Re: namespaces, class libraries, and VERY large projects

And your "using" statements should be in your .cpp files, not
in headers. You want don't want to have to be hunting through
a million .h files to find out where a name comes from.

Don't use "using namespace" statements. If the likelihood of name
collisions is high enough to require namespaces, then you'll have
to get rid of them, anyway, and adding qualifiers everywhere in
a million lines of code after you've written, debugged, and forgotten
them is a *lot* harder than doing it right the first time.

(A general rule: do your best to write code you won't have to revisit.
The cost of changing one line of code goes up both as time
passes and as the amount of code that depends upon it goes up.)

I don't even use "using namespace std" or "using std::string" or
"using std::cout" statements. It makes it easer to find them
with search commands.

I don't have a lot of experience with nested namespaces. My
experience with nested classes has run into enough annoying
restrictions that I would not use nested namespaces on a big
project until I had a fair amount of experiences on projects small
enough that un-nesting them later on wouldn't be a big problem.