OK, so I have this tiny little corner of my code where I’d like my function return either of (int, double, CString) to clean up the code a bit.
So I think: No problem to write a little union-like wrapper struct with three members etc. But wait! Haven’t I read of boost::variant? Wouldn’t this be exactly what I need? This would save me from messing around with a wrapper struct myself! (Note that I already have the boost library available in my project.)
So I fire up my browser, navigate to Chapter 28. Boost.Variant and lo and behold:
The variant class template is a safe, generic, stack-based discriminated union container, offering a simple solution for manipulating an object from a heterogeneous set of types […]
Great! Exactly what I need!
But then it goes on:
Boost.Variant vs. Boost.Any
- Boost.Any makes little use of template metaprogramming techniques (avoiding potentially hard-to-read error messages and significant compile-time processor and memory demands).
[…]
Troubleshooting
“Internal heap limit reached” — Microsoft Visual C++ — The compiler option /ZmNNN can increase the memory allocation limit. The NNN is a scaling percentage (i.e., 100 denotes the default limit). (Try /Zm200.)
[…]
Uh oh. So using boost::variant may significantly increase compile-time and generate hard-to-read error messages. What if someone moves my use of boost::variant to a common header, will our project suddenly take lots longer to compile? Am I introducing an (unnecessarily) complex type?
Should I use boost::variant for my simple tiny problem?
Boost.variant is not that complex, IMHO. Yes, it is template based, but it doesn’t use any really complex feature of C++. I’ve used quite a bit and no problem at all. I think in your case it would help better describing what your code is doing.
Another way of thinking is transforming what that function returns into a more semantically rich structure/class that allows interpreting which inner element is interesting, but that depends on your design.