Mercurial > hg
annotate tests/test-template-engine.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> |
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date | Sun, 24 Apr 2011 19:25:10 -0400 |
parents | dc6b9b3bf63e |
children | f2719b387380 |
rev | line source |
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8361
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templater: make the templating engine pluggable to some extent
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1 |
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2 $ cat > engine.py << EOF |
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3 > |
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4 > from mercurial import templater |
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5 > |
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6 > class mytemplater(object): |
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7 > def __init__(self, loader, filters, defaults): |
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8 > self.loader = loader |
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9 > |
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10 > def process(self, t, map): |
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11 > tmpl = self.loader(t) |
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12 > for k, v in map.iteritems(): |
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13 > if k in ('templ', 'ctx', 'repo', 'revcache', 'cache'): |
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14 > continue |
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15 > if hasattr(v, '__call__'): |
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16 > v = v(**map) |
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17 > v = templater.stringify(v) |
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18 > tmpl = tmpl.replace('{{%s}}' % k, v) |
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19 > yield tmpl |
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20 > |
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21 > templater.engines['my'] = mytemplater |
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22 > EOF |
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23 $ hg init test |
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24 $ echo '[extensions]' > test/.hg/hgrc |
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25 $ echo "engine = `pwd`/engine.py" >> test/.hg/hgrc |
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26 $ cd test |
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27 $ cat > mymap << EOF |
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28 > changeset = my:changeset.txt |
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29 > EOF |
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30 $ cat > changeset.txt << EOF |
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31 > {{rev}} {{node}} {{author}} |
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32 > EOF |
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33 $ hg ci -Ama |
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34 adding changeset.txt |
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35 adding mymap |
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36 $ hg log --style=./mymap |
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37 0 97e5f848f0936960273bbf75be6388cd0350a32b test |