From: "David A. Black" <dblack@...>
Date: 2009-07-21T06:30:52+09:00
Subject: Re: getting char from string as fixnum in 1.8 and 1.9

Hi --

On Tue, 21 Jul 2009, Joel VanderWerf wrote:

> brabuhr@gmail.com wrote:
>>> ruby -v -e 'p "foo"[2].ord'
>> ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-linux]
>> -e:1: undefined method `ord' for 111:Fixnum (NoMethodError)
>> 
>>> cat foo.rb
>> unless 0.respond_to?(:ord)
>>   class Integer
>>     def ord; self; end
>>   end
>> end
>> 
>>> ruby -v -rfoo -e 'p "foo"[2].ord'
>> ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-linux]
>> 111
>> 
>> Still meets the constraint: "without adding methods to String"
>> :-)
>
> That seems like a pretty good approach, actually, and it happens to be what 
> the snmp gem does (lib/ber.rb):
>
> #
> # Add ord method to Fixnum for forward compatibility with Ruby 1.9
> #
> if "a"[0].kind_of? Fixnum
>    unless Fixnum.methods.include? :ord
>        class Fixnum
>            def ord; self; end
>        end
>    end
> end

There's always a bit of fragility, since someone else might have added
an ord that does something else... unlikely, of course, but still.

Also, I didn't suggest adding String#ord because you had said you
didn't want to add methods to String (though your next post clarifies
what you meant by that). If you want to be more future-esque you could
add it to String instead of Fixnum (though that might involve one of
those unpack-based implementations and therefore not be as fast).


David

-- 
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