I need to be able to create an object and, based on the param that I
pass in on the class create_for_sport method, create an object with the
proper module included.
It can be seen at the bottom by the comments I made that the includes
are being added on to the Stats class and the methods from the first
include are still there after the second include. Is there a way to add
an include to an object instance rather than a class?
Thanks for the help
########
module SoftballStats
def to_sport
puts “softball”
end
def batting_average
0.563
end
def before_save
puts “in the softball before save”
end
end
module HockeyStats
def to_sport
puts “hockey”
end
def scoring_percentage
0.34
end
def before_save
puts “in the hockey before save”
end
end
class Stats
def self.create_by_sport(sport)
s = Stats.new
s.sport = sport
return s
end
def sport=(sport)
Stats.instance_eval do # have tried to use self.instance_eval
eval(“include #{sport.capitalize}Stats”)
end
end
end
s = Stats.create_by_sport(“softball”)
puts s.batting_average # 0.563
h = Stats.create_by_sport(“hockey”)
puts h.scoring_percentage # 0.34
puts h.batting_average # 0.563 -> still has this method
s.before_save # “in the hockey save” -> softball before_save is now
overridden
h.before_save # “in the hockey save”
On Jul 15, 11:38 pm, Chris O. [email protected] wrote:
def before_save
def scoring_percentage
end
Couple of ways. One is to use the singleton.
def sport=(sport)
(class << self; self; end).class_eval %{
include #{sport.capitalize}Stats
}
end
But I think you might want to reconsider and use delegation instead.
T.
Trans wrote:
On Jul 15, 11:38�pm, Chris O. [email protected] wrote:
� def before_save
� def scoring_percentage
� end
Couple of ways. One is to use the singleton.
def sport=(sport)
(class << self; self; end).class_eval %{
include #{sport.capitalize}Stats
}
end
But I think you might want to reconsider and use delegation instead.
T.
Thanks so much. To be honest I have no idea what the (class << self;
self; end), but it will make for good reading :). I will look into the
delegation as well.
Thanks again.
Hi Chris,
I need to be able to create an object and, based on the param that I
pass in on the class create_for_sport method, create an object with the
proper module included.
You can call extend on an instance to mix in a modules instance
methods to the instance (and leaving the class itself alone). In your
code, we also need to convert your string to a reference to the module
as well, via a call to const_get. And this would be your new sport=
method:
def sport=(sport)
extend(self.class.const_get(sport.capitalize + “Stats”))
end
I believe that will work for you.
Eric
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On Jul 16, 12:11 pm, “Eric I.” [email protected] wrote:
method:
LearnRuby.com offers Rails & Ruby HANDS-ON public & ON-SITE workshops.
Please visithttp://LearnRuby.comfor all the details.
you should put module(s) into class ,to ensure class Stats has the
permission of module,so try following code
class Stats
module HockeyStats
def to_sport
puts “hockey”
end
def scoring_percentage
0.34
end
def before_save
puts "in the hockey before save"
end
end
module SoftballStats
def to_sport
puts “softball”
end
def batting_average
0.563
end
def before_save
puts "in the softball before save"
end
end
def self.create_by_sport(sport)
s = Stats.new
s.sport = sport
return s
end
def sport=(sport)
eval “extend #{sport.to_s.capitalize}Stats”
end
end