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IO-Stringy-2.113
River stage three • 166 direct dependents • 850 total dependents
/ IO::Scalar

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 tiehandled (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.

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.