[fpc-devel] Improved RTTI compromise

Sven Barth pascaldragon at googlemail.com
Tue Dec 6 22:49:28 CET 2016

On 06.12.2016 21:17, Maciej Izak wrote:
> 2016-12-06 17:46 GMT+01:00 Michael Van Canneyt <michael at freepascal.org
> <mailto:michael at freepascal.org>>:
>     The Delphi TypInfo unit also exposes the attributes.
> My message was unclear - I mean that we can hide incompatible part of
> TypInfo. Type TAttributeData is located in TypInfo (sooner or later that
> part of TypInfo will be corrected - but IIRC for that "Invoke" function
> is needed). RTTI.pas is rather fine (need to check).

We won't need Invoke() function for attributes, since Joost's branch
generates a function that calls the attribute class' constructor with
the provided values and returns the created instance.
This has the advantage that it's a) faster and b) works on all supported
platforms whereas Invoke() will not be supported on all platforms at the
beginning and additionally requires the parameter RTTI to be in place
(basically what's introduced with the Interface RTTI branch).

> or second option:
> compiler hinting directive "experimental" for TypInfo.TAttributeData.
> Good temporary deal for all (I think)... 
> anyway any option is much better perspective than ignoring RTTI.pas for
> long long long time...

I've just looked through Joost's branch. One of the biggest problems is
the unit list and the list of types contained in each unit. Since this
is only introduced in the branch and the introduction of dynamic
packages completely shakes that up (I want to be able to look up types
of packages that were dynamically loaded after all ;) ).
So if we agree that for now TRttiContext either is removed or its
methods return Nil and attribute support is also removed for now then we
can indeed move the RTTI unit rather unceremoniously to trunk (I'll need
to rework Joost's branch anyway).
Since we now also support generic functions we can also add the missing
functions of TValue ;) (patches welcome once we've indeed merged it)


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