From: Matthew Desmarais <desmarm@...>
Date: 2006-04-15T00:57:42+09:00
Subject: Re: Default value for any type?

Victor Shepelev wrote:
>>> Hello all.
>>>
>>> I have code:
>>>
>>> def create_default(type)
>>>   type.new
>>> end
>>>
>>> But with, for example, Float, it suddenly said:
>>>
>>> create_default(Float) #<=== undefined method `new' for Float:Class
>>> (NoMethodError)
>>>
>>> Hmmm? How can I uniformly obtain default value for given class?
>>>       
>> What should the default value for a Float be? What are you trying to
>> really do here?
>>
>> There are a number of classes that you're not going to be able to call
>> #new on.
>>     
>
> Not so long time ago I've been a C++ guy. There we could do:
> float(); //0.0
> int(); //0
> ...etc...
>
> Generalized version:
> template<typename T>
> T create_default()
> {
>   return T();
> }
>
> //usage:
> create_default<float>();       // => 0.0
> create_default<std::string>(); // => ""
>
> and so on. I think, argument-less constructor, creating some "default"
> value, is a very useful thing.
>
> (yes, I can define Float#default and so on for myself ;) But I want to know,
> *why*?)
>
>  
>   
>> -austin
>> --
>> Austin Ziegler * halostatue@gmail.com
>>                * Alternate: austin@halostatue.ca
>>     
>
> Victor.
>   
Hi Victor,

I think that Austin's question about what you are trying to accomplish 
is probably a good. one.  If you can post some Ruby code that would rely 
on something like this that would be great.  Maybe the folks on the list 
can help you find a solution for you.

Regards,
Matthew Desmarais