A question on a couple things relating to extending a class and the use of
super.
In my main application I have the following class which extends an engine
class:
class User < ActiveRecord::Base
def self.find_for_database_authentication(login_value,
omniauth_provider=nil, omniauth_uid=nil)
super if login_value
where(''omniauth_provider=? AND omniauth_uid=?'',
omniauth_provider,
omniauth_uid)
end
end
And the engine has this class:
class User < ActiveRecord::Base
def self.find_for_database_authentication(login_value)
where(["username = :value OR email = :value", { :value =>
login_value
}]).first
end
end
When I run a spec to try out the method, I get this error:
Failure/Error:
User.find_for_database_authentication(@user.username).class == User
NoMethodError:
super: no superclass method `find_for_database_authentication''
for
#<Class:0x1057bbfa0>
I do understand why -- my application class is not a subclass of the engine
class, I am just extending the class. This leaves me with the question if
there is a way to have access to the original method (like using super in a
subclass situation) so I would not have to duplicate that code (I would have
subclassed my class to the engine class but is a bit nasty as they share the
same name, and that is structurally how the app is loaded)?
Also, I am confused also as to why I see in places that to extend a class
they use "MyClass.class_eval do ....." whereas it seems that if I just
do
what I have above, I get the same ability. Am I missing something?
Anyhow, any comments appreciated!
David
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On 11 May 2011, at 18:17, David Kahn <dk-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org> wrote:> A question on a couple things relating to extending a class and the use of super. > > In my main application I have the following class which extends an engine class:You are reopening the class (ie adding/changing methods in User), not subclassing it, so super is looking for methods in activerecord::base. Did you want to subclass User instead? Fred> > class User < ActiveRecord::Base > def self.find_for_database_authentication(login_value, omniauth_provider=nil, omniauth_uid=nil) > super if login_value > where(''omniauth_provider=? AND omniauth_uid=?'', omniauth_provider, omniauth_uid) > end > end > > And the engine has this class: > > class User < ActiveRecord::Base > def self.find_for_database_authentication(login_value) > where(["username = :value OR email = :value", { :value => login_value }]).first > end > end > > When I run a spec to try out the method, I get this error: > Failure/Error: User.find_for_database_authentication(@user.username).class == User > NoMethodError: > super: no superclass method `find_for_database_authentication'' for #<Class:0x1057bbfa0> > > I do understand why -- my application class is not a subclass of the engine class, I am just extending the class. This leaves me with the question if there is a way to have access to the original method (like using super in a subclass situation) so I would not have to duplicate that code (I would have subclassed my class to the engine class but is a bit nasty as they share the same name, and that is structurally how the app is loaded)? > > Also, I am confused also as to why I see in places that to extend a class they use "MyClass.class_eval do ....." whereas it seems that if I just do what I have above, I get the same ability. Am I missing something? > > Anyhow, any comments appreciated! > > David > > -- > You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. > To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org > To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. > For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
On Wed, May 11, 2011 at 12:52 PM, Frederick Cheung < frederick.cheung-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> > On 11 May 2011, at 18:17, David Kahn <dk-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org> wrote: > > A question on a couple things relating to extending a class and the use of > super. > > In my main application I have the following class which extends an engine > class: > > > You are reopening the class (ie adding/changing methods in User), not > subclassing it, so super is looking for methods in activerecord::base. > > Did you want to subclass User instead? >I tried but the thing is that the way the engine loads, the engine class and my class have the same name and reside in the local app. I guess I could give my class a different name to subclass it if I dont want to dup the code. Was just wondering if there was some other way but logically does not seem that there is.