[solved] autoflush STDOUT 1 does not need import?

basiliscos has asked for the wisdom of the Perl Monks concerning the following question:

Hello monks!

I do not understand, why the following code

use strict;
use warnings;


autoflush STDOUT 1;
[download]

Works without any import? I expected that strict/warnings should complain, unless I have something like:

use strict;
use warnings;
use IO::Handle;

autoflush STDOUT 1;
[download]

The autoflush isn't listed among perl build-in functions. Why it is imported by default? Where (perldoc) I can read about it and similar surprises?

WBR, basiliscos.

Comment on [solved] autoflush STDOUT 1 does not need import? Select or Download Code

Replies are listed 'Best First'.
Re: autoflush STDOUT 1 does not need import? by choroba (Cardinal) on Sep 14, 2015 at 12:42 UTC
Globs (and STDOUT is one of them) contain an IO object, even if its class hasn't been used. This blogpost describes the hairy details of the situation and gives advice on how to behave. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply]
Re: autoflush STDOUT 1 does not need import? by CountZero (Bishop) on Sep 14, 2015 at 12:53 UTC
In Perl-5.12-delta we read "Filehandles are now always blessed into IO::File". Hence the methods of IO::Handle are available. CountZero A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James My blog: Imperial Deltronics	[reply]
Re: autoflush STDOUT 1 does not need import? by nevdka (Pilgrim) on Sep 14, 2015 at 12:33 UTC
My understanding of this is that you're using indirect object notation, calling the autoflush method on the STDOUT file handle. That line is essentially the same as: `STDOUT->autoflush(1)` You don't need to import anything to call methods on objects. `STDOUT` is an object that supports the `autoflush` method, so you don't need to import anything to get it.	[reply] [d/l] [select]
Re^2: autoflush STDOUT 1 does not need import? by basiliscos (Pilgrim) on Sep 14, 2015 at 14:13 UTC
OMG, indeed! I was sure that this was used in early releases of Perl5, and should no longer present in modern Perl. WBR, basiliscos.	[reply]
Re: autoflush STDOUT 1 does not need import? by shmem (Chancellor) on Sep 14, 2015 at 14:23 UTC
When a method which cannot be resolved is invoked on a file handle, perl loads modules from the IO namespace to resolve it. The notation `autoflush STDOUT 1` is equivalent to `STDOUT->autoflush(1)`, which triggers the loading of `IO::Handle`: `qwurx [shmem] ~> perl -e 'use strict; use warnings; print$_.$/ for sor +t keys %INC; autoflush STDOUT 1' strict.pm warnings.pm qwurx [shmem] ~> perl -e 'use strict; use warnings; STDOUT->autoflush( +1); print$_.$/ for sort keys %INC' Carp.pm Exporter.pm Fcntl.pm IO.pm IO/File.pm IO/Handle.pm IO/Seekable.pm SelectSaver.pm Symbol.pm XSLoader.pm strict.pm warnings.pm` [download] This is documented in Method Call Variations in perlobj. perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'	[reply] [d/l] [select]


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