IO::Scalar(3pm) User Contributed Perl Documentation IO::Scalar(3pm)
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:\n";
### Open a handle on a string, and append to it:
$SH = new IO::Scalar \$data;
$SH->print("Hello");
$SH->print(", world!\nBye now!\n");
print "The string is now: ", $data, "\n";
### Open a handle on a string, read it line-by-line, then close it:
$SH = new IO::Scalar \$data;
while (defined($_ = $SH->getline)) {
print "Got line: $_";
}
$SH->close;
### Open a handle on a string, and slurp in all the lines:
$SH = new IO::Scalar \$data;
print "All lines:\n", $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}, "\n"; ### 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:\n";
### Open a handle on a string, and append to it:
$SH = new IO::Scalar \$data;
print $SH "Hello";
print $SH ", world!\nBye now!\n";
print "The string is now: ", $data, "\n";
### Open a handle on a string, read it line-by-line, then close it:
$SH = new IO::Scalar \$data;
while (<$SH>) {
print "Got line: $_";
}
close $SH;
### Open a handle on a string, and slurp in all the lines:
$SH = new IO::Scalar \$data;
print "All lines:\n", <$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}, "\n"; ### get at value
And for you folks with 1.x code out there: the old tie() style still
works, though this is unnecessary and deprecated:
use IO::Scalar;
### Writing to a scalar...
my $s;
tie *OUT, 'IO::Scalar', \$s;
print OUT "line 1\nline 2\n", "line 3\n";
print "String is now: $s\n"
### Reading and writing an anonymous scalar...
tie *OUT, 'IO::Scalar';
print OUT "line 1\nline 2\n", "line 3\n";
tied(OUT)->seek(0,0);
while (<OUT>) {
print "Got line: ", $_;
}
Stringification works, too!
my $SH = new IO::Scalar \$data;
print $SH "Hello, ";
print $SH "world!";
print "I printed: $SH\n";
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 \$s;
$SH->print("Hel", "lo, "); ### OO style
$SH->print("world!\n"); ### ditto
Or this:
my $s;
$SH = tie *OUT, 'IO::Scalar', \$s;
print OUT "Hel", "lo, "; ### non-OO style
print OUT "world!\n"; ### ditto
Causes $s to be set to:
"Hello, world!\n"
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 something?
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 compatibility.
fileno
Instance method. No-op, returns undef
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 context. Currently, lines are
delimited by "\n".
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 compatibility.
binmode
Instance method. No-op, provided for OO compatibility.
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.
AUTHOR
Eryq (eryq@zeegee.com). President, ZeeGee Software Inc
(http://www.zeegee.com).
CONTRIBUTORS
Dianne Skoll (dfs@roaringpenguin.com).
COPYRIGHT & LICENSE
Copyright (c) 1997 Erik (Eryq) Dorfman, ZeeGee Software, Inc. All rights
reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.38.2 2024-07-31 IO::Scalar(3pm)
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