what will be the effect of this when using the class instead of a real mapping?
You can't set weak flags on it using set_weak_flag.
can i get the name of this_program() as a string?)
function_name(this_program), but it's not always it gives the name you want to show. master()->describe_program(this_program) should do a better job.
`+= was documented as being used for a destructive append. since i want to emulate mappings, += should not be destructive.
It's only used when it's possible to be destructive without observable side-effects. Real mappings can do the same optimization.