CODEWITHSUNDEEP
c++qtqtquick2
A.J
A.J

Reputation: 348

How can I invoke a method of Qt Quick 2 Extension Plugin?

I have a Subdirs project, there are two subprojects. One is a Qt Quick Controls 2 Application, and other is a Qt Quick 2 Extension Plugin.

TestQtQuickPlugin    ( Subdirs project )
    |----app         ( Qt Quick Controls 2 Application )
    |     |------main.cpp
    |    ...
    |----plugin      ( Qt Quick 2 Extension Plugin )
    |       |----MyItem.h
    |       |----MyItem.cpp
    |      ...

MyItem class inherits from QQuickItem, and it has a method int getNum(). In main method, I will invoke this method by MyItem().getNum().

In Ubuntu, it compiles and runs successful. But in Windows, it occurs error:

main.obj : error LNK2019: unresolved external symbol "public: __cdecl MyItem::MyItem(class QQuickItem *)" (??0MyItem@@QEAA@PEAVQQuickItem@@@Z) referenced in function main

main.obj : error LNK2019: unresolved external symbol "public: virtual __cdecl MyItem::~MyItem(void)" (??1MyItem@@UEAA@XZ) referenced in function main

main.obj : error LNK2019: unresolved external symbol "public: int __cdecl MyItem::getNum(void)" (?getNum@MyItem@@QEAAHXZ) referenced in function main

What is wrong with my project?

Upvotes: 0

Views: 145

Answers (1)

Kevin Krammer
Kevin Krammer

Reputation: 5207

Windows uses "symbol hiding" when creating dynamically linked libraries.

In order for symbols to be "visible" outside such a library they need to be "exported".

See the documentation here.

This can actually also be enabled on Linux by setting a respective flag for g++.

Upvotes: 1

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