Options for Completion/Zsh/Command/_cd?

[James Devenish <j-devenish@users.sourceforge.net>]

Hi,

I always use a 'custom' version of _cd because:

 - I don't want tab completion to consider $cdpath
   (in fact, I hate when that happens!)
 - I like CVS and .svn directories to be ignored.

I achieve this by scrubbing out portions of _cd and then adding an -F
option to _path_files. It would probably be better if I were to be able
to set some options in my .zshrc rather than rolling a new _cd with each
release. What is the canonical or preferred way of passing options to
completion functions? I can envisage being able to solve my $cdpath
problem by being able to do, say,
    setopt comp_cd_nocdpath
and do my directory exclusions by setting
    COMP_CD_PATH_OPTIONS=-F "(*CVS *.svn)"

I assume completion scripts can could pick up the environment variable,
but is there a way to convey the setopt to the function? If not, would
it be necessary to set some environment variable, ala
    COMP_CD_OPTIONS=nocdpath

Are they any examples that anyone knows of?

I'm willing to bother doing the necessary patches, but my prowess with
zsh completion functions is at the novice end of the scale. (Having
said that, though, I have a completion function for Subversion version
control: _svn, which I should share sometime.)