Serialization for D. Comments, please!

[Bill Baxter]

On Tue, May 26, 2009 at 12:19 PM, Denis Koroskin <2korden at gmail.com> wrote:
> On Tue, 26 May 2009 21:44:49 +0400, Bill Baxter <wbaxter at gmail.com> wrote:
>
>> On Tue, May 26, 2009 at 2:35 AM, Denis Koroskin <2korden at gmail.com>
>> wrote:
>>> On Tue, 26 May 2009 13:29:39 +0400, Qian Xu
>>> <quian.xu at stud.tu-ilmenau.de>
>>> wrote:
>>>
>>>> BCS wrote:
>>>>
>>>>> I'm planning on taking a crack at a Serialization template library and
>>>>> I'm
>>>>> looking for feed back. My thinking so far is up on my blog here:
>>>>>
>>>>>
>>>>
>>>> http://arrayboundserror.blogspot.com/2009/05/serialization-for-d-part-1-of-n.html
>>>>>
>>>>> Please comment! (here or there, doesn't matter, I think I'll see both)
>>>>
>>>> A question:
>>>> Should every object contain "mixin Serializable!()" in its declaration?
>>>> It is easy to add this in own classes, but not easy to 3rd-party
>>>> libraries.
>>>> for instance: tango
>>>>
>>>>
>>>> --Qian
>>>>
>>>
>>> Good serialization library supports external serialization via template
>>> specialization (or similar tricks) :)
>>
>> I'll also add that you should be able to properly
>> serialize/deserialize a BaseClass pointer that actually points to a
>> DerivedClass.
>> This is pretty tricky to get working seamlessly when combined with the
>> external serialization requirement.
>> H3r3tic's xpose library has this working IIRC.
>>
>> --bb
>
> Sure! How about the following test:
>
> struct A
> {
>    mixin Serializable!();
>
>    B[] b;
> }
>
> struct B
> {
>    mixin Serializable!();
>
>    A a;
>    int i;
> }
>
> B[] b = new B[1];
> b[0].a.b = b;
> b[0].i = 42;
>
> A* a = &b[0].a;
>
> data = serialize(a); // should serialize outer struct (B), too, because it is accessible through a
>
> a = deserialize(data);
> assert(a.b.length == 1);
> assert(a.b[0].i == 42);
>
> BTW, thanks for reminding about xpose. I gotta compare it, doost.serialize and mine own one against each other in terms of efficiency and size (for binary output) someday.

That's not quite what I meant.

I mean this:

/// 3RD PARTY LIB
class BaseClass
{
     string toString() { return "base"; }
}

class DerivedClass
{
     string toString() { return "derived"; }
}


/// MY CODE

[...some kind of class registration here....]

BaseClass b = new DerivedClass;

data = serialize(b);
b2 = deserialize(data);

assert(b2.toString() == "derived");
------------------

The data stream should contain enough info about the instance to
reconstruct the exact derived type.

--bb