Commandline option -f doesn't override RDOCOPT's value

Hi there,

RDoc's help states this:

    Options can be specified via the RDOCOPT environment variable, which
    functions similar to the RUBYOPT environment variable for ruby.

      $ export RDOCOPT="--show-hash"

    will make rdoc show hashes in method links by default.  Command-line options
    always will override those in RDOCOPT.

However, this is not true for the -f commandline option as can be seen in this gist (the interesting part is the last execution of RDoc where I set RDOCOPT to -f hanna and request darkfish via rdoc -f darkfish.

Instead of RDoc using darkfish instead of RDOCOPT's hanna, RDoc states this:

    invalid options: -f generator already set to hanna
    (invalid options are ignored)

and continues to use the hanna generator.

ruby -v: ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux]
rdoc --version: rdoc 3.9.2
OS: Arch Linux

Valete,
Marvin

PS: Shouldn't the --formatter option be named --generator? darkfish, hanna, and all those are generators rather than formatters.

Start by reproducing the final command from the linked gist with RDOCOPT set to -f hanna and the command requesting darkfish. Trace RDoc's command-line option handling to determine why -f is rejected, then verify that the command-line generator takes precedence and that the option naming concern is addressed or documented.