Plugin Patterns eager loading

[Leandro Pedroni]

Hi, I was playing with the recipe on the plugin pattern pdf on page
21:

module MyModule

def self.included(base)
base.extend ClassMethods
base.include InstanceMethods
end

module ClassMethods...
module InstanceMethods...

end

But if I send the include to a class it complains since I'm calling -
include- on what is passed in the -self.included- hook
Changing that bit into:

def self.included (base)
base.extend ClassMethods
base.class_eval do
include InstanceMethods
end
end

produces the desired effect. Is the other one incorrect? Was the
module intended to included from somewhere in particular?

thanks,
Leandro

[Andrew Stewart]

Hi Leandro,

Please could you send me the code you're using to include your module
in a class? I'll have a better idea then what the problem might be.

Normally I would do something like this:

class MyClass
include MyModule
end

Or even:

MyClass.send :include, MyModule

Have you had a chance to read the section on Modules, pages 7-10? If
not, you might find the answer there.

Regards,
Andy

-------
Andrew Stewart
AirBlade Software Ltd
http://airbladesoftware.com

[Leandro Pedroni]

They both yield the same result:
=> NoMethodError: private method ‘include’ called for MyClass:Class

This is the full code (inspired by page 21) that throws me the error:

module MyModule
def self.included(base)
base.extend ClassMethods
base.include InstanceMethods
end

module ClassMethods

def classy
puts "Stay classy"
end
end

module InstanceMethods
def instance_m
puts "I'm an instance method"
end
end
end

class MyClass
include MyModule
end

MyClass.classy

Leandro

[Andrew Stewart]

On 3 Apr 2009, at 23:25, Leandro Pedroni wrote:
> They both yield the same result:
> => NoMethodError: private method ‘include’ called for MyClass:Class
>
> This is the full code (inspired by page 21) that throws me the error:
>
> module MyModule
> def self.included(base)
> base.extend ClassMethods
> base.include InstanceMethods
> end

<-- ... -->
> end

I think you have found a mistake on page 21, for which I apologise!
The problem is that +include+ is a private method of class Module; and
private methods cannot be called with receivers. The only way to call
+include+ on something other than +self+ is to bypass the private
restriction by sending the :include message like this:

base.send :include, InstanceMethods

You can see this technique on p.23 where the hook code in init.rb is
described:

ActiveRecord::Base.send :include, YourName::PluginName

Regards,
Andy Stewart

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