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<TITLE>IO::ScalarArray 2.103</TITLE>
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<FONT FACE="sans-serif" SIZE=-1><A HREF="http://www.zeegee.com" TARGET="_top"><IMG SRC="icons/zeegee.gif" ALT="ZeeGee Software" ALIGN="RIGHT" BORDER="0"></A><A NAME="__TOP__"><H1>IO::ScalarArray 2.103</H1>
</A><UL>
<LI> <A NAME="menu:NAME"><A HREF="#NAME">NAME</A></A>
<LI> <A NAME="menu:SYNOPSIS"><A HREF="#SYNOPSIS">SYNOPSIS</A></A>
<LI> <A NAME="menu:DESCRIPTION"><A HREF="#DESCRIPTION">DESCRIPTION</A></A>
<LI> <A NAME="menu:PUBLIC_INTERFACE"><A HREF="#PUBLIC_INTERFACE">PUBLIC INTERFACE</A></A>
<UL>
<LI> <A NAME="menu:Construction"><A HREF="#Construction">Construction</A></A>
<UL>
<LI> <A NAME="menu:item:new_ARGS"><A HREF="#item:new_ARGS">new [ARGS...]</A></A>
<LI> <A NAME="menu:item:open_ARRAYREF"><A HREF="#item:open_ARRAYREF">open [ARRAYREF]</A></A>
<LI> <A NAME="menu:item:opened"><A HREF="#item:opened">opened</A></A>
<LI> <A NAME="menu:item:close"><A HREF="#item:close">close</A></A>
</UL>
<LI> <A NAME="menu:Input_and_output"><A HREF="#Input_and_output">Input and output</A></A>
<UL>
<LI> <A NAME="menu:item:flush"><A HREF="#item:flush">flush </A></A>
<LI> <A NAME="menu:item:getc"><A HREF="#item:getc">getc</A></A>
<LI> <A NAME="menu:item:getline"><A HREF="#item:getline">getline</A></A>
<LI> <A NAME="menu:item:getlines"><A HREF="#item:getlines">getlines</A></A>
<LI> <A NAME="menu:item:print_ARGS"><A HREF="#item:print_ARGS">print ARGS...</A></A>
<LI> <A NAME="menu:item:read_BUF_NBYTES_OFFSET"><A HREF="#item:read_BUF_NBYTES_OFFSET">read BUF, NBYTES, [OFFSET];</A></A>
<LI> <A NAME="menu:item:write_BUF_NBYTES_OFFSET"><A HREF="#item:write_BUF_NBYTES_OFFSET">write BUF, NBYTES, [OFFSET];</A></A>
</UL>
<LI> <A NAME="menu:Seeking_telling_and_other_attributes"><A HREF="#Seeking_telling_and_other_attributes">Seeking/telling and other attributes</A></A>
<UL>
<LI> <A NAME="menu:item:autoflush"><A HREF="#item:autoflush">autoflush </A></A>
<LI> <A NAME="menu:item:binmode"><A HREF="#item:binmode">binmode</A></A>
<LI> <A NAME="menu:item:clearerr"><A HREF="#item:clearerr">clearerr</A></A>
<LI> <A NAME="menu:item:eof"><A HREF="#item:eof">eof </A></A>
<LI> <A NAME="menu:item:seek_POS_WHENCE"><A HREF="#item:seek_POS_WHENCE">seek POS,WHENCE</A></A>
<LI> <A NAME="menu:item:tell"><A HREF="#item:tell">tell</A></A>
<LI> <A NAME="menu:item:setpos_POS"><A HREF="#item:setpos_POS">setpos POS</A></A>
<LI> <A NAME="menu:item:getpos"><A HREF="#item:getpos">getpos</A></A>
<LI> <A NAME="menu:item:aref"><A HREF="#item:aref">aref</A></A>
</UL>
</UL>
<LI> <A NAME="menu:WARNINGS"><A HREF="#WARNINGS">WARNINGS</A></A>
<LI> <A NAME="menu:VERSION"><A HREF="#VERSION">VERSION</A></A>
<LI> <A NAME="menu:AUTHOR"><A HREF="#AUTHOR">AUTHOR</A></A>
<UL>
<LI> <A NAME="menu:Principal_author"><A HREF="#Principal_author">Principal author</A></A>
<LI> <A NAME="menu:Other_contributors"><A HREF="#Other_contributors">Other contributors</A></A>
</UL>
</UL>
<P><HR>
<A NAME="NAME"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> NAME</H2></A>
<P>IO::ScalarArray - IO:: interface for reading/writing an array of scalars
<P><HR>
<A NAME="SYNOPSIS"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> SYNOPSIS</H2></A>
<P>Perform I/O on strings, using the basic OO interface...
