Mercurial > hg
view tests/test-subrepo-missing.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 | d0e21c5fde41 |
children | f73c7b70df68 |
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$ hg init repo $ cd repo $ hg init subrepo $ echo a > subrepo/a $ hg -R subrepo ci -Am adda adding a $ echo 'subrepo = subrepo' > .hgsub $ hg ci -Am addsubrepo adding .hgsub committing subrepository subrepo $ echo b > subrepo/b $ hg -R subrepo ci -Am addb adding b $ hg ci -m updatedsub committing subrepository subrepo delete .hgsub and revert it $ rm .hgsub $ hg revert .hgsub warning: subrepo spec file .hgsub not found delete .hgsubstate and revert it $ rm .hgsubstate $ hg revert .hgsubstate delete .hgsub and update $ rm .hgsub $ hg up 0 warning: subrepo spec file .hgsub not found 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg st ! .hgsub $ ls subrepo a delete .hgsubstate and update $ hg up -C warning: subrepo spec file .hgsub not found 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ rm .hgsubstate $ hg up 0 remote changed .hgsubstate which local deleted use (c)hanged version or leave (d)eleted? c 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg st $ ls subrepo a