RE: When to use 'use' for accessing modules?
> > > > > Is $ENV{foo}='bar'; in startup.pl equivalent to
> > PerlSetEnv foo bar
> > > > > in httpd.conf?
> > > >
> > > > Yes.
>
> well, not exactly. PerlSetEnv sets the subprocess_env table.
> as a side effect of that, you get PerlSetEnv values in %ENV
> if you have PerlSetupEnv On. The other way to look at it is
> that anything set with PerlSetEnv is always accessible via
> $r->subprocess_env, but not necessarily with %ENV.
scratch that - too early in the morning :) I have no idea what I was
talking about
I'll just keep quiet now...
>
> > >
> > > Are you sure? I experimented a few months ago, and found that
> > > $ENV{foo}='bar'; would only last in each child until the
> > first request
> > > of the child completed.
>
> that's a bug
>
> http://marc.theaimsgroup.com/?l=apache-modperl-dev&m=995652277
11585&w=2
that's still true, though :)
--Geoff
RE: When to use 'use' for accessing modules?
> -Original Message-
> From: Perrin Harkins [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, October 24, 2001 1:41 AM
> To: Steve Piner
> Cc: Chris Allen; [EMAIL PROTECTED]
> Subject: Re: When to use 'use' for accessing modules?
>
>
> Steve Piner wrote:
> >
> > Perrin Harkins wrote:
> >
> > > Chris Allen wrote:
> > [...]
> > > > Is $ENV{foo}='bar'; in startup.pl equivalent to
> PerlSetEnv foo bar
> > > > in httpd.conf?
> > >
> > > Yes.
well, not exactly. PerlSetEnv sets the subprocess_env table. as a side
effect of that, you get PerlSetEnv values in %ENV if you have PerlSetupEnv
On. The other way to look at it is that anything set with PerlSetEnv is
always accessible via $r->subprocess_env, but not necessarily with %ENV.
> >
> > Are you sure? I experimented a few months ago, and found that
> > $ENV{foo}='bar'; would only last in each child until the
> first request
> > of the child completed.
that's a bug
http://marc.theaimsgroup.com/?l=apache-modperl-dev&m=99565227711585&w=2
>
> You may be right. Depends on the setting of PerlSetupEnv, I think.
> - Perrin
>
HTH
--Geoff
Re: When to use 'use' for accessing modules?
Steve Piner wrote:
>
> Perrin Harkins wrote:
>
> > Chris Allen wrote:
> [...]
> > > Is $ENV{foo}='bar'; in startup.pl equivalent to PerlSetEnv foo bar
> > > in httpd.conf?
> >
> > Yes.
>
> Are you sure? I experimented a few months ago, and found that
> $ENV{foo}='bar'; would only last in each child until the first request
> of the child completed.
You may be right. Depends on the setting of PerlSetupEnv, I think.
- Perrin
Re: When to use 'use' for accessing modules?
Perrin Harkins wrote:
> Chris Allen wrote:
[...]
> > Is $ENV{foo}='bar'; in startup.pl equivalent to PerlSetEnv foo bar
> > in httpd.conf?
>
> Yes.
Are you sure? I experimented a few months ago, and found that
$ENV{foo}='bar'; would only last in each child until the first request
of the child completed.
Steve
--
Steve Piner
Web Applications Developer
Marketview Limited
http://www.marketview.co.nz
Re: When to use 'use' for accessing modules?
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
When to use 'use' for accessing modules?
I have a modperl site that accesses a number of modules.
In my startup.pl I have:
#!/usr/bin/perl -w
use strict;
use lib('/path/to/my/installation'); # 'site' directory is here
use Apache::DBI;
use Apache::StatINC;
use site::customers;
use site::orders;
use site::products;
use site::base;
1;
None of the modules exports *any* symbols at all - all are called in
the form:
$product=site::products->new(23);
$product->get('price');
First question:
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?
Second question:
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?
Third (unrelated) question.
Is $ENV{foo}='bar'; in startup.pl equivalent to PerlSetEnv foo bar
in httpd.conf?
---
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. I would also be interested to know that
if the 'use' statements *are* unnecessary, does including them add any extra
overhead of processing/memory??
Many thanks,
Chris Allen.
