Mercurial > hg
view tests/get-with-headers.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 | bd98796c0b6f |
children | 953faba28e91 |
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#!/usr/bin/env python """This does HTTP GET requests given a host:port and path and returns a subset of the headers plus the body of the result.""" import httplib, sys try: import msvcrt, os msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY) msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY) except ImportError: pass twice = False if '--twice' in sys.argv: sys.argv.remove('--twice') twice = True reasons = {'Not modified': 'Not Modified'} # python 2.4 tag = None def request(host, path, show): global tag headers = {} if tag: headers['If-None-Match'] = tag conn = httplib.HTTPConnection(host) conn.request("GET", path, None, headers) response = conn.getresponse() print response.status, reasons.get(response.reason, response.reason) for h in [h.lower() for h in show]: if response.getheader(h, None) is not None: print "%s: %s" % (h, response.getheader(h)) print data = response.read() sys.stdout.write(data) if twice and response.getheader('ETag', None): tag = response.getheader('ETag') return response.status status = request(sys.argv[1], sys.argv[2], sys.argv[3:]) if twice: status = request(sys.argv[1], sys.argv[2], sys.argv[3:]) if 200 <= status <= 305: sys.exit(0) sys.exit(1)