Re: Re: Length of actual parameters in a function call.

*To*: mathgroup at smc.vnet.net*Subject*: [mg47130] Re: [mg47124] Re: Length of actual parameters in a function call.*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Sat, 27 Mar 2004 01:34:33 -0500 (EST)*References*: <c3udpe$9om$1@smc.vnet.net> <200403260856.DAA23010@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 26 Mar 2004, at 08:56, Paul Abbott wrote: > In article <c3udpe$9om$1 at smc.vnet.net>, > "E. Martin-Serrano" <eMartinSerrano at houston.rr.com> wrote: > >> A few weeks ago, reviewing some tutorials on pattern matching and >> error >> handling, I came across an undocumented function to monitor the >> number of >> parameters submitted to a function in a call; but somehow I lost its >> track >> later. I guess that it must be something well-known by our >> specialists. Any >> help about where to locate it? >> >> The undocumented feature helps in tracking situations as when we >> define >> "MyFunction[a_,b_,c_]:= something" and then it is called as >> "myFunction[a]" >> leaving the function unevaluated. > > MyFunction[a_, b_, c_] := something > > MyFunction[args___] := Null /; Length[{args}] != 3 && > Message[MyFunction::argx, MyFunction, Length[{args}]] > > MyFunction[a] > > Cheers, > Paul > > -- > Paul Abbott Phone: +61 8 9380 2734 > School of Physics, M013 Fax: +61 8 9380 1014 > The University of Western Australia (CRICOS Provider No 00126G) > 35 Stirling Highway > Crawley WA 6009 mailto:paul at physics.uwa.edu.au > AUSTRALIA http://physics.uwa.edu.au/~paul > > > This does not seem to produce the correct message; I think you need something like: MyFunction[a_, b_, c_] := something MyFunction::"argx" = "MyFunction called with `1` arguments, 3 arguments are \ expected." MyFunction[args___] := Null /; Length[{args}] != 3 && Message[MyFunction::argx, Length[{args}]] MyFunction[a] Andrzej Kozlowski Chiba, Japan http://www.mimuw.edu.pl/~akoz/

**References**:**Re: Length of actual parameters in a function call.***From:*Paul Abbott <paul@physics.uwa.edu.au>