Forum: Ruby problem accessing variables in module

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D15a45a973443d4562051eb675b60474?d=identicon&s=25 Tom Cloyd (Guest)
on 2009-05-04 12:29
(Received via mailing list)
I keep getting blocked trying to do a very simple thing - I want to
"include" - in the sense of causing a mere insertion of text - some
variables and methods, residing in an external file, in my main code. I
just want my main to read a file and insert what's in it into the code
stream and then forget where it came from. Apparently this isn't
possible in any way, sadly.

So, trying to play the game according to the rules, I find that a mere
"require {filename}", then an  "include {module name in that file}"
doesn't do it, because the namespaces aren't merged, as I would have
expected. (An include that doesn't include? Huh?)

So, I have learned to use Object::instance_eval - confusing because I
don't have an instance. But never mind that, 'cause it worked. But that
method only allows me to access module methods (i.e., they aren't in a
class). Now I want to access a variable that is set in the module, but
not in a method or anything else. If I make the variable a constant,
everything works, but I can't do that in my application, I need a
variable. When a mere ordinary variable didn't work, I tried making it
an instance variable. No good. Then I tried calling "attr_reader" in the
Module. Nope. Nothing works, not even using
Object::instance_variable_get.

I realize a real Ruby programmer would start creating classes everywhere
and then it would all work (I guess). I'm trying very hard to keep it
simple, because the concept is simple.  I don't need/want a class. Just
the variable, which is initialized in the module. Simple idea - not
simple to do - or at least I haven't discovered how to do it.

Here's a code outline.

=== file utils.rb ===

module Utils
@menu = [{data}]  # <= what I'm trying to access
def self.meth_x
{ code }
end
end

=== end file utils.rb ===

=== main ===

Class SN
require utils.rb
include Utils
def meth_a
   # attempt 1 - doesn't work
   Utils::@menu.each do |i|
      {code}
   end
   # attempt 2 - doesn't work
   x_menu = Utils.instance_variable_get( "menu" )
   utils_menu.each do |i|
     {code}
   end
end
end
=== end main ===

Can someone give me the "missing piece" or suggest what I need to do to
get this working?

Many thanks!

Tom
E0d864d9677f3c1482a20152b7cac0e2?d=identicon&s=25 Robert Klemme (Guest)
on 2009-05-04 13:14
(Received via mailing list)
Attachment: sn.rb (269 Bytes)
Attachment: utils.rb (266 Bytes)
2009/5/4 Tom Cloyd <tomcloyd@comcast.net>:
> I keep getting blocked trying to do a very simple thing - I want to
> "include" - in the sense of causing a mere insertion of text - some
> variables and methods, residing in an external file, in my main code. I just
> want my main to read a file and insert what's in it into the code stream and
> then forget where it came from. Apparently this isn't possible in any way,
> sadly.

That sounds as if you wanted to do

class SN
  eval(File.read("utils.rb")) # utils.rb contains method definitions
etc.
end

> So, trying to play the game according to the rules, I find that a mere
> "require {filename}", then an  "include {module name in that file}" doesn't
> do it, because the namespaces aren't merged, as I would have expected. (An
> include that doesn't include? Huh?)

> I realize a real Ruby programmer would start creating classes everywhere and

You do have classes already. :-)

> then it would all work (I guess). I'm trying very hard to keep it simple,
> because the concept is simple.  I don't need/want a class. Just the
> variable, which is initialized in the module. Simple idea - not simple to do
> - or at least I haven't discovered how to do it.

> Can someone give me the "missing piece" or suggest what I need to do to get
> this working?

There's a sample attached which allows do extend individual instances
as well as include in classes.

Kind regards

robert
D15a45a973443d4562051eb675b60474?d=identicon&s=25 Tom Cloyd (Guest)
on 2009-05-05 16:04
(Received via mailing list)
Robert Klemme wrote:
> That sounds as if you wanted to do
>>
>> variable, which is initialized in the module. Simple idea - not simple to do
>
> Kind regards
>
> robert
>
>
>
Robert, this is exactly what I was looking for. I'm a bit stunned, after
so many failure to even communicate to others what I was trying to do.
It's so straightforward. You got it solved right away. Thanks! This is
very helpful to be, in my modest efforts to make a tool from which  I
will get a lot use! Thanks for your time and help.

Tom

--

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tom Cloyd, MS MA, LMHC - Private practice Psychotherapist
Bellingham, Washington, U.S.A: (360) 920-1226
<< tc@tomcloyd.com >> (email)
<< TomCloyd.com >> (website)
<< sleightmind.wordpress.com >> (mental health weblog)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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