Python 2.7.2 在 OSX 上搁置失败

Question

使用 Python 2.7.2 上的 shelve 标准库，我编写了一个极其简单的测试来创建持久数据文件，然后立即打开它进行打印:

import os
import shelve

shelf_filename = str(__file__.split('.')[0] + '.dat')

#delete the shelf file if it exists already.
try:
    os.remove(shelf_filename)
    print "DELETED LEFTOVER SHELF FILE", shelf_filename
except OSError:
    pass

#create a new shelf, write some data, and flush it to disk
shelf_handle = shelve.open(shelf_filename)
print "OPENED", shelf_filename, "WITH SHELF"
shelf_handle['foo'] = 'bar'
shelf_handle.close()
print "FLUSHED AND CLOSED THE SHELF"

#re-open the shelf we just wrote, read/print the data, and close it
shelf_handle = shelve.open(shelf_filename)
print "RE-OPENED", shelf_filename, "WITH SHELF"
print 'foo:', shelf_handle.get('foo')
shelf_handle.close()

#delete the shelf file
os.remove(shelf_filename)

但是，当该脚本尝试重新打开刚刚创建的架子时，该脚本意外失败:

DELETED LEFTOVER SHELF FILE shelve_test.dat
OPENED shelve_test.dat WITH SHELF
FLUSHED AND CLOSED THE SHELF
Traceback (most recent call last):
  File "shelve_test.py", line 21, in <module>
    shelf_handle = shelve.open(shelf_filename)
  File ".../shelve.py", line 239, in open
    return DbfilenameShelf(filename, flag, protocol, writeback)
  File ".../shelve.py", line 223, in __init__
    Shelf.__init__(self, anydbm.open(filename, flag), protocol, writeback)
  File ".../anydbm.py", line 82, in open
    raise error, "db type could not be determined"
anydbm.error: db type could not be determined

这是关于搁置的最基本的可能用法，所以我真的不明白我错过了什么，而且据我所知，我正在严格遵循文档。有一点搁置经验的人可以告诉我发生了什么事吗？

更新:这个脚本显然可以在某些平台上运行，而不能在其他平台上运行，这对于 Python 标准库来说确实有点令人惊讶。明确证实这不适用于:

Python 2.7.2 (default, May 15 2013, 13:46:05) 
[GCC 4.2.1 Compatible Apple LLVM 4.2 (clang-425.0.28)] on darwin

Answer 1

此版本的 Python shelve 使用的是已弃用的 dbm 包，可以通过指定不同的 dbm 来解决该问题，如下所示:

import anydbm
anydbm._defaultmod = __import__('dumbdbm')

如果将这两行添加到上面的脚本中，那么一切都会按预期进行。这确实需要搁置解决。