Class Module

Hi, I'm still learning ruby and i'm trying, but I just can't understand
this result...

class Module
  @@docs = {}
  # Invoked during class definitions
  def doc(str)
    @@docs[self.name] = self.name + ":\n" + str.gsub(/^\s+/, '')
  end
  # invoked to get documentation
  def Module::doc(aClass)
    # If we're passed a class or module, convert to string
    # ('<=' for classes checks for same class or subtype)
    aClass = aClass.name if aClass.class <= Module
    @@docs[aClass] || "No documentation for #{aClass}"
  end
end
class Example
  doc("This is a sample documentation string")

  # .. rest of class
end

puts Module::doc(Example)

Produces:

Example:
This is a sample documentation string

But

class Module
  @@docs = {}
  # Invoked during class definitions
  def doc(str)
    @@docs[self.name] = self.name + ":\n" + str.gsub(/^\s+/, '')
  end
  # invoked to get documentation
  def Module::doc(aClass)
    # If we're passed a class or module, convert to string
    # ('<=' for classes checks for same class or subtype)
    aClass = aClass.name if aClass.class <= Module
    @@docs[aClass] || "No documentation for #{aClass}"
  end
end
class Example<Module
  doc("This is a sample documentation string")

  # .. rest of class
end

puts Module::doc(Example)

Produces:

No documentation for Example

Can anybody tell me why?

···

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

Hi --

Hi, I'm still learning ruby and i'm trying, but I just can't understand
this result...

class Module
@@docs = {}
# Invoked during class definitions
def doc(str)
   @@docs[self.name] = self.name + ":\n" + str.gsub(/^\s+/, '')
end
# invoked to get documentation
def Module::doc(aClass)
   # If we're passed a class or module, convert to string
   # ('<=' for classes checks for same class or subtype)
   aClass = aClass.name if aClass.class <= Module
   @@docs[aClass] || "No documentation for #{aClass}"
end
end
class Example
doc("This is a sample documentation string")

# .. rest of class
end

puts Module::doc(Example)

Produces:

Example:
This is a sample documentation string

But

class Module
@@docs = {}
# Invoked during class definitions
def doc(str)
   @@docs[self.name] = self.name + ":\n" + str.gsub(/^\s+/, '')
end
# invoked to get documentation
def Module::doc(aClass)
   # If we're passed a class or module, convert to string
   # ('<=' for classes checks for same class or subtype)
   aClass = aClass.name if aClass.class <= Module
   @@docs[aClass] || "No documentation for #{aClass}"
end
end
class Example<Module
doc("This is a sample documentation string")

# .. rest of class
end

puts Module::doc(Example)

Produces:

No documentation for Example

Can anybody tell me why?

When you do this:

   class Example < Module
     doc("string")
   end

the doc method you're calling is Module.doc. The object Example has
two doc methods in its method lookup path, and that's the one it hits
first.

If you change Module.doc to Module.show_doc (or whatever), you'll see
the difference.

David

···

On Sun, 1 Jun 2008, Wesley Silva wrote:

--
Rails training from David A. Black and Ruby Power and Light:
   INTRO TO RAILS June 9-12 Berlin
   ADVANCING WITH RAILS June 16-19 Berlin
See http://www.rubypal.com for details and updates!

Thanks a lot David!

I would like to make another question please...:slight_smile:

If i just change Modules's name for Father for example:

class Father
  @@docs = {}
  def doc(str)
    @@docs[self.name] = self.name + ":\n" + str.gsub(/^\s+/, '')
  end
  def Father::show_doc(aClass)
    aClass = aClass.name if aClass.class <= Module
    @@docs[aClass] || "No documentation for #{aClass}"
  end
end
class Example<Father
  doc("This is a sample documentation string")
end

puts Father::show_doc(Example)

Produces:

undefined method `doc' for Example:Class (NoMethodError)

Can you tell why? :slight_smile:

···

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

Hi --

···

On Sun, 1 Jun 2008, Wesley Silva wrote:

Thanks a lot David!

I would like to make another question please...:slight_smile:

If i just change Modules's name for Father for example:

class Father
@@docs = {}
def doc(str)
   @@docs[self.name] = self.name + ":\n" + str.gsub(/^\s+/, '')
end
def Father::show_doc(aClass)
   aClass = aClass.name if aClass.class <= Module
   @@docs[aClass] || "No documentation for #{aClass}"
end
end
class Example<Father
doc("This is a sample documentation string")
end

puts Father::show_doc(Example)

Produces:

undefined method `doc' for Example:Class (NoMethodError)

Can you tell why? :slight_smile:

doc is an instance method of Father, and Example is not an instance of
Father (it's an instance of Class). So you can't call doc on Example.

David

--
Rails training from David A. Black and Ruby Power and Light:
   INTRO TO RAILS June 9-12 Berlin
   ADVANCING WITH RAILS June 16-19 Berlin
See http://www.rubypal.com for details and updates!

Wesley, IMHO there is an easier as well as safer solution: safer, because a class's name may be unset. Also, your solution keeps documentation of all classes in memory even if they are GC'ed (if that's possible, I am not sure). So here's what I'd do:

class Module
   def doc(str = nil)
     if str
       @doc = (name + ":\n" + str.strip).freeze
     else
       @doc
     end
   end
end

Kind regards

  robert

···

On 01.06.2008 02:16, David A. Black wrote:

Hi --

On Sun, 1 Jun 2008, Wesley Silva wrote:

Thanks a lot David!

I would like to make another question please...:slight_smile:

If i just change Modules's name for Father for example:

class Father
@@docs = {}
def doc(str)
   @@docs[self.name] = self.name + ":\n" + str.gsub(/^\s+/, '')
end
def Father::show_doc(aClass)
   aClass = aClass.name if aClass.class <= Module
   @@docs[aClass] || "No documentation for #{aClass}"
end
end
class Example<Father
doc("This is a sample documentation string")
end

puts Father::show_doc(Example)

Produces:

undefined method `doc' for Example:Class (NoMethodError)

Can you tell why? :slight_smile:

doc is an instance method of Father, and Example is not an instance of
Father (it's an instance of Class). So you can't call doc on Example.

I hope it's possbile to GC a class, otherwise Class#new can be a memory leak.

···

On Sunday 01 June 2008 04:34:33 Robert Klemme wrote:

Also, your solution keeps
documentation of all classes in memory even if they are GC'ed (if that's
possible, I am not sure).