Exotic ways of fetching the tarbals

[Mojca Miklavec]

Hi,

I would like to know if there is any way to implement the following
inside a Portfile:
(a) if a tarball with the given checksums exists, use that one
(b) else, execute some relatively non-standard commands to generate
the tarball first, then continue with (a)

I don't care if the code would be a bit more complicated than usual. I
need this in order to create a port of yet-unreleased software and I
would prefer a "portable" way of creating the tarball as opposed to
just creating that file manually and placing it in
/opt/local/var/macports/distfiles/

Thank you,
    Mojca