I am relatively new to C++ and hope that this question is relevant. I
have spent some time at the local library and some time on dejanews,
but have no decided to go ahead with my question, since I found no
satisfactory answer yet.
It is about composed/aggregated classes. I am developing a scientific
code (Monte Carlo) in which I find it natural to have classes with several
levels of aggregation.
I am particularly keen on having members in my classes declared as
pointers to classes. For the large memory requirements I have, this
makes sense, since the actual information about class sizes presumably
comes from some input class/file.
I code this such that the top-class constructor recursively calls the
constructors of its member classes in the initializer list and this seems
very awkward to me.
To take a concrete example directly from the web:
// User.h
class PointerMember;
class RefParam;
class User{
public:
User( const RefParam &inParam );
virtual ~User()
private:
PointerMember *mPointerMember;
};
// User.cpp
#include "User.h"
User::User( const RefParam &inParam )
: mPointerMember( new PointerMember( inParam ) )
{
return;
}
User::~User()
{
delete mPointerMember;
return;
}
I would much rather do the following:
User::User( const RefParam &inParam )
{
mPointerMember = new PointerMember( inParam ); // DON'T
DO THIS
return;
}
i.e. I would love to use the constructor body, rather than the
initialization list.
To me this seems natural, as I might like to perform some branching in
the constructor or get some non-trivial input info, before building member
mPointerMember - operations that just don't fit the initializer list.
Now, someone in another thread pointed out that another way to proceed
in order to salvage the initializer list, would be to build a
mPointerMember
outside (before calling) the constructor User(....) and pass it as a
reference to User(.....), which then passes it on to a copy constructor
of the member mPointerMember. However, isn't this rather an awkward
thing to do? Why should I even think of defining member contents/size
outside of their belonging class.
To make a long story short. May I actually legally use the constructor
body as not suggested in the above (DON'T DO THIS)?
If not, then where is my reasoning/design wrong?
Thanks for your help,
Chris
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