QSignal(3qt)

📦 version 3.3.8b, in fedora 43, fedora 44

💖 QSignal — bestie edition 💖

okay so this is QSignal, straight out of the Qt manual, section 3qt 🌸. Pull up a chair, grab a boba, we're doing this.

✨ NAME ✨

QSignal — it can be used to send signals for classes that don't inherit QObject 💅

🦋 SYNOPSIS 🦋

#include <qsignal.h>

Inherits QObject.

🌟 Public Members 🌟

  • QSignal ( QObject * parent = 0, const char * name = 0 )
  • ~QSignal ()
  • bool connect ( const QObject * receiver, const char * member )
  • bool disconnect ( const QObject * receiver, const char * member = 0 )
  • void activate ()
  • bool isBlocked () const — (obsolete) 🙈
  • void block ( bool b ) — (obsolete) 🙈
  • void setParameter ( int value ) — (obsolete) 🙈
  • int parameter () const — (obsolete) 🙈
  • void setValue ( const QVariant & value )
  • QVariant value () const

💫 DESCRIPTION 💫

So the whole point of QSignal? It's for when you wanna send signals from a class that does not inherit QObject. Like, it's giving "I want signal energy but I'm not in the QObject family" 😭.

If you wanna send signals from a class that doesn't inherit QObject, you can create an internal QSignal object to emit the signal for you. You also gotta provide a function that connects the signal to an outside object slot. That's literally how signals were implemented in the QMenuData class, which is not a QObject 🫶.

But fr fr, in general we recommend just inheriting QObject instead. QObject provides so much more functionality. That's the move. 👑

You can set a single QVariant parameter for the signal with setValue() ✨.

Also — important — note that QObject is a private base class of QSignal, i.e. you cannot call any QObject member functions from a QSignal object. No cap. 💀

Example, bestie:

#include <qsignal.h>
class MyClass
{
public:
    MyClass();
    ~MyClass();
    void doSomething();
    void connect( QObject *receiver, const char *member );
private:
    QSignal *sig;
};
MyClass::MyClass()
{
    sig = new QSignal;
}
MyClass::~MyClass()
{
    delete sig;
}
void MyClass::doSomething()
{
    // ... does something
    sig->activate(); // emits the signal
}
void MyClass::connect( QObject *receiver, const char *member )
{
    sig->connect( receiver, member );
}

See also Input/Output and Networking and Miscellaneous Classes 🌈.

🎀 MEMBER FUNCTION DOCUMENTATION 🎀

QSignal::QSignal ( QObject * parent = 0, const char * name = 0 )

Constructs a signal object called name, with the parent object parent. These arguments are passed directly to QObject 💅.

QSignal::~QSignal ()

Destroys the signal. All connections are removed, as is the case with all QObjects. bye bye connections 👋💖

void QSignal::activate ()

Emits the signal 🚀. If the platform supports QVariant and a parameter has been set with setValue(), this value is passed in the signal ✨.

void QSignal::block ( bool b )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code. 🙈

Blocks the signal if b is TRUE, or unblocks the signal if b is FALSE.

And listen — an activated signal disappears into hyperspace if it is blocked 🌌. Not me losing signals to the void. 💀

See also isBlocked(), activate(), and QObject::blockSignals().

bool QSignal::connect ( const QObject * receiver, const char * member )

Connects the signal to member in object receiver 🫶.

See also disconnect() and QObject::connect().

bool QSignal::disconnect ( const QObject * receiver, const char * member = 0 )

Disconnects the signal from member in object receiver ✂️.

See also connect() and QObject::disconnect().

bool QSignal::isBlocked () const

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code. 🙈

Returns TRUE if the signal is blocked, or FALSE if it is not blocked.

The signal is not blocked by default ✨.

See also block() and QObject::signalsBlocked().

int QSignal::parameter () const

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code. 🙈

void QSignal::setParameter ( int value )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code. 🙈

void QSignal::setValue ( const QVariant & value )

Sets the signal's parameter to value 💖

QVariant QSignal::value () const

Returns the signal's parameter 🌟

🌈 SEE ALSO 🌈

Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the license file included in the distribution for a complete license statement. 📜

🧚 AUTHOR 🧚

Generated automatically from the source code. yes bestie, the robots did it 🤖✨

💀 BUGS 💀

If you find a bug in Qt, please report it as described in http://doc.trolltech.com/bughowto.html. Good bug reports help us to help you. Thank you. 🫶

The definitive Qt documentation is provided in HTML format; it is located at $QTDIR/doc/html and can be read using Qt Assistant or with a web browser. This man page is provided as a convenience for those users who prefer man pages, although this format is not officially supported by Trolltech. 😭

If you find errors in this manual page, please report them to qt-bugs@trolltech.com. Please include the name of the manual page (qsignal.3qt) and the Qt version (3.3.8). 🌸

Trolltech AS · 2 February 2007 · QSignal(3qt)

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