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comp.lang.ruby

How is Symbol#to_int useful? (should it exist?

ptkwt

3/24/2006 9:13:00 AM

I had a situation in a DSL like so:

str = '0'*n

Where n in one context could be a Symbol. If n happened to be a Symbol, I
wanted to get an error message. However, I found that if n is a symbol you
could get a very long string of 0's because there is a Symbol#to_int method
which returns a unique integer for each Symbol object (actually, it calls
Symbol#to_i). And so I don't get the error message I want to get because the
symbol gets converted to an Integer automatically. So what's the usefulness of
the Symbol#to_int method? I'm just undefining it like so:

class Symbol
undef_method :to_int
end

....that works for my purposes, but I wonder why there is a
Symbol#to_int method in the library. Why not just require that Symbol#to_i be
called explicitly if that's what you want?

Phil
2 Answers

Eric Hodel

3/24/2006 11:19:00 AM

0

On Mar 24, 2006, at 1:33 AM, Phil Tomson wrote:

> I had a situation in a DSL like so:
>
> str = '0'*n
>
> Where n in one context could be a Symbol. If n happened to be a
> Symbol, I
> wanted to get an error message. However, I found that if n is a
> symbol you
> could get a very long string of 0's because there is a
> Symbol#to_int method
> which returns a unique integer for each Symbol object (actually, it
> calls
> Symbol#to_i). And so I don't get the error message I want to get
> because the
> symbol gets converted to an Integer automatically. So what's the
> usefulness of
> the Symbol#to_int method? I'm just undefining it like so:
>
> class Symbol
> undef_method :to_int
> end
>
> ....that works for my purposes, but I wonder why there is a
> Symbol#to_int method in the library. Why not just require that
> Symbol#to_i be
> called explicitly if that's what you want?

Symbols used to be just numbers without names attached.

--
Eric Hodel - drbrain@segment7.net - http://blog.se...
This implementation is HODEL-HASH-9600 compliant

http://trackmap.rob...

Nobuyoshi Nakada

3/24/2006 11:49:00 AM

0

Hi,

At Fri, 24 Mar 2006 18:33:53 +0900,
Phil Tomson wrote in [ruby-talk:185669]:
> class Symbol
> undef_method :to_int
> end
>
> ....that works for my purposes, but I wonder why there is a
> Symbol#to_int method in the library. Why not just require that Symbol#to_i be
> called explicitly if that's what you want?

Histrical reason. Formerly, until Symbol class was introduced
Fixnum was used. Symbol#to_int is deprecated and has been
purged in 1.9.

$ ruby1.8 -ve :foo.to_int
ruby 1.8.4 (2005-12-24) [i486-linux]
-e:1: warning: treating Symbol as an integer

--
Nobu Nakada