Error in <TQClass::New>: cannot create object

[Gregor814]

Hello,

I have created some custom classes, so called “ROIs” (regions-of-interest) inheriting from TQObject and draw objects, and experience some funny behavior. Attached you find a minimal example.

The inheritance chart is:
TQObject
|
ROI (abstract base class)
|
ROIEllipse – TEllipse (graphics object for ROIEllipse and ROICircle)
|
ROICircle

Now, from right-clicking the image in the GUI you can create ROIEllipse and ROICircle and save the to a ROOT file. For ROIEllipse I get the warning

Warning in TKey::TKey: since ROIEllipse has no public constructor
which can be called without argument, objects of this class
can not be read with the current library. You will need to
add a default constructor before attempting to read it.

but NOT for its child ROICircle!!! The warning is nonsense anyway, because there actually IS a default constructor!!!

If I delete the ROIs and load them from file again (right-click the image), I get the error

Error in TQClass::New: cannot create object of class ROIEllipse

again not for child class ROICircle which loads fine.

I have implemented the copy constructor and operator= which is forced by TQObject and I don’t see why I would get the warnings/errors and why the child class ROICircle works while its parent ROIEllipse doesn’t.

Any ideas?
MyGui.zip (115 KB)

[Wile_E_Coyote]

In file included from MyGui.cxx:13:0: MyGui.h: In copy constructor ‘ROI::ROI(const ROI&)’: MyGui.h:40:2: warning: base class ‘class TQObject’ should be explicitly initialized in the copy constructor [-Wextra] ROI(const ROI &roi){} ^ MyGui.h: At global scope: MyGui.h:40:2: warning: unused parameter ‘roi’ [-Wunused-parameter] MyGui.cxx: In member function ‘virtual void MyMainFrame::LoadROIs()’: MyGui.cxx:88:102: warning: format not a string literal and no format arguments [-Wformat-security] Error("MyMainFrame::LoadROIs()", ("Cannot open file " + std::string(fi.fFilename) + " !!!").c_str()); ^ MyGui.cxx: In member function ‘virtual void MyMainFrame::SaveROIs()’: MyGui.cxx:123:82: warning: format not a string literal and no format arguments [-Wformat-security] Error("MyMainFrame::SaveROIs()", "No write access to file " + filename + " !!!"); ^ In file included from MyGuiDict.h:34:0, from MyGuiDict.cxx:17: MyGui.h: In copy constructor ‘ROI::ROI(const ROI&)’: MyGui.h:40:2: warning: base class ‘class TQObject’ should be explicitly initialized in the copy constructor [-Wextra] ROI(const ROI &roi){} ^ MyGui.h: At global scope: MyGui.h:40:2: warning: unused parameter ‘roi’ [-Wunused-parameter] BTW. The “compile” line should look like this: `root-config --cxx --cflags` -g -O2 -W -Wall -o ${ProjectName} ${ProjectName}.cxx ${ProjectName}Dict.cxx `root-config --glibs` -lASImage P.S. I noticed that the ROIEllipse problem is visible in ROOT 5.34 but not in recent 6.0[24].

[Gregor814]

Thanks for the comments regarding the flags, I have never seen these warnings before…

Took a full day to migrate my framework to ROOT 6, but currently it looks like everything is working and even some other C++11 workarounds aren’t necessary anymore. So far worth it…