[Proposal]

[Dave]

Sean Fritz wrote:
> In article <e7346j$1uo9$2 at digitaldaemon.com>, Walter Bright says...
>> Sean Fritz wrote:
>>>> T sqr(T) ( T x )
>>>> {
>>>>     return x*x;
>>>> }
>>> Is the way Java Generics do it,
>> I didn't think Java supported function templates (only class templates).
> 
> Yes, there are class and method level generics.  There are none of the linking
> issues that come up from function templates (thank gods!).
> 
> Class generics are (of course):
> 
> class Foo<T> {  ... }
> 
> While method generics are:
> 
> public void <T> T[] toArray(T[] arr) { ... }
> 

So let's say we want to implement a generic sqr method in Java... How 
would we do it? I came up w/ this after just a quick look at the spec. 
to get the syntax right:

public class Test
{
	public static void main(String args[])
	{
		Integer i = 100;
		System.out.println(sqr(i));
		int j = 1000;
		System.out.println(sqr(j));
	}
	public static <T> T sqr(T x)
	{
		return x * x;
	}
}

However, I get this when I compile:

Test.java:10: operator * cannot be applied to T,T
                 return x * x;

?

Thanks,

- Dave

> The distinction in placment of the type parameter is one of the weirdest
> syntactical choices in Java.  It doesn't take long to master, but it constantly
> leaves you wondering why they did it.
> 
> Also, they aren't really anything like templates except that they allow generic
> programming.  It really takes several months to fully grok generics (especially
> with the Java Language Spec being the only decent reference at the moment).
> 
> Sean
> 
>