Argument checking while allowing specific assignments

*To*: mathgroup at smc.vnet.net*Subject*: [mg61158] Argument checking while allowing specific assignments*From*: "Ofek Shilon" <ofek at simbionix.com>*Date*: Tue, 11 Oct 2005 04:49:55 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hello dear mathgroup. I'm writing a function that has certain argument checks, e.g. (a simplified version): F[x_,y_] := If[x>12 , Message[F::Overflow], MyF[x_,y_]] that is, the heart of the implementation is in MyF[x_,y_]. Now, further down the session i (or the user) may wish to set specific values for certain arguments. e.g: F[x_,8] := x^2 However, if i write it as above, argument checking is bypassed. the 'proper' way of doing this would be to set MyF[x_,8] as desired, but that holds much confusion potential: i wish for the user to be familiar with a single symbol per function. Anyone knows a mechanism by which i can check the arguments of F, and still be able to assign special values to F (and not it's internal representation)? thanks, Ofek