On 3/1/07, David Moreno Garza <[EMAIL PROTECTED]> wrote:
What's the proper way to handle buffering? I mean, to prevent it.
Sometimes you just want to output immediately; however as Tom mentioned
'cat' doesn't output until the buffer is closed; for example -
$|++; # Setting this has no effect on 'cat'
open(o,"|cat"); print o "Not first because of buffering.\n";
# close(o); # Uncomment this line for 'cat' to become closed 1st...
print o 0 x 99999; # Does cat get printed now? Buffer became full.
#sleep 1; # Yes, buffer is full; LINE 2 gets printed in the middle.
# But probably not a good thing ... LINE 2 appears out of context ...
$_ = "LINE 2: gets printed first?\n\n"; print;
sleep 1;
__END__
cat: Buffer gets closed here because all open buffers
are closed when the program finishes...
Note: In the 'buffer full' example, use -
perl oo.pl | less
Be careful to watch for the output of LINE 2;
with 100k characters you might miss LINE 2 -
it gets printed immediately after the 'buffer flush' and
before the 'end of the data stream' ...
The bottom-line? Be careful of your I/O -- things that seem to make
program (logical) order sense may not produce expected results...
One possible answer to your question -
# A long winded approach might use
# (modified from FAQ 8) -
use IPC::Open3;
$_ = "I am the Alpha and the Omega (UT99 Player Xan)\n";
open(o, "cat $_");
print;
print "Hmmmm?\n";
--
WC (Bill) Jones -- http://youve-reached-the.endoftheinternet.org/
http://pgp.mit.edu:11371/pks/lookup?op=vindex&search=0x2A46CF06&fingerprint=on
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