• lurker <lurker mailinator.com> Jul 26 2010
• bearophile <bearophileHUGS lycos.com> Jul 26 2010
• Robert Clipsham <robert octarineparrot.com> Jul 26 2010

lurker <lurker mailinator.com> writes:

Where's the vtable layout documented? I couldn't find it in the documentation.

Bonus points: How would it look like in C?

Thanks

bearophile <bearophileHUGS lycos.com> writes:

lurker:
 Where's T documented? I couldn't find it in the documentation.
 Bonus points: How would it look like in C?


There are two groups of specs, the D language specs, and the specs of how dmd
compiles D code. The vtable layout is a dmd spec, because in theory other D
compilers can implement virtual functions in another ways (for example with
dispatch tree, that are better for inlining, but have other disadvantages).

D language specs show that D classes have the .__vptr and .__monitor
properties, but I think the vptr can be just a ID pointer if a compiler
implements virtual calls with dispatch trees, because there is no need of a
virtual table.

Bye,
bearophile

Robert Clipsham <robert octarineparrot.com> writes:

On 26/07/10 21:56, lurker wrote:
 Where's the vtable layout documented? I couldn't find it in the documentation.

 Bonus points: How would it look like in C?

 Thanks


See:
http://www.digitalmars.com/d/1.0/abi.html
http://www.digitalmars.com/d/2.0/abi.html

For D2, you can take a look at this header for how a class should look 
to C (look at the Object struct):

http://dsource.org/projects/druntime/browser/trunk/src/rt/mars.h

I believe D1 has a similar file, I'll leave you to find that yourself 
though :)

-- 
Robert
http://octarineparrot.com/