How to modularize custom widgets?

[matkuki]

Hi,

I would like to define a custom widget in a separate module and import it into the main module. I tried putting a widget like this:

# gui/tabwidget.nim

import nimqt
import nimqt / [
    qtabwidget,
]

## Custom tab-widget
inheritQObject(CustomTabWidget, QTabWidget):
    override mousePressEvent(e: ptr QMouseEvent):
        echo "Pressed the mouse! ", e.button
        this.parent_mousePressEvent(e)

    override mouseReleaseEvent(e: ptr QMouseEvent):
        echo "Released the mouse! ", e.button
        this.parent_mouseReleaseEvent(e)

then importing it in the main module:

# exco.nim

import nimqt
import gui/tabwidget

nimqt.init

proc main() =
    # some code ...

    var tab_widget = newCustomTabWidget()

    # some more code ...

but that doesn't work. Then I tried exporting the creating proc in gui/tabwidget.nim with:

export newCustomTabWidget

but that makes it only compile in Nim, but the C++ compilation fails with:

cl : Command line warning D9002 : ignoring unknown option '-std=c++17'
cl : Command line warning D9027 : source file 'shell32.lib' ignored
@mexco.nim.cpp
cl : Command line warning D9002 : ignoring unknown option '-std=c++17'
cl : Command line warning D9027 : source file 'shell32.lib' ignored
@mgui@stabwidget.nim.cpp
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(108): error C2143: syntax error: missing ';' before 'public'
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(108): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(108): warning C4183: 'W_OBJECT': missing return type; assumed to be a member function returning 'int'
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(118): error C2144: syntax error: 'void' should be preceded by ';'
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(118): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
C:\Users\matic\nimcache\exco_d\@mexco.nim.cpp(683): error C2065: 'CustomTabWidget': undeclared identifier
C:\Users\matic\nimcache\exco_d\@mexco.nim.cpp(683): error C2065: 'tab_widget': undeclared identifier
C:\Users\matic\nimcache\exco_d\@mexco.nim.cpp(683): error C2061: syntax error: identifier 'CustomTabWidget'
C:\Users\matic\nimcache\exco_d\@mexco.nim.cpp(727): error C2065: 'tab_widget': undeclared identifier
C:\Users\matic\nimcache\exco_d\@mexco.nim.cpp(729): error C2065: 'tab_widget': undeclared identifier
C:\Users\matic\nimcache\exco_d\@mexco.nim.cpp(731): error C2065: 'tab_widget': undeclared identifier
C:\Users\matic\nimcache\exco_d\@mexco.nim.cpp(788): error C2065: 'tab_widget': undeclared identifier
Error: execution of an external compiler program 'vccexe.exe /c --platform:amd64  /nologo ...

What is the nimqt way of doing this modularization?

[jerous86]

Good question. I did not consider this yet, or naively thought it would be trivial :)

Currently, a c++ struct is emitted by the inheritQObject macro. This struct is not imported into exco.nim, hence it will give some undeclared identifier errors. I will see if I can fix this using some additional macro in the module that's importing the custom widget.

Will keep you updated.

[matkuki]

Excellent 👍 Can't wait for the update, thanks!

[jerous86]

Still looking into it, but don't have much time these days. And there seem to always be some small thing that doesn't work when I think I find something :)

[matkuki]

No worries, you're doing great 👍👍👍 I'm very impressed that you made it this far with nimqt! Sorry to have brought this issue up, but I am porting a big app (ExCo) from PyQt to nimqt, and this is one of the fundamentals that I need for the porting to work.

[jerous86]

Thank you :) No worries, it's indeed a very good and important issue that you raise.

