Cffunction - Accepting and Returning PDFs in memory

Question

Hello,
This is something that I should probably know by now in my CF career, but up until now I have never thought/had to do this type of thing.
I have defined a couple functions that I would like to handle accepting, manipulating, and returning PDFs in memory. What data types should I be using for accepting and returning the PDF in memory between functions?  I would prefer to stay away from "any" if possible, but let me know if that is the only choice.
<cffunction name="AddMeUhWaddaMak" returntype="any" access="public" output="no">
        <cfargument name="src" type="any" required="yes">
        <cfargument name="name" type="string" required="no">
               <cfpdf action="addWatermark"
                        source="#arguments.src#"
                        name="#arguments.name#"
                         ...>
                     <cfreturn arguments.name>
</cffunction>

Answer 1

Thanks again for the advice.  I was doing a little tinkering around with isPDFObject() just to see how it works and came to another question. See below..
<cfdocument format="pdf" name="test2">
test
</cfdocument>
<cfdump var="#isPDFObject(test2)#"><cfabort>
The result says "NO", even though when I dump out "test2" it shows up as binary.