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61 lines
1.8 KiB
Python
61 lines
1.8 KiB
Python
# Copyright Bruno da Silva de Oliveira 2003. Use, modification and
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# distribution is subject to the Boost Software License, Version 1.0.
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# (See accompanying file LICENSE_1_0.txt or copy at
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# http:#www.boost.org/LICENSE_1_0.txt)
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import os
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import md5
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#==============================================================================
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# SmartFile
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#==============================================================================
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class SmartFile(object):
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'''
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A file-like object used for writing files. The given file will only be
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actually written to disk if there's not a file with the same name, or if
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the existing file is *different* from the file to be written.
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'''
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def __init__(self, filename, mode='w'):
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self.filename = filename
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self.mode = mode
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self._contents = []
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self._closed = False
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def __del__(self):
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if not self._closed:
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self.close()
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def write(self, string):
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self._contents.append(string)
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def _dowrite(self, contents):
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f = file(self.filename, self.mode)
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f.write(contents)
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f.close()
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def _GetMD5(self, string):
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return md5.new(string).digest()
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def close(self):
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# if the filename doesn't exist, write the file right away
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this_contents = ''.join(self._contents)
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if not os.path.isfile(self.filename):
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self._dowrite(this_contents)
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else:
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# read the contents of the file already in disk
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f = file(self.filename)
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other_contents = f.read()
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f.close()
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# test the md5 for both files
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this_md5 = self._GetMD5(this_contents)
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other_md5 = self._GetMD5(other_contents)
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if this_md5 != other_md5:
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self._dowrite(this_contents)
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self._closed = True
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