This is something C# has had for ages, so it is great to finally get it in C++ too. The compiler feature allows a type’s constructor (the delegating constructor) to have another constructor of the type in its initialization list. So when you previously had to write code like this.
class Error
{
public:
Error()
{
Init(0, "Success");
}
Error(const char* message)
{
Init(-1, message);
}
Error(int errorCode, const char* message)
{
Init(errorCode, message);
}
private:
void Init(int errorCode, const char* message)
{
//...
}
};
With delegating constructors, you can now write it as following.
class Error
{
public:
Error() : Error(0, "Success")
{
}
Error(const char* message) : Error(-1, message)
{
}
Error(int errorCode, const char* message)
{
// ...
}
};
Bonus reading – Here’s a humorous article written 10 years ago (May 2003) by Herb Sutter and Jim Hyslop on delegating constructors, way before the standards body started considering it as a serious proposal.
