Good example (++). And for the benefit of our anonymous wisdom seeker there's always the relevant FAQ.

$| = 1; affects the currently selected handle. This is the handle print, printf and say use if you don't provide one., and it defaults to STDOUT.

In fact, ->autoflush changes the currently selected handle to the invocant, sets $|, then restores the originally selected handle.

Hello syphilis,

differences? perlvar says that $|++ flush right away and after every write or print on the currently selected output channel while *STDOUT->autoflush only affect STDOUT your example instead any select -ed FH and so also STDERR in case of warn or die

L*

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

See IO::Handle. There's no difference, just readability :-)
map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

There's a difference. $| = 1; is equivalent to select()->autoflush(), not STDOUT->autoflush().

Nice example! I prefer autoflush because the intent is much clearer than messing with the $| global variable.

As an aside, it's a shame Perl was originally released with so many evil global variables because by the time lexical file handles made it into Perl 5.6 a host of unfortunate idioms were in common use, such as:

select((select(FH), $|=1)[0]);
[download]

Of course, such old coding horrors like this can be expressed more clearly nowadays with a lexical file handle (see also):

use IO::Handle;    # update: not needed for Perl 5.14+
# ...
$fh->autoflush();
[download]

For more examples of historic interface design boo-boos, see the Some Examples of Interface Mistakes section at: On Interfaces and APIs