Pass a class with private constructor via signal/slot

[JSher]

Hello,

I am using the library SimpleXlsx. I create a CWorkbook book; and add sheets and data to it. I then try to pass it via SIGNAL like so:

emit sendBook(book);  

SIGNAL:
void sendBook(SimpleXlsx::CWorkbook);

The problem is that I get a compiler error on the emit: 'calling a private constructor of class 'SimpleXlsx::CWorkbook'

I cannot seem to find and documentation of passing classes with private constructors via SIGNAL.

Thanks,
--James

[Bonnie]

Are you using the signal and slot in the same thread?
If yes, you can try to change param type to (const SimpleXlsx::CWorkbook &) and see if it can work.

[JSher]

@Bonnie

Unfortunately I am passing to another thread

--James

[Bonnie]

@JSher I've checked the source code of SimpleXlsx::CWorkbook.

    private:
        //Disable copy and assignment
        CWorkbook( const CWorkbook & that );
        CWorkbook & operator=( const CWorkbook & );

The copy function is disabled.
Then I don't think it is possible to send it accross threads.

With queued connections, the parameters must be of types that are known to Qt's meta-object system, because Qt needs to copy the arguments to store them in an event behind the scenes.

I think the only way to pass it through signal/slot is to use a pointer and you need to assure that the pointer can be accessed by another thread correctly.

[JSher]

@Bonnie

Ok thank you. I am in the process of just passing the data back to the UI where the Workbook can be created. I do not want to get into using pointers from threads:)

Thanks

--James