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

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

Dianne Skoll (dfs@roaringpenguin.com).

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)

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"

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

Construction new [ARGS...] Classmethod. Return a new, unattached scalar handle. If any arguments are given, they're sent to open(). open [SCALARREF] Instancemethod. 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 Instancemethod. Is the scalar handle opened on something? close Instancemethod. Disassociate the scalar handle from its underlying scalar. Done automatically on destroy. Inputandoutput flush Instancemethod. No-op, provided for OO compatibility. fileno Instancemethod. No-op, returns undef getc Instancemethod. Return the next character, or undef if none remain. getline Instancemethod. 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 Instancemethod. Get all remaining lines. It will croak() if accidentally called in a scalar context. print ARGS... Instancemethod. 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] Instancemethod. 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] Instancemethod. Write some bytes to the scalar. sysread BUF, LEN, [OFFSET] Instancemethod. 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] Instancemethod. Write some bytes to the scalar. Seeking/tellingandotherattributes autoflush Instancemethod. No-op, provided for OO compatibility. binmode Instancemethod. No-op, provided for OO compatibility. clearerr Instancemethod. Clear the error and EOF flags. A no-op. eof Instancemethod. Are we at end of file? seek OFFSET, WHENCE Instancemethod. Seek to a given position in the stream. sysseek OFFSET, WHENCE Instancemethod. Identical to "seek OFFSET, WHENCE", q.v. tell Instancemethod. Return the current position in the stream, as a numeric offset. setpos POS Instancemethod. Set the current position, using the opaque value returned by getpos(). getpos Instancemethod. Return the current position in the string, as an opaque object. sref Instancemethod. Return a reference to the underlying scalar.

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 unnecessaryanddeprecated: 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";