Can someone explain how mixin is implemented?

[Matthew Ong]

On 5/19/2011 10:02 PM, Steven Schveighoffer wrote:
> On Thu, 19 May 2011 09:43:14 -0400, Matthew Ong <ongbp at yahoo.com> wrote:
>

According to Jonathan,
  In the case of template mixins, you're essentially copying and pasting 
code. Yes. Liked what you said, with optimization at compiled time.

I am not trying to ask D to use JVM. (Please Note, that is why I choose 
D and also Go for the system level programming over C++ or Java JFFI.

>
> Java does *not* use templates, they are generics. A generic seems like,
> but is vastly different from a template.
>
> A template *re-generates* the code as if you substituted the type for
> the given template parameter.

> A generic generates one object code file with a base class, and then
> simply enforces the type constraints at compile time when *using* the
> generic. Under the hood, the generic is compiled with the base class as
> the given type. It probably avoids doing any type checking at runtime as
> well (since it knows the compiler will check the type for it).
Can someone really say why this is a bad bad idea for memory with some 
automated
plumbing being done like in ActiveX.


> The huge advantages of templates over generics are:
Yes. I do agree that template are NOT exactly generics,

>
> 1. The generated type can be fully optimized (footprint and code) for
> the given type parameters.
Yes. All compiler from source to binary has some sort of binary 
optimization. That is a really good thing. Javac has also those feature.
Please do as much optimization as D can be.

> 2. You can execute different code paths depending on the parameter types.
> 3. You do not have to select a common base class/interface for a group
> of types. That is, you can select any set of types that will work with
> your template. With generics, all possible types need to have a common
> base.
That is a good good thing to have, it allows the runtime binary to be 
reduced in time where only the data type is different. I understand that 
Java has a JVM to do that but I believe similar thing has been also
proven by ActiveX/Com+/DCom. I think they termed it Object Brokering.

> 4. Boxing/unboxing is not necessary for non-object types.
>
> The advantage of generics are that you only have one compiled version.
> This is actually very important for bytecode-based languages such as
> Java and C#.
But perhaps some location about dynamic loading and unlaoding of DLL be 
part
of D automatically. That is proven technology in the Linux Kernel for 
Device
Driver module.


>> LinkedList<String> list=new LinkedList<String>();
>> LinkedList<Integer> list=new LinkedList<Integer>();
>>
>> // Can also apply for Account.
>> LinkedList<Account> list=new LinkedList<Account>();
>>
>>
>> But there is a single LinkedList Class File(single binary).
>
> Yes, it's a LinkedList with the type given as Object.
>
> -Steve


-- 
Matthew Ong
email: ongbp at yahoo.com