• Mike B Johnson (1/1) May 06 2017 how many elements(virtual functions) are in the __vptr?
• Jacob Carlborg (5/6) May 08 2017 I guess you can use __traits(allMembers) and __traits(isVirtualMethod) [...
• Basile B. (35/36) May 08 2017 You don't need the size. The index you get with

Mike B Johnson <Mikey Ikes.com> writes:

how many elements(virtual functions) are in the __vptr?

Jacob Carlborg <doob me.com> writes:

On 2017-05-07 06:01, Mike B Johnson wrote:
 how many elements(virtual functions) are in the __vptr?

I guess you can use __traits(allMembers) and __traits(isVirtualMethod) [1].

[1] http://dlang.org/spec/traits.html

-- 
/Jacob Carlborg

Basile B. <b2.temp gmx.com> writes:

On Sunday, 7 May 2017 at 04:01:43 UTC, Mike B Johnson wrote:
 how many elements(virtual functions) are in the __vptr?

You don't need the size. The index you get with 
__traits(virtualIndex) is always valid. 
(https://dlang.org/spec/traits.html#getVirtualIndex)

However as an exercise you can still count them:

- iterate all the member
- check each overload with __traits(isVirtualMethod)

---
template virtualMethodCount(T)
{
     size_t c()
     {
         size_t result;
         foreach (member; __traits(allMembers, T))
             static if (is(typeof(__traits(getMember, T, member))))
             {
                 foreach (overload; __traits(getOverloads, T , 
member))
                     result += __traits(isVirtualMethod, overload);
             }
         return result;
     }
     enum objectVmc = 4; // toHash, opCmp, opEquals, toString
     enum virtualMethodCount = c() - objectVmc;
}

unittest
{
     class Foo{}
     static assert( virtualMethodCount!Foo == 0);
     class Bar{void foo(){} int foo(){return 0;}}
     static assert( virtualMethodCount!Bar == 2);
     class Baz{private void foo(){} int foo(){return 0;}}
     static assert( virtualMethodCount!Baz == 1);
}
---