From: Vladimir Fekete <fekete@...>
Date: 2008-11-15T20:15:42+09:00
Subject: Re: how to call operator as function



On Sat, Nov 15, 2008 at 08:07:17PM +0900, Sebastian Hungerecker wrote:
> Vladimir Fekete wrote:
> > operators = { "+" => Fixnum.+,
> >               "-" => Fixnum.-,
> 
> "+" => Fixnum.instance_method(:+),
> "-" => Fixnum.instance_method(:-),
> 
> > ? ? ? ? ? ? ? "++" => Myclass.++}
> 
> There is no ++ operator in ruby and you can't define one.

it's Myclasses ++ operator

> 
> 
> > op = "+"
> >
> > result = operators[op](left,right) ?if left.class==Fixnum and
> > right.class==Fixnum
> 
> result = operators[op].bind(left).call(right) if left.is_a?(Fixnum) and 
> right.is_a?(Fixnum)
> 
> 
> Or you skip the whole thing with the hash and just do:
> 
> op = "+"
> result = left.send(op, right)
> 
> 
> HTH,
> Sebastian
> -- 
> Jabber: sepp2k@jabber.org
> ICQ: 205544826
> 
> 

What I'm trying to do is Domain specific language class, for which I could set
up names of variables, functions and operators and then parse and execute
a  string (f.e. "( a + ( b * c ) + sin ( d ) )", where
variables could be hash { "a" => 1, "b" => 2, "c" => 3, "d" => 4} and
functions could be hash again so naturaly I asked whether it is possible to
make it with operators). I tryied to use som ruby's or irb's native
 DSL but withouth success.

V.