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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, TIEHANDLE, 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 lists 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
FETCH this, key
STORE this, key, value
DELETE this, key
CLEAR this
EXISTS this, key
FIRSTKEY this
NEXTKEY this, lastkey
DESTROY this

A class implementing an ordinary array should have the following methods:

TIEARRAY classname, LIST
FETCH this, key
STORE this, key, value
FETCHSIZE this
STORESIZE this, count
CLEAR this
PUSH this, LIST
POP this
SHIFT this
UNSHIFT this, LIST
SPLICE this, offset, length, LIST
EXTEND this, count
DESTROY this

A class implementing a file handle should have the following methods:

TIEHANDLE classname, LIST
READ this, scalar, length, offset
READLINE this
GETC this
WRITE this, scalar, length, offset
PRINT this, LIST
PRINTF this, format, LIST
CLOSE this
DESTROY this

A class implementing a scalar should have the following methods:

TIESCALAR classname, LIST
FETCH this,
STORE this, value
DESTROY this

Not all methods indicated above need be implemented. See perltie, Tie::Hash, Tie::Array, Tie::Scalar, and Tie::Handle.

Unlike dbmopen(), the tie() function will not use or require a module for you--you need to do that explicitly yourself. See DB_File or the Config module for interesting tie() implementations.

For further details see perltie, "tied VARIABLE".