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.
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