overriding ~/.rpmmacros from commandline?

[Eli Carter <eli carter inet com>]

Is there a way to override the values stored in ~/.rpmmacros on the rpm
command line?

For instance, suppose ~/.rpmmacros sets topdir to dira, and I want it to
be dirb without changing ~/.rpmmacros.  (An empty or nonexistant
~/.rpmmacros would be preferable.)

Point me to documentation if it exists... I just haven't found it.

Eli 
-----------------------.           Rule of Accuracy: When working toward
Eli Carter             |            the solution of a problem, it always 
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