How do I determine number of matches in a regex?

[Bradford Ritchie]

Does anyone know how to count the number of times a regex (global) matches?  

According to the docs, m/$pattern/g will return true (which I think is "1") upon 
success, but not the nubmer of times matched.

I tried the following:
      $count = @matches = /$pattern/g;

and this works, but it seems like there must be a more straightforward way to do it.

Does anyone know why m//g only returns true on success instead of returning the number 
of matches like s///g and tr/// do.

Thanks.
-- Brad