Chances of D getting proper runtime reflection?

[Jacob Carlborg]

On 2011-08-24 08:41, Marco Leise wrote:
> Am 23.08.2011, 19:42 Uhr, schrieb jdrewsen <jdrewsen at nospam.com>:
>
>> Den 23-08-2011 17:03, Jacob Carlborg skrev:
>>> On 2011-08-23 16:38, Andrei Alexandrescu wrote:
>>>> On 8/23/11 12:55 AM, Jacob Carlborg wrote:
>>>>> On 2011-08-23 08:52, Andrei Alexandrescu wrote:
>>>>>> On 8/22/11 11:30 PM, Jacob Carlborg wrote:
>>>>>>> Ok, then I just change "register" to a static method.
>>>>>>
>>>>>> A static method of whom?
>>>>>>
>>>>>> Andrei
>>>>>
>>>>> Well, "register" currently an instance method of Serializer so I would
>>>>> change it to be a static method of Serializer.
>>>>
>>>> I think the ability of a class to be serialized would be independent of
>>>> the notion of a serializer. To me, "this class is serializable" really
>>>> means "this class has metadata associated with it that allows
>>>> interested
>>>> parties to serialize it". But perhaps this is splitting hairs.
>>>>
>>>> Andrei
>>>
>>> You don't want to have it in the class and don't want it in the
>>> serializer. I mean, it needs to be stored somewhere and I thought that a
>>> static method in Serializer would better than a completely global
>>> function.
>>>
>>> Are you thinking about having another serialization library that can use
>>> this information as well? I'm not sure if that's good idea, different
>>> serialization implementations might need to do very different things
>>> with the information.
>>
>> It could be used for network transmissions. Correct me if I'm wrong
>> but Orange serializes the entire object. When sending things over the
>> network or when saving something to disk for that matter you most
>> likely are only interested in serializing some of the fields of an
>> object. I really think it would be nice to declaratively mark fields
>> as serializable for certain purposes e.g.:
>>
>> class Foo {
>> int a; // Send over network and saved to file
>> int b; // Saved to file
>> ubyte[] cache; // not to be serialized
>> }
>>
>> mixin(serialize!(Network, Foo, a);
>>
>> mixin(serialize!(File, Foo, a);
>> mixin(serialize!(File, Foo, b);
>>
>> // but still support not specifying each field
>> class Bar { int a; }
>> mixin(serialize!(File, Bar));
>>
>>
>> Another way would be to just declare a class as serializable and then
>> for each serialization type (ie. Network, File) declare that they
>> should skip a field. Actually I think I better like this approach
>> since it would allow decoupling of serialization type and the
>> declaration of serializability.
>>
>> /Jonas
>
> These are good points Jonas. It's a good idea to read up on
> http://en.wikipedia.org/wiki/Serialization
> I used Java for a while and I they have their reasons to require a
> 'tag'/'annotation'/'interface' on serializable classes.
>
> Java's choice to not make serializable a default is explained in short
> like this:
> - structures like threads or files cannot maintain their semantics when
> serialized
> - classes and libraries change over time, this adds extra work for the
> maintanance of serializable classes
> - serialization means externalization of private attributes, even passwords
>
> .NET adds the option to mark newly added fields as OptionalField, so a
> previously serialized instance can be loaded without error.
> NonSerialized marks a field as not serializable which is what Jonas
> mentioned. Like Java they work with interfaces to declare methods called
> after deserialization, so the 'cache' in the above example can be
> reinitialized correctly.

Orange supports NonSerialized fields and classes, (de)serialization 
events and several other ways to customize the serialization process. 
It's inspired by how serialization in .NET works.

For more information see the Orange unit tests: 
https://github.com/jacob-carlborg/orange/tree/master/tests

-- 
/Jacob Carlborg