I think I might have found something: in examples/custom_widget_*.nim you can find examples, but basically I think you should be able to do

import tabwidget
tabwidget.import_CustomTabWidget()

and then you can proceed as if the custom widget was made in the module itself. This works for the simple example in examples, but I will not be surprised if there are many other scenarios where it will not work :)

In any case let me know how it works out for you

[matkuki]

Very good! Trying to test, but the nimble file needs to be updated, I think, it points to the wrong qt/6... directory for the source. I manually changed that and installed, but compiling now throws:

Hint: used config file 'J:\Nim\nimqt\ExCo2\src\exco.nim.cfg' [Conf]
.............................................................................................................................
C:\Users\matic\.nimble\pkgs\nimqt-0.1\nimqt\qtcore\qstring.nim(189, 1) Error: redefinition of 'arg'; previous declaration here: C:\Users\matic\.nimble\pkgs\nimqt-0.1\nimqt\qtcore\qstring.nim(179, 6)
stack trace: (most recent call last)

[jerous86]

Right, I updated the directory structure a bit, added some more modules and moved from Qt 6.4.2 to 6.4.3, but forgot to update it indeed. Should be now ok?

[matkuki]

nimble install still doesn't install any files (I'm on Windows):

[jerous86]

Ah, maybe because I'm using symlinks. That works on unix systems, but didn't try it on windows yet and might be causing troubles ... Can you try again?

[matkuki]

Yes, installation works 👍

But the compilation error is still there:

...
Hint: used config file 'C:\Users\matic\.choosenim\toolchains\nim-1.6.12\config\nim.cfg' [Conf]
Hint: used config file 'C:\Users\matic\.choosenim\toolchains\nim-1.6.12\config\config.nims' [Conf]
Hint: used config file 'J:\Nim\nimqt\ExCo2\src\exco.nim.cfg' [Conf]
.............................................................................................................................
C:\Users\matic\.nimble\pkgs\nimqt-0.1\nimqt\qtcore\qstring.nim(189, 1) Error: redefinition of 'arg'; previous declaration here: C:\Users\matic\.nimble\pkgs\nimqt-0.1\nimqt\qtcore\qstring.nim(179, 6)
stack trace: (most recent call last)
J:\Nim\nimqt\ExCo2\exco_build.nims(91, 9)
C:\Users\matic\.choosenim\toolchains\nim-1.6.12\lib\system\nimscript.nim(273, 7) exec
...

[jerous86]

I think that's because on windows clong and cint are the same type. I will fix that later, but if you want to move on, you can try to remove line 189 (and possibly other duplicates), and then it should hopefully work :)

[matkuki]

Commenting out lines in qstring.nim 189-191 and 195-197, makes the error go away 👍

I'm using now tabwidget.import_CustomTabWidget() and the Nim compilation succeeds, but the MSVC++ compilation throws:

Hint: used config file 'C:\Users\matic\.choosenim\toolchains\nim-1.6.12\config\nim.cfg' [Conf]
Hint: used config file 'C:\Users\matic\.choosenim\toolchains\nim-1.6.12\config\config.nims' [Conf]
Hint: used config file 'J:\Nim\nimqt\ExCo2\src\exco.nim.cfg' [Conf]
.............................................................................................................................................................................................................................................................................
CC: gui/tabwidget.nim
cl : Command line warning D9002 : ignoring unknown option '-std=c++17'
cl : Command line warning D9027 : source file 'shell32.lib' ignored
@mgui@stabwidget.nim.cpp
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(119): error C2143: syntax error: missing ';' before 'public'
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(119): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(119): warning C4183: 'W_OBJECT': missing return type; assumed to be a member function returning 'int'
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(135): error C2143: syntax error: missing ';' before '<class-head>'
C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp(135): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
Error: execution of an external compiler program 'vccexe.exe /c --platform:amd64  /nologo /EHsc -DWIN32_LEAN_AND_MEAN -std=c++17 -IC:\Users\matic\.nimble\pkgs\nimqt-0.1 -permissive- -Zc:__cplusplus -std:c++17 -IJ:/Qt6/6.3.1/msvc2019_64/include -IJ:/Qt6/6.3.1/msvc2019_64/include\QtWidgets -IJ:/Qt6/6.3.1/msvc2019_64/include\QtGui -IJ:/Qt6/6.3.1/msvc2019_64/include\QtCore -IJ:/Qt6/6.3.1/msvc2019_64/include\..\mkspecs\win32-msvc /Zc:strictStrings- shell32.lib -Zc:wchar_t -FS -Zc:rvalueCast -Zc:inline -Zc:throwingNew -permissive- -Zc:__cplusplus -Zc:externConstexpr -O2 -MD -utf-8 -W3 -w34100 -w34189 -w44996 -w44456 -w44457 -w44458 -wd4577 -wd4467 -EHsc -DUNICODE -D_UNICODE -DWIN32 -D_ENABLE_EXTENDED_ALIGNED_STORAGE -DWIN64 -DNDEBUG -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -IC:\Nim\lib -I..\..\Qt6\6.3.1\msvc2019_64\include -I..\..\Qt6\6.3.1\msvc2019_64\include\QtWidgets -I..\..\Qt6\6.3.1\msvc2019_64\include\QtGui -I..\..\Qt6\6.3.1\msvc2019_64\include\QtCore -I/include -I..\..\Qt6\6.3.1\msvc2019_64\mkspecs\win32-msvc /Zc:strictStrings-   /IC:\Users\matic\.choosenim\toolchains\nim-1.6.12\lib /IJ:\Nim\nimqt\ExCo2\src /nologo /FoC:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp.obj C:\Users\matic\nimcache\exco_d\@mgui@stabwidget.nim.cpp' failed with exit code: 2

