Re: Checking function syntax

*To*: mathgroup at smc.vnet.net*Subject*: [mg64582] Re: [mg64555] Checking function syntax*From*: jmt <jmt at dxdydz.net>*Date*: Thu, 23 Feb 2006 00:34:19 -0500 (EST)*References*: <200602221058.FAA23476@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On Wednesday 22 February 2006 11:58, Chris Rodgers wrote: > Hi, > > How can I make my own functions give an error if they are called with > the wrong syntax? Try this : Here is your standard definition : MyFunc1[x_, y_] := Tuples[{x, y}, 2] Define your error message : MyFunc1::"WrongInput" = "A sensible error message for incorrect input `1`" Create the rule that match wrong input : MyFunc1[u___] := Message[MyFunc1::"WrongInput", u] Check normal function call : Map[MyFunc2, MyFunc1[a, b]] And incorrect one : Map[MyFunc2, MyFunc1[a, b, c]] Mind the fact that in some situations some rules might have equal priorities, in which case rule definition ordering defines which rule will be called.

**References**:**Checking function syntax***From:*Chris Rodgers <rodgers@physchem.NOSPAMox.aREMOVEc.uk>