On 01/19/2008 02:22 PM, Jon S. Berndt wrote in part:
> .... Pushing an object instance onto a vector is a bad idea, as a proper
> copy constructor must then be created,
Well ... that is exactly the point I'm trying to discuss.
IMHO if you are going to write 23,000 lines of c++, it
might be worth your trouble to figure out how to write a
copy constructor. It ain't that tricky. You only need
to figure it out once, and then you can use the technique
over and over again.
Actually you usually need four things: the basic
constructor, the copy constructor, the assignment
operator, and the destructor. Or just use something
like ref_ptr.
You might want to take a look at
http://andesengineering.com/OSG_ProducerArticles/RefPointers/RefPointers.html
which says in part: "the concept of reference counted
objects will add years to your life in the long run."
I am aware that JSBsim doesn't want to have an OSG
dependence, but there are plenty of ways of having
reference-counted objects without OSG dependence.
C++ was invented for a reason.
> We create instances of engines
> and other components at runtime and place pointers to those objects in the
> vector. Each object instance is [supposed to be] properly destroyed as the
> sim shuts down.
Computers are good at counting things. Why not let the
computer keep track of the reference count?
For example, stdlib lets you have strings, and then lets
you have lists of strings, maps from strings to strings,
et cetera. Stdlib does all the memory management so
that the memory used by the string is freed when the
last reference to the string goes away.
Why not set it up so that we can have a std::list of
engines? Reference-counted objects make that easy.
It's not rocket science.
I would say that pushing an object (such as an engine)
onto a list is a good idea. A very good idea.
C++ was invented for a reason.
Switching from c-- to c++ does *not* consist of replacing
malloc with new and replacing free with delete.
Using automatic variables makes the code more reliable,
and reduces the burden on those who want to read, debug,
maintain, re-use, and/or extend the code.
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