Best way to implement project specific captures

[Richard Riley <rileyrg@gmail.com>]

Currently I maintain a datetree journal capture using a template so

,----
| 			      ("j" "journal" entry (file+datetree "journal.org")
| 			       "* %?\n\t:PROPERTIES:\n\t:DateCreated: %T\n\t:Link: %a\n\t:END:\n")
`----

I also use j rockways' eproject set up that allows a hook to be run when
a file is opened inside a "project". e.g

,----
| (add-hook 'web-project-file-visit-hook '(lambda ()
| 					  (ignore-errors
| 					    (message "Web Project : %s" eproject-root)
| 					    )))
`----

where "web-project" is created this:-

,----
| (define-project-type web (generic)
|   (look-for "plan.org")
|   :relevant-files ("\\.php$" "\\.js$" "\\.org$" "\\.sql$" "\\.css$" "authinfo" "vhost"))
`----

So whenever I open a file in a directory hierarchy which contains a
plan.org matching those types then my web-project-file-visit-hook is run.

What is the best emacs/elisp approach to setting a capture file
destination specific to a particular project? THe main point being that
the default capture template above should only be replaced if I am
actually in a "project" : any capture done in a file NOT contained
within a project should default to the capture template above. Is it
someting to do with buffer-locals perhaps or is there a
better/alternative way? e.g Perhaps "journal.org" becomes a variable and
this is overwritten (or whatever the elisp jargon is) in the project
hook as a buffer local?

Hope was clear!

regards

r.