«

hi list.

I have the following code:

#! /usr/bin/ruby


class B
def fun_b
p "B"
end
end

class A
b =3D B.new
end

a =3D A.new
a.b.fun_b

The part that bugs me is this error:
/test.rb:15: undefined method `b' for #<A:0xb7cafb24> (NoMethodError)

What is the way to code the above ideea, so that the last line would be cor=
rect.

I'm running ruby 1.8.3 (2005-09-21) [i486-linux].


--
Regards, Groleo!

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On 16/11/05, Groleo Marius <> wrote:
> hi list.
>
> I have the following code:
>
> #! /usr/bin/ruby
>
>
> class B
> def fun_b
> p "B"
> end
> end
>
> class A
> b =3D B.new
> end
>
> a =3D A.new
> a.b.fun_b
>
> The part that bugs me is this error:
> ./test.rb:15: undefined method `b' for #<A:0xb7cafb24> (NoMethodError)
>
> What is the way to code the above ideea, so that the last line would be c=
orrect.
>
> I'm running ruby 1.8.3 (2005-09-21) [i486-linux].
>

What problem do you want to solve?

Is this maybe nearer to you goals:

class A
class B
def fun_b
p "B"
end
end
end

A::B.new.fun_b

cheers,

Brian

--
http://ruby.brian-schroeder.de/

Stringed instrument chords: http://chordlist.brian-schroeder.de/

Groleo Marius schrieb:
>
> class B
> def fun_b
> p "B"
> end
> end
>
> class A
> b = B.new
> end
>
> a = A.new
> a.b.fun_b
>
> The part that bugs me is this error:
> ./test.rb:15: undefined method `b' for #<A:0xb7cafb24> (NoMethodError)
>
> What is the way to code the above ideea, so that the last line would be correct.

Maybe this is what you want:

class A
attr_reader :b
def initialize
@b = B.new
end
end

Note that here each instance of A has its own instance of B, which might
not be what you want.

Regards,
Pit

On 11/16/05, Brian Schr=F6der <> wrote:
>
> What problem do you want to solve?
>
> Is this maybe nearer to you goals:
>
> class A
> class B
> def fun_b
> p "B"
> end
> end
> end
>
> A::B.new.fun_b
>
> cheers,
>
> Brian
>

Consider the case when class B would have more member functions.
In your example I would have to create a new object for each call to a
B function.
OTOH, a solution that I dont like could be :
class A
class B
def fun_b
p "B"
end
def other_b
p "_B"
end
end
end
b =3D A::B.new
b.fun_b
b.other_b

By the instantion of a new B object in the code from the first post,
and refering to it, I was searching to keep a hierarchy inside a
network protocol.
I couldn't find any hint on google though



--
Regards, Groleo!

# Use "Reply to All" on mailing lists.
# touch universe
# chmod +x universe
# ./universe

On 16/11/05, Groleo Marius <> wrote:
> On 11/16/05, Brian Schr=F6der <> wrote:
> >
> > What problem do you want to solve?
> >
> > Is this maybe nearer to you goals:
> >
> > class A
> > class B
> > def fun_b
> > p "B"
> > end
> > end
> > end
> >
> > A::B.new.fun_b
> >
> > cheers,
> >
> > Brian
> >
>
> Consider the case when class B would have more member functions.
> In your example I would have to create a new object for each call to a
> B function.
> OTOH, a solution that I dont like could be :
> class A
> class B
> def fun_b
> p "B"
> end
> def other_b
> p "_B"
> end
> end
> end
> b =3D A::B.new
> b.fun_b
> b.other_b
>
> By the instantion of a new B object in the code from the first post,
> and refering to it, I was searching to keep a hierarchy inside a
> network protocol.
> I couldn't find any hint on google though
>

Maybe you should look at the delegation pattern. That may be
applicable here. But I have not yet understood your use case. Could
you describe it in a bit more detail?

