How to define signals with macros in Qt - c++

Question

I try to create a some standart signal definitionsfor some classes with macros like:
#define CREATE_SIGNALS signals: void error_signal(QString error);
Functions are created, but moc did not create methods for these functions. It seems that moc is running before macros processed. How can i make this work?

Answer 1

Moc preprocesses the sources it works on, so your macro will work once you actually make the macro define some signals, and not regular methods.
The following is a complete example:
#include <QtCore>
#include <array>
#include <algorithm>
#define CREATE_SIGNALS\
Q_SIGNAL void signal1(const QString & = QString());\
Q_SIGNAL void signal2(int = 0);
struct Foo : QObject {
CREATE_SIGNALS
Q_OBJECT
};
struct Bar : QObject {
CREATE_SIGNALS
Q_OBJECT
};
int main()
{
std::array<int, 4> s;
Foo foo;
Bar bar;
s.fill(0);
QObject::connect(&foo, &Foo::signal1, [&]{++s[0];});
QObject::connect(&foo, &Foo::signal2, [&]{++s[1];});
QObject::connect(&bar, &Bar::signal1, [&]{++s[2];});
QObject::connect(&bar, &Bar::signal2, [&]{++s[3];});
emit foo.signal1();
emit foo.signal2();
emit bar.signal1();
emit bar.signal2();
Q_ASSERT(std::all_of(std::begin(s), std::end(s), [](int val) { return val == 1; }));
}
#include "main.moc"