From: Randy Kramer <rhkramer@...>
Date: 2007-11-02T04:06:59+09:00
Subject: Ahh, Ruby's symbol table (was Re: Garbage collection and symbols)

On Thursday 01 November 2007 12:09 pm, Tim Pease wrote:
> Symbols are never freed during the lifetime of a ruby program. Once  
> they are *allocated in the symbol hash table*, they are there forever.

(Emphasis added.)

Thanks, that helps me a lot (I guess I (sometimes) like to know what's going 
on behind the scenes).  And that helps me understand some of the stuff I was 
pondering over a few weeks ago during the discussion of (iirc) references vs. 
pointers.

Hmm, thinking of that, maybe you or someone else can confirm a few points:

   * one difference between a C pointer and a Ruby reference that I'm "walking 
away with" is that the C pointer is stored in a location (and takes up space)  
where the programmer can access it (and can notice that it takes up space).  
In contrast, a Ruby variable (which is a reference) is not as easily 
accessible to the programmer, but it does take up space in the (Ruby's) 
symbol hash table.

   * in Ruby's symbol hash table, a symbol is stored (in the hash table) with 
all the characters that make up the symbol.  For example, if I have a 
symbol :test, in Ruby's hash table, the string "test" is stored.   (I'm 
guessing as the key--I presume the value is something that somehow eventually 
is translated into a location in memory.)

Is there a way for the programmer to manipulate Ruby's symbol hash table 
within Ruby more directly than occurs when defining variables or symbols?

Randy Kramer