Forum: Ruby How to access a classes private method

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Charlie B. (Guest)
on 2006-05-26 16:30
(Received via mailing list)
I'm trying to call a classes protected method but I can't seem to get it
to work.  Here's an example of the method I'm trying to call

moule Foo
  Class Bar
   protected
        def bars_method(a=2)
            a
        end
    end
end

Here's what the relevant parts of my script look like

def calling_protected_method
    result = Foo::Bar.bars_method
end


This is resulting in a method not found error.  I know I can't access a
protected method this way, but I don't know how to open up the class and
access this method.  Thanks in advance for any help.




Charlie B.
http://www.recentrambles.com
Charlie B. (Guest)
on 2006-05-26 16:33
(Received via mailing list)
Sorry, just realized that the subject said private method, I meant to
say protected.

On Fri, 2006-05-26 at 21:29 +0900, Charlie B. wrote:

> end
> access this method.  Thanks in advance for any help.
>
>
>
>
> Charlie B.
> http://www.recentrambles.com

Charlie B.
Programmer
Castle Branch Inc.
Simen (Guest)
on 2006-05-26 16:58
Charlie B. wrote:
> Sorry, just realized that the subject said private method, I meant to
> say protected.
>
> On Fri, 2006-05-26 at 21:29 +0900, Charlie B. wrote:
>
>> end
>> access this method.  Thanks in advance for any help.
>>
>>
>>
>>
>> Charlie B.
>> http://www.recentrambles.com
>
> Charlie B.
> Programmer
> Castle Branch Inc.

If you need to access it outside of an instance, why make it protected?
How are you using this?

Anyway, onto the solution:

  def calling_protected_method
    result = Foo::Bar.new.method(:bars_method).call
  end
Tim B. (Guest)
on 2006-05-26 17:17
(Received via mailing list)
...
>         def bars_method(a=2)
>             a
>         end
...
> Here's what the relevant parts of my script look like
>
> def calling_protected_method
>     result = Foo::Bar.bars_method
> end

You do realize that the whole point of making methods protected is NOT
to be able to call them, right?
   -tim
Charlie B. (Guest)
on 2006-05-26 17:20
(Received via mailing list)
Yes, I'm assuming the reason this method is marked as protected in the
rails framework is so that it can't be called arbitrarily from the web.
I don't think I'll be causing any trouble by calling it from a plugin.

On Fri, 2006-05-26 at 22:15 +0900, Tim B. wrote:

>
> You do realize that the whole point of making methods protected is NOT
> to be able to call them, right?
>    -tim
>


Charlie B.
http://www.recentrambles.com
unknown (Guest)
on 2006-05-26 17:26
(Received via mailing list)
On May 26, 2006, at 8:29 AM, Charlie B. wrote:

>     end
> end
>
> Here's what the relevant parts of my script look like
>
> def calling_protected_method
>     result = Foo::Bar.bars_method
> end

This is wrong for two reasons:
   1) you are calling bars_method on the class object 'Foo::Bar' and
not on an *instance* of Foo::Bar
   2) the standard calling syntax will trip the protected method check


bar = Foo::Bar.new          # get an instance of Foo::Bar
bar.bars_method             # method found now but is protected
NoMethodError: protected method `bars_method' called for #<Foo::Bar:
0x1c8e50>

In order to bypass the protected method check you need to use send,
which ignores visibility attributes (private/protected).

bar.send(:bars_method)		# 2
bar.send(:bars_method, "arg1")  # "arg1"


Gary W.
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