Runtime introspection, or how to get class members at runtime Fin D

[concepthf]

On Friday, 8 June 2018 at 08:21:39 UTC, evilrat wrote:
> On Friday, 8 June 2018 at 08:06:27 UTC, Arafel wrote:
>> On Thursday, 7 June 2018 at 13:07:21 UTC, evilrat wrote:
>>>
>>> I don't think so. It clearly states that children must mixin 
>>> too, which can mean it just grabs symbols in scope only, and 
>>> base class has no way of knowing about its subclasses. It 
>>> also has "agressive mode" that will make metadata for all 
>>> public symbols(?) it can walk, this may or may not be helpful 
>>> depending on your requirements.
>>>
>>
>> Yes, that's what I understood from looking at it, but perhaps 
>> I was just missing something. I wonder though how the 
>> "agressive mode" would work with separate compilation / 
>> dlopen'ed libraries. Perhaps I should give it a try and see 
>> what happens.
>>
>>> Besides there is no way(not that I am aware of) to make self 
>>> registering stuff happen, you still need to call it 
>>> somewhere. The most transparent option is probably just doing 
>>> a mixin in each module that performs registration of all 
>>> module symbols in module ctor.
>>> The point is that there is absolute requirement to make 
>>> explicit call for that, be it a module ctor mixin, class 
>>> mixin or even user provided registration both at compile time 
>>> or run time.
>>> But since it is MIT licensed you can probably use the code as 
>>> the starting point and adjust to your own needs.
>>>
>>>
>>>
>>> BTW plug-ins is something that is right now possible on 
>>> Linux(not sure about support on other *NIX systems), but in a 
>>> very primitive form on Windows.
>>> This is related to DLL support issues(such as type 
>>> information not being passed across process/DLL boundaries), 
>>> these issues also may include runtime issues as well such as 
>>> inability to delegate the GC, which will mean there will be 
>>> 2(or more) concurrent running GC's. But again I am not aware 
>>> of the current situation.
>>
>> Well, I'm already tightly coupled to linux, so this is not a 
>> big concern for me :-)
>>
>> I'll keep trying, as I said, my intention was to let plugin 
>> writers do it as easily as possible, but well, adding some 
>> kind of "register" function might be necessary in the end...
>>
>> A.
>
> Yep. Like I said probably the easiest to use way is to place 
> single call in each module. And there probably no other 
> solution, because modules creates sort of isolated graph via 
> imports. And I am not aware of any way to get list of modules 
> passed in with compiler invocation to perform some sort of 
> centralized one-liner registration.
>
> But anyway look at this, might give some tips on how it can be 
> done
>
> mixin
> https://github.com/Circular-Studios/Dash/blob/b7d589ad4ca8993445c136b6a4ae170932bb7962/source/dash/components/component.d#L208
>

> (note that it uses static this() - module constructor. I think 
> this behavior was changed around 2015-2016 and now it will 
> cause cyclic dependency errors when modules with ctors import 
> each other)
>
> usage
> https://github.com/Circular-Studios/Dash/blob/b7d589ad4ca8993445c136b6a4ae170932bb7962/source/dash/components/lights.d#L12

Thanks very much for these links!

I'm currently also trying to get a crack at runtime introspection 
for enabling richer serialization capabilities. It is nice to 
have compile time code generation, but it really sucks when 
dealing with object hierarchies and API interfaces.

I'm doing kind of the same thing as witchcraft with explicit 
mixins (putting a "mixin reflect" into every stuff I want to 
reflect on.)
But I'd like to have selective reflection/introspection, with a 
C#-esque flavor of having a "centralised repository" of reflected 
stuff.


Also I need to inject static this(). A serious drawback.

On that note, you can pass:
--DRT-oncycle=ignore

to your compiled app to instruct the runtime to ignore cycle 
warnings.
linux ex.: "./app --DRT-oncycle=ignore"

It is ugly as hell to disable this check, but I would accept it 
gladly if this would be the only impediment of getting runtime 
reflection.

Sadly it is not, and I don't want to ramble right now :)