From: Kris <iamkris@...>
Date: 2005-12-05T06:57:34+09:00
Subject: Re: Getting Over Symbols

Very interesting post to a newbie like me. Coming from a "C" family of
languages, you just broadened my understanding of Ruby. Until now I
failed to see the importance of exposing the runtime data structures of
the language. Java/.NET allow it to some extent with their Reflection
capabilities. Unlike Ruby (and probably Lisp family of languages) the
reflection capablities of these platforms are limited. I guess this is
by design.


gwtmp01@mac.com wrote:
> When I was first learning Ruby, symbols were a bit of a mystery.
> I understand them now, and in hindsight, I don't really understand
> why they were so confusing.  In teaching other people about Ruby and
> in reading ruby-talk it is quite clear that symbols are an early
> stumbling block for learning Ruby.  I'd take an educated guess that
> people learning Rails (or any other Ruby framework) struggle with
> trying to understand if symbols are a magic feature of the framework
> or the language or something else.
>
> My question to the list is, why?  What is it about Symbols that
> creates such confusion?  I'm getting ready to prepare a two-hour
> "Intro to Ruby" seminar and I'd like to find an approach to Symbols
> that cuts through the confusion.
>
> One thought that I've had is that Ruby's reflection capabilities
> expose the names of various internal structures (classes, methods,
> modules, constants) in a way that is quite foreign to many programmers.
> For example, in C you don't have any runtime access to the symbol table
> so you would never see a value that could be mapped to a function like
> 'printf', 'scanf', or 'main' unless the programmer took the trouble to
> construct an explicit symbol table (mapping strings to function
> pointers,
> for example).  An explicit table isn't much of a mystery.
>
> When you switch to a language like Ruby, Smalltalk, and certainly the
> entire family of Lisp languages you are now in an environment where the
> data structures of the language runtime are exposed to the programmer.
> For a while, the novice will struggle because their mental model of
> a runtime environment just doesn't match their new reality and symbols
> just happen to be the bridge between the two worlds.  One of the first
> features of Ruby that many people learn are the 'attr*' methods.  Right
> off the bat, the novice is exposed to the mappings from strings to
> symbols to methods.
>
> Do folks coming from the Lisp/Scheme world have trouble with symbols or
> do they absorb symbols right away because they already struggled with
> the concept when learning about atoms?
> 
> Thoughts?
> 
> Gary Wright