A selfish ruby question

Ruby
1

why is it that:

class Akill
def astop(seq)
self.select{|astop| astop.first==seq}.collect
end
end
=> nil

grr.astop(b[0])
i get this error…
NoMethodError: private method select' called for #<Akill:0x2dd01f8> from (irb):86:inastop’
from (irb):89
from ?:0

…and when i do this:

class Akill
def astop(seq)
@arte.select{|astop| astop.first==seq}.collect
end
end

i don’t…?

…and what is the difference in it’s use if both worked…
i mean…what is the difference between making a method
that uses ‘self’ and one that uses a instance variable…

when would one to want to design a method with self and/or with a
instance variable?

…and even though i add to the Akill class:

attr_reader :arte, :stops, :rtes

…i still get these errors…

class Akill
def astop(seq)
self.select{|astop| astop.first==seq}.collect
end
end
=> nil

grr.arte.astop(b[0])
NoMethodError: undefined method `astop’ for #Array:0x2dd01b0
from (irb):143
from :0

grr.astop([b0])
NameError: undefined local variable or method `b0’ for main:Object
from (irb):144
from :0

grr.astop(b[0])
NoMethodError: private method select' called for #<Akill:0x2dd01f8> from (irb):140:inastop’
from (irb):145
from :0

2

You can’t have an explicit receiver for private methods. See below.

class Foo
def try1
something_private()
end

def try2
self.something_private()
end

private
def something_private()
puts “I’m doing private things!”
end
end

f = Foo.new
f.try1
#=> I’m doing private things!

f.try2
#=> tmp.rb:7:in try2': private methodsomething_private’ called for
#Foo:0x282dd70 (NoMethodError)
#=> from tmp.rb:19

f.something_private
#=> tmp.rb:21: private method `something_private’ called for
#Foo:0x282ddd4 (NoMethodError)

3

Phrogz wrote:

You can’t have an explicit receiver for private methods. See below.
in trying to understand this…
why is it then the Array.select instance method is private? here?..

4

Dave R. wrote:

in trying to understand this…
why is it then the Array.select instance method is private? here?..

You need to provide more details. You have explicitly stated that you
have another class, not an Array. Does your class inherit from Array?

Create the smallest program you can that showcases your problem, and
perhaps then we can help you.

5

On Sep 2, 2006, at 5:09 PM, Rick DeNatale wrote:

I guess that you’ve defined select as a private method in Akill or one
of it’s superclasses. It’s not complaining about select being a
private method of Array, but of Akill.

This select is most likely Kernel#select (as in IO).

6

On 9/1/06, Dave R. [email protected] wrote:

Phrogz wrote:

You can’t have an explicit receiver for private methods. See below.
in trying to understand this…
why is it then the Array.select instance method is private? here?..

It’s not.

Quoting from your original post

grr.arte.astop(b[0])
NoMethodError: undefined method `astop’ for #Array:0x2dd01b0
from (irb):143
from :0

Here grr.arte is returning an Array, and Array doesn’t have an astop
method.

grr.astop([b0])
NameError: undefined local variable or method `b0’ for main:Object
from (irb):144
from :0

Did you mean to say b[0] instead of b0?

grr.astop(b[0])
NoMethodError: private method select' called for #<Akill:0x2dd01f8> from (irb):140:in astop’
from (irb):145
from :0

I guess that you’ve defined select as a private method in Akill or one
of it’s superclasses. It’s not complaining about select being a
private method of Array, but of Akill.

As has been pointed out, it’s illegal to use an explicit receiver on
private methods.
This is the way that the Ruby runtime enforces privacy. So

self.publicMethod
is the same as just
publicMethod

but
privateMethod
works and
self.privateMethod raises an exception.

Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/