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

[Peter Vrabel]

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