Ellipsis Function Arguments
Added October 2018
The use of ellipsis (...) in argument lists facilitates passing arguments through a wrapper function. An example will make this more clear. Consider the following function:
Function Fn'DynFunc$(fn$ as s260:inputonly, ...) as s0
on error goto trap
Fn'DynFunc$ = dynfunc$(fn$, ...)
exitfunction
trap:
if err(0) = 72 then ! if function not found
Fn'DynFunc$ = .NULL ! set result to null
resume endfunction ! and return with no error
else
resume endfunction with_error ! else pass error through
endif
EndFunction
The function serves as a wrapper to the underlying dynfunc$() call; it adds value by trapping the function-not-found error and returning .NULL instead. The ellipsis mechanism eliminates what would otherwise be a sticky problem - we have no idea how many parameters will be passed, so there is no good way to code the dynfunc$() call. With the ellipsis mechanism, the "..." in the dynfunc$(fn$, ...) call is replaced by the actual parameters corresponding to the ...in the Fn'DynFunc$() call, allowing us to pass them through without knowing anything about them.
History
2018 September, A-Shell 6.5.1647, compiler edit 880: Added function to A-Shell
