From: "Olie D." <ruby-forum@...>
Date: 2007-11-05T02:27:14+09:00
Subject: Re: class from string

Olie D. wrote:
> Guest wrote:
>> Thanks all for the responses -- it's obvious this is a FAQ, but just try
>> and filter thru all the cruft with the words 'class' and 'string'!! -dan
> 
> FWIW, I searched the Ruby forum for
> 
>    "class from string"
> 
> and this rather helpful thread was the 1st one.
> 
> (Saved me from asking a FAQ :D)

Bah!  I was too quick on that -- now I'll probably end up asking FAQ' 
<sigh>

I'm trying to read-in a folder full of "plug-ins" and call each of them, 
in turn.  Once I get the class-name, I do something like:

            require "#{PLUG_IN_DIR}/#{one_plugin}"
            plugin_class=Object.const_get(plugin_class_name).new
            plugin_class.some_method

I *thought* that require worked a bit like the C pre-processor 
"include", in that it would read and execute the named file at that 
point, thereby defining my class and its methods.  However, when I get 
to the middle line, I get

     uninitialized constant PluginClassName

Since rails is mistaking my class-name for a constant, I'm guessing that 
require didn't execute the way I think it does, so my class-name isn't 
initialized.

...Or maybe I've completely mis-diagnosed the problem.

At any rate, can someone offer a suggestion for how to read a folder 
full of class-definition-files and, once at a time,

  * Execute the class definition, so that my app knows about it
  * Instantiate an instance of the class (I think we have this part, 
above)
  * Call a method on that class (should just be able to say 
"a_class.a_method", right?)

Thanks!
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