[Catalyst] best practice: where to put constants

[Alejandro Imass]

Although I think there is no best practice as such, I mean there are
many ways to do this in Perl in general, but Catalyst offers the nice
feature of the main config file in YAML, so I keep all my constants
and configuration values there.

YAML is so powerful that IMHO it's the best place not ony to store
your constants but to structure them intelligently. Of course, all the
constants you put in your YAML file will be vailable through
$c->config->{foo}

Best,
Alejandro Imass


On Fri, Jun 5, 2009 at 10:50 AM, Jarom Smith <jarom at jaromsmith.net> wrote:
> Hi all:
>
> This is probably my lack of Perl knowledge showing... but where would be
> the best-practice place to put constants in my code?  I'm talking about
> magic numbers that I use internally but need to reference in multiple
> locations of the code.  Things like
>
>    "VENDOR_COMMIT" => 1,
>    "VENDOR_DECLINE" => 2,
>    "TIME_OUTSIDE_WINDOW" => 3,
>
> In Java I would declare them as "public static final" members the class
> that describes that particular object (in this case, a vendor
> notification) and I would refer to them like
>
>    if (notification.getAction() == Notification.VENDOR_COMMIT) ....
>
> So I think the analog to that in Catalyst would be to define the
> constant(s) in the ResultSource classes that are automatically generated
> for me (below the line) and then refer to them like
>
>    if ($notification->action ==
> MyApp::Schema::ResultSet::Notification::VENDOR_COMMIT) ....
>
> The problem with doing it that way is that the namespace starts to become
> unwieldly, and I have to remember where I put the thing I'm trying to
> reference.  The alternative would be to put them at the top level, i.e., in
> MyApp.pm:
>
>    use constant NOTIFICATION_VENDOR_COMMIT => 1;
>    use constant NOTIFICATION_VENDOR_DECLINE => 2;
>    use constant NOTIFICATION_TIME_OUTSIDE_WINDOW => 3;
>
>    use constant NOTIFICATION_PROPERTY_ACCEPT => 1;
>    use constant NOTIFICATION_PROPERTY_CANCEL => 2;
>    use constant NOTIFICATION_PROPERTY_OFFER_NEW_WINDOW => 3;
>
> and then in the code I just say
>
>    if ($notification->action == MyApp::VENDOR_COMMIT) ....
>
> In the end, this is what I decided to do because I have relatively few of
> these guys (so far) and I'd rather have them thrown together all in one
> place than spread all over the system.  But I'm wondering if there is a best
> practice?
>
> I don't want to put them in the config hash or in a configuration file
> because these are not things that a user should be able to change or
> override.
>
> Thanks in advance for the advice/insight; this group has been a great help
> so far.
>
> jarom smith
> tech go-to guy
>
>
>
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