Non-class method in Qt ( with qtcreator ) unresolved external symbol - c++

Question

I have an application that was built without problems in Linux, now I'm trying to compile it against Windows, I created a .pro file specially for compiling it in windows.
I use a pseudo-class ( just a namespace with a buch of methods, but without a class statement so I can use it without creating an object ) that's working just fine in Linux, but
when I try to compile against windows I get an 'unresolved external symbol' throughout all the code where this pseudo-class's being used.
The pseudo-class goes like this:
namespace foo {
bool method_bar();
}
Then I use it like this:
foo:method_bar();
Pretty straight-forward, somewhat like static methods.
Before somebody asks me, why not use static methods in first place; I have some special situations in which I cannot use these methods as static. That's why I buit the methods directly under the namespace.
So, at my .PRO file, I added the .h and .cpp files from my pseudo-class like this:
HEADERS += \
....
include/foo.h
....
SOURCES += \
....
include/foo.cpp
----
Although it includes the files in my projects, it's throwing that LNK2019: unresolved external symbol error.
I'm no beginner with programming, but I'm a beginner with Qt.
Any help will be deeply appreciated.
ps: forgive my English mistakes.

Answer 1

first of all the scope operator is foo"::"method_bar();
See that the header is included before the usage of the function so that the places where ever you are calling this function knows about the declarations of the function
There is no problem in using namespace in QT.
One more suggestion would be
using namespace foo;
Looking at the complete code would really help me in resolving the problem