XOTcl - Documentation -- xotcl/library/store/Storage.xotcl

xotcl/library/store/Storage.xotcl xotcl/library/store/Storage.xotcl

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Filename: xotcl/library/store/Storage.xotcl

Description: Simple generic storage interface for hashtable-like (persistent) storages. There are several different existing stores, including a memory storage, a GDBM storage, a SDBM storage, and a TextFile storage.
Date: $Date: 2005/09/09 21:09:01 $

Class: Storage

Class: Class
Procs/Instprocs: close, exists, firstkey, names, nextkey, open, set, someNewChildStore, unset.
Description: Abstract storage interface class (superclass of all storages).


  • open filename
    Arguments: filename: database filename (or filename base, if more than one file has to be created)
    Description: Each storage object represents exactly one database table. The db has to be opened, before it can it used. If it is not opened all other methods return errors.
    Return: empty string
  • close
    Description: Close associated database.
    Return: empty string
  • exists key
    Arguments: key: Key to be searched for.
    Description: Search for a key whether it exists or not.
    Return: 1, if key exists in the database, otherwise 0
  • set key ?value?
    Arguments: key: Key to be set.
    ?value?: Optional value that might be set
    Description: Set or query a database key in the same way as Tcl's set functions.
    Return: Key value.
  • unset key
    Arguments: key: Key to be unset.
    Description: Unset a database key in the same way as Tcl's unset functions.
    Return: empty string
  • names
    Description: Return a list of keys in the database (functions in the same way as Tcl's array names)
    Return: List of keys in the db.
  • firstkey
    Description: Start a traversal of the database, starting with any key.
    Return: Name of first key.
  • nextkey
    Description: Proceed with the db traversal. Requires a firstkey before first usage, otherwise it returns an error.
    Return: Name of next key, if one exists. Otherwise an empty string is returned.


  • someNewChildStore
    Description: Create a childStore according to a preference list depending on which storages are available. Currently the preference list has the following order: Gdbm, Sdbm and TextFile.
    Return: name of the created storage object.

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