<FONT SIZE=3 FACE="courier"><PRE>
use IO::ScalarArray;
@data = ("My mes", "sage:\n");
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### 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";
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### 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;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open a handle on an array, and slurp in all the lines:
$AH = new IO::ScalarArray \@data;
print "All lines:\n", $AH->getlines;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Get the current position (either of two ways):
$pos = $AH->getpos;
$offset = $AH->tell;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Set the current position (either of two ways):
$AH->setpos($pos);
$AH->seek($offset, 0);
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open an anonymous temporary array:
$AH = new IO::ScalarArray;
$AH->print("Hi there!");
print "I printed: ", @{$AH->aref}, "\n"; ### get at value
</PRE></FONT>
<P>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");
<FONT SIZE=3 FACE="courier"><PRE>
### 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";
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### 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;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open a handle on a string, and slurp in all the lines:
$AH = new IO::ScalarArray \@data;
print "All lines:\n", <$AH>;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Get the current position (WARNING: requires 5.6):
$offset = tell $AH;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Set the current position (WARNING: requires 5.6):
seek $AH, $offset, 0;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### Open an anonymous temporary scalar:
$AH = new IO::ScalarArray;
print $AH "Hi there!";
print "I printed: ", @{$AH->aref}, "\n"; ### get at value
</PRE></FONT>
<P>And for you folks with 1.x code out there: the old tie() style still works,
though this is <I>unnecessary and deprecated</I>:
<FONT SIZE=3 FACE="courier"><PRE>
use IO::ScalarArray;
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### 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"
</PRE></FONT>
<FONT SIZE=3 FACE="courier"><PRE>
### 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: ", $_;
}
</PRE></FONT>
<P><HR>
<A NAME="DESCRIPTION"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> DESCRIPTION</H2></A>
<P>This class is part of the IO::Stringy distribution;
see <A HREF="../IO/Stringy.pm.html">IO::Stringy</A> for change log and general information.
<P>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 <A HREF="#WARNINGS">WARNINGS</A>
for information relevant to your Perl version).
<P>For writing large amounts of data with individual print() statements,
this class is likely to be more efficient than IO::Scalar.
<P>Basically, this:
<FONT SIZE=3 FACE="courier"><PRE>
my @a;
$AH = new IO::ScalarArray \@a;
$AH->print("Hel", "lo, "); ### OO style
$AH->print("world!\n"); ### ditto
</PRE></FONT>
<P>Or this:
<FONT SIZE=3 FACE="courier"><PRE>
my @a;
$AH = new IO::ScalarArray \@a;
print $AH "Hel", "lo, "; ### non-OO style
print $AH "world!\n"; ### ditto
</PRE></FONT>
<P>Causes @a to be set to the following array of 3 strings:
<FONT SIZE=3 FACE="courier"><PRE>
( "Hel" ,
"lo, " ,
"world!\n" )
</PRE></FONT>
<P>See <A HREF="../IO/Scalar.pm.html">IO::Scalar</A> and compare with this class.
<P><HR>
<A NAME="PUBLIC_INTERFACE"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> PUBLIC INTERFACE</H2></A>
<P><HR>
<A NAME="Construction"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Construction</H3></A>
<DL>
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:new"><A NAME="item:new_ARGS">new [ARGS...]</A></A></B></DT>
<DD>
<I>Class method.</I>
Return a new, unattached array handle.
If any arguments are given, they're sent to open().
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:open"><A NAME="item:open_ARRAYREF">open [ARRAYREF]</A></A></B></DT>
<DD>
<I>Instance method.</I>
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.
<P>Returns the self object on success, undefined on error.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:opened">opened</A></B></DT>
<DD>
<I>Instance method.</I>
Is the array handle opened on something?
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:close">close</A></B></DT>
<DD>
<I>Instance method.</I>
Disassociate the array handle from its underlying array.
Done automatically on destroy.
</DL>
<P><HR>
<A NAME="Input_and_output"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Input and output</H3></A>
<DL>
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:flush">flush</A></B></DT>
<DD>
<I>Instance method.</I>
No-op, provided for OO compatibility.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:getc">getc</A></B></DT>
<DD>
<I>Instance method.</I>
Return the next character, or undef if none remain.
This does a read(1), which is somewhat costly.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:getline">getline</A></B></DT>
<DD>
<I>Instance method.</I>
Return the next line, or undef on end of data.
Can safely be called in an array context.
Currently, lines are delimited by "\n".
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:getlines">getlines</A></B></DT>
<DD>
<I>Instance method.</I>
Get all remaining lines.
