.\" Automatically generated by Pod::Man 2.25 (Pod::Simple 3.16) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. 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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" IO::Seekable \- supply seek based methods for I/O objects .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 3 \& use IO::Seekable; \& package IO::Something; \& @ISA = qw(IO::Seekable); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\f(CW\*(C`IO::Seekable\*(C'\fR does not have a constructor of its own as it is intended to be inherited by other \f(CW\*(C`IO::Handle\*(C'\fR based objects. It provides methods which allow seeking of the file descriptors. .ie n .IP "$io\->getpos" 4 .el .IP "\f(CW$io\fR\->getpos" 4 .IX Item "$io->getpos" Returns an opaque value that represents the current position of the IO::File, or \f(CW\*(C`undef\*(C'\fR if this is not possible (eg an unseekable stream such as a terminal, pipe or socket). If the \fIfgetpos()\fR function is available in your C library it is used to implements getpos, else perl emulates getpos using C's \fIftell()\fR function. .ie n .IP "$io\->setpos" 4 .el .IP "\f(CW$io\fR\->setpos" 4 .IX Item "$io->setpos" Uses the value of a previous getpos call to return to a previously visited position. Returns \*(L"0 but true\*(R" on success, \f(CW\*(C`undef\*(C'\fR on failure. .PP See perlfunc for complete descriptions of each of the following supported \f(CW\*(C`IO::Seekable\*(C'\fR methods, which are just front ends for the corresponding built-in functions: .ie n .IP "$io\->seek ( \s-1POS\s0, \s-1WHENCE\s0 )" 4 .el .IP "\f(CW$io\fR\->seek ( \s-1POS\s0, \s-1WHENCE\s0 )" 4 .IX Item "$io->seek ( POS, WHENCE )" Seek the IO::File to position \s-1POS\s0, relative to \s-1WHENCE:\s0 .RS 4 .IP "WHENCE=0 (\s-1SEEK_SET\s0)" 8 .IX Item "WHENCE=0 (SEEK_SET)" \&\s-1POS\s0 is absolute position. (Seek relative to the start of the file) .IP "WHENCE=1 (\s-1SEEK_CUR\s0)" 8 .IX Item "WHENCE=1 (SEEK_CUR)" \&\s-1POS\s0 is an offset from the current position. (Seek relative to current) .IP "WHENCE=2 (\s-1SEEK_END\s0)" 8 .IX Item "WHENCE=2 (SEEK_END)" \&\s-1POS\s0 is an offset from the end of the file. (Seek relative to end) .RE .RS 4 .Sp The SEEK_* constants can be imported from the \f(CW\*(C`Fcntl\*(C'\fR module if you don't wish to use the numbers \f(CW0\fR \f(CW1\fR or \f(CW2\fR in your code. .Sp Returns \f(CW1\fR upon success, \f(CW0\fR otherwise. .RE .ie n .IP "$io\->sysseek( \s-1POS\s0, \s-1WHENCE\s0 )" 4 .el .IP "\f(CW$io\fR\->sysseek( \s-1POS\s0, \s-1WHENCE\s0 )" 4 .IX Item "$io->sysseek( POS, WHENCE )" Similar to \f(CW$io\fR\->seek, but sets the IO::File's position using the system call \fIlseek\fR\|(2) directly, so will confuse most perl \s-1IO\s0 operators except sysread and syswrite (see perlfunc for full details) .Sp Returns the new position, or \f(CW\*(C`undef\*(C'\fR on failure. A position of zero is returned as the string \f(CW"0 but true"\fR .ie n .IP "$io\->tell" 4 .el .IP "\f(CW$io\fR\->tell" 4 .IX Item "$io->tell" Returns the IO::File's current position, or \-1 on error. .SH "SEE ALSO" .IX Header "SEE ALSO" perlfunc, \&\*(L"I/O Operators\*(R" in perlop, IO::Handle IO::File .SH "HISTORY" .IX Header "HISTORY" Derived from FileHandle.pm by Graham Barr