Delegating class constructors in C++ using Qt

Question

I try to delegate a class constructor in Qt 5.4.0 using C++. The problematic code looks as follows:

//.h
class A : public QObject
{

public:
  A(QObject *parent = 0) : A(10, parent) {};   <--COMPILER ERROR
  A(int x, QObject *parent = 0);
  ...
};

//.cpp
A::A(int x, QObject *parent) : QObject(parent)
{
  do_something();
}

The compiler claims that the element initialization 'A' is neither Basis nor Element. Isn't this supported? If so, what causes this error?

What compiler are you using? This feature is likely not supported by yours. — anderas, Aug 06 '15 at 08:58
Also, which flags are you using? Even if it is supported, you likely need to add a c+11 flag (`-std=c++11` for gcc). — Armaghast, Aug 06 '15 at 09:00
@user3482407 Then my answer applies: It is not supported in that version. — anderas, Aug 06 '15 at 09:06

score 2 · Accepted Answer · edited May 23 '17 at 12:14

Constructor delegation is a C++11 feature that is not supported by all compilers yet. Chances are that it does not work if you are using a Visual Studio compiler (or an old GCC).

See for example this question, with answers stating that it is not even fully supported in VS2012: Is there a way to use delegating constructors in Visual Studio 2012?

For reference, here you can find all features that are supported by the respective MSVC versions (delegating Constructors is mentioned as not supported on MSVC11): https://msdn.microsoft.com/en-us/library/hh567368.aspx

Delegating class constructors in C++ using Qt

1 Answers1