# Ellipsis Function Arguments

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_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