[Dovecot] string expansion *in* dovecot config?

hi all,

is it possible to define/use 'MACROS' (string expansion, ala Exim) in dovecot's config file?

specifically, e.g. --

rather than:

login_executable = /some/crazy/path/to/dovecot/libexec/dovecot/imap-login

i'd LIKE to do something like

MY_PATH          = /some/crazy/path/to
login_executable = MY_PATH/dovecot/libexec/dovecot/imap-login

i'm reading the wiki docs, and it's just not obvious to me ...

thanks!

richard