[ruby-talk:14859] Re: Polymorphic methods

>===== Original Message From Chris Uzdavinis <[e-mail]> =====
>"J J" <[e-mail]> writes:
[...]
>> I'm thinking of instances (for example) where you can create an object from
>> several different objects passed to the constructor. E.g.
>>
>> m = Month.new(12)
>> m = Month.new('December')
>> m = Month.new(anotherMonth)
>>
>> thus, Month.initialize has to have a case or if statement.
>>
>> Thanks in advance!
>
>I'd like to know how to do that in ruby too, but my impression is that
>you just have to test the type.  A hash may be faster than a linear
>search if you have lots of potential types, but it's still testing
>type.  But if there is a way (and I'm often surprised by ruby's
>capabilitiess), that would be useful.

I am not sure what you want to be possible.  The way I
am reading it, it is trivially impossible, but I probably
am misreading your intent.  However I will respond to my
misreading.

The basic problem is that you want the type to matter, so
somewhere (explicitly or implicitly) it has to be tested.
And you have logic that you want to happen so somewhere
that logic must be written.  You can write the code in
many ways, move the logic around, find ways to have one
case "feed off of" another, etc.  Ruby offers facilities
to do all of that including if statements, closures,
OO programming, and modules.

But there is no way to remove the fact that if the type is
to matter then it must be tested, and logic that exists
must be written.

Cheers,
Ben