stack trace: (most recent call last)
J:\Nim\nimqt\ExCo2\exco_build.nims(91, 9)
C:\Users\matic\.choosenim\toolchains\nim-1.6.12\lib\system\nimscript.nim(273, 7) exec
C:\Users\matic\.choosenim\toolchains\nim-1.6.12\lib\system\nimscript.nim(273, 7) Error: unhandled exception: FAILED: nim cpp --cc:vcc --outdir:build --mm:orc --passC:" -Zc:wchar_t -FS -Zc:rvalueCast -Zc:inline -Zc:throwingNew -permissive- -Zc:__cplusplus -Zc:externConstexpr -O2 -MD -utf-8 -W3 -w34100 -w34189 -w44996 -w44456 -w44457 -w44458 -wd4577 -wd4467 -EHsc -DUNICODE -D_UNICODE -DWIN32 -D_ENABLE_EXTENDED_ALIGNED_STORAGE -DWIN64 -DNDEBUG -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -IC:\Nim\lib -I..\..\Qt6\6.3.1\msvc2019_64\include -I..\..\Qt6\6.3.1\msvc2019_64\include\QtWidgets -I..\..\Qt6\6.3.1\msvc2019_64\include\QtGui -I..\..\Qt6\6.3.1\msvc2019_64\include\QtCore -I/include -I..\..\Qt6\6.3.1\msvc2019_64\mkspecs\win32-msvc /Zc:strictStrings-" --passL:"/link /NOLOGO /DYNAMICBASE /NXCOMPAT /OPT:REF /OPT:ICF /INCREMENTAL:NO /SUBSYSTEM:CONSOLE shell32.lib" --clib:J:\Qt6\6.3.1\msvc2019_64\lib\Qt6Widgets --clib:J:\Qt6\6.3.1\msvc2019_64\lib\Qt6Gui --clib:J:\Qt6\6.3.1\msvc2019_64\lib\Qt6Core --clib:J:\Qt6\6.3.1\msvc2019_64\lib\Qt6EntryPoint src/exco.nim [OSError]

[matkuki]

Compiling the custom_widget_main.nim example works 👍👍👍 So the problem with my CustomTabWidget has something to do with my code.

[matkuki]

Got it to compile! Had to insert the nimqt.init and nimqt.insertAllSlotImplementations into the gui/tabwidget.nim module.

[jerous86]

Nice! Good to hear it's working!

Then I think this issue can be closed, for now, until you find something else? :)

[matkuki]

Yes, thanks 😊

If you are able to, please also add some documentation about nimqt.init and nimqt.insertAllSlotImplementations somewhere, thanks.