Python in a Nutshell

Name

btopen, hashopen, rnopen

Synopsis

btopen(filename,flag='r',*many_other_optional_arguments)
hashopen(filename,flag='r',*many_other_optional_arguments)
rnopen(filename,flag='r',*many_other_optional_arguments)

btopen opens or creates the binary tree format file named by filename (a string that denotes any path to a file, not just a name), and returns a suitable BTree object to access and manipulate the file. Argument flag has exactly the same values and meaning as for anydbm.open. Other arguments indicate low-level options that allow fine-grained control, but are rarely used.

hashopen and rnopen work the same way, but open or create hash format and record format files, returning objects of type Hash and Record. hashopen is generally the fastest format and makes sense when you are using keys to look up records. However, if you also need to access records in sorted order, use btopen, or if you need to access records in the same order in which you originally wrote them, use rnopen. Using hashopen does not keep records in order in the file.

An object b of any of the types BTree, Hash, and Record can be indexed as a mapping, with both keys and values constrained to being strings. Further, b also supports sequential access through the concept of a current record. b supplies the following methods.