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[REBOL] nargs

From: maarten::vrijheid::net at: 17-Oct-2003 11:53

Here is a nargs function that also counts the optional arguments if you use refinements (e.g. nargs copy == 1 nargs copy/part == 2). Enjoy it. ----------------------------------- nargs: func [ {Returns the total number of args of a function (with and without refinements)} f [word! lit-path!] /local argc f-blk f-ref f-sig ref-pos next-ref-pos ] [ ;The total number or arguments argc: 0 ;We either have a path or a function ;If we have a path, we count the number ;of arguments of the supplied refinements first. either path? f [ ;Translate the path to a block f-blk: to-block f ;Is it a function? if not any-function? get/any first f-blk [throw make error! "Rugby error: invocation not on a function"] bind f-blk 'do ;The refinements used f-ref: next head f-blk ;the function signature f-sig: first get first f-blk ;Now get the number of arguments foreach refinement ;and add them to argc repeat ref f-ref [ ;Find the ref refinement ref-pos: find/tail f-sig to-refinement ref ;If succeed in the find if not none? ref-pos [ ;try to find the next one next-ref-pos: find ref-pos refinement! if not none? next-ref-pos [ argc: argc + ((index? next-ref-pos) - (index? ref-pos)) ];if not none next-ref-pos ];if not none? ref-pos ];foreach ref f-ref ];either path? f first clause [ if not any-function? get/any f [ throw make error! "Rugby error: invocation not on a function" ] f-sig: first get f ];either path? f second clause ;Add the number of function arguments argc: argc + -1 + index? any [ find f-sig refinement! tail f-sig ] ];nargs