Class and Mixin with same method name problem

[petermichaux]

Hi,

I'm trying to call a modual method from a class method with the same
name. The code I tried and error are below. I think my "Debug.whoAmI?"
line is the problem. What is the correct syntax to call the moduals
method?

Thanks,
Peter

==== CODE ===

module Debug
def whoAmI?
"#{self.class.name}"
end
end

class EightTrack
include Debug
def whoAmI?
Debug.whoAmI?
end
end

et = EightTrack.new

p et.whoAmI?


=== OUTPUT ERROR ===

peter$ ruby mixin.rb
mixin.rb:10:in `whoAmI?': undefined method `whoAmI?' for Debug:Module
(NoMethodError)
from mixin.rb:16

 

[Stefan Lang]

Hi,

I'm trying to call a modual method from a class method with the
same name. The code I tried and error are below. I think my
"Debug.whoAmI?" line is the problem. What is the correct syntax to
call the moduals method?

Thanks,
Peter

=3D=3D=3D=3D CODE =3D=3D=3D

module Debug
def whoAmI?
"#{self.class.name}"
end
end

class EightTrack
include Debug
def whoAmI?
Debug.whoAmI?
end
end

et =3D EightTrack.new

p et.whoAmI?


=3D=3D=3D OUTPUT ERROR =3D=3D=3D

peter$ ruby mixin.rb
mixin.rb:10:in `whoAmI?': undefined method `whoAmI?' for
Debug:Module (NoMethodError)
from mixin.rb:16

Try this:
=2D---------------------
module Debug
=A0 def whoAmI?
=A0 =A0 "#{self.class.name}"
=A0 end
end

class EightTrack
=A0 include Debug
end

et =3D EightTrack.new

p et.whoAmI?
=2D---------------------

Regards,
Stefan

 

[ts]

p> class EightTrack
p> include Debug
p> def whoAmI?
p> Debug.whoAmI?

super

p> end
p> end


Guy Decoux

 

[petermichaux]

ts, Thank you. Peter

 

[petermichaux]

What if two moduals are included and each uses the same method name? In
the example below the Debug whoAmI? method is called. How do I call the
Burp whoAmI? method?

Thanks,
Peter

module Debug
def whoAmI?
"#{self.class.name}"
end
end

module Burp
def whoAmI?
"Burp #{self.class.name}"
end
end

class EightTrack
include Burp
include Debug
def whoAmI?
super
end
end

et = EightTrack.new

p et.whoAmI?

 

[Stefan Lang]

What if two moduals are included and each uses the same method
name? In the example below the Debug whoAmI? method is called. How
do I call the Burp whoAmI? method?

There is no clean and simple way to do so.

module Debug
def whoAmI?
"#{self.class.name}"
end
end

module Burp
def whoAmI?
"Burp #{self.class.name}"
end
end

class EightTrack
include Burp
include Debug

The following method definition is useless.
Remove it and you'll get the same result.

 

[petermichaux]

no clean and simple way? bummer. I thought there would be some sort of
namespace separation between the two moduals. When they are mixed into
the EightTrack class are the namespaces lost?

 

[Robert Klemme]

What if two moduals are included and each uses the same method name?
In the example below the Debug whoAmI? method is called. How do I
call the Burp whoAmI? method?

You don't (although you could with
Burp.instance_methodwhoAmI?).bind(self).call). Messing like this with
names is not advisable.

Note also that "self.class.name" will always yield the same result
regardless in which module the method was defined. Note also that by
convention a) methods ending in a question mark are reserved for boolean
queries and b) Ruby uses lowe_case_method_names.

Kind regards

robert

 

[petermichaux]

You don't (although you could with
Burp.instance_methodwhoAmI?).bind(self).call). Messing like this with names is not advisable.

Good to know that there is a way to do this. Too bad it is so messy
though. I'm thinking about using two Rails plugins in one model class.
Since rails has a magic after_find callback method I was thinking about
using this in each plugin since the plugins can be used independently.
Since my model must call both of these methods I will have a third
after_find callback method in the model that calls the other two. Now
why doesn't the example below make two who_am_i calls? One to Burp and
one to Debug. It only calls Burp.

Note also that by
convention a) methods ending in a question mark are reserved for boolean
queries and b) Ruby uses lowe_case_method_names.

Good to know. I just cut and pasted the example from the the first
edition of Ruby Programming

http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_modules.html

Peter


module Debug
def who_am_i
"Debug"
end
end

module Burp
def who_am_i
"Burp"
end
end

class EightTrack
include Burp
include Debug
def who_am_i
Debug.instance_methodwho_am_i).bind(self).call
Burp.instance_methodwho_am_i).bind(self).call
end
end

et = EightTrack.new

p et.who_am_i

 

[Robert Klemme]

Good to know that there is a way to do this. Too bad it is so messy
though. I'm thinking about using two Rails plugins in one model class.
Since rails has a magic after_find callback method I was thinking
about using this in each plugin since the plugins can be used
independently. Since my model must call both of these methods I will
have a third after_find callback method in the model that calls the
other two.

I don't know Rails so I can't comment on this. I just would assume that DHH
would have thought of this scenario. At least it sounds reasonable. Or
you're abusing these plugins.

Now why doesn't the example below make two who_am_i calls?
One to Burp and one to Debug. It only calls Burp.

Wrong. Look again.

Good to know. I just cut and pasted the example from the the first
edition of Ruby Programming

http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_modules.html

Indeed. Then that's a sub optimal example.

Peter


module Debug
def who_am_i
"Debug"
end
end

module Burp
def who_am_i
"Burp"
end
end

class EightTrack
include Burp
include Debug
def who_am_i
Debug.instance_methodwho_am_i).bind(self).call
Burp.instance_methodwho_am_i).bind(self).call
end
end

et = EightTrack.new

p et.who_am_i

Kind regards

robert

 

[daz]

Wrong. Look again.

Peter, you've annoyed Robert - he won't help you now ;-)

If you go to the trouble of calling a method, you may as well
do something with its return value rather than just losing it.


module Debug
def who_am_i
'Debug'
end
end

module Burp
def who_am_i
'Burp'
end
end

module Throb
# #def who_am_i
# # 'Throb'
# #end
end

class EightTrack
include Burp
include Throb
include Debug
def who_am_i
wai = [self.class]
( self.class.ancestors - [Object, Kernel] - wai ).each do |a|
( wai << a.instance_methodwho_am_i).bind(self).call ) rescue nil
end
wai
end
end

et = EightTrack.new

p et.who_am_i # [EightTrack, "Debug", "Burp"]



daz

 

[petermichaux]

(e-mail address removed) wrote:

Wrong. Look again.

Victim of a new language. I got it. Thanks!

Peter

 

[petermichaux]

If you go to the trouble of calling a method, you may as well
do something with its return value rather than just losing it.

Actually Robert's cryptic smiley lead me to this. But thanks for the
straight goods.

Peter

 

[Robert Klemme]

Peter, you've annoyed Robert - he won't help you now ;-)

LOL. No, not really. (Now you want to know where that "no" refers to...
))

Kind regards

robert