Programming

Ok, so this is one method.

I also outline another method

Code:

int main(int argc, char *argv[])
{

  Tomog T;
  T.set_parameter("dist",dist);
  T.set_parameter("ifmodl",ifmodl);
  T.set_parameters(dist,ifmodl,...etc);
}

or pass a structure if I have a lot of parameters

Code:

int main(int argc, char *argv[])
{

  Tomog T;
  T.set_parameter("dist",dist);
  T.set_parameter("ifmodl",ifmodl);
  T.set_parameters(config_parameters); 
}

How does this method compare with what you propose and what would ideally be your suggestion?

The namespace is the exact same thing done a simpler way, avoiding some pitfalls that could happen when using Tomog.

It's possible for there to be more than one Tomog object, which can cause confusion and bugs. You could make bad, shallow copies of Tomog that crash later if you accidentally pass by value instead of reference. You might accidentally use the wrong Tomog, or a new/blank Tomog, instead of the one you set up in main(). You might try and change a value in one Tomog and not have it show up later because you changed a copy, not the original. You might end up with multiple Tomog's slightly different from each other.

If you use your Tomog class exactly perfectly correctly, keeping one and only one instance which you pass by reference everywhere, that's exactly what a namespace acts like anyway.

I understand what you mean. I only have a single Tomog used in Main. With the discussion here, both methods are better than how I was doing things, passing everything.

Do you see the use of namespaces for passing variables to classes in this way in actual applications?

Passing by-value instead of by-reference will make duplicates, potentially leading to one or more of the problems mentioned above. All it takes is a single missed &. But you can't duplicate a namespace even by accident. Yes. The standard cin, cout, and cerr variables exist inside the std namespace, for example.

Brilliant. I am upgrading this old code written by someone else and am grateful for the suggestions to redo some thing better. It's my first big project in C++. Before, they were mainly toy problems.