[fpc-devel] RTTI interface & variant late binding issue (mORMot)

Steve Hildebrandt Steve.Kassel at web.de
Sat Feb 7 11:45:01 CET 2015

Am 07.02.2015 um 11:27 schrieb Sven Barth:
> On 06.02.2015 19:49, Steve Hildebrandt wrote:
>> Am 06.02.2015 um 09:49 schrieb Michael Van Canneyt:
>>> On Thu, 5 Feb 2015, Alfred wrote:
>>>> Hello to all,
>>>> While enjoying variant late binding for a couple of month now, I
>>>> would like to ask for an update on the status of RTTI.
>>>> The mORMot developer has designed a work-around for the missing RTTI.
>>>> This works well.
>>>> But it would be (much) nicer to be able to use RTTI without 
>>>> workaround.
>>>> Does anybody have some info about the status of this (feature) 
>>>> request ?
>>> If you are referring to http://bugs.freepascal.org/view.php?id=26774
>>> Work on it was started by Steve Hildebrandt, but I got the impression
>>> that
>>> due to the cross-platform nature of FPC he ran into some problems. I
>>> may be wrong, though. I do not know enough about the compiler
>>> internals to assess the situation.
>>> Michael.
>> Your assesment is correct.
>> I have a version that is nearly complete for Windows(for other platforms
>> I have't done anything). But to have RTTI on all platforms, that is
>> still delphi compatible is not possible(at least for me), due to the
>> nature of some architetures / calling conventions.
>> When I have some free time(after the tests for this semester) I will
>> probably be able to post a patch.
> You don't need to implement Invoke for all platforms for now. Just 
> raise an exception and hopefully platform maintainers will take it 
> from there. The most important part is that the parameter description 
> is flexible enough to potentially allow for all platforms to be 
> supported.
> Regards,
> Sven
And here is the problem, depending on the calling convention it may not 
fit into the delphi compatible RTTI layout.
If more information is needed than a stack offset or a single register 
index, you will need to acomodate that somehow.


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