where's the best place to dynamically add singleton method?

[Iain Barnett]

Hi,

If I've got a simple bit of initialisation code

def initialize( blah )
@listener =3D Blah.new blah
end

and I'd like to add a singleton method to instance (because I don't want =
to monkey patch the Blah library) where's the best place to do that? I =
know I could do:

def initialize( blah )
@listener =3D Blah.new blah
def @listener.my_mental_method
self.give_it_up! "quickly"
end
end

but is this a good place to do it, or is there something more =
eloquent/perfomant? I'd like all instances, wherever they are created, =
to have this method, so is there a better way altogether?

Just wondering.

Regards,
Iain=

 

[Robert Klemme]

Hi,

If I've got a simple bit of initialisation code

=A0 =A0def initialize( blah )
=A0 =A0 =A0@listener =3D Blah.new blah
=A0 =A0end

and I'd like to add a singleton method to instance (because I don't want =

to monkey patch the Blah library) where's the best place to do that? I know=
I could do:

=A0 =A0def initialize( blah )
=A0 =A0 =A0@listener =3D Blah.new blah
=A0 =A0 =A0def @listener.my_mental_method
=A0 =A0 =A0 =A0self.give_it_up! "quickly"

No self needed here.

=A0 =A0 =A0end
=A0 =A0end

but is this a good place to do it, or is there something more eloquent/pe=

rfomant? I'd like all instances, wherever they are created, to have this me=
thod, so is there a better way altogether?

First of all, I'd place the method in a module so you have less
definitions around. Then I'd extend all instances with that module.
That also makes for easy addition of more methods.

module BlahExt
def your_mental_method
give_it_up! 'rather sooner than later'
end
end

The automatic part could be handled by changing Bar's #new:

class <<Blah
alias _new new

def new(*a,&b)
_new(*a,&b).extend BlahExt
end
end

Note that this does not deal with inheritance nicely. For that you
could do something similar with Bar's #initialize instead of #new.

If you do not need a global automatic I'd simply stick with

def initialize( blah )
@listener =3D Blah.new(blah).extend BlahExt
end

Kind regards

robert

--=20
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

 

[Kresimir Bojcic]

[Note: parts of this message were removed to make it a legal post.]

I think you can achieve functionality that you desire by using mixins,
modules and include statement... like this


module CoolMethods
def my_mental_method
....
end
end

class UnfortunateUserOfCoolMethod

include CoolMethods
....

end

Also if you need method on a class you can use extend intstead of
include....


Best Regards,

Kresimir Bojcic

www.kresimirbojcic.com

 

[Iain Barnett]

want to monkey patch the Blah library) where's the best place to do =
that? I know I could do:

=20
No self needed here.
=20

eloquent/perfomant? I'd like all instances, wherever they are created, =
to have this method, so is there a better way altogether?

=20
First of all, I'd place the method in a module so you have less
definitions around. Then I'd extend all instances with that module.
That also makes for easy addition of more methods.
=20
module BlahExt
def your_mental_method
give_it_up! 'rather sooner than later'
end
end
=20
The automatic part could be handled by changing Bar's #new:
=20
class <<Blah
alias _new new
=20
def new(*a,&b)
_new(*a,&b).extend BlahExt
end
end
=20
Note that this does not deal with inheritance nicely. For that you
could do something similar with Bar's #initialize instead of #new.
=20
If you do not need a global automatic I'd simply stick with
=20
def initialize( blah )
@listener =3D Blah.new(blah).extend BlahExt
end
=20
Kind regards
=20
robert
=20
--=20
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/
=20

I think you can achieve functionality that you desire by using mixins,
modules and include statement... like this
=20
=20
module CoolMethods
def my_mental_method
....
end
end
=20
class UnfortunateUserOfCoolMethod
=20
include CoolMethods
....
=20
end
=20
Also if you need method on a class you can use extend intstead of
include....
=20
=20
Best Regards,
=20
Kresimir Bojcic
=20
www.kresimirbojcic.com

Thanks to you both for the input. Sorry I didn't reply sooner but was =
snowed under with other things and wanted to think about it and do a bit =
of research. I've been reading a lot more on what's going on with =
details of the Ruby inheritance model, all that stuff in the background =
that I was getting along with fine without till now (which I think is a =
testament to the language), and your answers helped.=20

Due to this I refactored things quite significantly so I've ended up not =
using this directly, but I've gone further for it.

Much appreciated

Regards,
Iain

 

[Robert Klemme]

Thanks to you both for the input. Sorry I didn't reply sooner but was
snowed under with other things and wanted to think about it and do a
bit of research. I've been reading a lot more on what's going on with
details of the Ruby inheritance model, all that stuff in the
background that I was getting along with fine without till now (which
I think is a testament to the language), and your answers helped.

Due to this I refactored things quite significantly so I've ended up
not using this directly, but I've gone further for it.

Much appreciated

I'm glad to hear that we could help you. Thank you for letting us know!

Kind regards

robert