Problem with macro expantion when '::' is within a string

[Felix Lee]

Lars Holm <lars.holm@bonetmail.com>:
> #define FOO(a,b)  a##::Foo(#b)
> The compiler complains with:
> foo.cxx:35:41: pasting "txBoolean" and "::" does not give a valid preprocessing token

You don't need the "##".  "##" is only useful when you want to
make a single word out of two separate words, such as
    tx ## Boolean
--