Dynamic include

Ruby
1

Hello,

I try to include some modules to a class instance, but I have
problems with the scope, here’s what I did:

person.roles.each do |role|
class << person
include role.class.const_get(‘Functions’)
end if role.class.const_defined?(‘Functions’)
end unless person.nil?

As you can see role is not defined when I include it, does anybody
know how I can add some singleton methods to person?

Regards
Florian

2

Florian AÃ?mann wrote:

As you can see role is not defined when I include it, does anybody know
how I can add some singleton methods to person?

Maybe the module Functions is the culprit? Are the methods module
functions (“def self.some_method”), or mixin functions (“def
some_method”) in the module?

David V.

3

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Am 01.10.2006 um 20:53 schrieb David V.:

David V.

Mixin:

class ManagerRole < Role
module Functions
def hire( person )
self.company << person
end
end
end

Florian
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4

Florian AÃ?mann wrote:

To be complete here if the Exception:

NameError: undefined local variable or method `role’ for
#<Class:#Person:0x2869aa0>

I smell a Ruby bug / gotcha.

Apparently, in metaclass scope, the surrounding scope just isn’t
visible.

Try a workaround:

person.roles.each do |role|
if role.class.const_defined?(‘Functions’)
class << person
self
end.class_eval do
include role.class.const_get(‘Functions’)
end
end
end unless person.nil?

David V.

PS: Statement modifiers after whole blocks? Ick.

5

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Am 01.10.2006 um 21:14 schrieb David V.:

visible.
end
end unless person.nil?

David V.

PS: Statement modifiers after whole blocks? Ick.

Ok, I just tested it, but now even a person with a CustomerRole and
no ManagerRole role has the methods once they are included, thanks
anyway. :smiley:
dblack, extend works excactly the way I want it to, thank you too :slight_smile:

Result…

if person = self.send( dyn_finder, *find_args )
m_name = ‘Functions’
functions = person.roles.inject([]) do |f,r|
r.class.const_defined?(m_name) and
f << r.class.const_get(m_name)
end and person.extend *functions
end

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6

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Am 01.10.2006 um 20:53 schrieb David V.:

David V.

To be complete here if the Exception:

NameError: undefined local variable or method role' for #<Class:#<Person:0x2869aa0>> /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/ active_record/base.rb:1129:inmethod_missing’
/Users/boof/Documents/Workspaces/rails/comany/config/…/app/
models/person.rb:63:in auth' /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/ active_record/associations/association_proxy.rb:110:ineach’
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/
active_record/associations/association_proxy.rb:110:in send' /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/ active_record/associations/association_proxy.rb:110:inmethod_missing’
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.14.4/lib/
active_record/associations/has_and_belongs_to_many_association.rb:
81:in method_missing' /Users/boof/Documents/Workspaces/rails/comany/config/../app/ models/person.rb:60:inauth’
test/unit/person_test.rb:37:in `test_4_change_password’

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