> > Fred > > > class User < ActiveRecord::Base > def self.find_for_database_authentication(login_value, > omniauth_provider=nil, omniauth_uid=nil) > super if login_value > where(''omniauth_provider=? AND omniauth_uid=?'', omniauth_provider, > omniauth_uid) > end > end > > And the engine has this class: > > class User < ActiveRecord::Base > def self.find_for_database_authentication(login_value) > where(["username = :value OR email = :value", { :value => login_value > }]).first > end > end > > When I run a spec to try out the method, I get this error: > Failure/Error: > User.find_for_database_authentication(@user.username).class == User > NoMethodError: > super: no superclass method `find_for_database_authentication'' for > #<Class:0x1057bbfa0> > > I do understand why -- my application class is not a subclass of the engine > class, I am just extending the class. This leaves me with the question if > there is a way to have access to the original method (like using super in a > subclass situation) so I would not have to duplicate that code (I would have > subclassed my class to the engine class but is a bit nasty as they share the > same name, and that is structurally how the app is loaded)? > > Also, I am confused also as to why I see in places that to extend a class > they use "MyClass.class_eval do ....." whereas it seems that if I just do > what I have above, I get the same ability. Am I missing something? > > Anyhow, any comments appreciated! > > David > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Talk" group. > To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org > To unsubscribe from this group, send email to > rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org > For more options, visit this group at > http://groups.google.com/group/rubyonrails-talk?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Talk" group. > To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org > To unsubscribe from this group, send email to > rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org > For more options, visit this group at > http://groups.google.com/group/rubyonrails-talk?hl=en. >-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
On May 11, 7:01 pm, David Kahn <d...-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org> wrote:> On Wed, May 11, 2011 at 12:52 PM, Frederick Cheung < > > frederick.che...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: > > > On 11 May 2011, at 18:17, David Kahn <d...-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org> wrote: > > > A question on a couple things relating to extending a class and the use of > > super. > > > In my main application I have the following class which extends an engine > > class: > > > You are reopening the class (ie adding/changing methods in User), not > > subclassing it, so super is looking for methods in activerecord::base. > > > Did you want to subclass User instead? > > I tried but the thing is that the way the engine loads, the engine class and > my class have the same name and reside in the local app. I guess I could > give my class a different name to subclass it if I dont want to dup the > code. Was just wondering if there was some other way but logically does not > seem that there is. >You another way is to use alias_method_chain - you''d do something like class Foo class << self def something_with_foo end alias_method_chain :something, :foo end end end What this does is rename the existing something method to something_without_foo and renames your something_with_foo method to something. Instead of calling super you call something_without_foo to call the old something_method Fred -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
On Wed, May 11, 2011 at 3:29 PM, Frederick Cheung < frederick.cheung-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> On May 11, 7:01 pm, David Kahn <d...-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org> wrote: > > On Wed, May 11, 2011 at 12:52 PM, Frederick Cheung < > > > > frederick.che...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: > > > > > On 11 May 2011, at 18:17, David Kahn <d...-rfEMNHKVqOwNic7Bib+Ti1W1rNmOCjRP@public.gmane.org> > wrote: > > > > > A question on a couple things relating to extending a class and the use > of > > > super. > > > > > In my main application I have the following class which extends an > engine > > > class: > > > > > You are reopening the class (ie adding/changing methods in User), not > > > subclassing it, so super is looking for methods in activerecord::base. > > > > > Did you want to subclass User instead? > > > > I tried but the thing is that the way the engine loads, the engine class > and > > my class have the same name and reside in the local app. I guess I could > > give my class a different name to subclass it if I dont want to dup the > > code. Was just wondering if there was some other way but logically does > not > > seem that there is. > > > > You another way is to use alias_method_chain - you''d do something like > > class Foo > class << self > def something_with_foo > > end > > alias_method_chain :something, :foo > end > end > end > > What this does is rename the existing something method to > something_without_foo and renames your something_with_foo method to > something. Instead of calling super you call something_without_foo to > call the old something_method >Oh, that is interesting. I guess which would have be used carefully or could get confusing. This will be fun to play with. Thanks!> > Fred > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Talk" group. > To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org > To unsubscribe from this group, send email to > rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org > For more options, visit this group at > http://groups.google.com/group/rubyonrails-talk?hl=en. > >-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.