From: Mike <michaelst@...>
Date: 2007-03-12T18:00:25+09:00
Subject: Re: #define alternative for Ruby

On Mar 12, 4:21 pm, ara.t.how...@noaa.gov wrote:
> On Mon, 12 Mar 2007, Mike wrote:
>
> > I was talking more about macros rather then constants.  But I agree that
> > constant are convenient way to substitute "#define myconst 15". But can you
> > substitute "#define myfunc(x) (sin(x)*cos(x)*exp(x))"?  You should know that
> > "x" could be as much other functions as a constant/variable.
>
> perhaps i'm being dense, but i fail to see how the above example is none other
> than a simple function in ruby:
>
>      harp:~ > cat a.rb
>      def myfunc x
>        Math.sin(x) * Math.cos(x) * Math.exp(x)
>      end
>
>      # x as function
>      def x() 42 end
>      p myfunc(x)
>
>      # x as constant
>      X = 42
>      p myfunc(X)
>
>      # x as variable
>      x = 42
>      p myfunc(x)
>
>      harp:~ > ruby a.rb
>      6.37609775534436e+17
>      6.37609775534436e+17
>      6.37609775534436e+17
>
> text macros like the above are really only useful in static/strong typed
> languages.  in ruby, they are rather meaningless.
>
> regards.
>
> -a
> --
> be kind whenever possible... it is always possible.
> - the dalai lama

Just try to implement:
set_default(var, val)
-- if variable "var" is not defined (not existed) then assign value
"val"