Why is this D code slower than C++?

[Bill Baxter]

%u wrote:
> Bill Baxter Wrote:
>> D still not as fast as the C++, but close.
> 
> I refuse to analyze this any further.
> 
> On comparing the implementations of Primary, I noticed, that the OP has introduced a constructor which executes "new Material". There is no "new" in the cpp-version of Primary but a "SetMaterial" function.
> 
> On deleting the new expression in the D-version an exception was raised on executing the newly compiled binary.
> 
> Astonishingly grepping over the .cpp and .h -files with agent ransack no calls of "SetMaterial" were delivered---but "GetMaterial" is called---which uses the unset "Material" pointer. :-(
> 
> Conclusion: at least one of the following is true
> 1) I have near to no ability to understand c++ 
> 2) the c++-version is lucky to run at all
> 
> In case of 2) the OP has silently changed the algorithm on porting to D.

It's case 1) I'm afraid.  :-)

Material is a by-value member of Primitive in the C++ version.  This 
means it acts more like a D struct than a D class.  GetMaterial calls 
return a pointer to the Material that's part of the class, and it will 
have been initialized implicitly by the Primitive constructor using 
whatever Material's default constructor does.

So the C++ code is ok.  But it's not clear why Material became a class 
in the D version rather than a struct.

--bb