Something inconsistent in ruby syntax?

Please take a look at some exemplary code first.

class MailTruck
  instance_eval <<-EOS
    define_method(:hello1) {puts "hello1"}
  EOS

  define_method(:hello2) {puts "hello2"}

  instance_eval <<-EOS
    def hello3
      puts "hello3"
    end
  EOS

  def hello4
      puts "hello4"
  end
end

hello1 and hello2 are instance methods.
hello3 is a class method.
hello4 is a instance method.

Why hello1 and hello2 are same, but hello3 and hello4 are different?

It seems a little inconsistent . Somebody can give a clear explanation?
Thanks in advance.

uncutstone

···

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hello1, hello2, and hello4 are all equivalent. They are the same thing as writing

class A
  def hello1
  ...
  end

  def hello2
  ...
  end

  def hello4
  ...
  end
end

For hello3 you've done the equivalent of

class A
   def self.hello3
     ...
   end
end

The reason doesn't happen with hello1 is

instance_eval { # self is MailTruck in this block
   define_method(...) { ... } # this is like self.define_method(...) { ... }
                              # since define_method is a method,
                              # which is the same as define_method outside of the instance_eval in this case

···

On Jun 11, 2006, at 11:10 PM, uncutstone wu wrote:

hello1 and hello2 are instance methods.
hello3 is a class method.
hello4 is a instance method.

Why hello1 and hello2 are same, but hello3 and hello4 are different?

It seems a little inconsistent . Somebody can give a clear explanation?
Thanks in advance.

uncutstone

Please take a look at some exemplary code first.

class MailTruck
        instance_eval <<-EOS
                define_method(:hello1) {puts "hello1"}
        EOS

        define_method(:hello2) {puts "hello2"}

        instance_eval <<-EOS
                def hello3
                        puts "hello3"
                end
        EOS

        def hello4
                        puts "hello4"
        end
end

hello1 and hello2 are instance methods.
hello3 is a class method.

I am as surprised as you are and I could not find any hint in the
documentation why it should be?
instance_eval is an equivalent to self.instance_eval, I fail to see any
reason why the method definition is
evaluated as a class method.

Can anyone explain while instance_eval without a receiver could change the
context of self?

Ty in advance

Robert

hello4 is a instance method.

Why hello1 and hello2 are same, but hello3 and hello4 are different?

It seems a little inconsistent . Somebody can give a clear explanation?
Thanks in advance.

I agree

Robert

···

On 6/12/06, uncutstone wu <uncutstone@sina.com> wrote:

uncutstone

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--
Deux choses sont infinies : l'univers et la bêtise humaine ; en ce qui
concerne l'univers, je n'en ai pas acquis la certitude absolue.

- Albert Einstein

Logan Capaldo wrote:

The reason doesn't happen with hello1 is

instance_eval { # self is MailTruck in this block
   define_method(...) { ... } # this is like self.define_method(...)
{ ... }
                              # since define_method is a method,
                              # which is the same as define_method
outside of the instance_eval in this case

So I can say the reason is that define_method is a method and def isn't
a method but a reserved keyword.

Thanks for your explanation, I think I've got it now.

uncutstone

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