[ITK] [ITK-users] Smartpointer as a default parameter for a function

[Bradley Lowekamp]

Hello,

You can use just about any object type for a default parameter, and pass parameters to the constructor too.

You want to be very careful with constructor with only one parameter especial just an integer. A constructor with just one parameter can be used for implicit conversion. Add the "explicit" keyword before to prevent this:

class A {
  explicit A(int A, PointerType ptr = NULL )
};

And that takes advantage of the implicit conversion with the smart pointer constructor.

Hope that help,
Brad

On Jul 22, 2014, at 4:49 AM, vincent ngai <vincent.ngai at gmail.com> wrote:

> Technically it should be A(int a, ImageType::Pointer ptr = ImageType::Pointer() );
> 
> But I"m not sure if parameter defaults are supported on non-POD parameter types. Why not just overload the ctor and create another 
> class A
> {
>  A(int a, ImageType::Pointer ptr);
>  A( int a );
> };
> 
> 
> On Tue, Jul 22, 2014 at 3:37 PM, <ahmed at mufradat.com> wrote:
> Hello All,
> 
> Suppose I have class like
> 
> class A{
>     public:
>     A(int a, ImageType::Pointer ptr){
>         // whatever!
>     }
> };
> 
> My question is, what's the default value for that ptr? I'd like to be able to create an instance of that class using
> 
> A myA(5);
> 
> so for the definition of the constructor of A:
> 
> A(int a, ImageType::Pointer ptr = WHAT?)
> 
> Best regards,
> Ahmed
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> -- 
> Regards,
> Vincent
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