Re: Other Globals in %once

----- Original Message -----
From: "Dave Rolsky" <[email protected]>
To: "David Wheeler" <[email protected]>
Cc: "Jonathan Swartz" <[email protected]>; "Mason Developers"
<[email protected]>; "Serge Sozonoff" <[email protected]>
Sent: Saturday, May 01, 2004 11:58 AM
Subject: Re: [Mason-devel] Other Globals in %once


> On Sat, 1 May 2004, David Wheeler wrote:
>
> > No, I mean that $m is available but undefined in %once blocks. If what
> > Dave tells me is correct, then other globals created by allow_globals
> > and set_global() are already assigned before the %once block executes,
> > so ignore the "other globals" part. So yes, I'm referring to loading
> > the component before the globals are defined.
> >
> > $m and $r are undefined in %once blocks, and I'm not sure the reasons
> > for that are compelling enough. Seems to me that the Perl way is to
> > allow the flexibility to use them, with the caveats well documented.
> > IOW, give Masonites enough rope to shoot themselves in the foot. ;-)
>
> Actually, I thought of a compelling reason that this won't go into the
> current stable branch, at least ;)
>
> The changes to make this work would require a bit more code surgery than
> I'd like.  Specifically, we currently set the $m variable in
> Request->exec.  To make it available in <%once>, we'd have to set it in
> the Interp object instead, and I'm not sure where.  It could be in load(),
> but then it'd get reset every time a new component is loaded, which can
> happen multiple times in a request.  Also, we'd need to think about this
> should work in the face of subrequests.
>
> So while I'm not entirely opposed to this, I don't think it's something
> that can go in the stable branch.

I'm opposed to it, for these reasons:

1. $m isn't guaranteed to be defined in <%once>, since you can load a
component outside the context of a request, e.g. when preloading. I don't
think a component should stop working when you preload it. That's a decision
that might be made by someone far from the person developing the component.

2. As Serge points out, <%once> may execute or not execute for any arbitrary
request, depending on the whim of the component cache. So you shouldn't be
defining anything in <%once> that depends on the current request ($m).

David, I'm not clear on what you were planning to use $m for in <%once>. Was
it for something that would always be the same regardless of the current
request?

Jon



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