Query about barewords

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

While putting together some examples of using Gtk and Perl I came across the following behaviour which I hope someone can explain.

This piece of code complains of a BAREWORD under strict.

$switch->signal_connect( notify::active => \&toggle );

As you would expect, if I add some quotes the code works with no complaints.

$switch->signal_connect( 'notify::active' => \&toggle );

So - my question is - why does the following work and not complain about barewords.

$update_button->signal_connect ( clicked => \&update );

It seems that Perl sees notify::active and clicked differently and that seems inconsistent to my mind.

Can someone explain the behaviour?

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Re: Query about barewords by Athanasius (Archbishop) on Sep 06, 2012 at 14:25 UTC
From Comma Operator: The `=>` operator is a synonym for the comma except that it causes a word on its left to be interpreted as a string if it begins with a letter or underscore and is composed only of letters, digits and underscores. Hope that helps, Athanasius <°(((>< contra mundum	[reply]
Re^2: Query about barewords by johngg (Canon) on Sep 06, 2012 at 15:23 UTC
Empirically, the documentation seems to be a little inaccurate as the fat comma also seems to work if the word on the left starts with a number and consists only of numbers. $ perl -Mstrict -Mwarnings -MData::Dumper -E ' > my %hash = ( > 1 => q{one}, > 11 => q{eleven} > ); > print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ hash } ] );' %hash = ( '11' => 'eleven', '1' => 'one' ); $ $ perl -Mstrict -Mwarnings -MData::Dumper -E ' > my %hash = ( > 1 => q{one}, > 11 => q{eleven}, > 2t => q{fruity}, > ); > print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ hash } ] );' syntax error at -e line 5, near "2t" Execution of -e aborted due to compilation errors. $ $ perl -Mstrict -Mwarnings -MData::Dumper -E ' > my %hash = ( > 1 => q{one}, > 11 => q{eleven}, > _2t => q{fruity}, > ); > print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ *hash } ] );' %hash = ( '11' => 'eleven', '1' => 'one', '_2t' => 'fruity' ); $ [download] I hope this is of interest. Cheers, JohnGG	[reply] [d/l]
Re^3: Query about barewords by runrig (Abbot) on Sep 06, 2012 at 15:53 UTC
...if the word on the left starts with a number and consists only of numbers. As long as you don't want to keep any leading zeros.	[reply]
Re^4: Query about barewords (octal) by tye (Sage) on Sep 06, 2012 at 17:12 UTC
Re^2: Query about barewords by runrig (Abbot) on Sep 06, 2012 at 15:57 UTC
The "bareword" may also start with a "-".	[reply]
Re^3: Query about barewords by johngg (Canon) on Sep 06, 2012 at 16:31 UTC
It seems to treat as an octal number, converts to decimal and then stringifies by the look of it. $ perl -Mstrict -Mwarnings -MData::Dumper -E ' > my %hash = ( > 011 => q{nine}, > 11 => q{eleven}, > _2t => q{fruity}, > ); > print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ hash } ] );' %hash = ( '11' => 'eleven', '_2t' => 'fruity', '9' => 'nine' ); $ $ perl -Mstrict -Mwarnings -MData::Dumper -E ' > my %hash = ( > 08 => q{eight}, > 11 => q{eleven}, > _2t => q{fruity}, > ); > print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ hash } ] );' Illegal octal digit '8' at -e line 3, at end of line Execution of -e aborted due to compilation errors. $ [download] A zero on its own is fine. Update: I'm an idiot, I meant to post as a reply to this :-( Cheers, JohnGG	[reply] [d/l]
Re: Query about barewords by remiah (Hermit) on Sep 06, 2012 at 16:52 UTC
Hello. "clicked" may be a constant. It maybe imported when you declare to use some module. `#!/usr/bin/perl use warnings; use strict; package notify; use constant { active => 2, }; 1; package main; use constant { clicked=>1, }; print clicked . "\n"; print notify::active . "\n"; exit;` [download] So, currently, you don't have package "notify" declaring "active" is a constant. If I am looking different direction, forgive me please.	[reply] [d/l]