Re: what is the meaning of $| in perl? (Buffering/autoflush/Unicode/UTF-8 References)

[eyepopslikeamosquito]

Now that you know what $| is, I suggest you don't use it! For Perl 5.8+, instead of your global LOGFILE file handle and:

select(LOGFILE); $| = 1;
select(STDOUT);

it is preferable to use a lexical file handle ($logfile say) and then simply:

use IO::Handle;    # not needed for Perl 5.14+
# ...
$logfile->autoflush();

Note that for Perl 5.14+ you don't need use IO::Handle because:

Before Perl 5.14, lexical filehandles were objects of the IO::Handle class, but you had to load IO::Handle explicitly before you could call methods on them. As of Perl 5.14, lexical filehandles are instances of IO::File and Perl loads IO::File for you.

Extra References Added Later

From On Interfaces and APIs:

Lexical file handles are, for me, the most important feature introduced in Perl 5.6. Those evil old global file handles spawned a host of unfortunate idioms, such as:

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

In terms of a clear and simple interface to perform a simple task (set autoflush on a file handle), it doesn't get much worse than that, a compelling illustration of why keeping state in global variables is just plain evil ...

See also:

• Perl Best Practices, chapter 10 (I/O) by TheDamian
• Perl tip: Buffering and IO::Handle by TheDamian (tip for Melbourne Perl Mongers)
• Suffering from Buffering by MJD

PM References

• Is it possible at all to flush buffer and commit file write, if UTF-8 encoding is being used?? by dissident (2023)
• Re: Is it possible at all to flush buffer and commit file write, if UTF-8 encoding is being used?? - response from kcott
• Re: Is it possible at all to flush buffer and commit file write, if UTF-8 encoding is being used?? - response by ikegami

• Detect whether a writeable filehandle has closed? by jdporter (2021)
• Re: Detect whether a writeable filehandle has closed? (signal handlers) by me (with a Perl Monks history aside)

• Re^3: Telnet Client/Server: What am I doing wrong? by me (2012)
• Printing Unicode on the Windows Console and the importance of of i/o layers by nikosv (2010)

Unicode/UTF-8

• Unicode (wikipedia)
• UTF-8 (wikipedia)

• Emoji can be hard to see on the command line by kcott (2021) - see also Re: Add "Image Miniatures" to your HTML (Fun References)
• Re: Is it possible at all to flush buffer and commit file write, if UTF-8 encoding is being used?? by kcott (2023)
• Re^2: uparse - Parse Unicode strings (uparse/uchar/unichars/uniprops) by me (2023)

• Proper Unicode handling in Perl by VK (2019)