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Diffstat (limited to 'lib/python2.7/anydbm.py')
-rw-r--r-- | lib/python2.7/anydbm.py | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/lib/python2.7/anydbm.py b/lib/python2.7/anydbm.py new file mode 100644 index 0000000..ba7e905 --- /dev/null +++ b/lib/python2.7/anydbm.py @@ -0,0 +1,85 @@ +"""Generic interface to all dbm clones. + +Instead of + + import dbm + d = dbm.open(file, 'w', 0666) + +use + + import anydbm + d = anydbm.open(file, 'w') + +The returned object is a dbhash, gdbm, dbm or dumbdbm object, +dependent on the type of database being opened (determined by whichdb +module) in the case of an existing dbm. If the dbm does not exist and +the create or new flag ('c' or 'n') was specified, the dbm type will +be determined by the availability of the modules (tested in the above +order). + +It has the following interface (key and data are strings): + + d[key] = data # store data at key (may override data at + # existing key) + data = d[key] # retrieve data at key (raise KeyError if no + # such key) + del d[key] # delete data stored at key (raises KeyError + # if no such key) + flag = key in d # true if the key exists + list = d.keys() # return a list of all existing keys (slow!) + +Future versions may change the order in which implementations are +tested for existence, and add interfaces to other dbm-like +implementations. +""" + +class error(Exception): + pass + +_names = ['dbhash', 'gdbm', 'dbm', 'dumbdbm'] +_errors = [error] +_defaultmod = None + +for _name in _names: + try: + _mod = __import__(_name) + except ImportError: + continue + if not _defaultmod: + _defaultmod = _mod + _errors.append(_mod.error) + +if not _defaultmod: + raise ImportError, "no dbm clone found; tried %s" % _names + +error = tuple(_errors) + +def open(file, flag='r', mode=0666): + """Open or create database at path given by *file*. + + Optional argument *flag* can be 'r' (default) for read-only access, 'w' + for read-write access of an existing database, 'c' for read-write access + to a new or existing database, and 'n' for read-write access to a new + database. + + Note: 'r' and 'w' fail if the database doesn't exist; 'c' creates it + only if it doesn't exist; and 'n' always creates a new database. + """ + + # guess the type of an existing database + from whichdb import whichdb + result=whichdb(file) + if result is None: + # db doesn't exist + if 'c' in flag or 'n' in flag: + # file doesn't exist and the new + # flag was used so use default type + mod = _defaultmod + else: + raise error, "need 'c' or 'n' flag to open new db" + elif result == "": + # db type cannot be determined + raise error, "db type could not be determined" + else: + mod = __import__(result) + return mod.open(file, flag, mode) |