NAME
IO::Seekable - supply seek based methods for I/O objects
SYNOPSIS
use IO::Seekable; package IO::Something; @ISA = qw(IO::Seekable);
DESCRIPTION
IO::Seekable
does not have a constructor of its own as it is intended to
be inherited by other IO::Handle
based objects. It provides methods
which allow seeking of the file descriptors.
- $io->getpos
Returns an opaque value that represents the current position of the IO::File, or
undefif this is not possible (eg an unseekable stream such as a terminal, pipe or socket). If the fgetpos() function is available in your C library it is used to implements getpos, else perl emulates getpos using C's ftell() function. - $io->setpos
Uses the value of a previous getpos call to return to a previously visited position. Returns "0 but true" on success,
undefon failure.
See perlfunc for complete descriptions of each of the following
supported IO::Seekable
methods, which are just front ends for the
corresponding built-in functions:
- $io->seek ( POS, WHENCE )
Seek the IO::File to position POS, relative to WHENCE:
- WHENCE=0 (SEEK_SET)
POS is absolute position. (Seek relative to the start of the file)
- WHENCE=1 (SEEK_CUR)
POS is an offset from the current position. (Seek relative to current)
- WHENCE=2 (SEEK_END)
POS is an offset from the end of the file. (Seek relative to end)
The SEEK_* constants can be imported from the
Fcntlmodule if you don't wish to use the numbers01or2in your code.Returns
1upon success,0otherwise. - WHENCE=0 (SEEK_SET)
- $io->sysseek( POS, WHENCE )
Similar to $io->seek, but sets the IO::File's position using the system call lseek(2) directly, so will confuse most perl IO operators except sysread and syswrite (see perlfunc for full details)
Returns the new position, or
undefon failure. A position of zero is returned as the string"0 but true" - $io->tell
Returns the IO::File's current position, or -1 on error.
SEE ALSO
perlfunc, "I/O Operators" in perlop, IO::Handle IO::File
HISTORY
Derived from FileHandle.pm by Graham Barr <gbarr@pobox.com>

