Mercurial > hg
view tests/test-merge6.t @ 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 | ffb5c09ba822 |
children | f2719b387380 |
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$ cat <<EOF > merge > import sys, os > print "merging for", os.path.basename(sys.argv[1]) > EOF $ HGMERGE="python ../merge"; export HGMERGE $ hg init A1 $ cd A1 $ echo This is file foo1 > foo $ echo This is file bar1 > bar $ hg add foo bar $ hg commit -m "commit text" $ cd .. $ hg clone A1 B1 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd A1 $ rm bar $ hg remove bar $ hg commit -m "commit test" $ cd ../B1 $ echo This is file foo22 > foo $ hg commit -m "commit test" $ cd .. $ hg clone A1 A2 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg clone B1 B2 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd A1 $ hg pull ../B1 pulling from ../B1 searching for changes adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge) $ hg merge 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg commit -m "commit test" bar should remain deleted. $ hg manifest --debug f9b0e817f6a48de3564c6b2957687c5e7297c5a0 644 foo $ cd ../B2 $ hg pull ../A2 pulling from ../A2 searching for changes adding changesets adding manifests adding file changes added 1 changesets with 0 changes to 0 files (+1 heads) (run 'hg heads' to see heads, 'hg merge' to merge) $ hg merge 0 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg commit -m "commit test" bar should remain deleted. $ hg manifest --debug f9b0e817f6a48de3564c6b2957687c5e7297c5a0 644 foo