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Improve warning messages (and readability) of connectSlotsByName()

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While adding a test case for the new behavior, two issues
with the connectSlotsByName implementation came up:

  1. for auto-connected slots that don't exactly match a signal,
     a 'compatible' one is searched. There might be more than
     one of those. The implementation randomly picks any.
  2. The "No matching signal for %s" warning gets printed even for
     slots that can never be connected via connectSlotsMyName
     anyway (e.g. "on_something"). This is inconsistent.

This fixed both: an explicit warning is printed if more than one
'compatible' signal is found and the "No matching signal for %s"
warning is only printed if the slot adheres to the full
"on_child_signal()" naming convention.

In the process I added comments and changed the code slightly to
make it more readable and explicitly hint at non-obvious behavior.

Change-Id: Icc8e3b9936188d2da8dfff9f0373c8e5c776eb14
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
This commit is contained in:
Axel Waggershauser 2013-03-06 17:44:15 +01:00 committed by The Qt Project
parent 2f0756a63c
commit 3c2748afd5
2 changed files with 45 additions and 12 deletions
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50
src/corelib/kernel/qobject.cpp
View File

@ -3234,38 +3234,62 @@ void QMetaObject::connectSlotsByName(QObject *o)
o->findChildren<QObject *>(QString()) // all children of 'o'...
<< o; // and the object 'o' itself
// for each method/slot of o ...
for (int i = 0; i < mo->methodCount(); ++i) {
QByteArray slotSignature = mo->method(i).methodSignature();
const QByteArray slotSignature = mo->method(i).methodSignature();
const char *slot = slotSignature.constData();
Q_ASSERT(slot);
// ...that starts with "on_", ...
if (slot[0] != 'o' || slot[1] != 'n' || slot[2] != '_')
continue;
// ...we check each object in our list, ...
bool foundIt = false;
for(int j = 0; j < list.count(); ++j) {
const QObject *co = list.at(j);
QByteArray objName = co->objectName().toLatin1();
int len = objName.length();
if (!len || qstrncmp(slot + 3, objName.data(), len) || slot[len+3] != '_')
const QByteArray coName = co->objectName().toLatin1();
// ...discarding those whose objectName is not fitting the pattern "on_<objectName>_...", ...
if (coName.isEmpty() || qstrncmp(slot + 3, coName.constData(), coName.size()) || slot[coName.size()+3] != '_')
continue;
const char *signal = slot + coName.size() + 4; // the 'signal' part of the slot name
// ...for the presence of a matching signal "on_<objectName>_<signal>".
const QMetaObject *smeta;
int sigIndex = co->d_func()->signalIndex(slot + len + 4, &smeta);
if (sigIndex < 0) { // search for compatible signals
int sigIndex = co->d_func()->signalIndex(signal, &smeta);
if (sigIndex < 0) {
// if no exactly fitting signal (name + complete parameter type list) could be found
// look for just any signal with the correct name and at least the slot's parameter list.
// Note: if more than one of thoses signals exist, the one that gets connected is
// chosen 'at random' (order of declaration in source file)
QList<QByteArray> compatibleSignals;
const QMetaObject *smo = co->metaObject();
int slotlen = qstrlen(slot + len + 4) - 1;
for (int k = 0; k < QMetaObjectPrivate::absoluteSignalCount(smo); ++k) {
QMetaMethod method = QMetaObjectPrivate::signal(smo, k);
if (!qstrncmp(method.methodSignature().constData(), slot + len + 4, slotlen)) {
int sigLen = qstrlen(signal) - 1; // ignore the trailing ')'
for (int k = QMetaObjectPrivate::absoluteSignalCount(smo)-1; k >= 0; --k) {
const QMetaMethod method = QMetaObjectPrivate::signal(smo, k);
if (!qstrncmp(method.methodSignature().constData(), signal, sigLen)) {
smeta = method.enclosingMetaObject();
sigIndex = k;
break;
compatibleSignals.prepend(method.methodSignature());
}
}
if (compatibleSignals.size() > 1)
qWarning() << "QMetaObject::connectSlotsByName: Connecting slot" << slot
<< "with the first of the following compatible signals:" << compatibleSignals;
}
if (sigIndex < 0)
continue;
// we connect it...
if (Connection(QMetaObjectPrivate::connect(co, sigIndex, smeta, o, i))) {
foundIt = true;
// ...and stop looking for further objects with the same name.
// Note: the Designer will make sure each object name is unique in the above
// 'list' but other code may create two child objects with the same name. In
// this case one is chosen 'at random'.
break;
}
}
@ -3274,6 +3298,10 @@ void QMetaObject::connectSlotsByName(QObject *o)
while (mo->method(i + 1).attributes() & QMetaMethod::Cloned)
++i;
} else if (!(mo->method(i).attributes() & QMetaMethod::Cloned)) {
// check if the slot has the following signature: "on_..._...(..."
int iParen = slotSignature.indexOf('(');
int iLastUnderscore = slotSignature.lastIndexOf('_', iParen-1);
if (iLastUnderscore > 3)
qWarning("QMetaObject::connectSlotsByName: No matching signal for %s", slot);
}
}

5
tests/auto/corelib/kernel/qobject/tst_qobject.cpp
View File

@ -427,6 +427,9 @@ public slots:
protected slots:
void o() { called_slots << -1; }
void on() { called_slots << -1; }
void on_() { called_slots << -1; }
void on_something() { called_slots << -1; }
void on_child_signal() { called_slots << -1; }
signals:
void on_Sender_signalLoopBack();
@ -441,6 +444,8 @@ void tst_QObject::connectSlotsByName()
AutoConnectSender sender(&receiver);
sender.setObjectName("Sender");
QTest::ignoreMessage(QtWarningMsg, "QMetaObject::connectSlotsByName: No matching signal for on_child_signal()");
QTest::ignoreMessage(QtWarningMsg, "QMetaObject::connectSlotsByName: Connecting slot on_Sender_signalManyParams() with the first of the following compatible signals: (\"signalManyParams(int,int,int,QString,bool)\", \"signalManyParams(int,int,int,QString,bool,bool)\") ");
QMetaObject::connectSlotsByName(&receiver);
receiver.called_slots.clear();