[REBOL] Re: Reflectivity: How a function can know its own name ?
From: sunandadh:aol at: 24-Mar-2002 15:10
laplace:
> In rebol doc, it is said that function can know himself
> (its argument, its code) but I can't see how it can know
> just its name : it would seem logical that it is the firts
> thing it should know :) ?
the "name" of a function is a problematic concept in Rebol. Take this code,
for example:
myfunc1: func [] [
print "what's my name?"
do func [] [
print "what's _my_ name?"
] ; end unnamed func
0 / 0 ; cause error in myfunc1
] ; end myfunc1
;; we've just defined a function "called" myfunc1 that creates and executes
;; an unnamed function on the fly
myfunc1
;; we get an error message saying error in myfunc1. So far, so normal.
myfunc2: :myfunc1
myfunc2
;; But we've now assigned a second name to the function: both
;; myfunc1 and myfunc2 refer to the _same_ definition.
myfunc3: do load mold :myfunc1
myfunc3
;; Unlike this where myfunc3 is a different function
same? :myfunc1 :myfunc2
same? :myfunc1 :myfunc3
equal? :myfunc1 :myfunc3
equal? mold :myfunc1 mold :myfunc3
;; (A little mystery: why are :myfunc1 and :myfunc3
;; different, but molds of them are equal?)
;; Next: make five copies of the function in a
;; block, and execute one of them. You could
;; argue that the name of the function is
;; myfuncs/5 -- but what if the block had no
;; name?
myfuncs: copy []
loop 5 [append myfuncs :myfunc1]
myfuncs/5
Sunanda.
