I need to implement a modify operation whose semantics is "add if not
present", an add that only takes place if that attribute is not yet
present in the entry.
I need it as an internal operation, so right now I wouldn't bother
formalizing it as an extension of the semantics of the modify operation.
Something like the SLAP_MOD_SOFTADD, which in turn consists in adding an
attribute value only if that value is not already present.
I'd introduce a SLAP_MOD_ADD_IF_NOT_PRESENT flag and add code to support
it in all (well, most) backends/overlays that need to muck with modify
Comments? Objections? p.