This whole discussion is caused by the way Rails handles form
submissions of text fields. If a user enters no value, the controller
action gets a param that is an empty string instead of nil. That's
probably the simplest thing to do in most cases, but the implication
is that model attributes will have empty strings instead of nil in the
record. That means you can't do the idiomatic Ruby:
user.nickname || user.name
Now we have #presence which lets us do:
user.nickname.presence || user.name
That's reasonably concise, but just keep in mind that all of this is
just to make Ruby act more like Perl where empty strings are false-ish
values. I'm sure there are other use cases for #presence, but empty
strings that come from form submissions seem like at least 90% of the
issue.
--josh
On Dec 28, 2009, at 7:07 AM, Rick DeNatale wrote:
> On Sun, Dec 27, 2009 at 2:51 PM, Yehuda Katz <[email protected]> wrote:
>> My biggest concern with nonblank? is that idiomatic Ruby is to
>> return a
>> boolean from question mark methods. I like Pratik's solution, and
>> would like
>> to see a scenario where the short-circuit logic is important (and
>> common
>> enough to justify an core class extension).
>>
>> Yehuda Katz
>> Developer | Engine Yard
>> (ph) 718.877.1325
>
> Well IMHO, I think it's more idiomatic Ruby to have a predicate only
> worry about the truthiness or falsiness of what it returns. Any value
> other than nil or false is a perfectly good, and true return value
> from a predicate, and in many cases more useful.
>
> Insisting that a predicate return either true or false, smells more
> Java or C++ish than Rubyish to me.
>
> But what do I know?
>
> --
> Rick DeNatale
>
> Blog: http://talklikeaduck.denhaven2.com/
> Twitter: http://twitter.com/RickDeNatale
> WWR: http://www.workingwithrails.com/person/9021-rick-denatale
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>
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--
Josh Susser
http://blog.hasmanythrough.com
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