Chris Allen wrote:
> If site::products calls functions from site::customers, do I need
> a 'use site::customers' in site::products, when I have already
> done a 'use' in my startup.pl?
No, but I always do. It's good documentation, to remind you that if you
ever ran this code outside of mod_perl it would be necessary to have
that 'use' in place.
> site::products contains the line:
>
> @ISA=('site::base');
>
> so that methods from site::base can be overridden in site::products.
>
> Do I need a 'use site::base' in site::products for this to work
> correctly?
Only if site::base has not been loaded already, but I always do it
anyway, for the same reason as above.
> Is $ENV{foo}='bar'; in startup.pl equivalent to PerlSetEnv foo bar
> in httpd.conf?
Yes.
> Experience has shown that I *don't* need the 'use' statements anywhere
> other than startup.pl - but I am not sure why, and would find some pointers
> to a discussion of this very useful.
You don't need them because the modules they would load are already loaded.
> I would also be interested to know that
> if the 'use' statements *are* unnecessary, does including them add any extra
> overhead of processing/memory??
There is a very fast check that happens once when the module containing
the 'use' is called. It checks to see if the used module is already
loaded (i.e. if it is in %INC). It also calls the used module's export
function, unless you pass an empty list:
use Foo ();
You should avoid importing symbols all over the place, as explained in
the Guide, but otherwise there is no significant overhead from having
use statements all over the place.
- Perrin
