which escalates badly. You would expect a simple
TypeError crash in that case, but you actually get an infinite
recursion that is surprisingly difficult to kill: it happens between
__del__() and __getattr__(), and Python does not handle infinite
recursion from __del__() well.
The fix is to not implement __getattr__(), but instead assign instance
attributes for the methods we wish to delegate to the builtin file
type: write() and fileno(). I've audited mercurial.* and hgext.* and
found no users of atomictempfile using methods other than write() and
rename(). I audited third-party extensions and found one (snap)
passing an atomictempfile to util.fstat(), so I also threw in
fileno().
The last time I submitted a similar patch, Matt proposed that we make
atomictempfile a subclass of file instead of wrapping it. Rejected on
grounds of unnecessary complexity: for one thing, it would make the
Windows implementation of posixfile quite a bit more complex. It would
have to become a subclass of file rather than a simple function -- but
since it's written in C, this is non-obvious and non-trivial.
Furthermore, there's nothing wrong with wrapping objects and
delegating methods: it's a well-established pattern that works just
fine in many cases. Subclassing is not the answer to all of life's
problems.
author | Greg Ward <greg@gerg.ca> |
---|---|
date | Sun, 24 Apr 2011 19:25:10 -0400 |
parents | 938fbeacac84 |
children | 0b21ae0a2366 |
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import os from mercurial import hg, ui from mercurial.scmutil import walkrepos from os import mkdir, chdir from os.path import join as pjoin u = ui.ui() sym = hasattr(os, 'symlink') and hasattr(os.path, 'samestat') hg.repository(u, 'top1', create=1) mkdir('subdir') chdir('subdir') hg.repository(u, 'sub1', create=1) mkdir('subsubdir') chdir('subsubdir') hg.repository(u, 'subsub1', create=1) chdir(os.path.pardir) if sym: os.symlink(os.path.pardir, 'circle') os.symlink(pjoin('subsubdir', 'subsub1'), 'subsub1') def runtest(): reposet = frozenset(walkrepos('.', followsym=True)) if sym and (len(reposet) != 3): print "reposet = %r" % (reposet,) print "Found %d repositories when I should have found 3" % (len(reposet),) if (not sym) and (len(reposet) != 2): print "reposet = %r" % (reposet,) print "Found %d repositories when I should have found 2" % (len(reposet),) sub1set = frozenset((pjoin('.', 'sub1'), pjoin('.', 'circle', 'subdir', 'sub1'))) if len(sub1set & reposet) != 1: print "sub1set = %r" % (sub1set,) print "reposet = %r" % (reposet,) print "sub1set and reposet should have exactly one path in common." sub2set = frozenset((pjoin('.', 'subsub1'), pjoin('.', 'subsubdir', 'subsub1'))) if len(sub2set & reposet) != 1: print "sub2set = %r" % (sub2set,) print "reposet = %r" % (reposet,) print "sub1set and reposet should have exactly one path in common." sub3 = pjoin('.', 'circle', 'top1') if sym and not (sub3 in reposet): print "reposet = %r" % (reposet,) print "Symbolic links are supported and %s is not in reposet" % (sub3,) runtest() if sym: # Simulate not having symlinks. del os.path.samestat sym = False runtest()