From: Victor Shepelev <vshepelev@...>
Date: 2006-04-14T23:57:30+09:00
Subject: Re: Default value for any type?

> > 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.