Extending a class

ruby-talk
1

Hi All

I'm trying to add methods to a class like:

class Person
  def refresh
    p "refresh"
  end
  def dup
    P "DUP"
  end

  TIMED_M = [:refresh, :dup]
  TIMED_M.each do |method|
    p method
    alias_method :"#{method}_without_timing", method

    define_method :"{#method}_with_timing" do
      p "timing"
      start_time = Time.now.to_f
      returning(self.send(:"#{method}_without_timing")) do
        end_time = Time.now.to_f
        puts "#{method}: #{"%.3f" % (end_time - start_time)} s."
      end
    end
  end
end

class << Person
  def start_trace
    TIMED_M.each do |method|
      p "x"
      alias_method method, :"#{method}_with_timing"
    end
  end
end
p = Person.new
p.refresh
Person.start_trace
p.refresh

For some unknown reason I get the following error:
:refresh
:dup
"refresh"
./t2.rb:31:in `start_trace': uninitialized constant Class::TIMED_METHODS
(NameError)
  from ./t2.rb:39

Any suggestions why I get this error ?

thnx a lot
LuCa

···

--
Posted via http://www.ruby-forum.com/.

2

Hi --

Hi All

I'm trying to add methods to a class like:

class Person
def refresh
   p "refresh"
end
def dup
   P "DUP"
end

TIMED_M = [:refresh, :dup]
TIMED_M.each do |method|
   p method
   alias_method :"#{method}_without_timing", method

   define_method :"{#method}_with_timing" do
     p "timing"
     start_time = Time.now.to_f
     returning(self.send(:"#{method}_without_timing")) do
       end_time = Time.now.to_f
       puts "#{method}: #{"%.3f" % (end_time - start_time)} s."
     end
   end
end
end

class << Person
def start_trace
   TIMED_M.each do |method|
     p "x"
     alias_method method, :"#{method}_with_timing"
   end
end
end
p = Person.new
p.refresh
Person.start_trace
p.refresh

For some unknown reason I get the following error:
:refresh
:dup
"refresh"
./t2.rb:31:in `start_trace': uninitialized constant Class::TIMED_METHODS
(NameError)
from ./t2.rb:39

Any suggestions why I get this error ?

Here's a boiled-down version:

irb(main):001:0> class C; X = 1; end
=> 1
irb(main):002:0> class << C; X; end
NameError: uninitialized constant Class::X

The reason is that there's no constant X in the singleton class of C.

I also suspect that what's above is not actually cut-and-pasted, since
you don't actually use "TIMED_METHODS" anywhere :slight_smile:

David

···

On Mon, 23 Jun 2008, Luca Scaljery wrote:

--
Rails training from David A. Black and Ruby Power and Light:
   ADVANCING WITH RAILS June 16-19 Berlin
   ADVANCING WITH RAILS July 21-24 Edison, NJ
See http://www.rubypal.com for details and updates!

3

David A. Black wrote:

Hi --

end
       end_time = Time.now.to_f
     alias_method method, :"#{method}_with_timing"
:dup
"refresh"
./t2.rb:31:in `start_trace': uninitialized constant Class::TIMED_METHODS
(NameError)
from ./t2.rb:39

Any suggestions why I get this error ?

Here's a boiled-down version:

irb(main):001:0> class C; X = 1; end
=> 1
irb(main):002:0> class << C; X; end
NameError: uninitialized constant Class::X

The reason is that there's no constant X in the singleton class of C.

I also suspect that what's above is not actually cut-and-pasted, since
you don't actually use "TIMED_METHODS" anywhere :slight_smile:

David

TIMED_M is used:

class << Person
  def start_trace
    TIMED_M.each do |method|
      p "x"
      alias_method method, :"#{method}_with_timing"
    end
  end

Here 'method' is aliased using TIMED_M

···

On Mon, 23 Jun 2008, Luca Scaljery wrote:

--
Posted via http://www.ruby-forum.com/\.