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IO::ScalarArray(3pm)  User Contributed Perl Documentation IO::ScalarArray(3pm)



NAME
       IO::ScalarArray - IO:: interface for reading/writing an array of
       scalars

SYNOPSIS
       Perform I/O on strings, using the basic OO interface...

           use IO::ScalarArray;
           @data = ("My mes", "sage:\n");

           ### Open a handle on an array, and append to it:
           $AH = new IO::ScalarArray \@data;
           $AH->print("Hello");
           $AH->print(", world!\nBye now!\n");
           print "The array is now: ", @data, "\n";

           ### Open a handle on an array, read it line-by-line, then close it:
           $AH = new IO::ScalarArray \@data;
           while (defined($_ = $AH->getline)) {
               print "Got line: $_";
           }
           $AH->close;

           ### Open a handle on an array, and slurp in all the lines:
           $AH = new IO::ScalarArray \@data;
           print "All lines:\n", $AH->getlines;

           ### Get the current position (either of two ways):
           $pos = $AH->getpos;
           $offset = $AH->tell;

           ### Set the current position (either of two ways):
           $AH->setpos($pos);
           $AH->seek($offset, 0);

           ### Open an anonymous temporary array:
           $AH = new IO::ScalarArray;
           $AH->print("Hi there!");
           print "I printed: ", @{$AH->aref}, "\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 IO::ScalarArray;
           @data = ("My mes", "sage:\n");

           ### Open a handle on an array, and append to it:
           $AH = new IO::ScalarArray \@data;
           print $AH "Hello";
           print $AH ", world!\nBye now!\n";
           print "The array is now: ", @data, "\n";

           ### Open a handle on a string, read it line-by-line, then close it:
           $AH = new IO::ScalarArray \@data;
           while (<$AH>) {
               print "Got line: $_";
           }
           close $AH;

           ### Open a handle on a string, and slurp in all the lines:
           $AH = new IO::ScalarArray \@data;
           print "All lines:\n", <$AH>;

           ### Get the current position (WARNING: requires 5.6):
           $offset = tell $AH;

           ### Set the current position (WARNING: requires 5.6):
           seek $AH, $offset, 0;

           ### Open an anonymous temporary scalar:
           $AH = new IO::ScalarArray;
           print $AH "Hi there!";
           print "I printed: ", @{$AH->aref}, "\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::ScalarArray;

           ### Writing to a scalar...
           my @a;
           tie *OUT, 'IO::ScalarArray', \@a;
           print OUT "line 1\nline 2\n", "line 3\n";
           print "Array is now: ", @a, "\n"

           ### Reading and writing an anonymous scalar...
           tie *OUT, 'IO::ScalarArray';
           print OUT "line 1\nline 2\n", "line 3\n";
           tied(OUT)->seek(0,0);
           while (<OUT>) {
               print "Got line: ", $_;
           }

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

       The IO::ScalarArray class implements objects which behave just like
       IO::Handle (or FileHandle) objects, except that you may use them to
       write to (or read from) arrays of scalars.  Logically, an array of
       scalars defines an in-core "file" whose contents are the concatenation
       of the scalars in the array.  The handles created by this class are
       automatically tiehandle'd (though please see "WARNINGS" for information
       relevant to your Perl version).

       For writing large amounts of data with individual print() statements,
       this class is likely to be more efficient than IO::Scalar.

       Basically, this:

           my @a;
           $AH = new IO::ScalarArray \@a;
           $AH->print("Hel", "lo, ");         ### OO style
           $AH->print("world!\n");            ### ditto

       Or this:

           my @a;
           $AH = new IO::ScalarArray \@a;
           print $AH "Hel", "lo, ";           ### non-OO style
           print $AH "world!\n";              ### ditto

       Causes @a to be set to the following array of 3 strings:

           ( "Hel" ,
             "lo, " ,
             "world!\n" )

       See IO::Scalar and compare with this class.

PUBLIC INTERFACE
       Construction

       new [ARGS...]
           Class method.  Return a new, unattached array handle.  If any
           arguments are given, they're sent to open().

       open [ARRAYREF]
           Instance method.  Open the array handle on a new array, pointed to
           by ARRAYREF.  If no ARRAYREF is given, a "private" array is created
           to hold the file data.

           Returns the self object on success, undefined on error.

       opened
           Instance method.  Is the array handle opened on something?

       close
           Instance method.  Disassociate the array handle from its underlying
           array.  Done automatically on destroy.

       Input and output

       flush
           Instance method.  No-op, provided for OO compatibility.

       getc
           Instance method.  Return the next character, or undef if none
           remain.  This does a read(1), which is somewhat costly.

       getline
           Instance method.  Return the next line, or undef on end of data.
           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 array.

           Currently, this always causes a "seek to the end of the array" and
           generates a new array entry.  This may change in the future.

       read BUF, NBYTES, [OFFSET];
           Instance method.  Read some bytes from the array.  Returns the
           number of bytes actually read, 0 on end-of-file, undef on error.

       write BUF, NBYTES, [OFFSET];
           Instance method.  Write some bytes into the array.

       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 POS,WHENCE
           Instance method.  Seek to a given position in the stream.  Only a
           WHENCE of 0 (SEEK_SET) is supported.

       tell
           Instance method.  Return the current position in the stream, as a
           numeric offset.

       setpos POS
           Instance method.  Seek to a given position in the array, using the
           opaque getpos() value.  Don't expect this to be a number.

       getpos
           Instance method.  Return the current position in the array, as an
           opaque value.  Don't expect this to be a number.

       aref
           Instance method.  Return a reference to the underlying array.

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::ScalarArray will not work prior to 5.005_57.
       IO::ScalarArray 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 functions on an
       IO::ScalarArray with an old Perl.  The remedy is to simply use the OO
       version; e.g.:

           $AH->seek(0,0);    ### GOOD: will work on any 5.005
           seek($AH,0,0);     ### WARNING: will only work on 5.005_57 and beyond

VERSION
       $Id: ScalarArray.pm,v 1.7 2005/02/10 21:21:53 dfs Exp $

AUTHOR
       Primary Maintainer

       David F. Skoll (dfs@roaringpenguin.com).

       Principal author

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

       Other contributors

       Thanks to the following individuals for their invaluable contributions
       (if I've forgotten or misspelled your name, please email me!):

       Andy Glew, for suggesting "getc()".

       Brandon Browning, for suggesting "opened()".

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

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



perl v5.10.0                      2005-02-10              IO::ScalarArray(3pm)