如何使用可变函数名称调用standardGeneric

Question

The following code throws a warning:

test_slot = "testslot"

setGeneric(name = test_slot, 
           def = function(object){
               standardGeneric(test_slot)
           },
           where = globalenv()
)



[1] "testslot"
Warning message:
In .recursiveCallTest(body, fname) :
  the body of the generic function for ‘testslot’ calls 'standardGeneric' to dispatch on a different name ("test_slot")!

I would have expected that it would have been equivalent to:

setGeneric(name = "testslot", 
           def = function(object){
               standardGeneric("testslot")
           },
           where = globalenv()
)

What happened?

Answer 1

This does not answer why the original block of code failed, but a workaround would be to do:

test_slot = "testslot"

setGeneric(name = test_slot, 
           def = eval(parse(text = paste0("function(object){",

           "standardGeneric('", test_slot, "')",
       "}")))
           },
           where = globalenv()
)

that is, construct the entire def argument to be an evaluated function.