[cozzyd]

Yeah I agree. Macros can be used to avoid some of the typing in defining the interface when the implementation really is common, but unfortunately that makes it harder to document the generated interface. I wish doxygen had some way of supporting comments for macro-generated interfaces.

In defining the implementation, it's easy enough to do something like this (if the implementation really is common):

    static int pdf_ll_foo_impl(pdf_ll_ctx_t c, pdf_ll_type_t t, ...)
    {  
       //real implementation goes here, perhaps switching on t
    } 

    int pdf_page_foo(pdf_page_ctx_t c, ..) { pdf_ll_foo_impl((pdf_ll_ctx_t) c, PDF_PAGE_TYPE, ..); } 
    int pdf_pattern_foo (pdf_pattern_ctx_t c, ..) { pdf_ll_foo_impl(pdf_ll_ctx_t) c, PDF_PATTERN_TYPE, ..); } 

which you can also use macros to help generate if you want to.