Can a function find its own name?
I am looking for things I can put it a program so that if the program crashes to a command prompt I can probe around for helpful information. It occurred to me that if, when I call a function, that function could make a note of its own name in some place, then I could probe that 'some place' to find the last function called. Of course I could just hard-code the function name, but where would the fun be in that:
FUNCTION-1: does [
MOST-RECENT-FUNCTION-CALL: copy 'FUNCTION-1'
...other function code...
]
Thank you.
posted by: Steven White 10-Feb-2016/11:53:13-8:00
It can’t because the function is anonymous, it doesn’t have any name. What you have is word FUNCTION-1 that holds value of type FUNCTION!.
To explain it bit more: you can do FUNCTION-2: :FUNCTION-1 and now both FUNCTION-1 and FUNCTION-2 point to same function. What should it log in this case? So if you want to log it somehow, some hardcoded solution is probably the easiest way to go.
posted by: rebolek 10-Feb-2016/12:24:47-8:00
As rebolek says, functions do not necessarily have names.
When they do, this R2 trick gets you the name:
function-1: func [][print get in disarm try [0 / 0] 'where]
The trick works because the error! returned from the try [0 / 0] contains the name of the function - if it has one.
posted by: Sunanda 10-Feb-2016/13:24:24-8:00
Thank you both. This hits my "third-generation" thinking that I have so much trouble getting out of.
If I pursue this idea I will go with the hard-coding because it is more obvious to the reader.
posted by: Steven White 10-Feb-2016/13:47:05-8:00
R3-Alpha had a STACK function which can give you the name of the word a function was invoked with...if you happened to invoke the function with a word:
>> foo: func [] [stack 0]
>> bar: func [] [foo]
>> baz: func [] [apply :bar []]
>> baz
== [stack foo -apply- apply baz]
Ren-C has much more powerful features in the form of BACKTRACE and FRAME!.
>> foo: func [x y] [
frame: context-of 'x
print ["The type of frame is" type-of frame]
print mold frame
print ["The frame was labeled with" label-of frame]
]
>> foo 10 "Twenty"
The type of frame is frame!
make frame! [
x: 10
y: "Twenty"
return: ...
]
The frame was labeled with foo
Debug features are new developments, being worked on alongside other foundational fixes, and will be a priority after "specific binding", which will hopefully be solved once and for all...eliminating the need for CLOSURE!.
https://github.com/metaeducation/ren-c/wiki/Relative-Binding-and-FRAME!-Internals
posted by: Fork 10-Feb-2016/15:07:35-8:00
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posted by: nike air max 90 dam rea 24-Aug-2016/20:41:52-7:00
1. >> ? trace
2. >> ? disarm
3. >> ? throw-on-error
Let the RVC work for you.
posted by: Time Series Lord 4-Oct-2016/18:30:38-7:00
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