Specifying revisions in the future

Hello.

Is it possible to specify revisions in the future? The gitrevisions man page implies otherwise. Alternatively, is there a way to find out the number of commits between two revs---assuming one is an ancestor of the other?

I want to do a certain arbitrary operation for each revision between where I am now and the tip of the branch.

          v1.0-a     master
            \          \
o---o---o---o---o---o---o
            |
           I am here

I've been using the following to do what I want:

ref=master; \
for i in {5..1}; do \
  echo; \
  git log --stat $ref~$i^\!; \
  read -p 'Full diff? '; \
  echo; \
  if [[ $REPLY == 'y' ]]; then \
    git diff $ref~$i^\!; \
  fi; \
done;

which lists the log and diffstat for last 5 commits between master and where I am (e.g. an older tag/branch) with an optional full diff. I know implementing revision specifiers to the future is nontrivial. (I realized that when I considered non-linear histories.) In this case, I've distilled it to the point that all I need is the number of commits between two revs. Can this be had without manually inspecting git log? Or, is there a better way to get detailed diffs like this?

Thanks. Jonathan Paugh