Tgdbm/Qgdbm library for Tcl (Version 0.5)

Tgdbm is an easy-to-use Tcl-wrapper to the GNU-dbm-library (gdbm).

Overview

Tgdbm provides an easy to understand interface to the
GNU-dbm-library (gdbm).
Gdbm uses extendible hashing and stores key/value pairs, where each key must be unique (Gdbm can be downloaded at the GNU-Website, there
is also my windows-port of gdbm).
Though gdbm provides compatibility for ndbm and dbm only the gdbm-commands are supported in Tgdbm.

Furthermore you can use Tgdbm for transparently accessing and storing tcl-arrays (persistant arrays). An array is attached to the gdbm-file as a handle. With this you can set an array-entry which is stored or updated transparently in the corresponding gdbm-file.

Tgdbm is meant to be used in Tcl-Applications which has to store some small/medium amount of data. In many cases there is not enough data to be stored, so that a “real” database is justified.

But though there is only a small amount of data, you often have to use an efficient way to store them (not just write them in a plain text-file).

Qgdbm is wrapped around Tgdbm and provides a more convenient way to store and retrieve data. It is however not a replacement for a “professional” database. But serves well for applications which simply have to store a small/medium amount of data which fits into a simple table-structure.

With Qgdbm you can access information from gdbm-files in an SQL-like fashion. Not really SQL, but a more Tcl-adopted SQL, let’s name it TSQL for (Tcl or Tiny(?)-SQL).

Because Tgdbm is provided as a loadable Tcl-Module, it can be easily
integrated into any Tcl-Application.

Download

You can download Tgdbm/Qgdbm with the following links:

• Download Tgdbm 0.5 (as zip)
• Tgdbm documentation
• README.txt
• Qgdbm documentation

History

14. April 2005

Released Version 0.5:

Yes it’s still 0.5 but has some improvements. All those fixes were sent to me from Thomas Maeder (thanks a lot). Have a look at the file CHANGES.txt inside the distribution to see what happened.

9. Jan. 2004

Released Version 0.5:

Persistant arrays were added to Tgdbm. Because of a nearly equivalent concept for tcl-arrays (which have unique keys) and gdbm-key-value pairs which also have unique keys, these are now combined to have a transparent handling of persistant arrays.

You can simply attach an array-name to a gdbm-file. Afterwards every operation on the array (read/write/unset) is traced and the key/values are automatically fetched/stored or updated/deleted in/from the gdbm-file.

For further information see README.txt.

Cleanup and restructuring of the C-Code, added sync-command …

1. Feb. 2000

Released Version 0.4

A quick and simple example

Even though the Tgdbm-commands should be easy enough (if you know the gdbm-library) a few examples should help to start immediately.

package require tgdbm

proc store_array {file data} {
    upvar $data dat
    # create file if it doesn't exist
    set gdbm [gdbm_open -wrcreat $file]

    foreach entry [array names dat] {
        $gdbm -replace store $entry $dat($entry)
    }
    $gdbm close
}

You can also try the file tests/demo.tcl which implements a simple gdbm-file-viewer. This viewer stores it’s configuration-options (like colors or window-positions) in option.gdbm (like an INI-file).
Gdbm-viewer needs the tablelist-widget from Dr. Casa Nemethi (which can be obtained from: http://www.nemethi.de).

More examples.

Documentation

More documentation