multiple constructors and class reference variables

[Neil Zanella]

Hello,

AFAIK the only way to initialize a reference variable defined inside a class
is to initialize it in an initializer list. However, when there are multiple
constructors, this means that the initializer lists have to be cut and pasted
from one constructor to another. This does not seem to lend itself particularly
well to maintainablility. Calling a constructor from another in C++ is not legal
unlike in Java. Also, functions other than constructors cannot have initializer
lists. So, if there are multiple constructors, it seems to me that the references
need be copied and constructed the same in each initializer list. This seems
somewhat tedious. Of course, one could always use the preprocessor and
declare the list of common reference initializers in a macro and
then paste the macro instead. I don't regard this particuar
style very good either.

Comments welcome,

Regards,

Neil

 

[Niels Dybdahl]

AFAIK the only way to initialize a reference variable defined inside a
class

is to initialize it in an initializer list. However, when there are multiple
constructors, this means that the initializer lists have to be cut and pasted
from one constructor to another. This does not seem to lend itself particularly
well to maintainablility. Calling a constructor from another in C++ is not legal
unlike in Java. Also, functions other than constructors cannot have initializer
lists. So, if there are multiple constructors, it seems to me that the references
need be copied and constructed the same in each initializer list. This seems
somewhat tedious. Of course, one could always use the preprocessor and
declare the list of common reference initializers in a macro and
then paste the macro instead. I don't regard this particuar
style very good either.

You might create an additional constructor as a constructor in a second
class:

class a {
int & n;
public:
a(int & i):
n(i)
{
...
}
};

class b: public a {
public:
b(int & i; int j):
a(i)
{
...
}
};

This would actually work as if the constructors can call each other (which
they do).

Niels Dybdahl

 

[Nick Hounsome]

Hello,

AFAIK the only way to initialize a reference variable defined inside a class
is to initialize it in an initializer list. However, when there are multiple
constructors, this means that the initializer lists have to be cut and pasted
from one constructor to another. This does not seem to lend itself particularly
well to maintainablility. Calling a constructor from another in C++ is not legal
unlike in Java. Also, functions other than constructors cannot have initializer
lists. So, if there are multiple constructors, it seems to me that the references
need be copied and constructed the same in each initializer list. This seems
somewhat tedious. Of course, one could always use the preprocessor and
declare the list of common reference initializers in a macro and
then paste the macro instead. I don't regard this particuar
style very good either.

Comments welcome,

Regards,

Neil

Don't put references in classes - use pointers.
- people reading the impl wont realize it is a ref
- you can't copy references so you can't implement copy ctor or assignment
properly