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POIs there any way to use Qt without using dynamic memory for everything?
 

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  1. POIs there any way to use Qt without using dynamic memory for everything?
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    <p>So, I think I've searched the web quite thoroughly about this and found nothing really useful (just confusing at most...).</p> <p>I'd like to know how I can (if possible) use Qt with non-dynamic memory. The problem I face is that for many widgets, I know exactly what I want to use (these sub-widgets, these layouts, in fixed numbers, etc.). Yet, everything in Qt seems to get in the way when you don't use dynamic memory. A simple example is <code>QLayout</code>, which <a href="http://qt-project.org/doc/qt-5.0/qtwidgets/qlayout.html#addItem" rel="nofollow">from the Qt documentation</a> is designed to take ownership of anything it is added. So basically, the following code:</p> <pre><code>//In header class ThumbnailDialog : public QDialog { Q_OBJECT public: ThumbnailDialog(QWidget* parent = 0); ~ThumbnailDialog(void); private: QPushButton m_confirm; QPushButton m_cancel; QHBoxLayout m_buttonsLayout; }; //Implementation of ctor ThumbnailDialog::ThumbnailDialog(QWidget* parent): QDialog(parent) { //... m_buttonsLayout.addWidget(&amp;m_confirm); m_buttonsLayout.addWidget(&amp;m_cancel); //... setLayout(&amp;m_dialogLayout); } </code></pre> <p>...will end up (on MSVC) in a debug assertion fail for <code>_BLOCK_TYPE_IS_VALID(pHead-&gt;nBlockUse)</code> because, in the <code>ThumbnailDialog</code>'s dtor, the layout tries to delete the buttons... which it obviously shouldn't.</p> <p>So, am I forced to use dynamic memories everywhere, <a href="http://qt-project.org/forums/viewthread/10160/#57700" rel="nofollow">as this "Qt Expert"</a> advocates (while mentioning "heap", though...) ? This seems wrong as this prevents taking advantage of RAII (if parent-child relation means there'll be a delete, one can't use smart pointers to do that I suppose, then). It also feels terribly wrong to resort to dynamic memory for things known at compile-time... (but I could be wrong, that's just my feeling).</p> <p>So: is there any way of using Qt without resorting to dynamic memory and <code>new</code>s for every single widget/layout ? </p>
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    1. USJerry Coffin
    1. USJBL
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    1. COI think Qt designed in that way. But if it guarantees the deletion of child objects when parent is destroyed - it also acceptable approach.
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      1. POIs there any way to use Qt without using dynamic memory for everything?
      1. USvahancho
    2. CO@JBL, I think you are overthinking this. If you are using QT (or any other UI library), say bye bye to efficiency on such small things already. They are built on top of layers over layers of passing values around while doing nothing, a couple `new`s won't change anything. It is also not conceptually wrong. If you can allocate a lot of objects on the fly, there is no need to make them static, force it to be written to the executable and stored on disk. Not to mention later you would regret not being able to have a more dynamic UI.
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      1. USShahbaz
    3. COThere are no exception issues, non of the Qt API's throw.
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      1. USpaulm
 

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