[web-devel] More power, more configurable subsites

[Michael Snoyman]

On Sat, Jan 22, 2011 at 8:34 PM, Matt Brown <matt at softmechanics.net> wrote:
>> That's basically it, but I'm not sure what you mean by "global site
>> preparation." The idea here is to do as little as possible before
>> dispatching to the subsite, that way if a subsite does not want to
>> deal with sessions, it doesn't involve that overhead.
>>
>
> I just meant it as a way to enable middleware for all subsites at
> once.  It should still be configurable though, so the author can
> switch to a per-subsite setup.  For example, it may be appropriate for
> the scaffolder to enable sessions globally, and let the author switch
> to per-subsite if/when performance becomes a concern.

The basic approach I'm leaning towards is having a method in the Yesod
typeclass (call it yesodRunner for now) which converts a Handler to an
Application. This would be where middlewares are defined. We will keep
the default behavior the same as in Yesod 0.6, but allow the ability
to override this to provide a more slimmed-down experience.

Then there will also be a yesodSubRunner method (I guess on
YesodSubSite) which, by default, will use the yesodRunner method from
the master site, but which can be overridden to allow custom behavior
for subsites. This would be the control over customization in the
hands of the subsite authors.

The one downside I see is if there's a subsite which requires
sessions, and a user turns off sessions for his/her master site,
things will break. But I think that's an issue addressed best with
proper documentation.

Michael