From: John Johnson <jj5412@...>
Date: 2003-06-02T00:13:21+09:00
Subject: Re: Advantages of Symbols over constants

One of my concerns with symbols is they spring into exsistence on their own,
ie.

def foo(op)
    case op
    when :Bar
        puts "Bar"
    else
        puts "a bug!"
    end
end

foo(:bar)

-- 
Regards,
  JJ

Be Kind, Be Careful, Be Yourself



on 6/1/03 9:51 AM, Jim Freeze at jim@freeze.org wrote:

> On Sunday,  1 June 2003 at 22:00:23 +0900, Marek Janukowicz wrote:
>> 
>> I wonder what are the advantages of using symbols over constants.  For
>> example: I want to define representation of SQL comparison operators. If
>> I use constants - I have to define them, but I don't have to do explicit
>> check when using them (because exception will be raised on non-existing
>> constant). It is also easy to see which operators are defined when
>> looking at the source code. Another advantage - constants have
>> namespaces: they can be defined in the class scope. If I use symbols - I
>> don't have to define them, but I need to verify whether the symbol is
>> valid. I have also to write additional documentation to indicate valid
>> Symbols for operators.
>> 
>> I find kind of general tendency on this group to recommend using symbols
>> rather then constants. From what I wrote above I'd rather use constants.
>> Could you please explain me why should I use symbols? Am I missing some
>> important symbols advantage?
> 
> One advantage is that symbols are faster than constants.
> Regarding the namespace issue, it may be ok to ask yourself
> if it really is needed. It may be that if an invalid symbol
> is passed, then it just falls off the end of some if/else or case
> statement and throws an error.
> If, on the other hand you can't do without the name space, create
> a hash with the valid symbols as the key, and use #has_key?
> to validate the symbol.
>