Fetching proc arguments and other information

ID:2892719
 
Oct 10 2023, 3:02 am
Applies to:DM Language
Status: Open
Issue hasn't been assigned a status value.
It would be very useful for debug purposes and automatic code testing to be able to read the arguments on a proc path. For debug, we could use this when manually calling specific procs with debug tools so that the user doesn't need to remember the arguments. For automatic testing, we could use it to make sure procs being given to certain automated systems have the arguments needed to be used.

Something like the following:
// Usage
ProcInfo(Object, ProcName)
ProcInfo(ProcRef)

// Example
/datum/proc/ExampleProc(atom/foo=1, obj/bar=2)
  set waitfor = FALSE
  [...]

/datum/proc/GetProcArgs()
  return ProcInfo(src, "ExampleProc")

/datum/proc/AltGetProcArgs()
  return ProcInfo(.proc/ExampleProc)


As for what it returns, the minimum would be the argument names and their types, which could fit within a keyed list. However, ideally it would be good if this could return default argument values and anything that has been set, like set waitfor and such. To get full information out like that you probably need to implement a new type entirely to hold all the info.

// The returned object for the previous example
/datum/procinfo
  var/list/arg_types = list("foo"=/atom, "bar"=/obj)
  var/list/arg_defaults = list("foo"=1, "bar"=2)
  var/list/settings = list("waitfor"=FALSE)


Alternatively multiple procs could be used for this.

ProcArgTypes(src, "ExampleProc")
ProcArgDefaults(src, "ExampleProc")
ProcSettings(src, "ExampleProc")


This ties prety closely with previous requests to make it so you could use initial(thing.args) to be able to get all arg names on uninstanced types and initial(thing.parent_type) which when all combined would allow variable debug tools to display vars grouped by the type they're defined on and could also allow us to do the same for all procs on the object being debugged. The feature in this post alone though would allow for some nice improvements regardless.
Oct 24 2023, 8:26 pm
It came up in conversation that this would be very useful along side the ability to add our own settings. As in:
/atom/proc/has_additional_metadata()
  set nonstandard_setting = TRUE


This would allow us to store and retrieve custom metadata about procs for testing purposes, or some kinds of generic systems. Perhaps define new settings like:

/proc/setting/nonstandard_setting = FALSE