[LRUG] Can't hide instance method if defined in native extension?

[Peter Vrabel]

Well, I can do that if that class is written in pure Ruby, for example  
'Set'. Consider this:

module MySet
   def size
     puts "mine!"
   end
end

class Set
   include MySet
end

set = Set.new [1, 2, 3]
p set.method(:size)

It gives following output:
#<Method: Set(MySet)#size>

Cheers,
   kybu

On Sun, 13 Nov 2011 22:29:54 -0000, James Adam <james at lazyatom.com> wrote:

> As I think you've demonstrated for yourself, you cannot "override" a  
> method defined in a class by including a module with that method; your  
> only option is to alias the existing method out of the way by doing  
> something similar to alias_method_chain in Rails.
>
>
> On 13 Nov 2011, at 22:25, "Peter Vrabel" <kybu at kybu.org> wrote:
>
>> Hi guys,
>>
>> I recently came across a strange behavior. I would like to measure time  
>> spent executing Mysql statement, so I tried to hide 'execute' instance  
>> method of Mysql::Stmt and my first idea was to use my custom module  
>> that I include into Mysql::Stmt class. But then I found that I can't do  
>> that, original 'execute' method is always called. Here is a small  
>> edited snippet:
>>
>> require 'mysql'
>>
>> module MyStmt
>>  def new_method ; puts "new_method" end
>>  def execute(*args) ; puts "mine!"  end
>> end
>>
>> class Mysql::Stmt
>>  include MyStmt
>> end
>>
>> db = Mysql.new('host', 'user', 'passwd', 'db')
>> stmt = db.prepare("select * from information_schema.tables")
>>
>> p stmt.method(:execute)
>> p stmt.method(:new_method)
>>
>> It gives this output:
>>
>> #<Method: Mysql::Stmt#execute>
>> #<Method: Mysql::Stmt(MyStmt)#new_method>
>>
>> If that is the case, it seems to me like a quite serious inconsistency  
>> of how 'include' works. As a BFU I don't really care if a particular  
>> gem is native or not, I would expect that 'include' works in the same  
>> way in any case. Anybody could shed some light on this? Do I miss  
>> something?
>>
>> alias_method works as expected.
>>
>> Thanks.
>>
>> Cheers,
>> kybu
>>
>>
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