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    <p>I don't think that's a good idea. You are wrapping every float of your hash with a QObject which sounds very heavy to me.</p> <p>You can hap the whole HashMap inside the QObject and emit the signal from there when the value you are interested in has changed.</p> <pre><code>class MyHashMap : public QObject { Q_OBJECT public: explicit MyHashMap(QObject *parent = 0); float Get(const QString&amp; key) const; void SetValue(const QString&amp; key, float value) { // only emit value changed if the value has actually changed QHashMap&lt;QString, float&gt;::iterator it = myHashMap.find(key); if(it != myHashMap.end()){ if(it.value != value){ myHashMap[key] = value; emit ValueChanged(key, value); } } } private: QHashMap&lt;QString, float&gt; myHashMap; signals: void ValueChanged(const QString&amp; key, float newValue); }; </code></pre> <p>According to your comment, you want to update a label when a value has changed. Simply add all the labels to a QHashMap, then connect the ValueChanged signal to a slot that updates the right label:</p> <pre><code>class MyWidget : public QWidget { Q_OBJECT public: explicit MyWidget(QWidget *parent = 0) { ... ... myLabels["label1"] = myLabel1; myLabels["label2"] = myLabel2; QObject::connect(myLabels, SIGNAL(ValueChanged(const QString&amp;, float)), this, OnValueChanged(const QString&amp;, float)); } public slots: void OnValueChanged(const QString&amp; key, float newValue){ QHashMap&lt;QString, QLabel*&gt;::iterator it = myLabels.find(key); if(it != myLabels.end()){ it.value()-&gt;setText(QString::number(newValue)); } } private: QHashMap&lt;QString, QLabel*&gt; myLabels; }; </code></pre>
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    1. POQt signal for changed hashmap
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    1. COWell thats seems like a neat start! The thing is then that I want to connect each ValueChanged signal with different actions, eg. change a specific text label. Should I aim for connecting the key in the emitted signal with perhaps a hashmap with function pointers that does the things I want? Or just call a function that prints all values in MyHash each time a value is changed? There are so many ways to do these things, and I'm looking for the "best" way.
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    2. COI edited the answer according to your comment. You might wanna update the question.
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    3. COThank you for great answers! What do you generally think about the concept of storing function pointers in a map?
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