tie - bind a variable to an object class
tie VARIABLE,CLASSNAME,LIST
This function binds a variable to a package class that will provide the implementation for the variable. VARIABLE is the name of the variable to be enchanted. CLASSNAME is the name of a class implementing objects of correct type. Any additional arguments are passed to the "new" method of the class (meaning TIESCALAR, TIEARRAY, or TIEHASH). Typically these are arguments such as might be passed to the dbm_open() function of C. The object returned by the "new" method is also returned by the tie() function, which would be useful if you want to access other methods in CLASSNAME.
Note that functions such as keys() and values() may return huge array values when used on large objects, like DBM files. You may prefer to use the each() function to iterate over such. Example:
# print out
history file offsets
use NDBM_File;
tie(%HIST, ’NDBM_File’,
’/usr/lib/news/history’, 1, 0);
while (($key,$val) = each %HIST) {
print $key, ’ = ’, unpack(’L’,$val),
"\n";
}
untie(%HIST);
A class implementing a hash should have the following methods:
TIEHASH
classname, LIST
DESTROY this
FETCH this, key
STORE this, key, value
DELETE this, key
EXISTS this, key
FIRSTKEY this
NEXTKEY this, lastkey
A class implementing an ordinary array should have the following methods:
TIEARRAY
classname, LIST
DESTROY this
FETCH this, key
STORE this, key, value
[others TBD]
A class implementing a scalar should have the following methods:
TIESCALAR
classname, LIST
DESTROY this
FETCH this,
STORE this, value
Unlike dbmopen(), the tie() function will not use or require a module for you--you need to do that explicitly yourself. See the DB_File manpage or the Config module for interesting tie() implementations.