io::scalar(3)

NAME

IO::Scalar - IO:: interface for reading/writing a scalar

SYNOPSIS

Perform I/O on strings, using the basic OO interface...
    use 5.005;
    use IO::Scalar;
    $data = "My message:0;
    ### Open a handle on a string, and append to it:
    $SH = new IO::Scalar ata;
    $SH->print("Hello");
    $SH->print(", world!0ye now!0);
    print "The string is now: ", $data, "0;
    ### Open a handle on a string, read  it  line-by-line,
then close it:
    $SH = new IO::Scalar ata;
    while (defined($_ = $SH->getline)) {
        print "Got line: $_";
    }
    $SH->close;
    ###  Open  a  handle on a string, and slurp in all the
lines:
    $SH = new IO::Scalar ata;
    print "All lines:0, $SH->getlines;
    ### Get the current position (either of two ways):
    $pos = $SH->getpos;
    $offset = $SH->tell;
    ### Set the current position (either of two ways):
    $SH->setpos($pos);
    $SH->seek($offset, 0);
    ### Open an anonymous temporary scalar:
    $SH = new IO::Scalar;
    $SH->print("Hi there!");
    print "I printed: ", ${$SH->sref}, "0;      ### get at
value
Don't like OO for your I/O?  No problem.  Thanks to the
magic of an invisible tie(), the following now works out
of the box, just as it does with IO::Handle:
    use 5.005;
    use IO::Scalar;
    $data = "My message:0;
    ### Open a handle on a string, and append to it:
    $SH = new IO::Scalar ata;
    print $SH "Hello";
    print $SH ", world!0ye now!0;
    print "The string is now: ", $data, "0;
    ###  Open  a handle on a string, read it line-by-line,
then close it:
    $SH = new IO::Scalar ata;
    while (<$SH>) {
        print "Got line: $_";
    }
    close $SH;
    ### Open a handle on a string, and slurp  in  all  the
lines:
    $SH = new IO::Scalar ata;
    print "All lines:0, <$SH>;
    ### Get the current position (WARNING: requires 5.6):
    $offset = tell $SH;
    ### Set the current position (WARNING: requires 5.6):
    seek $SH, $offset, 0;
    ### Open an anonymous temporary scalar:
    $SH = new IO::Scalar;
    print $SH "Hi there!";
    print "I printed: ", ${$SH->sref}, "0;      ### get at
value
And for you folks with 1.x code out there: the old tie()
style still works, though this is unnecessary and depre_
cated:
    use IO::Scalar;
    ### Writing to a scalar...
    my $s;
    tie *OUT, 'IO::Scalar', ;
    print OUT "line 10ine 20, "line 30;
    print "String is now: $s0
    ### Reading and writing an anonymous scalar...
    tie *OUT, 'IO::Scalar';
    print OUT "line 10ine 20, "line 30;
    tied(OUT)->seek(0,0);
    while (<OUT>) {
        print "Got line: ", $_;
    }
Stringification works, too!
    my $SH = new IO::Scalar ata;
    print $SH "Hello, ";
    print $SH "world!";
    print "I printed: $SH0;

DESCRIPTION

This class is part of the IO::Stringy distribution; see
IO::Stringy for change log and general information.

The IO::Scalar class implements objects which behave just
like IO::Handle (or FileHandle) objects, except that you
may use them to write to (or read from) scalars. These
handles are automatically tiehandle'd (though please see
"WARNINGS" for information relevant to your Perl version).

