Hi *,
could you help me please ? I'm trying to write a code where I could have
operators' functions as values of hash and executing them in way like this
(formal code):
#=============================
operators = { "+" => Fixnum.+,
"-" => Fixnum.-,
"++" => Myclass.++}
op = "+"
result = operators[op](left,right) if left.class==Fixnum and right.class==Fixnum
#============================
is it possible ? Thanks,
Cheers,
V.
++ is not supported by Ruby 
I would do
1.send '+'.to_sym, 2
unless you want to use some esoteric operator mappings, you don't need the hash.
Fixnum.+ doesn't make that much sense because of Ruby's duck typing (and why would you want to restrict yourself to work with just certain objects?)
p.s.: dobre tu vidiet matfyzaka
Cheers,
Peter
On 2008.11.15., at 11:56, Vladimir Fekete wrote:
Hi *,
could you help me please ? I'm trying to write a code where I could have
operators' functions as values of hash and executing them in way like this
(formal code):#=============================
operators = { "+" => Fixnum.+,
"-" => Fixnum.-,
"++" => Myclass.++}op = "+"
result = operators[op](left,right) if left.class==Fixnum and right.class==Fixnum
#============================
Use send, if all operators are binary:
left.send(:+, right)
left.send(:-, right)
etc.
Stefan
2008/11/15 Vladimir Fekete <fekete@melkor.dnp.fmph.uniba.sk>:
Hi *,
could you help me please ? I'm trying to write a code where I could have
operators' functions as values of hash and executing them in way like this
(formal code):#=============================
operators = { "+" => Fixnum.+,
"-" => Fixnum.-,
"++" => Myclass.++}op = "+"
result = operators[op](left,right) if left.class==Fixnum and right.class==Fixnum
#============================is it possible ? Thanks,
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.
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
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==Fixnumresult = 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.
On Sat, Nov 15, 2008 at 08:07:17PM +0900, Sebastian Hungerecker wrote:
Vladimir Fekete wrote:
it's Myclasses ++ operator
You can't define ++ on any class. You just can't. If the parser sees ++
anywhere it interprets it as two calls to +@ or one call to + and one to +@.
HTH,
Sebastian
--
NP: Dire Straits - Your Latest Trick
Jabber: sepp2k@jabber.org
ICQ: 205544826