Basic question: Including headers with INCLUDEPATH doesn't work

Binary91

I know what moc files are, but they were not permanently created by QtCreator (not in my build folder).
But can you tell me why I should have to generate them and manually include them when it works to simply add the headers to the project?
I mean, I wanted to reduce work by using INCLUDEPATH and NOT adding all the included headers.
Generating moc files and manually adding them is not reducing but increasing work.

Also I do not understand why I should include them when I don't need it if I add the headers directly...

jsulm

@Binary91 Where is myudp.cpp ?

jsulm

@jsulm With some fixes I can build your project.
pro file:

QT       += core network

QT       -= gui

TARGET = test
CONFIG   += console
CONFIG   -= app_bundle

TEMPLATE = app

INCLUDES += lib/headers/myQLineEdit.h

SOURCES += main.cpp \
    #myudp.cpp

#HEADERS += \
#    myudp.h

main.cpp

#include <QCoreApplication>

int main(int argc, char *argv[])
{
  QCoreApplication applicationApp(argc, argv);
  //clsWindowMain windowMain;

  //QTimer::singleShot(0, &windowMain, SLOT(slotStart()));
  int ret = applicationApp.exec();
  return ret;
}

jsulm

@Binary91 Where I did say you have to create moc_ files manually?
They are generated for you. And they are completely unrelated to your problem!

Binary91

It's getting strange now :-D

What is a myudp.cpp ?? I didn't ever used this...

@jsulm
But you are including the header directly now. That is exaclty what I tried to avoid...

Why is main.h unusual? I think using headers as a bundle of #include directives for my purposes is the correct way, so in the source file, there only exists one #include directive to its corresponding header file. Not good?

jsulm

@Binary91 That is what you uploaded:

SOURCES += main.cpp \
    myudp.cpp

main.h is unusual because there is no need for it. You only need a header file if you need to include some functionality provided in one source code file in another one. Where do you want to include main.h and why (and please do not say in main.cpp, because there is no need to do it this way)?
I will try to change your project to use INCLUDEPATH.

jsulm

@Binary91 It builds here if I do:

QT       += core network

QT       -= gui

TARGET = test
CONFIG   += console
CONFIG   -= app_bundle

TEMPLATE = app

#INCLUDES += lib/headers/myQLineEdit.h
INCLUDEPATH += lib/headers

SOURCES += main.cpp

Binary91

I really don't know from where this "myudp.cpp" comes. Maybe a de-zipping error. That should mean "lib/sources/myQLineEdit.cpp"

Yeah this way its getting built on my computer as well, but there you manually added the header file to the project:
INCLUDES += ...
or
HEADERS +=...

That is what I try to avoid by using INCLUDEPATH. That was what the discussion is all about...

jsulm

@Binary91 Where did I add the header file manually?
I commented out the old line, please take a look again:

QT       += core network

QT       -= gui

TARGET = test
CONFIG   += console
CONFIG   -= app_bundle

TEMPLATE = app

#INCLUDES += lib/headers/myQLineEdit.h <-- this line is commented out
INCLUDEPATH += lib/headers

SOURCES += main.cpp

Binary91

but where is the myQLineEdit.cpp ?
You just added the main.cpp. The error occures in myQLineEdit.cpp, because it holds methods of myQLineEdit class in myQLineEdit.h that has a Q_OBJECT within...

jsulm

@Binary91 Your project is really broken:

QT       += core network

QT       += gui widgets

TARGET = test
CONFIG   += console
CONFIG   -= app_bundle

TEMPLATE = app

HEADERS += lib/headers/myQLineEdit.h
INCLUDEPATH += lib/headers

SOURCES += main.cpp \
    lib/sources/myQLineEdit.cpp

myQLineEdit.cpp

#include <myQLineEdit.h> // absolute path or absolute path with whitespaces also doesn't work


// ----- constructors -----

myQLineEdit::myQLineEdit(QWidget* widgetParent) : QLineEdit(widgetParent)
{
   // stuff
}

myQLineEdit::~myQLineEdit()
{

}

#include "../build-test-Desktop-Debug/moc_myQLineEdit.cpp"

Without HEADERS moc_ file is not generated and the header file is not shown in QtCreator, so you should use HEADERS.

jsulm

@jsulm said in Basic question: Including headers with INCLUDEPATH doesn't work:

#include "../build-test-Desktop-Debug/moc_myQLineEdit.cpp"

you can change it to:

#include "moc_myQLineEdit.cpp"

It builds now on my machine.

jsulm

@Buckwheat You need to include moc_ files for your own classes which are derived from QObject (directly or indirectly).

Binary91

Hi jsulm,

so you say, I need to include the headers with HEADERS in the project file. Well, then I'm asking myself what the INCLUDEPATH command is for?

mrjj

@Binary91 said in Basic question: Including headers with INCLUDEPATH doesn't work:

INCLUDEPATH
http://doc.qt.io/qt-5/qmake-variable-reference.html#includepath

Its used to specify where to look for headers.
So when it sees #include "YYYY" it will search for them there.

as shown with

INCLUDEPATH += ../../Common/CONET
../../Common/XML/pugixml-1.5/src/ \

the pugixml.h is in the src and i can just use
it like
#include "pugixml.h"

Without it I would have to do use full path to it.

That is its role and it works fine here.

You seem to expect that point to a folder with INCLUDEPATH,
implies that all should be used ?

Like all where already added to HEADERS ?

There is one issue if it did that.
For all HEADERS , it need to run moc on them so
if you use INCLUDEPATH to point to a place with many .H files
you be wasting tons of time running moc on those completely unrelated files.
Hence HEADERS tells us what files to run moc on.
Of course this could be fixed checking against which are actually seen via #include
but it's not the way it works currently. :)

Binary91

thank you mrjj, that was the explanation I was looking for!

I didn't know that with HEADERS I tell the compiler which moc files should be generated!

So all in all, I have to include those headers to my project and everything is going well.

Thank you for your help.

Kind regards,
Binary

Buckwheat

@jsulm Actually you don't. When the build system sees the Q_OBJECT, it will build and compile a MOC file for you. It will link into the application and be part of it. No inclusion is necessary. None at all. The only think you would ever include is a form generated header file (ie. ui_MainWindow.h) that will hold the form variables for you.

If doubting, watch your build on any system. You will see the CPP files compile and then the moc_*.cpp files compile and then the linker will have both on it. The MOC files tie your class to the signal/slots and meta object data all under the scenes. It is quite beautifully designed.

SGaist

If your QObject based class is in a .cpp file then you need to include the moc file at the bottom. See the unit tests form Qt for example.