| CARVIEW |
- #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 appropriate constructor method of the class (meaning
TIESCALAR,TIEHANDLE,TIEARRAY, orTIEHASH). Typically these are arguments such as might be passed to the dbm_open(3) function of C. The object returned by the constructor is also returned by thetiefunction, which would be useful if you want to access other methods in CLASSNAME.Note that functions such as
keysandvaluesmay return huge lists when used on large objects, like DBM files. You may prefer to use theeachfunction to iterate over such. Example:# print out history file offsets use NDBM_File; tie(my %HIST, 'NDBM_File', '/usr/lib/news/history', 1, 0); while (my ($key,$val) = each %HIST) { print $key, ' = ', unpack('L', $val), "\n"; }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 SCALAR this DESTROY this UNTIE thisA 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 DELETE this, key EXISTS this, key DESTROY this UNTIE thisA class implementing a filehandle 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 BINMODE this EOF this FILENO this SEEK this, position, whence TELL this OPEN this, mode, LIST CLOSE this DESTROY this UNTIE thisA class implementing a scalar should have the following methods:
TIESCALAR classname, LIST FETCH this, STORE this, value DESTROY this UNTIE thisNot all methods indicated above need be implemented. See perltie, Tie::Hash, Tie::Array, Tie::Scalar, and Tie::Handle.
Unlike
dbmopen, thetiefunction will notuseorrequirea module for you; you need to do that explicitly yourself. See DB_File or the Config module for interestingtieimplementations.
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