How to send data from a static function of other Class to a MainWindow function?

[hakermania]

It's an interesting interpretation, but I would make this in other way: make this object as a singleton

class Global: public QObject
{
    Q_OBJECT
 
public:
    static Global *instance();
 
    void send_name(const QString &color_name);
...
 
Q_SIGNALS:
   void send_color(const QString &color_name);
 
private:
   Q_DISABLE_COPY(Global);
};
 
#define myGlobal Global::instance()    //shortcut

class Global: public QObject
{
    Q_OBJECT

public:
    static Global *instance();

    void send_name(const QString &color_name);
...

Q_SIGNALS:
   void send_color(const QString &color_name);

private:
   Q_DISABLE_COPY(Global);
};

#define myGlobal Global::instance()    //shortcut

To copy to clipboard, switch view to plain text mode 

Then

...
connect(myGlobal, SIGNAL(send_color(const QString &)), SLOT(applyColor(const QString &)));
...
myGlobal->send_name("lightgray");

...
connect(myGlobal, SIGNAL(send_color(const QString &)), SLOT(applyColor(const QString &)));
...
myGlobal->send_name("lightgray");

To copy to clipboard, switch view to plain text mode 

Thanks for your reply but I am not 100% sure that I understand your code. I want to call a Global static function from my MainWindow class, let's say

Global::set_new_color();

Global::set_new_color();

To copy to clipboard, switch view to plain text mode 

and then, from within set_new_color I want to send a message back to mainwindow getting the color_name. From your code I assume that the send_name function then emits the send_color signal? If I use

Q_EMIT send_color(color_name);

Q_EMIT send_color(color_name);

To copy to clipboard, switch view to plain text mode 

it doesn't let me emit it without an object... And I cannot create a new Global instance, because, as far as I understood from your code, Q_DISABLE_COPY avoids me from doing so...

If you want, I will provide you with example files.