[QGIS-Developer] Upgrading to V3

[Etienne Trimaille]

Hi,

I can't really answer your question but you should use
https://qgis.org/api/classQgsMapLayerComboBox.html instead of creating your
own combobox. (if possible).

Etienne

Le dim. 15 sept. 2019 à 10:11, Maaza Mekuria <mcmekuria at gmail.com> a écrit :

> QGIS Layer List upgrade to V3 C++ plugin - Geographic Information Systems
> Stack Exchange <style>body,.top-bar{margin-top:1.9em}</style>
>
> I was upgrading a c++ plugin that I had used in the past and almost
> eliminated all the the usual compiler errors due to version changes
> according for the current version (3.6). The plugin used to collect current
> map canvas layers in a combo list box for selection. I am getting two
> errors that I can't figure out what to do with. This code compiled without
> problem pre-2.0.
>
> The first happens to be about QGSMapLayer that can't be instantiated
> because it is turned as an abstract class and I am getting an error
> [Severity Code Description Project File Line Source Suppression State Error
> C2259 'QgsMapLayer': cannot instantiate abstract class tarjan_sccplugin
> C:\OSGeo4W64\apps\Qt5\include\QtCore\qlist.h 214 Build ]
>
> This is portion of the code generating the error.  Where cmbNetSourceLayer
> is a combo-box .
>
> void tarjan_sccGui::populateLayers( QString const& url ) {
> cmbNetSourceLayer->clear();
>
> QString layerName; QString layerType;
>
> // fill list of layersQMap<QString, QgsMapLayer*> mapLayers = QgsProject::instance()->mapLayers();QMap<QString, QgsMapLayer*>::iterator layer_it = mapLayers.begin();
> for (; layer_it != mapLayers.end(); ++layer_it){
>     QgsVectorLayer* vl = dynamic_cast<QgsVectorLayer*>(layer_it.value());
>     if (!vl)
>         continue;
>     else
>
>      cmbNetSourceLayer->addItem(vl->name() );}
>
> The second error appears to be in explicit declaration for the plugin.
> Something has changed in how the plugins are initiated. [Severity Code
> Description Project File Line Source Suppression State Error (active)
> invalid explicit instantiation declaration tarjan_sccplugin
> d:\GIS\v3\Quantum-GIS\src\core\qgsoptionalexpression.h 82 IntelliSense ]
>
> No idea what must be done to overcome this error.  The cited module
> appears to be an optional data module.
>
>
> Any help is appreciated.
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