Shared Library

ReneUafasah

Hello,

I am trying to apply the shared library method of compilation as recommended here
https://doc.qt.io/qt-5/sharedlibrary.html#header-file-considerations

I follow the script in an app:

set(sources
          MyClient.cpp
          MucosClient.cpp
          MyTopic.cpp
          ${PROJECT_SOURCE_DIR}/include/MyClient.h
          ${PROJECT_SOURCE_DIR}/include/MyTopic.h
          MucosClient.h
        )

add_definitions(-DMY_CLIENT_LIBRARY)

set(linked_libraries
            PUBLIC Qt5::Core
            PUBLIC Qt5::Network
            PUBLIC ${mucos}
            PUBLIC my-api::utils
            PUBLIC my-api::persistence(


sas_add_library(my-client SOURCES ${sources} DEPENDENCIES ${linked_libraries})



#pragma once
#include <QtCore/QtGlobal>

#if defined(MY_CLIENT_LIBRARY)
#  define MY_CLIENT_EXPORT Q_DECL_EXPORT
#else
#  define MY_CLIENT_EXPORT Q_DECL_IMPORT
#endif

Despite the fact that I have properly prefixed the class in MucosClient.cpp

class MY_CLIENT_EXPORT MuscosClient final : public QObject
{
  Q_OBJECT
 public:

Linker errors (filtered, 1of 32):

MucosClient.obj:-1: error: LNK2019: unresolved external symbol __imp_mucos_lib_init referenced in 
function "public: __cdecl mb::sas::sas_common::MucosClient::MucosClient(class QString const &,unsigned short,class QString const &,bool)" 


(??0MucosClient@sas_common@sas@mb@@QEAA@AEBVQString@@G0_N@Z) [C:\.....common\my-client\my-client.vcxproj]

The LNK2019 unresolved error as we now is associated with not finding the body implementation of the class elements.
Are there any zipped "Hello World" examples using the shared library that show it working ?

kkoehne

@ReneUafasah said in Shared Library:

The LNK2019 unresolved error as we now is associated with not finding the body implementation of the class elements.

It rather looks like you are not linking the mucos library.

Your code snippet contains

${mucos}

Do you initialize the variable anywhere?

In general, there are different ways to let CMake link against a library, from find_package() calls (preferred) to hardcoding linker commands, like qmake does. See e.g. https://gitlab.kitware.com/cmake/community/-/wikis/doc/tutorials/How-To-Find-Libraries for an overview.

ReneUafasah

I guess the answer lies in working through a CMakeLists.txt equivalent of the following tutorial:

https://wiki.qt.io/How_to_create_a_library_with_Qt_and_use_it_in_an_application

ReneUafasah

@ReneUafasah

How can these PRO file contents be written in CMakeLists.txt?
TEMPLATE = app
TARGET =
DEPENDPATH += . ../testLib
INCLUDEPATH += ../testLib
LIBS += -L../testLib/debug -ltestLib
#Input
SOURCES += main.cpp

kkoehne