[sf-perl] Unusual Perl "feature"

[Mark Kvale]

On 02/17/2013 06:40 PM, Quinn Weaver wrote:
> On Feb 15, 2013, at 4:14 PM, Mark Kvale wrote:
>
>> This is documented behavior; see
>>
>> http://perldoc.perl.org/perlop.html#Symbolic-Unary-Operators
>>
>> My guess on use? As the man says, '-bareword is equivalent to the
>> string "-bareword"', allowing for fat comma keys without needing
>> quotes, e.g.
>>
>> (-bareword => 1, -title => 2)
>
> But you don't need to quote keys anyway. This feature must exist for
> some other reason.
>
> Perl is like hobbits, to paraphrase Gabdalf: you can know it for
> years, and yet still it can surprise you. :)
>
> Regards,
>
> -- Quinn Weaver PostgreSQL Experts, Inc. http://pgexperts.com/
> 1-888-743-9778 (my extension: 510)

Sorry for not being clear. You do need the quotes if you want a leading 
'-', unless there is a special rule. From perlop, comma 
(http://perldoc.perl.org/perlop.html#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."

My guess is that the interpreter sees -title as '-' and 'title', 
converts 'title' to a string because it starts with a letter, then 
prepends '-' to the string according to the special rule.

Regards,
Mark