[pgh-pm] Why you want a subroutine instead of a package variable....

[Daniel J. Wright]

One of the issues presented in the talk last night is why you'd want to have

my $DEBUG
sub DEBUG { $DEBUG = shift if @_; return $DEBUG }

instead of just

our $DEBUG

One excellent reason that I don't think was covered is that one of those
will catch typo mistakes and the other will not:

$Class::Observable::Debug = 1;

Class::Observable::Debug(1);

In the first case, Perl will do what you tell it to do, it sets $Debug to
1.  It doesn't matter that in the rest of your code you only cares about
$DEBUG.   In the second case, if you or one of your users accidentally use
the Debug subroutine, Perl will yell at you and tell you that it can't
find the Debug subroutine.

I can personally vouch for many hours of yelling at my computer because I
*knew* I had set that variable before realizing that I was doing something
stupid like this.

Accessor subs helps find errors like these quicker and saves debugging time.

-Dan