QFile, QDir, QXmlStreamWriter and other classes from QtCore in plain C++ project.

QLab

Hi,

It is possible to use classes from QtCore, especially QFile, QFileInfo, QDir, QXmlStreamWritter, QXmlStreamReader, QMimeDatabase, QMimeType and some other in plain c++ project without any problems?

Then i only need QtCore5.dll, i am right?

mrjj

Hi
In theory yes.
But you might need platforms plugin too.

Should be fast to test.

QLab

Ok, but what with signals and slots?

When some Qt classes from QtCore emit signal, and in my project I do not have QApplication instance, it will not be a problem?

mrjj

Yes it will. you need to supply event loop for signals to work.
http://stackoverflow.com/questions/12718296/is-there-a-way-to-use-qt-without-qapplicationexec

I think Qt::DirectConnection might work without event loop.

Can I ask why you want to use Qt and then not?
You could get nice file handling with pure c++and
xml with pugixml and have no dlls what so ever.

QLab

I prefer Qt classes for filesystem / xml because I already have some code which use this classes but in Qt project.

I can use boost for filesystem / xml ( propertytree? ), but then I also need dll but from boost so it nothing changes.

"You could get nice file handling with pure c++"
I think that this is not possible ;)

mrjj

@QLab
Ok. but why not just use it ?
and not worry if 1 or 2 dlls?
But yes, if you cut back on what class you use,
you should be able to cut some of the DLLS too.

C++ io not so bad. (IMHO) :)

        list data;
        string line;       
        ifstream myfile ("test.txt");
        if (myfile.is_open())    {
            for(line; getline(myfile, line);){
                data.push_back(line);
            }
            myfile.close();
        }

QLab

It is more complicated ;)

One example - detect mime type for file?
And many more which using Qt is simple but without Qt can take much more time.

I ask because sometimes simple task can works but later when i writed more code i can make troubles and then it will horrible.
Maybe someone know about problems using QtCore in plain c++ project. Only that ;)

I do not worry about dlls, but i do not want segfault or crash when i run my application which using some Qt classes in plain c++ project.

mrjj

@QLab
Ok. I see your point.
Well I don't think you can really get in trouble using only core.
But with no default event loop, you might get a few surprises. :)
Good luck

QLab

"But with no default event loop, you might get a few surprises"

Oh you know somethink more? ;) Please tell me ;)
I will have a trouble even if i do not connect signals?

mrjj

@QLab
HI
No No :) It's just that Qt uses signals
all over so some functions might use a signal to inform you of something or
two Qt objects might use signal internally.

But currently I made a small console project using QFile and to my surprise
it ask for no DLL when i click it, so i'm a bit ??:)

mrjj

Hi
I must do something wrong as for console app with Qfile it wants
(win 7 , mingw compiler)
icudt52.dll
icuin52.dll
icuuc52.dll
libgcc_s_dw2-1.dll
libstdc++-6.dll
libwinpthread-1.dll
Qt5Cored.dll
on a clean machine (virtual)
Not as tiny as i had hoped for :)