Name
open
Synopsis
open(filename
,flag
='r',mode
=0666)
Opens or creates the DBM file named by
filename
(a string that can denote any
path to a file, not just a name), and returns a suitable mapping
object corresponding to the DBM file. When the DBM file already
exists, open
uses module
whichdb
to determine which DBM library can handle
the file. When open
creates a new DBM file,
open
chooses the first available DBM module in
order of preference: dbhash
,
gdbm
, dbm
, and
dumbdbm
.
flag
is a one-character string that tells
open
how to open the file and whether to create
it, as shown in Table 11-1.
mode
is an integer that
open
uses as the file’s
permission bits if open
creates the file, as
covered in Section 10.2.2 in Chapter 10. Not all DBM modules use
flags
and mode
,
but for portability’s sake you should always supply
appropriate values for these arguments when you call
anydbm.open
.
Table 11-1. flag values for anydbm.open
Flag |
Read-only? |
If file exists |
If file does not exist |
---|---|---|---|
'r' |
yes |
|
|
'w' |
no |
|
|
'c' |
no |
|
|
'n' |
no |
|
|
anydbm.open
returns a mapping object
m
that supplies a subset of the
functionality of dictionaries (covered in Chapter 4). m
only accepts
strings as keys and values, and the only mapping methods
m
supplies are
m
.has_key
and
m
.keys
. However, you
can bind, rebind, access, and unbind items in
m
with the ...
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