It will croak() if accidentally called in a scalar context.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:print"><A NAME="item:print_ARGS">print ARGS...</A></A></B></DT>
<DD>
<I>Instance method.</I>
Print ARGS to the underlying array.
<P>Currently, this always causes a "seek to the end of the array"
and generates a new array entry. This may change in the future.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:read"><A NAME="item:read_BUF_NBYTES_OFFSET">read BUF, NBYTES, [OFFSET];</A></A></B></DT>
<DD>
<I>Instance method.</I>
Read some bytes from the array.
Returns the number of bytes actually read, 0 on end-of-file, undef on error.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:write"><A NAME="item:write_BUF_NBYTES_OFFSET">write BUF, NBYTES, [OFFSET];</A></A></B></DT>
<DD>
<I>Instance method.</I>
Write some bytes into the array.
</DL>
<P><HR>
<A NAME="Seeking_telling_and_other_attributes"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Seeking/telling and other attributes</H3></A>
<DL>
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:autoflush">autoflush</A></B></DT>
<DD>
<I>Instance method.</I>
No-op, provided for OO compatibility.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:binmode">binmode</A></B></DT>
<DD>
<I>Instance method.</I>
No-op, provided for OO compatibility.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:clearerr">clearerr</A></B></DT>
<DD>
<I>Instance method.</I> Clear the error and EOF flags. A no-op.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:eof">eof</A></B></DT>
<DD>
<I>Instance method.</I> Are we at end of file?
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:seek"><A NAME="item:seek_POS_WHENCE">seek POS,WHENCE</A></A></B></DT>
<DD>
<I>Instance method.</I>
Seek to a given position in the stream.
Only a WHENCE of 0 (SEEK_SET) is supported.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:tell">tell</A></B></DT>
<DD>
<I>Instance method.</I>
Return the current position in the stream, as a numeric offset.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:setpos"><A NAME="item:setpos_POS">setpos POS</A></A></B></DT>
<DD>
<I>Instance method.</I>
Seek to a given position in the array, using the opaque getpos() value.
Don't expect this to be a number.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:getpos">getpos</A></B></DT>
<DD>
<I>Instance method.</I>
Return the current position in the array, as an opaque value.
Don't expect this to be a number.
<P><DT><B><A HREF="#__TOP__"><IMG SRC="icons/itembullet.gif" ALT="Top" BORDER="0"></A> <A NAME="item:aref">aref</A></B></DT>
<DD>
<I>Instance method.</I>
Return a reference to the underlying array.
</DL>
<P><HR>
<A NAME="WARNINGS"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> WARNINGS</H2></A>
<P>Perl's TIEHANDLE spec was incomplete prior to 5.005_57;
it was missing support for <CODE>seek()</CODE>, <CODE>tell()</CODE>, and <CODE>eof()</CODE>.
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 <CODE>$^W</CODE> or <CODE>perl -w</CODE>),
and you see something like this...
<FONT SIZE=3 FACE="courier"><PRE>
attempt to seek on unopened filehandle
</PRE></FONT>
<P>...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.:
<FONT SIZE=3 FACE="courier"><PRE>
$AH->seek(0,0); ### GOOD: will work on any 5.005
seek($AH,0,0); ### WARNING: will only work on 5.005_57 and beyond
</PRE></FONT>
<P><HR>
<A NAME="VERSION"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> VERSION</H2></A>
<P>$Id: ScalarArray.pm,v 2.103 2001/08/09 08:04:44 eryq Exp $
<P><HR>
<A NAME="AUTHOR"><H2><A HREF="#__TOP__"><IMG SRC="icons/h1bullet.gif" ALT="Top" BORDER="0"></A> AUTHOR</H2></A>
<P><HR>
<A NAME="Principal_author"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Principal author</H3></A>
<P>Eryq (<I><FILE><A HREF="mailto:eryq@zeegee.com">eryq@zeegee.com</A></FILE></I>).
President, ZeeGee Software Inc (<I><FILE><A HREF="http://www.zeegee.com">http://www.zeegee.com</A></FILE></I>).
<P><HR>
<A NAME="Other_contributors"><H3><A HREF="#__TOP__"><IMG SRC="icons/h2bullet.gif" ALT="Top" BORDER="0"></A> Other contributors</H3></A>
<P>Thanks to the following individuals for their invaluable contributions
(if I've forgotten or misspelled your name, please email me!):
<P><I>Andy Glew,</I>
for suggesting <CODE>getc()</CODE>.
<P><I>Brandon Browning,</I>
for suggesting <CODE>opened()</CODE>.
<P><I>Eric L. Brine,</I>
for his offset-using read() and write() implementations.
<P><I>Doug Wilson,</I>
for the IO::Handle inheritance and automatic tie-ing.
<P><HR>
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