connect problem!!! QObject::connect: Cannot queue arguments of type "myStruct" (Make sure 'myStruct' is registered using qRegisterMetaType(). )

opengpu2

mrjj

we need the actual code also :)

JohanSolo

The solution is in the error message, use this:

qRegisterMetaType<myStruct>("myStruct");

Have a look here or there.

opengpu2

so even this 'myInt' need register?
typedef int myInt;
connect(this, SIGNAL(xxx(myInt), this, SLOT(myInt)));

JohanSolo

To be honest I don't know about typedef'ed basic types. A workaround which I like to use is to send pointers instead of instances (when applicable). You don't need to register the type as long as you're using pointers in your signals / slots.

SGaist

Hi,

Yes, even for myInt. myInt is unknown to the Qt MetaObject system.

@JohanSolo beware when passing pointers especially if it's a multithreaded environment. You have to handle carefully the lifetime of your objects.

JohanSolo

@SGaist said:

@JohanSolo beware when passing pointers especially if it's a multithreaded environment. You have to handle carefully the lifetime of your objects.

Yeah, actually I've been bitten recently by this... That's why I said `(when applicable)', I should have put more emphasise on potential problems. Thank you for the warning!

opengpu2

so if i use 'myInt*' as signal and slot 's param. so i need not register, right?

SGaist

Just don't do that, it's a base type. Register it and keep your code clean.

opengpu2

This post is deleted!

opengpu2

and why Qt need register myInt? it's just simply int: typedef int myInt;

SGaist

Again: myInt is an unknown type to the Qt Meta Object system

opengpu2

@SGaist but i found that my code works fine when i use 'myStruct*', and even 'myInt' as signal&slot param.