regards,

Brian

--
http://ruby.brian-schroeder.de/

Stringed instrument chords: http://chordlist.brian-schroeder.de/

On 11/16/05, Brian Schr=F6der <> wrote:
> On 16/11/05, Groleo Marius <> wrote:
> > On 11/16/05, Brian Schr=F6der <> wrote:
> > >
> > > What problem do you want to solve?
> > >
> > > Is this maybe nearer to you goals:
> > >
> > > class A
> > > class B
> > > def fun_b
> > > p "B"
> > > end
> > > end
> > > end
> > >
> > > A::B.new.fun_b
> > >
> > > cheers,
> > >
> > > Brian
> > >
> >
> > Consider the case when class B would have more member functions.
> > In your example I would have to create a new object for each call to a
> > B function.
> > OTOH, a solution that I dont like could be :
> > class A
> > class B
> > def fun_b
> > p "B"
> > end
> > def other_b
> > p "_B"
> > end
> > end
> > end
> > b =3D A::B.new
> > b.fun_b
> > b.other_b
> >
> > By the instantion of a new B object in the code from the first post,
> > and refering to it, I was searching to keep a hierarchy inside a
> > network protocol.
> > I couldn't find any hint on google though
> >
>
> Maybe you should look at the delegation pattern. That may be
> applicable here. But I have not yet understood your use case. Could
> you describe it in a bit more detail?

Sure.
Consider a client script that has to querry a server.
The server operate on users/domains of a running qmail.

So, I would have a class named Client, with the folowing members:
login( user, pass ) logins to the remote administration server
domain an instantion of a domain class.

OTOH Domain class has X member functions:
add( domain_name) adds a new domain
remove
update

So a scenario would look like:

c =3DClient.new #creates a new Domain object
c.login( "foo", "bar" )
c.domain.add( "localdomain" )

Now , back to the code ,the attr_reader was the magic word from what
Pit posted .
Maybe you too observed, but why in ruby
this attr_reader : b is different from attr_reader :b
^space ^no space



--
Regards, Groleo!

# Use "Reply to All" on mailing lists.
# touch universe
# chmod +x universe
# ./universe

On 16/11/05, Groleo Marius <> wrote:
> On 11/16/05, Brian Schr=F6der <> wrote:
> > On 16/11/05, Groleo Marius <> wrote:
> > > On 11/16/05, Brian Schr=F6der <> wrote:
> > > >
> > > > What problem do you want to solve?
> > > >
> > > > Is this maybe nearer to you goals:
> > > >
> > > > class A
> > > > class B
> > > > def fun_b
> > > > p "B"
> > > > end
> > > > end
> > > > end
> > > >
> > > > A::B.new.fun_b
> > > >
> > > > cheers,
> > > >
> > > > Brian
> > > >
> > >
> > > Consider the case when class B would have more member functions.
> > > In your example I would have to create a new object for each call to =
a
> > > B function.
> > > OTOH, a solution that I dont like could be :
> > > class A
> > > class B
> > > def fun_b
> > > p "B"
> > > end
> > > def other_b
> > > p "_B"
> > > end
> > > end
> > > end
> > > b =3D A::B.new
> > > b.fun_b
> > > b.other_b
> > >
> > > By the instantion of a new B object in the code from the first post,
> > > and refering to it, I was searching to keep a hierarchy inside a
> > > network protocol.
> > > I couldn't find any hint on google though
> > >
> >
> > Maybe you should look at the delegation pattern. That may be
> > applicable here. But I have not yet understood your use case. Could
> > you describe it in a bit more detail?
>
> Sure.
> Consider a client script that has to querry a server.
> The server operate on users/domains of a running qmail.
>
> So, I would have a class named Client, with the folowing members:
> login( user, pass ) logins to the remote administration server
> domain an instantion of a domain class.
>
> OTOH Domain class has X member functions:
> add( domain_name) adds a new domain
> remove
> update
>
> So a scenario would look like:
>
> c =3DClient.new #creates a new Domain object
> c.login( "foo", "bar" )
> c.domain.add( "localdomain" )
>
> Now , back to the code ,the attr_reader was the magic word from what
> Pit posted .
> Maybe you too observed, but why in ruby
> this attr_reader : b is different from attr_reader :b
> ^space ^no space
>

Because :b is the symbol :b while : b is a colon followed by a b which
is not allowed syntax here.

cheers,

Brian

--
http://ruby.brian-schroeder.de/

Stringed instrument chords: http://chordlist.brian-schroeder.de/

Groleo Marius <> writes:

> [ ... ]
>
> Now , back to the code ,the attr_reader was the magic word from what
> Pit posted .
> Maybe you too observed, but why in ruby
> this attr_reader : b is different from attr_reader :b
> ^space ^no space

Because colon-identifier represents a symbol, and attr_reader takes
symbols as arguments. The colon is not a separator. For example:]

attr_reader :a, :b, :c

Each of :a, :b, and :c are symbols.


--
Lloyd Zusman

God bless you.