Private methods and self:

ruby-talk
1

FOR ruby 1.8.4 (2005-12-24) [i386-linux]:

···

#--------------------------------------------------------------------------
def foo1
  self.bar
end

def foo2
  bar
end

def bar
  puts "In bar"
end

private :bar

if __FILE__ == $0

foo2 -> 'In bar'
foo1 -> 'NoMethodError: private method `bar' called for main:Object'

#--------------------------------------------------------------------------

Why the difference in treatment between the explict self reciever and
the implict self receiver?

Regards,
Jim

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

2

James Byrne wrote:

FOR ruby 1.8.4 (2005-12-24) [i386-linux]:

#--------------------------------------------------------------------------
def foo1
  self.bar
end

def foo2
  bar
end

def bar
  puts "In bar"
end

private :bar

if __FILE__ == $0

foo2 -> 'In bar'
foo1 -> 'NoMethodError: private method `bar' called for main:Object'

#--------------------------------------------------------------------------

Why the difference in treatment between the explict self reciever and
the implict self receiver?

Private methods are not allowed to have an explicit receiver
(using the 'self' there is like going out of the object and
then sending the message). The only exception to this rule
are writer methods (def foo=(); ...; end) because without
the self., foo = x is always interpreted as an assignment
to a local variable.

Regards,
Jim

E

···

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

3

E. Saynatkari wrote:

Private methods are not allowed to have an explicit receiver
(using the 'self' there is like going out of the object and
then sending the message). The only exception to this rule
are writer methods (def foo=(); ...; end) because without
the self., foo = x is always interpreted as an assignment
to a local variable.

E

Curious that this restriction does not appear to be mentioned in the
Pickaxe book. It also seems, to me, somewhat counter-intuitive. Is it
purposeful behaviour or an artifact of a stylistic convention?

Regards,
Jim

···

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

4

James Byrne wrote:

E. Saynatkari wrote:

Private methods are not allowed to have an explicit receiver
(using the 'self' there is like going out of the object and
then sending the message). The only exception to this rule
are writer methods (def foo=(); ...; end) because without
the self., foo = x is always interpreted as an assignment
to a local variable.

E

Curious that this restriction does not appear to be mentioned in the Pickaxe book. It also seems, to me, somewhat counter-intuitive. Is it purposeful behaviour or an artifact of a stylistic convention?

Regards,
Jim

Page 35 in the 2nd Edition: "Private methods cannot be called with an explicit receiver—the receiver is always self. This means that private methods can be called only in the context of the current object; you can’t invoke another object’s private methods."