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From: Walton Hoops on 5 Mar 2010 17:27
On 3/5/2010 2:36 PM, Nick Brown wrote:
>>>> mymethod(h = {:this => 'green'} && condition ? h.merge({:that =>
>>>> 'blue'}) : h)
>>>>
>>> You could also do it this way:
>>>
>>> method {:Apples => 1}.merge(condition ? {:Oranges => 2} : {})
>>>
>
> For the love of all that is good and holy, please do not try to cram two
> elegant lines of code into one disgusting line. That way lies madness...
>
> ;-)
>
It's called Perl golf. It amazes and terrifies me how much it is still
played.

From: Caleb Clausen on 5 Mar 2010 17:43
On 3/5/10, Walton Hoops <walton(a)vyper.hopto.org> wrote:
>> For the love of all that is good and holy, please do not try to cram two
>> elegant lines of code into one disgusting line. That way lies madness...
>>
>> ;-)
>>
> It's called Perl golf. It amazes and terrifies me how much it is still
> played.
>
>

I must say that I vastly prefer Sven's original formulation:

mymethod :this => 'green, :that => ('blue' if condition)

to any of the alternatives that have been suggested since. It's too
bad that it doesn't quite do the job for him. Sven, are you sure you
absolutely can't tolerate an options hash with a nil value in it?

From: Sven S. on 5 Mar 2010 18:23
> to any of the alternatives that have been suggested since. It's too
> bad that it doesn't quite do the job for him. Sven, are you sure you
> absolutely can't tolerate an options hash with a nil value in it?

Yep, I need it with form_for in Rails which doesn't like :method => nil.
--
Posted via http://www.ruby-forum.com/.

From: Joel VanderWerf on 5 Mar 2010 19:02
Sven S. wrote:
> Hi
>
> Cumbersome title, here's what I'd like to do both elegantly and without
> monkey patching Hash:
>
> Say, I need to pass a hash to a method:
>
> mymethod :this => 'green'
>
> Now I'd like to include a second hash member only if a condition is met:
>
> mymethod :this => 'green, :that => ('blue' if condition)
>
> This of course leaves ":that => nil" in the hash if the condition is not
> met - which is no good, the key should just not be present at all. I
> could delete_if after that, but isn't there a more elegant way?
>
> Thanks for your ideas!

Here are two suggestions that are more verbose, but also more readable,
especially if you have many arguments or more complex logic:

def with_params
h = {}
yield h
h
end

def mymethod h
p h
end

a = 1
mymethod with_params {|h|
h[:this] = 'green'
h[:that] = 'blue' if a==2
}

You can make this a little tighter, at the expense of changing scope
within the block:

class ParamHash < Hash
def method_missing(k, v, *)
self[k] = v
end
end

def with_params2(&block)
ph = ParamHash.new
ph.instance_eval(&block)
ph
end

a = 1
mymethod with_params2 {
this 'green'
that 'blue' if a==2
}

Warning: because of the instance_eval, self is not useful in this block.
For example,

something 'red' if @x==1

or

something 'red' if foo()==1

won't work as expected. Also, in this second example, unlike the first,
your keys will be limited to symbols which are not instance methods of
Object or Kernel (or you could use a blank slate).

From: Rick DeNatale on 6 Mar 2010 08:59
On Fri, Mar 5, 2010 at 6:23 PM, Sven S. <svoop(a)delirium.ch> wrote:
>> to any of the alternatives that have been suggested since. It's too
>> bad that it doesn't quite do the job for him. Sven, are you sure you
>> absolutely can't tolerate an options hash with a nil value in it?
>
> Yep, I need it with form_for in Rails which doesn't like :method => nil.

If you can't use the resource oriented form of form_for which lets
Rails figure out the method based on whether the resource is new or
existing, then why not handle it on the other side of the interface

def mymethod(options={})
options[:method] ||= :put
#...
end


--
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale

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