Detecting the arity of a constructor at compile time

[Michael Feathers]

I was wondering if it is at all possible to detect the arity of
constructors at compile time using some combination of macros and
template metaprogramming. I'd like to be able to determine whether
a class has, for instance, a constructor with two arguments or a
constructor with three arguments. Is there any way to do this?

Michael

[Victor Bazarov]

Michael Feathers wrote:

I was wondering if it is at all possible to detect the arity of
constructors at compile time using some combination of macros and
template metaprogramming. I'd like to be able to determine whether
a class has, for instance, a constructor with two arguments or a
constructor with three arguments. Is there any way to do this?

I'd like to educate myself in this matter. Could you explain why you
want to do that?

Many thanks!

V
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[Michael Feathers]

Victor Bazarov wrote:

Michael Feathers wrote:

>>I was wondering if it is at all possible to detect the arity of
constructors at compile time using some combination of macros and
template metaprogramming. I'd like to be able to determine whether
a class has, for instance, a constructor with two arguments or a
constructor with three arguments. Is there any way to do this?

I'd like to educate myself in this matter. Could you explain why you
want to do that?

Many thanks!

V

I'd like to write a dependency injection framework that doesn't place
many constraints on the types it manages. I suspect that it would
be easier to use setter-based injection and something like
Alexandrescu's GenLinearHierarchy, but I was wondering if there is
a way to do constructor injection.

Michael Feathers
www.objectmentor.com

[Roland Pibinger]

On Fri, 04 Aug 2006 13:43:14 GMT, Michael Feathers
<mf*******@objectmentor.comwrote:

>I'd like to write a dependency injection framework that doesn't place
many constraints on the types it manages. I suspect that it would
be easier to use setter-based injection and something like
Alexandrescu's GenLinearHierarchy, but I was wondering if there is
a way to do constructor injection.

In Java DI is usually implemented with interfaces. You do them same in
C++ with abstract base classes. WRT the 'arity of constructors' have
you considered default arguments?

Best regards,
Roland Pibinger