It depends on the use case really. Impotency is great, but the user of the
gem might need to know if it's been done before. I wouldn't use an
exception, that should be just for a condition that should never really
occur under the normal workflow. An easy solution may be to make the method
idempotent and add another method to your api so if the user of your api
needs to know if it's been done before, they can e.g.
if !user.done_something?
user.do_something
else
puts "it's already been done"
end
or if the user of your gem doesn't really care, they can just call the
user.do_something and carry on (especially without having to handle some
frustrating exception condition that they dont care about).
But it all depends... if you have lot's of different possible results from
do_something, then you may want to return some object that can be
inspected. If it should never happen (like the file not existing) then you
may want to throw and exception and force the user of you api to deal with
it.
On Fri, Apr 26, 2013 at 7:05 AM, Sebastian Porto <[email protected]>wrote:
> (Sorry if this ends as a double post, as I send this using email, but for
> some reason it doesn't show in the group. So I am posting it again directly
> on the group page.)
>
> Hi All
>
> I'm building a gem and trying to decide what is the best way to provide
> return values.
>
> Let's say that my gem add the do_something method to user:
>
> user.do_something
>
> But if that something is already done I want to provide meaningful
> feedback, I can't decide what is a best practice here or what is better,
> these is what I can think of:
>
> Option 1. return false
>
> res = user .do_something
> res //=> false
> user.errors //=> ['already done'] information about the errors, like
> active record
>
> Option 2. raise an exception (seems a little drastic)
>
> begin
> res = user .do_something
> rescue MyGem::AlreadyDoneException => e
>
> end
>
> Option 3. return an error code
>
> res = user.do_something
> res //=> 3 (meaning already done)
>
> Option 4. return an object
>
> res = user.do_something
> res.success //=> false
> res.messages //=> ['already done']
>
> Any recommendations on what is a best practice here?
>
> Thanks,
> Sebastian
>
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