From: Rick DeNatale <rick.denatale@...>
Date: 2010-03-31T00:33:33+09:00
Subject: Re: coercing nil/obj to false/true

On Tue, Mar 30, 2010 at 3:17 AM, Robert Klemme
<shortcutter@googlemail.com> wrote:
> 2010/3/30 Steve Howell <showell30@yahoo.com>:
>
>> Is there a way to avoid this idiom?
>>
>> def is_there_one(whatever)
>>  !some_call_to_lib_that_returns_object_or_nil(whatever).nil?
>> end
>
>> Finally, I can just have my method return obj or nil, and let the
>> callers use it in boolean expressions, but my fear there is that I set
>> the wrong expectation for the caller, if I later return a different
>> object, when my intention is only to indicate whether a query succeeds
>> or not.  (You guessed it, this is motivated by ActiveRecord, but it's
>> really a Ruby question.)
>
> Your method's documentation and naming the method with a question mark
> at the end will help avoid this.  I would be more concerned with
> leaking internal information.  That's why people often do this in
> order to force conversion to true / false:
>
> def is_there_one? whatever
>  !! some_call_to_lib_that_returns_object_or_nil(whatever)
> end

I almost never find that I need to 'force' a 'true' boolean value in Ruby.

I pretty much agree with Koz about this.
http://www.therailsway.com/2007/8/1/dangers-of-cargo-culting

-- 
Rick DeNatale

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