Basically, this:: my $s;
$SH = new IO::Scalar ;
$SH->print("Hel", "lo, "); ### OO style
$SH->print("world!0); ### ditto
Or this:: my $s;
$SH = tie *OUT, 'IO::Scalar', ;
print OUT "Hel", "lo, "; ### non-OO style
print OUT "world!0; ### ditto
Causes $s to be set to:: "Hello, world!0

PUBLIC INTERFACE

Construction

new [ARGS...]: Class method. Return a new, unattached scalar handle. If any arguments are given, they're sent to open().
open [SCALARREF]: Instance method. Open the scalar handle on a new scalar, pointed to by SCALARREF. If no SCALARREF is
given, a "private" scalar is created to hold the file
data.; Returns the self object on success, undefined on
error.
opened: Instance method. Is the scalar handle opened on some thing?
close: Instance method. Disassociate the scalar handle from its underlying scalar. Done automatically on destroy.
Input and output
flush: Instance method. No-op, provided for OO compatibil ity.
getc: Instance method. Return the next character, or undef if none remain.
getline: Instance method. Return the next line, or undef on end of string. Can safely be called in an array con
text. Currently, lines are delimited by "0.
getlines: Instance method. Get all remaining lines. It will croak() if accidentally called in a scalar context.
print ARGS...: Instance method. Print ARGS to the underlying scalar.; Warning: this continues to always cause a seek to the end of the string, but if you perform seek()s and
tell()s, it is still safer to explicitly seek-to-end
before subsequent print()s.
read BUF, NBYTES, [OFFSET]: Instance method. Read some bytes from the scalar. Returns the number of bytes actually read, 0 on
end-of-file, undef on error.
write BUF, NBYTES, [OFFSET]: Instance method. Write some bytes to the scalar.
sysread BUF, LEN, [OFFSET]: Instance method. Read some bytes from the scalar. Returns the number of bytes actually read, 0 on
end-of-file, undef on error.
syswrite BUF, NBYTES, [OFFSET]: Instance method. Write some bytes to the scalar.
Seeking/telling and other attributes
autoflush: Instance method. No-op, provided for OO compatibil ity.
binmode: Instance method. No-op, provided for OO compatibil ity.
clearerr: Instance method. Clear the error and EOF flags. A no-op.
eof Instance method. Are we at end of file?
seek OFFSET, WHENCE: Instance method. Seek to a given position in the stream.
sysseek OFFSET, WHENCE: Instance method. Identical to "seek OFFSET, WHENCE", q.v.
tell: Instance method. Return the current position in the stream, as a numeric offset.
setpos POS: Instance method. Set the current position, using the opaque value returned by "getpos()".
getpos: Instance method. Return the current position in the string, as an opaque object.
sref: Instance method. Return a reference to the underlying scalar.

WARNINGS

Perl's TIEHANDLE spec was incomplete prior to 5.005_57; it was missing support for "seek()", "tell()", and "eof()". Attempting to use these functions with an IO::Scalar will not work prior to 5.005_57. IO::Scalar will not have the relevant methods invoked; and even worse, this kind of bug can lie dormant for a while. If you turn warnings on (via $^W or "perl -w"), and you see something like this...: attempt to seek on unopened filehandle
...then you are probably trying to use one of these func tions on an IO::Scalar with an old Perl. The remedy is to simply use the OO version; e.g.:: $SH->seek(0,0); ### GOOD: will work on any 5.005
seek($SH,0,0); ### WARNING: will only work on; 5.005_57 and beyond

VERSION

$Id: Scalar.pm,v 2.104 2001/08/09 08:04:44 eryq Exp $

AUTHORS

Principal author

Eryq (eryq@zeegee.com). President, ZeeGee Software Inc (http://www.zeegee.com).

Other contributors

The full set of contributors always includes the folks
mentioned in "CHANGE LOG" in IO::Stringy. But just the
same, special thanks to the following individuals for
their invaluable contributions (if I've forgotten or mis
spelled your name, please email me!):

Andy Glew, for contributing "getc()".

Brandon Browning, for suggesting "opened()".

David Richter, for finding and fixing the bug in "PRINTF()".

Eric L. Brine, for his offset-using read() and write() implementations.

Richard Jones, for his patches to massively improve the performance of "getline()" and add "sysread" and
"syswrite".

B. K. Oxley (binkley), for stringification and inheritance improvements, and sundry good ideas.

Doug Wilson, for the IO::Handle inheritance and automatic tie-ing.

docs.sk

comprehensive documentation repository

In section