[Zope] Is there any way to turn off the publishing of external methods to the web in Zope?

I have an external method which uses eval(). I would like to prevent anyone from calling this method from inside a URL, e.g., myzopesite/myexternalmethod?myvar=deletemyfiles() Rather, I wish for only Zope objects such as Python Scripts to be able to call this external method. Is there any way to turn off the publishing of external methods to the web in Zope?